• Authors:
    • Cui, L.
    • Wu, B.
    • Zhang, Z.
    • Xu, W.
  • Source: Acta Agronomica Sinica
  • Volume: 35
  • Issue: 12
  • Year: 2009
  • Summary: Oat ( Avena L.) is one of the most important cereal crops in the world, ranked at the sixth top place in planting area and yield among all cereal crops, and possesses high values in food and nutrition, health protection and feeding livestock. Naked oat ( A. nuda) is an endemic type in China. However, a few studies on naked oat germplasm at molecular level have been reported. The aim of this study was to evaluate the genetic diversity of core collection of naked oat using AFLP markers. A total of 281 accessions of naked oat were analyzed using 20 AFLP primer combinations. Selective amplification created 1 137 bands, of which 260 were polymorphic, accounting for 22.96% of the total bands. The mean polymorphism information content (PIC) was 0.0326. For different geographic groups, Simpson's index ranged from 1.235 to 1.495, and Shannon's index varied from 0.1558 to 0.4437. The majority (83.45%) of the AFLP variation resided within accessions of each group, and the rest (16.55%) existed among accessions between groups. The sample size of geographic groups was significantly associated with the number of polymorphic loci, proportion of within-group variation, Simpson's index and Shannon's index. Accessions from Inner Mongolia and Shanxi were most diverse, and those from northeastern China were most distinct. Genetic resemblance was found within accessions from western China. Germplasm from East Europe was genetically close to that from Inner Mongolia, China. The genetic diversity of Chinese accessions was significantly higher than that of exotic accessions. Compared with breeding cultivars, landraces presented a higher proportion of within-group variation. Naked oat landraces were suggested to be collected in the regions where are not well represented by the current collections, and collecting activities should be continuous in the diversity-rich areas such as northwestern and southwestern China in order to enrich naked oat gene pool in China.
  • Authors:
    • Bernardi, A.
    • Harden, S.
    • Wilson, B.
    • Young, R.
  • Source: Australian Journal of Soil Research
  • Volume: 47
  • Issue: 3
  • Year: 2009
  • Summary: Australian agriculture contributes an estimated 16% of all national greenhouse gas emissions, and considerable attention is now focused on management approaches that reduce net emissions. One area of potential is the modification of cropping practices to increase soil carbon storage. This paper report short-medium term changes in soil carbon under zero tillage cropping systems and perennial vegetation, both in a replicated field experiment and on nearby farmers' paddocks, on carbon-depleted Black Vertosols in the upper Liverpool Plains catchment. Soil organic carbon stocks (C S ) remained unchanged under both zero tillage long fallow wheat ( Triticum aestivum)-sorghum ( Sorghum) rotations and zero tillage continuous winter cereal in a replicated field experiment from 1994 to 2000. There was some evidence of accumulation of C S under intensive (>1 crop/year) zero tillage response cropping. There was significant accumulation of C S (~0.35 tonnes/ha/year) under 3 types of perennial pasture, despite removal of aerial biomass with each harvest. Significant accumulation was detected in the 0-0.1, 0.1-0.2, and 0.2-0.4 m depth increments under lucerne and the top 2 increments under mixed pastures of lucerne and phalaris and of C3 and C4 perennial grasses. Average annual rainfall for the period of observations was 772 mm, greater than the 40-year average of 680 mm. A comparison of major attributes of cropping systems and perennial pastures showed no association between aerial biomass production and accumulation rates of C S but a positive correlation between the residence times of established plants and accumulation rates of C S . C S also remained unchanged (1998/2000-07) under zero tillage cropping on nearby farms, irrespective of paddock history before 1998/2000 (zero tillage cropping, traditional cropping, or ~10 years of sown perennial pasture). These results are consistent with previous work in Queensland and central western New South Wales suggesting that the climate (warm, semi-arid temperate, semi-arid subtropical) of much of the inland cropping country in eastern Australia is not conducive to accumulation of soil carbon under continuous cropping, although they do suggest that C S may accumulate under several years of healthy perennial pastures in rotation with zero tillage cropping.
  • Authors:
    • Sanginga, N.
    • Olufajo, O.
    • Iwuafor, E.
    • Abaidoo, R.
    • Yusuf, A.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 129
  • Issue: 1/3
  • Year: 2009
  • Summary: Understanding changes in soil chemical and biological properties is important in explaining the mechanism involved in the yield increases of cereals following legumes in rotation. Field trials were conducted between 2003 and 2005 to compare the effect of six 2-year rotations involving two genotypes each of cowpea (IT 96D-724 and SAMPEA-7) and soybean (TGx 1448-2E and SAMSOY-2), a natural bush fallow and maize on soil microbial and chemical properties and yield of subsequent maize. Changes in soil pH, total nitrogen (N tot), organic carbon (C org), water soluble carbon (WSC), microbial biomass carbon (C mic) and nitrogen (N mic) were measured under different cropping systems. Cropping sequence has no significant ( P>0.05) effect on soil pH and C org, while WSC increased significantly when maize followed IT 96D-724 (100%), SAMPEA-7 (95%), TGx 1448-2E (79%) and SAMSOY-2 (106%) compared with continuous maize. On average, legume rotation caused 23% increase in N tot relative to continuous maize. The C mic and N mic values were significantly affected by cropping sequence. The highest values were found in legume-maize rotation and the lowest values were found in fallow-maize and continuous maize. On average, C mic made up to 4.8% of C org and N mic accounted for 4.4% of N tot under different cropping systems. Maize grain yield increased significantly following legumes and had strong positive correlation with C mic and N mic suggesting that they are associated with yield increases due to other rotation effects. Negative correlation of grain yield with C mic:N mic and C org:N tot indicate that high C:N ratios contribute to nitrogen immobilization in the soil and are detrimental to crop productivity. The results showed that integration of grain legumes will reverse this process and ensure maintenance of soil quality and maize crop yield, which on average, increased by 68% and 49% following soybean and cowpea, respectively compared to continuous maize.
  • Authors:
    • Bahrani, M.
    • Ahmadi, M.
  • Source: American-Eurasian Journal of Agricultural and Environmental Science
  • Volume: 5
  • Issue: 6
  • Year: 2009
  • Summary: Irrigated rapeseed ( Brassica napus L.) cultivation is currently expanding in rotation with winter cereals in Iran where its reproductive growth is often exposed to water deficit in many parts, particularly in the south. A two growing seasons (2006-2008) field experiment was conducted at the Experimental Research Center, Shiraz University to study the effects of water stress at different growth stages [Normal irrigation at all growth stages (control), water stress at flowering, at pod development and at seed filling stages] and nitrogen (N) levels (0, 75, 150 and 225 kg ha -1) on yield and yield components of rapeseed (Telayeh cultivar). The design was split plots arranged in randomized complete block with four replications. Full irrigation and the highest N level had the highest plant height, number of branches per plant, pods per plant, seed and oil yields. However, increased N levels decreased seed oil content and had no significant effect on 1000-seed weight. Flowering was the most sensitive stage for water stress damage resulting a drastic reduction in seed and oil yields by 29.5% and 31.7%, respectively. Pods per plants was the most sensitive yield components to water stress during reproductive growth in both year and it had the highest significant positive correlation with seed and biological yields. The seed and oil yields of the 1st season were more than the 2nd season due to favorable weather conditions for growth. Overall, supplying sufficient water to rapeseed crop, particularly at flowering and pod formation, in comparison with 225 kg ha -1 of N fertilizer are important to produce higher yields.
  • Authors:
    • Smith, M.
    • Barnard, A.
  • Source: Field Crops Research
  • Volume: 112
  • Issue: 2/3
  • Year: 2009
  • Summary: Preharvest sprouting (PHS) is a risk factor in winter cereal farming in certain environments as even mild sprouting affects the suitability of wheat for end-use products. This is because even mild sprouting affects the suitability of wheat for end-use products. The extent of PHS is hard to predict. To establish a quantitative relationship between PHS and different climatic characteristics, eighteen winter wheat cultivars were planted in three regions representative of the wheat growing conditions of the Free State Province of South Africa over four years. Climatic characteristics during six environmental periods were investigated, namely planting to harvest (PH), anthesis to harvest (AH), grain filling (GF), 14 days prior to physiological maturity (14M) and 10 and 20 days prior to harvest (10H and 20H) respectively. These data sets were correlated with PHS resistance determined in a rain simulator to determine if climate during various stages of grain development had an effect on the expression of dormancy and subsequent PHS. Principal component analysis (PCA) on mean PHS values identified three distinct groupings of cultivars, ranging from PHS susceptible to PHS resistant. A fairly strong positive correlation ( r=0.715, P=0.008) was found between PHS and minimum temperature during grain filling. Large variations in PHS values were also observed between the various cultivars, indicating that certain cultivars, such as Caledon, Gariep, Limpopo, Matlabas, PAN 3118, PAN 3120, PAN 3377 and SST 334, are more sensitive to environmental effects than others and that the variation in cultivar PHS is not consistent across sites and years.
  • Authors:
    • Hill, J.
    • Jacobs, J. L.
    • Jenkin, T.
  • Source: Animal Production Science
  • Volume: 49
  • Issue: 7
  • Year: 2009
  • Summary: The efficient production and subsequent utilisation of home-grown forage is seen as the cornerstone of profitability of the dairy industry as it leads to lower unit costs of milk production compared with purchased forage or grain supplements. Cereals such as wheat ( Triticum aestivum L.), oats ( Avena sativa L.) and triticale ( Triticum * Triticosecale) all have the potential to produce high forage dry matter (DM) yields. These forages are not widely grown within dryland Australian dairy systems and there is a paucity of information on both the agronomic requirements and subsequent ensiling and feed-out management under these conditions. The experiment reported in this paper examines the DM yield, nutritive and ensiling characteristics of three small-grain cereals (triticale, wheat and oats) cut at various stages of development and ensiled with or without silage additives. We hypothesised that: (1) delaying harvesting until later stages of growth would result in higher DM yields, but negatively impact on both nutritive and fermentation characteristics of subsequent silages; (2) ensiling wilted material at earlier harvests would improve fermentation characteristics compared with direct ensiled material; and (3) the use of silage additives at all harvests would improve fermentation characteristics of resultant silages compared with untreated silages. Apart from winter oats, the estimated metabolisable energy of forages was highest at the boot stage of growth, declined during anthesis and then rose again during milk and soft-dough stage of growth. The crude protein content of forages declined with maturity, with final values at soft dough below 90 g/kg DM. Neutral detergent fibre content was highest at anthesis and then declined, with lowest values observed at soft dough (497-555 g/kg DM). In the majority of cases silages were well preserved, with direct ensiled material having pH values generally below 4.5 and wilted material below 5.0, with limited proteolysis as assessed by ammonia-N contents in the range of 5-15% of total-N. The production of volatile fatty acids and lactic acid was influenced by wilting and the use of additives. Generally, wilted silages fermented less than the corresponding direct ensiled forages, whereas the use of Sil-All 4*4 additive resulted in a lactic acid-dominant fermentation compared with LaSil additive, which resulted in a greater proportion of acetic acid as an end product of fermentation. The findings of the present study highlight the potential of forage cereals to produce high DM yields for whole crop cereal silage. The timing of harvest directly influences nutritive characteristics of forages for ensiling. The use of silage additives can assist in controlling fermentation pathways during ensilage, ensuring the production of silages with fermentation attributes more likely to lead to higher intakes when fed to animals.
  • Authors:
    • Penfold, C. M.
    • McNeill, A. M.
  • Source: Crop and Pasture Science
  • Volume: 60
  • Issue: 2
  • Year: 2009
  • Summary: Maintenance of available phosphorus (P) is a problem faced by both conventional and organic systems but it is exacerbated in the latter given that manufactured inorganic sources of P fertiliser are not permitted under the International Federation of Organic Agriculture Movements certification guidelines. The focus of this paper is a discussion of potential agronomic strategies to assist in sustainable management of the soil P resource in organic and low-input broadacre farming systems within the Australian rain-fed cereal-livestock belt. The paper considers three broad strategies for agronomic management of P in this context and draws on reported research from overseas and within Australia. An analysis of the current knowledge suggests that the option most likely to ensure that soluble P is not a limitation in the system is the importation of allowable inputs that contain P from off-farm, although for much of the Australian cereal-livestock belt the immediate issue may be access to economically viable sources. Research targeted at quantifying the economic and biological benefits to the whole-farm system associated with the adoption of these practices is required. Improving the P-use efficiency of the system by incorporating species into rotation or intercropping systems that are able to use P from less soluble sources has been a successful strategy in parts of the world with climate similar to much of the Australian cereal-sheep belt, and deserves further research effort in Australia. Agronomic management to maximise quantity and quality of pasture and crop plant residues undoubtedly builds labile soil organic matter and facilitates P cycling, but the strategy may be of limited benefit in low-rainfall areas that do not have the capacity to produce large biomass inputs. Evidence that organic or low-input systems naturally increase the numbers and diversity of soil organisms is sparse and published studies from Australian systems suggest that P nutrition is not enhanced. However, seed and soil microbial inoculants to facilitate improved P uptake have been developed and are currently being field tested in Australia. Progress in selection and breeding for cereal genotypes that are more P efficient and other plant genotypes that can use less labile P sources, is gaining momentum but still remains a long-term prospect, and may involve genetic modification which will not be acceptable for organic systems.
  • Authors:
    • Vanderlinden, K.
    • Murillo, J. M.
    • Madejon, E.
    • Lopez-Garrido, R.
    • Melero, S.
    • Ordonez, R.
    • Moreno, F.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 133
  • Issue: 1-2
  • Year: 2009
  • Summary: Long-term field experiments can provide relevant information regarding soil organic carbon sequestration under different soil tillage systems. Especially, conservation tillage (CT) has been proved to be a practice that highly contributes to improve soil quality. For that reason, the study of soil quality indicators, such as organic fractions, are useful tools to assess changes caused by different soil tillage systems in long-term field experiments. We evaluated long-term effects of conservation tillage on soil carbon fractions and biological properties in a sandy clay loam Entisol (soil A) and in a clay Vertisol (soil B) located in semi-arid SW Spain. Cereal-sunflower-legume rotations under rainfed conditions were used in both soils in which conservation tillage (CT) was compared to traditional tillage (TT). Soil samples were collected at three depths (0-5, 5-10 and 10-20 cm) four months after sowing a pea crop ( Pisum arvense L.) in the Entisol and a wheat crop ( Triticum aestivum L.) in the Vertisol. Labile fractions of the total organic carbon (TOC) were determined as active carbon (AC) and water soluble carbon (WSC). Biological status was evaluated using soil microbial biomass carbon (MBC) and enzymatic activities [dehydrogenase activity (DHA), o-diphenol oxidase activity (Dphox), and beta-glucosidase activity (beta-glu)]. As a rule, the contents of AC, WSC, MBC, beta-glu and Dphox in soil A and contents of TOC, AC and DHA in soil B were higher in CT than in TT, at the 0-5 cm depth. In both soils, the studied parameters decreased with depth under both tillage treatments (TT and CT). Values of AC, TOC, MBC and beta-glu were positively correlated with each other ( p
  • Authors:
    • Ruiz, J. C.
    • Vanderlinden, K.
    • Melero, S.
    • Madejon, E.
  • Source: The Journal of Agricultural Science
  • Volume: 147
  • Issue: 1
  • Year: 2009
  • Summary: Soil enzyme activities are widely utilized as rapid and sensitive indicators in discriminating among soil management effects. The objective of the present study was to compare the influence of conservation tillage, i.e. direct drilling (DD) (residue cover is left on the soil surface) v. conventional tillage (CT), on soil chemical and biochemical properties in a crop rotation (cereals-sunflower-legumes) under dryland production in a semi-arid Mediterranean Vertisol after 23 years. A randomized experimental design was established. Soil biological status was evaluated by measuring of enzymatic activities (dehydrogenase, beta-glucosidase, alkaline phosphatase and protease). Total organic carbon (TOC) contents were greater in soils managed by DD than those found by CT. Except for protease activity, enzymatic activity values were approximately 2-fold higher in soils under DD than in soils under CT. The beta-glucosidase, alkaline phosphatase and dehydrogenase values showed a high correlation (from r=0.481 to r=0.886, P≤0.01) with TOC contents and they were correlated with each other (from r=0.664 to r=0.923, P≤0.01). The coefficient of variation of biochemical properties was higher than those of chemical properties in both treatments. Principal component analysis (PCA) showed that two principal components explained 58% and 20% of the total variability. The first principal component was influenced mostly by beta-glucosidase, dehydrogenase and TOC, whereas the second was influenced by pH. The first component effectively differentiated managed soil under both agriculture practices. In general, long-term soil conservation management by DD in a dryland farming system improved the quality of this Vertisol by enhancing its organic matter content and biochemical activity.
  • Authors:
    • Erenstein, O.
  • Source: Agricultural Water Management
  • Volume: 96
  • Issue: 12
  • Year: 2009
  • Summary: The intensive irrigated rice-wheat systems in the northwest Indo-Gangetic Plains of South Asia are built on a long tradition of canal irrigation and the more recent advent of tubewells. Findings from farm surveys are used to examine water management and water productivity in the rice-wheat belt of India's Haryana State and Pakistan's Punjab province. Attributes of the irrigation sources help explain the widespread interest in groundwater use and the relative demise of canal water use. In each area groundwater now is the main irrigation source, used either solely or in conjunction with surface water. The ownership of tubewells is near universal among the surveyed farms, whereas conjunctive water use is more widespread during the monsoon season, among better endowed farmers and in the Pakistan Punjab. In Pakistan Punjab farmers primarily rely on diesel powered tubewells whereas Haryana farmers mainly use relatively cheaper electric power. Water productivity indicators for rice are markedly lower than those for wheat - largely reflecting significantly higher water inputs in paddy cultivation - but also vary between the study areas and by the prevailing water use, reflecting the limited incentives for farmers to use water wisely. A combination of technological, land use and market based approaches is likely to be most effective in achieving sustainable water management in these intensive cereal systems.