In order to restore a degraded alkaline grassland, the local government implemented a large restoration project using fences in Changling county, Jilin province, China, in 2000. Grazing was excluded from the protected...In order to restore a degraded alkaline grassland, the local government implemented a large restoration project using fences in Changling county, Jilin province, China, in 2000. Grazing was excluded from the protected area, whereas the grazed area was continuously grazed at 8.5 dry sheep equivalent（DSE）/hm2. In the current research, soil and plant samples were taken from grazed and fenced areas to examine changes in vegetation and soil properties in 2005, 2006 and 2008. Results showed that vegetation characteristics and soil properties improved significantly in the fenced area compared with the grazed area. In the protected area the vegetation cover, height and above- and belowground biomass increased significantly. Soil pH, electrical conductivity and bulk density decreased significantly, but soil organic carbon and total nitrogen concentration increased greatly in the protected area. By comparing the vegetation and soil characteristics with pre-degraded grassland, we found that vegetation can recover 6 years after fencing, and soil pH can be restored 8 years after fencing. However, the restoration of soil organic carbon, total nitrogen and total phosphorus concentrations needed 16, 30 and 19 years, respectively. It is recommended that the stocking rate should be reduced to 1/3 of the current carrying capacity, or that a grazing regime of 1-year of grazing followed by a 2-year rest is adopted to sustain the current status of vegetation and soil resources. However, if N fertilizer is applied, the rest period could be shortened, depending on the rate of application.展开更多
Rice(Oryza sativa L.) is one of the most important staple crops in China. Increasing atmospheric greenhouse gas concentrations and associated climate change may greatly affect rice production. We assessed the potentia...Rice(Oryza sativa L.) is one of the most important staple crops in China. Increasing atmospheric greenhouse gas concentrations and associated climate change may greatly affect rice production. We assessed the potential impacts of climate change on cold rice production in the Heilongjiang province, one of China's most important rice production regions. Data for a baseline period(1961–1990) and the period 2010–2050 in A2 and B2 scenarios were used as input to drive the rice model ORYZA2000 with and without accounting for the effects of increasing atmospheric CO2 concentration. The results indicate that mean,maximum, and minimum temperature during the rice growing season, in the future period considered, would increase by 1.8 °C under the A2 scenario and by 2.2 °C under the B2 scenario compared with those in the baseline. The rate of change in average maximum and minimum temperatures would increase by 0.6 °C per 10-year period under the A2 scenario and by 0.4 °C per 10-year period under the B2 scenario. Precipitation would increase slightly in the rice growing season over the next 40 years. The rice growing season would be shortened and the yield would increase in most areas in the Heilongjiang province. Without accounting for CO2 effect, the rice growing season in the period 2010–2050 would be shortened by 4.7 and 5.8 days,and rice yields would increase by 11.9% and 7.9%, under the A2 and B2 scenarios, respectively.Areas with simulated rice yield increases greater than 30.0% were in the Xiaoxing'an Mountain region. The simulation indicated a decrease in yield of less than 15% in the southwestern Songnen Plain. The rate of change in simulated rice yield was 5.0% and 2.5% per 10 years under the A2 and B2 scenarios, respectively. When CO2 effect was accounted for, rice yield increased by 44.5% and 31.3% under the A2 and B2 scenarios, respectively. The areas of increasing yield were sharply expanded. The area of decreasing yield in the western region of Songnen Plains disappeared when increasing CO2 concentration was considered. The stability of rice yield would increase from 2010 to 2050. Overall, the simulation indicates that rice production will be affected positively by climate change in the next 40 years in the Heilongjiang province, China.展开更多
Conservation agriculture has been practised for three decades and has been spread widely. There are many nomenclatures surrounding conservation agriculture and differ to each other lightly. Conservation agriculture ...Conservation agriculture has been practised for three decades and has been spread widely. There are many nomenclatures surrounding conservation agriculture and differ to each other lightly. Conservation agriculture （CA） is a system approach to soil and water conservation, high crop productivity and profitability, in one word, it is a system approach to sustainable agriculture. Yet, because conservation agriculture is a knowledge-intensive and a complex system to learn and implement, and also because of traditions of intensive cultivation, adoption rates have been low, since to date, only about seven percent of the world＇s arable and permanent cropland area is farmed under conservation agriculture. The practice and wider extention of conservation agriculture thus requires a deeper understanding of its ecological underpinnings in order to manage its various elements for sustainable intensification, where the aim is to conserve soil and water and improve sustainability over the long term. This paper described terms related to conservation agriculture, presented the effects of conservation agriculture on soil and water conservation, crop productivity, progress and adoption of CA worldwide, emphasized obstacles and possible ways to increase CA adoption to accelerate sustainable development of China agriculture.展开更多
A simulated grazing field experiment was conducted to determine the effect of timing and intensity of grazing on the growth and yield of a mid-late maturing spring wheat(cv. Flanker) under different watering regimes, ...A simulated grazing field experiment was conducted to determine the effect of timing and intensity of grazing on the growth and yield of a mid-late maturing spring wheat(cv. Flanker) under different watering regimes, at Wagga Wagga in southeastern Australia. The experiment was a factorial design of watering regime and pasture "grazing" as factors, with three replications. The two watering regimes were rainfed(R) and supplemental irrigation(I). There were four simulated grazing treatments: no grazing, "crash" grazing by mowing to 5 cm height on 13 June(Cut1-5), "crash" grazing by mowing to 5 cm on 15 July(Cut2-5) and "clip" grazing by mowing to 15 cm height on 15 July(Cut2-15). The lowest dry matter(simulated grazing) was obtained from RCut1-5(0.13 t ha^(–1)) and the highest(0.86 t ha^(–1)) was from ICut2-5. There was no significant difference(P<0.05) among the grain yields of the grazing treatments in the respective watering regimes. However, there was significant difference(P<0.05) between the grain yields of the rainfed(3.60 t ha^(–1)) and irrigated(6.0 t ha^(–1)) treatments. Under both watering regimes, the highest grain yield was obtained from the late "clip" grazings: 3.79 t ha^(–1)(RCut2-15) for rainfed and 6.47 t ha^(–1)(ICut2-15) for irrigated treatments. The lowest grain yield for the rainfed treatment was 3.26 t ha^(–1)(RCut1-5) and for the irrigated treatments, the lowest grain yield was 5.50 t ha^(–1)(ICut2-5). Harvest index(HI) was not significantly affected(P>0.05) by either the watering regime or grazing. Seed weight was significantly(P<0.05) affected both by the watering regime and grazing with the lowest value for 1 000-seed weight of 30.05 g(RCut2-5) and the highest value of 38.00 g(ICut2-15). Water use efficiency was significantly(P<0.05) affected both by the watering regime and grazing with the lowest value of 9.94 kg ha^(–1) mm^(–1)(ICut2-5) and the highest value 13.43 kg ha^(–1) mm^(–1)(RCut2-5). By "crash" grazing late(just before stem elongation stage) to a height of 5 cm, a significantly higher(P<0.05) above ground dry matter can be grazed without significantly affecting the yield both in seasons with low amount of rainfall and high amount of rainfall(irrigated in this study) although in a wet season a slightly lower(15% lower) grain yield is obtained relative to "clip grazing" to 15 cm height. Grazing of mid-late maturing wheat cultivars has the potential to fill the feed gap without significantly affecting grain yield.展开更多
Phosphorus (P) is necessary for growth and nitrogen fixation, and thus its deficiency is a major factor limiting legume production in most agricultural soils. The effect of phosphorus supply on nodule development and ...Phosphorus (P) is necessary for growth and nitrogen fixation, and thus its deficiency is a major factor limiting legume production in most agricultural soils. The effect of phosphorus supply on nodule development and its role in soybeans (Glycine max L.) was studied in a nutrient solution. Plants were inoculated with Bradyrhizobium japonicum and grown for 35 days in a glasshouse at a day and night temperature of 25℃and 15℃, respectively. Although increasing P supply increased the concentrations of P and N in the shoots and roots, the external P supply did not significantly affect the P concentration in the nodules, and the N fixed per unit nodule biomass decreased with increasing P supply. The nitrogen content in the shoots correlated well with the P content (r = 0.92**). At an inoculation level of 102 cells mL-1, the P supply did not affect the number of nodules; however, at inoculation levels of 103.5 and 105 cells mL-1, increasing P supply increased both the number and size of nodules. Irrespective of the inoculation level, increasing P supply increased the nodule biomass relative to the biomass of the host plant. It is suggested that the P deficiency specifically inhibited the nodule development and thereby the total N2 fixation.展开更多
PCR-based genic and microarray-based Diversity Arrays Technology (DArTTM) markers were used to determine genetic diversity in 94 accessions of white lupin (Lupinus albus L.) comprising Australian and foreign cultivars...PCR-based genic and microarray-based Diversity Arrays Technology (DArTTM) markers were used to determine genetic diversity in 94 accessions of white lupin (Lupinus albus L.) comprising Australian and foreign cultivars, landraces, and advanced breeding lines from Australian breeding programs. A total of 345 (50 PCR-based and 295 DArT-based) polymorphic fragments were identified, which were used to determine the genetic diversity among accessions. Both cluster analysis of bivariate marker data using UPGMA, and principal coordinate analysis, indicated a high level of genetic diversity in the germplasm. Our results showed that both types of markers used in this study are suitable for estimation of genetic diversity. Landrace accessions from Ethiopia formed a very distinct and separate grouping with both marker systems. Australian cultivars and breeding lines were clustered together and tended to be distinct from European landraces. These findings will allow breeders to select appropriate, diverse parents to broaden the genetic base of white lupin breeding populations.展开更多
L. albus is an annual grain-legume crop mainly grown for high-protein fodder worldwide but also to produce large seeds for human consumption as a snack-food. In order to make genetic gains in grain yield, assessment o...L. albus is an annual grain-legume crop mainly grown for high-protein fodder worldwide but also to produce large seeds for human consumption as a snack-food. In order to make genetic gains in grain yield, assessment of the genetic variation in the germplasm and identification of loci associated with agronomic traits are essential. Phomopsis blight (PB) and Pleiochaeta root rot (PRR), caused by the fungal pathogens Diaporthe toxica and, Pleiochaeta setosa respectively, are two major yield-limiting diseases of the L. albus crop. The extent of genetic diversity in 94 accessions of L. albus comprising: Australian and exotic cultivars, advanced breeding lines, and landraces originating from 26 different countries was determined utilizing PCR-based genic, and microarray-based Diversity Arrays Technology (DArT™), markers. All accessions were evaluated for resistance to PB in two plant tissues (leaves and stems) using either sprayed or injected spore inoculum. A subset of 58 accessions was further evaluated for resistance to PRR by growing seedlings in spore-infested potting mix. The combined data of 724 (50 genic- and 674 DArT) markers were used for cluster analysis. A subset of 324 markers with call rate ≥95% and predicted disease scores of different genotypes were used to identify marker loci accounting for phenotypic variation in PB and PRR resistance using linear regression analysis. Several markers showed significant association with PB or PRR resistance at P < 0.05. Our results showed that favourable alleles for PB and PRR resistance are present in the diverse accessions investigated and they will provide valuable materials for lupin breeding.展开更多
Many of the important questions facing farming systems in the world today require long-term studies to provide meaningful information and answers. A long-term agronomic experiment (LTAE) should (1) have long-term obje...Many of the important questions facing farming systems in the world today require long-term studies to provide meaningful information and answers. A long-term agronomic experiment (LTAE) should (1) have long-term objectives; (2) study important soil processes or ecological processes; and (3) be related to the productivity and sustainability of systems. A well established LTAE can provide both insights into how the system operates and foresight into where the system goes. The prerequisites for setting up a LTAE are the secured land, continuous funding and dedicated scientists. A number of principles must be considered carefully when establishing a LTAE, (1) the site must be representative of large areas; (2) the treatments should be simple, but focusing on the big questions; (3) the plots should be large enough to allow subsequent modification of the experiment if this becomes necessary; (4) crop rotations should minimise, wherever possible, the risk of build-up of pests and diseases, and rotational phase should be considered in a rotational experiment; (5) a clearly defined experimental protocol should be developed to ensure data collected is scientifically valid and statistically analysable, but with flexibility to allow essential changes; (6) soil samples, possibly plant samples, should be achieved to provide better answer to the original questions when new, perhaps more accurate analytical techniques are developed, or answer new research questions that were not considered in the original design. The MASTER experiment in Australia was used as a case study to demonstrate how these principles are implemented in practice.展开更多
This study investigated the effect of a computer assisted learning (CAL) tool on the development of skills in palpation of the reproductive tract of the cow per rectum (rectal palpation) by fourth-year students in a B...This study investigated the effect of a computer assisted learning (CAL) tool on the development of skills in palpation of the reproductive tract of the cow per rectum (rectal palpation) by fourth-year students in a Bachelor of Veterinary Science (BVSc) degree program. A secondary aim was to determine if animal welfare could be improved by the CAL intervention. The CAL tool was developed to provide: vivid, three-dimensional interactive graphics of the relevant anatomy and skills;a comprehensive glossary of terminology used in association with the skills;and formative assessment tasks. Prior to its introduction to the course, industry stakeholders assessed the CAL tool graphics as an accurate depiction of the procedures. Two consecutive cohorts of students were surveyed prior to (n = 91) and after the CAL intervention (n = 111). Responses to student surveys suggested that post-intervention skills were learned at approximately the same rate as pre-intervention. However, tutor surveys indicated that students in the pre-intervention group may have had insufficient understanding for accurate self-assessment compared to post-intervention students. According to tutors, substantially more students in the post-intervention group gained practical skills at an improved rate and to a higher level of competency. Both student and tutor surveys indicated that there was a minimal discomfort to animals in these practical classes. From an animal welfare point-of-view, it was concluded that the intervention would not result in a reduction in the number of animals required during practical sessions. However, due to the preparation and reinforcement provided by the CAL tool, animals were used more efficiently by students after the intervention, resulting in the attainment of a higher level of skill. Knowledge gained from this study may be relevant to other disciplines requiring students to develop practical skills associated with animals or humans.展开更多
Weeds are a major constraint in canola (<i>Brassica napus</i> L.) production worldwide, as they cause significant reductions in seed yield and quality. Crop interference is one of the approaches to tackle ...Weeds are a major constraint in canola (<i>Brassica napus</i> L.) production worldwide, as they cause significant reductions in seed yield and quality. Crop interference is one of the approaches to tackle weed infestation along with other agronomic interventions. In Australia, studies have shown genetic variation in the canola capability to suppress annual ryegrass (<i>Lolium rigidum</i> Gaudin) in the field and under in vitro conditions. Early-season crop biomass accumulation and greater plant height are desired attributes for suppression weeds in canola. However, the canola ideotype for interference traits against this weed has not been studied under glasshouse conditions. In this study, we compared the competitive ability of 26 canola genotypes against annual ryegrass under both glasshouse and field conditions. Five canola genotypes consistently showed the ability to suppress growth of annual ryegrass. Both at glasshouse and field conditions, the shoot biomass, largely contributed by leaf biomass, was significantly associated with suppression ability. Our results suggest that a glasshouse-based evaluation approach can be used to determine the suppressive ability of advanced breeding lines for suppression of ryegrass growth. Based on our analysis, we suggest that initial screening of large collections of germplasm can be conducted under glasshouse conditions, with selected genotypes further evaluated in the field.展开更多
Trifolium alexandrinum, an important forage legume, suffers from narrow genetic base. The present investigation was envisaged to reveal the inter- and intra-species genetic diversity and lineage among 64 accessions, r...Trifolium alexandrinum, an important forage legume, suffers from narrow genetic base. The present investigation was envisaged to reveal the inter- and intra-species genetic diversity and lineage among 64 accessions, representing a global collection, of T. alexandrinum;it’s two probable progenitor species (T. salmoneum and T. subterraneum) and the three genetically distant species (T. repens, T. vesiculosum, T. michelianum). A set of Simple Sequence Repeats (SSR) primer-pairs developed from T. alexandrinum have shown to amplify alleles across the species under study, suggesting utility of the newly developed resource for assessing molecular diversity among Trifolium species. These SSRs markers together with previously reported SSRs, derived from T. repens, enabled to reveal high intra-species polymorphism in T. alexandrinum and successfully discriminate different species investigated in this study. The diverse accessions determined herein provide a superior resource for further breeding of T. alexandrinum. High allelic similarity of T. alexandrinum with T. subterraneum and T. salmoneum indicated close relatedness among the species, suggesting polyphyletic evolution of T. alexandrinum.展开更多
Twelve Australian grown faba bean genotypes with seed colour ranging from white, different shades of buff/beige, green, red and purple, were extracted using 80% methanol (v/v) or 70% acetone (v/v). The findings showed...Twelve Australian grown faba bean genotypes with seed colour ranging from white, different shades of buff/beige, green, red and purple, were extracted using 80% methanol (v/v) or 70% acetone (v/v). The findings showed that commonly consumed buff-coloured genotypes have comparable phenolic contents and antioxidant activities to those with exotic seed coat colour (red, green and purple). In general, the extraction yield for methanol and acetone extracts of faba bean genotypes were similar. However, the acetone extracts of faba bean varieties with coloured seed coats exhibited higher antioxidant activities than their methanol extracts counterparts. Phenolic compounds and antioxidant activities of the genotypes were compared in an array of chemical-based assays and profiled using an on-line high-performance liquid chromatography-post column derivatization (HPLC-PCD) system. The total phenolic content (TPC) and total flavonoid content (TFC) of acetone extracts were approximately twice those of methanol extracts. The acetone extracts contained six times higher levels of di(phenyl)-(2,4,6-trinitrophenyl) imi- noazanium radical scavenging activity (DPPH), six times higher Total Equivalent Antioxidant Capacity (TEAC) and two times higher Ferric Reducing Antioxidant Power (FRAP) than those of methanol extracts. In general, the methanol extracts of white-coloured faba bean genotype exhibited comparable phenolic contents and antioxidant activities to varieties with coloured seed coats. However, the TPC, TFC, DPPH, TEAC and FRAP of acetone extracts from white-coloured genotype were 2 - 4, 1 - 2, 5 - 9, 2 - 3 and 1 - 2 times lower than those of faba bean varieties with coloured seed coats. HPLC-PCD analyses showed substantial antioxidant responses, represented as a dense “hump” of peaks in the HPLC chromatograms of acetone extracts from coloured-genotypes. This “hump” was not detected in the chromatograms of white-genotype acetone extracts, or in chromatograms of methanol extracts regardless of genotype or seed coat colour. All coloured-beans had higher phenolic contents and antioxidant activities than the white-genotype. Hydroxybenzoic acids/flavanols, hydroxycinnamic acids and flavonols were dominant in coloured beans. The findings suggest potentials in selecting commonly consumed buff-coloured faba bean genotypes within the breeding programs for enhanced levels of phenolic compounds and antioxidant activities, potentially increasing their health-promoting properties. And, there might also be potentials in developing faba bean extracts for pharmaceutical or natural medicines.展开更多
Sowing time of wheat in south eastern Australia varies from autumn to early winter, depending on the seasonal ＇break＇. Wheat yields are often reduced by frost damage at flowering time and by heat-and/or water-stress...Sowing time of wheat in south eastern Australia varies from autumn to early winter, depending on the seasonal ＇break＇. Wheat yields are often reduced by frost damage at flowering time and by heat-and/or water-stress during grain filling. Selecting suitable varieties for specific sowing times is a complex decision farmers make because these varietal phenology and climate risks have to be assessed together. In order to help farmers make decisions, they need tools that simulate and analyse agronomically-suitable sowing dates （ASSD） for a given variety of wheat. The hypothesis underlining this study is the integration of a wheat phenology model with historical climate data is an effective approach to modelling the ASSD of current varieties used in the wheat growing areas of Southern NSW. The parameters of the wheat phenology model were based on data from five years of field experimentation across 15 sites. Data from four sites were used to examine varietal suitability in relation to sowing time and its associated risks of frost and heat damage. The optimum ASSD for any variety at 72 locations across Southern NSW was investigated. The results showed that there were substantial spatial variations in the ASSD across the target region. ASSD for a late maturing wheat genotype （EGA Gregory） can range from early March to late April, while the earliest acceptable sowing date for an early maturing spring wheat genotype （H46） can range from early to late May. The wide range of spatial variation in the earliest and latest sowing dates, as well as the varied length of sowing opportunities, highlighted the importance of being able to apply a modelling approach which can integrate information on crop phenology with climate risk for a given location. This approach would allow better decision-making on suitable varieties and sowing dates in order to minimise the risk of frost and heat damage affecting crop yield.展开更多
Reduction in vegetation cover caused by human activities has a great impact on soil temperature. It is important to assess how soil temperature responds to reduction of vegetation height and density. In this paper we ...Reduction in vegetation cover caused by human activities has a great impact on soil temperature. It is important to assess how soil temperature responds to reduction of vegetation height and density. In this paper we first report the trends of mean annual soil surface and air temperatures recorded at the meteorological stations near the Ecological Research Station for Grassland Farming (ERSGF) from 1961 to 2007, then we setup an experiment using reed (Phragmites australis) stalks with different heights and densities to simulate effects of different vegetation height and density on soil and air temperatures. The warming rates of the mean annual soil and air temperatures were 0.043 and 0.041C a 1 , respectively. Changes of soil temperature were characterized by both increased mean annual maximum and minimum soil temperatures. At the experimental site, mean daily temperature, mean daily maximum soil and air temperatures increased significantly. In contrast, mean daily minimum soil temperature increased significantly while mean daily minimum air temperature decreased significantly as the height and density of reed stalks reduced during the experimental period. Mean diurnal soil temperature ranges were smaller than mean diurnal air temperature ranges. These results highlight that the importance of vegetation cover on soil and air temperatures.展开更多
Reduction of noncrop habitats, intensive use of pesticides and high levels of disturbance associated with intensive crop production simplify the farming landscape and bring about a sharp decline of biodiversity. This,...Reduction of noncrop habitats, intensive use of pesticides and high levels of disturbance associated with intensive crop production simplify the farming landscape and bring about a sharp decline of biodiversity. This, in turn, weakens the biological control ecosystem service provided by arthropod natural enemies. Strategic use of flowering plants to enhance plant biodiversity in a well-targeted manner can provide natural enemies with food sources and shelter to improve biological control and reduce dependence on chemical pesticides. This article reviews the nutritional value of various types of plant-derived food for natural enemies, possible adverse effects on pest management, and the practical application of flowering plants in orchards, vegetables and field crops, agricultural systems where most research has taken place. Prospects for more effective use of flowering plants to maximize biological control of insect pests in agroecosystem are good but depend up on selection of optimal plant species based on information on the ecological mechanisms by which natural enemies are selectively favored over pest species.展开更多
Salinity is a major soil contamination problem in Australia. To explore salinity remediation, we evaluated the concentrations of sodium （Na）, potassium （K）, magnesium （Mg）, and calcium （Ca） in roots and shoots...Salinity is a major soil contamination problem in Australia. To explore salinity remediation, we evaluated the concentrations of sodium （Na）, potassium （K）, magnesium （Mg）, and calcium （Ca） in roots and shoots and in the supporting soil of the naturally occurring grasses, Cynodon dactylon and Thinopyrurn ponticum, at two salt-affected sites, Gumble and Cundumbul in central-western New South Wales, Australia. The physiological parameters of the two grass species, including net photosynthetic rate （Pn）, stomatal conductance （gs）, and intercellular CO2 concentration （Ci）, were investigated using one mature leaf from C. dactylon and T. ponticum populations. Increasing salinity levels in the topsoil had a significant influence on Ci and gs, whereas no significant effect occurred on Pn in C. dactylon and T. ponticum. The Pn values in C. dactylon and T. ponticum were greater at Cundumbul than at Gumble. The greater Mg concentration facilitated greater Pn in C. dactylon and T. ponticum populations at Cundumbul than Gumble. With increasing salinity levels in the soil, Na accumulation increased in C. dactylon and T. ponticum. The ratio between K and Na was ~ 1 in roots and shoots of both populations irrespective of the sites. Bioaccumulation factor （BF） and translocation factor （TF） results revealed that K and Na translocations were significantly higher in T. ponticum than in C. dactylon, whereas Ca and Mg translocations were significantly higher in C. dactylon than in T. ponticum. Accumulation of Na, K, Mg, and Ca ions was higher in T. ponticum than in C. dactylon; therefore, we suggest that T. ponticum as a greater salt accumulator than C. dactylon could be used for revegetation and phytoremediation of the salt-affected soils.展开更多
基金supported by the National Key Basic Research Program of China (2011CB403203)the Strategic Science and Technology Guide Project of Chinese Academy of Sciences (XDA05050401)
文摘In order to restore a degraded alkaline grassland, the local government implemented a large restoration project using fences in Changling county, Jilin province, China, in 2000. Grazing was excluded from the protected area, whereas the grazed area was continuously grazed at 8.5 dry sheep equivalent（DSE）/hm2. In the current research, soil and plant samples were taken from grazed and fenced areas to examine changes in vegetation and soil properties in 2005, 2006 and 2008. Results showed that vegetation characteristics and soil properties improved significantly in the fenced area compared with the grazed area. In the protected area the vegetation cover, height and above- and belowground biomass increased significantly. Soil pH, electrical conductivity and bulk density decreased significantly, but soil organic carbon and total nitrogen concentration increased greatly in the protected area. By comparing the vegetation and soil characteristics with pre-degraded grassland, we found that vegetation can recover 6 years after fencing, and soil pH can be restored 8 years after fencing. However, the restoration of soil organic carbon, total nitrogen and total phosphorus concentrations needed 16, 30 and 19 years, respectively. It is recommended that the stocking rate should be reduced to 1/3 of the current carrying capacity, or that a grazing regime of 1-year of grazing followed by a 2-year rest is adopted to sustain the current status of vegetation and soil resources. However, if N fertilizer is applied, the rest period could be shortened, depending on the rate of application.
基金supported by the National Natural Science Foundation of China (30771249)the National Key Technology R&D Program of China (2012BAD20B04)
文摘Rice(Oryza sativa L.) is one of the most important staple crops in China. Increasing atmospheric greenhouse gas concentrations and associated climate change may greatly affect rice production. We assessed the potential impacts of climate change on cold rice production in the Heilongjiang province, one of China's most important rice production regions. Data for a baseline period(1961–1990) and the period 2010–2050 in A2 and B2 scenarios were used as input to drive the rice model ORYZA2000 with and without accounting for the effects of increasing atmospheric CO2 concentration. The results indicate that mean,maximum, and minimum temperature during the rice growing season, in the future period considered, would increase by 1.8 °C under the A2 scenario and by 2.2 °C under the B2 scenario compared with those in the baseline. The rate of change in average maximum and minimum temperatures would increase by 0.6 °C per 10-year period under the A2 scenario and by 0.4 °C per 10-year period under the B2 scenario. Precipitation would increase slightly in the rice growing season over the next 40 years. The rice growing season would be shortened and the yield would increase in most areas in the Heilongjiang province. Without accounting for CO2 effect, the rice growing season in the period 2010–2050 would be shortened by 4.7 and 5.8 days,and rice yields would increase by 11.9% and 7.9%, under the A2 and B2 scenarios, respectively.Areas with simulated rice yield increases greater than 30.0% were in the Xiaoxing'an Mountain region. The simulation indicated a decrease in yield of less than 15% in the southwestern Songnen Plain. The rate of change in simulated rice yield was 5.0% and 2.5% per 10 years under the A2 and B2 scenarios, respectively. When CO2 effect was accounted for, rice yield increased by 44.5% and 31.3% under the A2 and B2 scenarios, respectively. The areas of increasing yield were sharply expanded. The area of decreasing yield in the western region of Songnen Plains disappeared when increasing CO2 concentration was considered. The stability of rice yield would increase from 2010 to 2050. Overall, the simulation indicates that rice production will be affected positively by climate change in the next 40 years in the Heilongjiang province, China.
基金supported by the National Natural Science Foundation of China (40771132)the Key Technologies R&D Program of China during the 11th Five-Year Plan period (2006BAD15B06)+3 种基金the Australian Center for International Agricultural Research (CIM-1999-094)the Education Department of Gansu Province, China (0802-07)the Research Fund for the Doctoral Program of Higher Education of China (20106202120004)the Gansu Provincial Key Laboratory of Aridland Crop Science
文摘Conservation agriculture has been practised for three decades and has been spread widely. There are many nomenclatures surrounding conservation agriculture and differ to each other lightly. Conservation agriculture （CA） is a system approach to soil and water conservation, high crop productivity and profitability, in one word, it is a system approach to sustainable agriculture. Yet, because conservation agriculture is a knowledge-intensive and a complex system to learn and implement, and also because of traditions of intensive cultivation, adoption rates have been low, since to date, only about seven percent of the world＇s arable and permanent cropland area is farmed under conservation agriculture. The practice and wider extention of conservation agriculture thus requires a deeper understanding of its ecological underpinnings in order to manage its various elements for sustainable intensification, where the aim is to conserve soil and water and improve sustainability over the long term. This paper described terms related to conservation agriculture, presented the effects of conservation agriculture on soil and water conservation, crop productivity, progress and adoption of CA worldwide, emphasized obstacles and possible ways to increase CA adoption to accelerate sustainable development of China agriculture.
基金supported by the Graham Centre for Agricultural Innovation,Australia
文摘A simulated grazing field experiment was conducted to determine the effect of timing and intensity of grazing on the growth and yield of a mid-late maturing spring wheat(cv. Flanker) under different watering regimes, at Wagga Wagga in southeastern Australia. The experiment was a factorial design of watering regime and pasture "grazing" as factors, with three replications. The two watering regimes were rainfed(R) and supplemental irrigation(I). There were four simulated grazing treatments: no grazing, "crash" grazing by mowing to 5 cm height on 13 June(Cut1-5), "crash" grazing by mowing to 5 cm on 15 July(Cut2-5) and "clip" grazing by mowing to 15 cm height on 15 July(Cut2-15). The lowest dry matter(simulated grazing) was obtained from RCut1-5(0.13 t ha^(–1)) and the highest(0.86 t ha^(–1)) was from ICut2-5. There was no significant difference(P<0.05) among the grain yields of the grazing treatments in the respective watering regimes. However, there was significant difference(P<0.05) between the grain yields of the rainfed(3.60 t ha^(–1)) and irrigated(6.0 t ha^(–1)) treatments. Under both watering regimes, the highest grain yield was obtained from the late "clip" grazings: 3.79 t ha^(–1)(RCut2-15) for rainfed and 6.47 t ha^(–1)(ICut2-15) for irrigated treatments. The lowest grain yield for the rainfed treatment was 3.26 t ha^(–1)(RCut1-5) and for the irrigated treatments, the lowest grain yield was 5.50 t ha^(–1)(ICut2-5). Harvest index(HI) was not significantly affected(P>0.05) by either the watering regime or grazing. Seed weight was significantly(P<0.05) affected both by the watering regime and grazing with the lowest value for 1 000-seed weight of 30.05 g(RCut2-5) and the highest value of 38.00 g(ICut2-15). Water use efficiency was significantly(P<0.05) affected both by the watering regime and grazing with the lowest value of 9.94 kg ha^(–1) mm^(–1)(ICut2-5) and the highest value 13.43 kg ha^(–1) mm^(–1)(RCut2-5). By "crash" grazing late(just before stem elongation stage) to a height of 5 cm, a significantly higher(P<0.05) above ground dry matter can be grazed without significantly affecting the yield both in seasons with low amount of rainfall and high amount of rainfall(irrigated in this study) although in a wet season a slightly lower(15% lower) grain yield is obtained relative to "clip grazing" to 15 cm height. Grazing of mid-late maturing wheat cultivars has the potential to fill the feed gap without significantly affecting grain yield.
基金Project supported by the National Basic Research Program of China (Nos. 2005CB121101 and 2003CCB001)the Basic Research Program of Heilongjiang Province (Nos. GB05C201-01 and CC055303)the Field Station Foundation of the Chinese Academy of Sciences.
文摘Phosphorus (P) is necessary for growth and nitrogen fixation, and thus its deficiency is a major factor limiting legume production in most agricultural soils. The effect of phosphorus supply on nodule development and its role in soybeans (Glycine max L.) was studied in a nutrient solution. Plants were inoculated with Bradyrhizobium japonicum and grown for 35 days in a glasshouse at a day and night temperature of 25℃and 15℃, respectively. Although increasing P supply increased the concentrations of P and N in the shoots and roots, the external P supply did not significantly affect the P concentration in the nodules, and the N fixed per unit nodule biomass decreased with increasing P supply. The nitrogen content in the shoots correlated well with the P content (r = 0.92**). At an inoculation level of 102 cells mL-1, the P supply did not affect the number of nodules; however, at inoculation levels of 103.5 and 105 cells mL-1, increasing P supply increased both the number and size of nodules. Irrespective of the inoculation level, increasing P supply increased the nodule biomass relative to the biomass of the host plant. It is suggested that the P deficiency specifically inhibited the nodule development and thereby the total N2 fixation.
文摘PCR-based genic and microarray-based Diversity Arrays Technology (DArTTM) markers were used to determine genetic diversity in 94 accessions of white lupin (Lupinus albus L.) comprising Australian and foreign cultivars, landraces, and advanced breeding lines from Australian breeding programs. A total of 345 (50 PCR-based and 295 DArT-based) polymorphic fragments were identified, which were used to determine the genetic diversity among accessions. Both cluster analysis of bivariate marker data using UPGMA, and principal coordinate analysis, indicated a high level of genetic diversity in the germplasm. Our results showed that both types of markers used in this study are suitable for estimation of genetic diversity. Landrace accessions from Ethiopia formed a very distinct and separate grouping with both marker systems. Australian cultivars and breeding lines were clustered together and tended to be distinct from European landraces. These findings will allow breeders to select appropriate, diverse parents to broaden the genetic base of white lupin breeding populations.
文摘L. albus is an annual grain-legume crop mainly grown for high-protein fodder worldwide but also to produce large seeds for human consumption as a snack-food. In order to make genetic gains in grain yield, assessment of the genetic variation in the germplasm and identification of loci associated with agronomic traits are essential. Phomopsis blight (PB) and Pleiochaeta root rot (PRR), caused by the fungal pathogens Diaporthe toxica and, Pleiochaeta setosa respectively, are two major yield-limiting diseases of the L. albus crop. The extent of genetic diversity in 94 accessions of L. albus comprising: Australian and exotic cultivars, advanced breeding lines, and landraces originating from 26 different countries was determined utilizing PCR-based genic, and microarray-based Diversity Arrays Technology (DArT™), markers. All accessions were evaluated for resistance to PB in two plant tissues (leaves and stems) using either sprayed or injected spore inoculum. A subset of 58 accessions was further evaluated for resistance to PRR by growing seedlings in spore-infested potting mix. The combined data of 724 (50 genic- and 674 DArT) markers were used for cluster analysis. A subset of 324 markers with call rate ≥95% and predicted disease scores of different genotypes were used to identify marker loci accounting for phenotypic variation in PB and PRR resistance using linear regression analysis. Several markers showed significant association with PB or PRR resistance at P < 0.05. Our results showed that favourable alleles for PB and PRR resistance are present in the diverse accessions investigated and they will provide valuable materials for lupin breeding.
基金supported by the CAS/SAFEA International Partnership Program for Creative Research Teams (CXTD-Z2005-2-4)
文摘Many of the important questions facing farming systems in the world today require long-term studies to provide meaningful information and answers. A long-term agronomic experiment (LTAE) should (1) have long-term objectives; (2) study important soil processes or ecological processes; and (3) be related to the productivity and sustainability of systems. A well established LTAE can provide both insights into how the system operates and foresight into where the system goes. The prerequisites for setting up a LTAE are the secured land, continuous funding and dedicated scientists. A number of principles must be considered carefully when establishing a LTAE, (1) the site must be representative of large areas; (2) the treatments should be simple, but focusing on the big questions; (3) the plots should be large enough to allow subsequent modification of the experiment if this becomes necessary; (4) crop rotations should minimise, wherever possible, the risk of build-up of pests and diseases, and rotational phase should be considered in a rotational experiment; (5) a clearly defined experimental protocol should be developed to ensure data collected is scientifically valid and statistically analysable, but with flexibility to allow essential changes; (6) soil samples, possibly plant samples, should be achieved to provide better answer to the original questions when new, perhaps more accurate analytical techniques are developed, or answer new research questions that were not considered in the original design. The MASTER experiment in Australia was used as a case study to demonstrate how these principles are implemented in practice.
文摘This study investigated the effect of a computer assisted learning (CAL) tool on the development of skills in palpation of the reproductive tract of the cow per rectum (rectal palpation) by fourth-year students in a Bachelor of Veterinary Science (BVSc) degree program. A secondary aim was to determine if animal welfare could be improved by the CAL intervention. The CAL tool was developed to provide: vivid, three-dimensional interactive graphics of the relevant anatomy and skills;a comprehensive glossary of terminology used in association with the skills;and formative assessment tasks. Prior to its introduction to the course, industry stakeholders assessed the CAL tool graphics as an accurate depiction of the procedures. Two consecutive cohorts of students were surveyed prior to (n = 91) and after the CAL intervention (n = 111). Responses to student surveys suggested that post-intervention skills were learned at approximately the same rate as pre-intervention. However, tutor surveys indicated that students in the pre-intervention group may have had insufficient understanding for accurate self-assessment compared to post-intervention students. According to tutors, substantially more students in the post-intervention group gained practical skills at an improved rate and to a higher level of competency. Both student and tutor surveys indicated that there was a minimal discomfort to animals in these practical classes. From an animal welfare point-of-view, it was concluded that the intervention would not result in a reduction in the number of animals required during practical sessions. However, due to the preparation and reinforcement provided by the CAL tool, animals were used more efficiently by students after the intervention, resulting in the attainment of a higher level of skill. Knowledge gained from this study may be relevant to other disciplines requiring students to develop practical skills associated with animals or humans.
文摘Weeds are a major constraint in canola (<i>Brassica napus</i> L.) production worldwide, as they cause significant reductions in seed yield and quality. Crop interference is one of the approaches to tackle weed infestation along with other agronomic interventions. In Australia, studies have shown genetic variation in the canola capability to suppress annual ryegrass (<i>Lolium rigidum</i> Gaudin) in the field and under in vitro conditions. Early-season crop biomass accumulation and greater plant height are desired attributes for suppression weeds in canola. However, the canola ideotype for interference traits against this weed has not been studied under glasshouse conditions. In this study, we compared the competitive ability of 26 canola genotypes against annual ryegrass under both glasshouse and field conditions. Five canola genotypes consistently showed the ability to suppress growth of annual ryegrass. Both at glasshouse and field conditions, the shoot biomass, largely contributed by leaf biomass, was significantly associated with suppression ability. Our results suggest that a glasshouse-based evaluation approach can be used to determine the suppressive ability of advanced breeding lines for suppression of ryegrass growth. Based on our analysis, we suggest that initial screening of large collections of germplasm can be conducted under glasshouse conditions, with selected genotypes further evaluated in the field.
文摘Trifolium alexandrinum, an important forage legume, suffers from narrow genetic base. The present investigation was envisaged to reveal the inter- and intra-species genetic diversity and lineage among 64 accessions, representing a global collection, of T. alexandrinum;it’s two probable progenitor species (T. salmoneum and T. subterraneum) and the three genetically distant species (T. repens, T. vesiculosum, T. michelianum). A set of Simple Sequence Repeats (SSR) primer-pairs developed from T. alexandrinum have shown to amplify alleles across the species under study, suggesting utility of the newly developed resource for assessing molecular diversity among Trifolium species. These SSRs markers together with previously reported SSRs, derived from T. repens, enabled to reveal high intra-species polymorphism in T. alexandrinum and successfully discriminate different species investigated in this study. The diverse accessions determined herein provide a superior resource for further breeding of T. alexandrinum. High allelic similarity of T. alexandrinum with T. subterraneum and T. salmoneum indicated close relatedness among the species, suggesting polyphyletic evolution of T. alexandrinum.
文摘Twelve Australian grown faba bean genotypes with seed colour ranging from white, different shades of buff/beige, green, red and purple, were extracted using 80% methanol (v/v) or 70% acetone (v/v). The findings showed that commonly consumed buff-coloured genotypes have comparable phenolic contents and antioxidant activities to those with exotic seed coat colour (red, green and purple). In general, the extraction yield for methanol and acetone extracts of faba bean genotypes were similar. However, the acetone extracts of faba bean varieties with coloured seed coats exhibited higher antioxidant activities than their methanol extracts counterparts. Phenolic compounds and antioxidant activities of the genotypes were compared in an array of chemical-based assays and profiled using an on-line high-performance liquid chromatography-post column derivatization (HPLC-PCD) system. The total phenolic content (TPC) and total flavonoid content (TFC) of acetone extracts were approximately twice those of methanol extracts. The acetone extracts contained six times higher levels of di(phenyl)-(2,4,6-trinitrophenyl) imi- noazanium radical scavenging activity (DPPH), six times higher Total Equivalent Antioxidant Capacity (TEAC) and two times higher Ferric Reducing Antioxidant Power (FRAP) than those of methanol extracts. In general, the methanol extracts of white-coloured faba bean genotype exhibited comparable phenolic contents and antioxidant activities to varieties with coloured seed coats. However, the TPC, TFC, DPPH, TEAC and FRAP of acetone extracts from white-coloured genotype were 2 - 4, 1 - 2, 5 - 9, 2 - 3 and 1 - 2 times lower than those of faba bean varieties with coloured seed coats. HPLC-PCD analyses showed substantial antioxidant responses, represented as a dense “hump” of peaks in the HPLC chromatograms of acetone extracts from coloured-genotypes. This “hump” was not detected in the chromatograms of white-genotype acetone extracts, or in chromatograms of methanol extracts regardless of genotype or seed coat colour. All coloured-beans had higher phenolic contents and antioxidant activities than the white-genotype. Hydroxybenzoic acids/flavanols, hydroxycinnamic acids and flavonols were dominant in coloured beans. The findings suggest potentials in selecting commonly consumed buff-coloured faba bean genotypes within the breeding programs for enhanced levels of phenolic compounds and antioxidant activities, potentially increasing their health-promoting properties. And, there might also be potentials in developing faba bean extracts for pharmaceutical or natural medicines.
文摘Sowing time of wheat in south eastern Australia varies from autumn to early winter, depending on the seasonal ＇break＇. Wheat yields are often reduced by frost damage at flowering time and by heat-and/or water-stress during grain filling. Selecting suitable varieties for specific sowing times is a complex decision farmers make because these varietal phenology and climate risks have to be assessed together. In order to help farmers make decisions, they need tools that simulate and analyse agronomically-suitable sowing dates （ASSD） for a given variety of wheat. The hypothesis underlining this study is the integration of a wheat phenology model with historical climate data is an effective approach to modelling the ASSD of current varieties used in the wheat growing areas of Southern NSW. The parameters of the wheat phenology model were based on data from five years of field experimentation across 15 sites. Data from four sites were used to examine varietal suitability in relation to sowing time and its associated risks of frost and heat damage. The optimum ASSD for any variety at 72 locations across Southern NSW was investigated. The results showed that there were substantial spatial variations in the ASSD across the target region. ASSD for a late maturing wheat genotype （EGA Gregory） can range from early March to late April, while the earliest acceptable sowing date for an early maturing spring wheat genotype （H46） can range from early to late May. The wide range of spatial variation in the earliest and latest sowing dates, as well as the varied length of sowing opportunities, highlighted the importance of being able to apply a modelling approach which can integrate information on crop phenology with climate risk for a given location. This approach would allow better decision-making on suitable varieties and sowing dates in order to minimise the risk of frost and heat damage affecting crop yield.
基金supported by the National Basic Research Program of China(2011CB403200, 2011CB403203)
文摘Reduction in vegetation cover caused by human activities has a great impact on soil temperature. It is important to assess how soil temperature responds to reduction of vegetation height and density. In this paper we first report the trends of mean annual soil surface and air temperatures recorded at the meteorological stations near the Ecological Research Station for Grassland Farming (ERSGF) from 1961 to 2007, then we setup an experiment using reed (Phragmites australis) stalks with different heights and densities to simulate effects of different vegetation height and density on soil and air temperatures. The warming rates of the mean annual soil and air temperatures were 0.043 and 0.041C a 1 , respectively. Changes of soil temperature were characterized by both increased mean annual maximum and minimum soil temperatures. At the experimental site, mean daily temperature, mean daily maximum soil and air temperatures increased significantly. In contrast, mean daily minimum soil temperature increased significantly while mean daily minimum air temperature decreased significantly as the height and density of reed stalks reduced during the experimental period. Mean diurnal soil temperature ranges were smaller than mean diurnal air temperature ranges. These results highlight that the importance of vegetation cover on soil and air temperatures.
文摘Reduction of noncrop habitats, intensive use of pesticides and high levels of disturbance associated with intensive crop production simplify the farming landscape and bring about a sharp decline of biodiversity. This, in turn, weakens the biological control ecosystem service provided by arthropod natural enemies. Strategic use of flowering plants to enhance plant biodiversity in a well-targeted manner can provide natural enemies with food sources and shelter to improve biological control and reduce dependence on chemical pesticides. This article reviews the nutritional value of various types of plant-derived food for natural enemies, possible adverse effects on pest management, and the practical application of flowering plants in orchards, vegetables and field crops, agricultural systems where most research has taken place. Prospects for more effective use of flowering plants to maximize biological control of insect pests in agroecosystem are good but depend up on selection of optimal plant species based on information on the ecological mechanisms by which natural enemies are selectively favored over pest species.
文摘Salinity is a major soil contamination problem in Australia. To explore salinity remediation, we evaluated the concentrations of sodium （Na）, potassium （K）, magnesium （Mg）, and calcium （Ca） in roots and shoots and in the supporting soil of the naturally occurring grasses, Cynodon dactylon and Thinopyrurn ponticum, at two salt-affected sites, Gumble and Cundumbul in central-western New South Wales, Australia. The physiological parameters of the two grass species, including net photosynthetic rate （Pn）, stomatal conductance （gs）, and intercellular CO2 concentration （Ci）, were investigated using one mature leaf from C. dactylon and T. ponticum populations. Increasing salinity levels in the topsoil had a significant influence on Ci and gs, whereas no significant effect occurred on Pn in C. dactylon and T. ponticum. The Pn values in C. dactylon and T. ponticum were greater at Cundumbul than at Gumble. The greater Mg concentration facilitated greater Pn in C. dactylon and T. ponticum populations at Cundumbul than Gumble. With increasing salinity levels in the soil, Na accumulation increased in C. dactylon and T. ponticum. The ratio between K and Na was ~ 1 in roots and shoots of both populations irrespective of the sites. Bioaccumulation factor （BF） and translocation factor （TF） results revealed that K and Na translocations were significantly higher in T. ponticum than in C. dactylon, whereas Ca and Mg translocations were significantly higher in C. dactylon than in T. ponticum. Accumulation of Na, K, Mg, and Ca ions was higher in T. ponticum than in C. dactylon; therefore, we suggest that T. ponticum as a greater salt accumulator than C. dactylon could be used for revegetation and phytoremediation of the salt-affected soils.
