• Authors:
    • Iqbal, N.
    • Goher, M.
    • Hameed, A.
  • Source: Cereal Research Communications
  • Volume: 38
  • Issue: 2
  • Year: 2010
  • Summary: Detection of genotypic variation in response to water stress at seedling stage could help in escalating selection intensity in breeding drought tolerant varities. Nine genotypes were tested for seedling survivability under drought stress. Four genotypes, i.e. 'Sarsabz', 'Sitta', 'Fareed' and 'FD-83', showed complete survival on resumption of irrigation after drought stress. These genotypes were late dying as they withered slowly under drought. Percent wilting and percent survival on resumption of irrigation were negatively correlated. Six genotypes were selected on the basis of seedling survivability (late and early dying) and evaluated for seedling growth response under drought. Root length and dry weight increased significantly under stress in 'Sitta', 'FD-83' and 'Fareed'. Drought stress also increased the root-to-shoot length ratio in 'FD-83' and 'Fareed'. However, seedling fresh and dry weight significantly reduced in 'Nesser' and 'Inqalab-91' under stress. In 'FD-83', seedling fresh and dry weight increased over control under stress. Results indicated that seedling survivability, root-to-shoot length ratio, root length and dry weight were most important traits for screening drought tolerance at seedling stage. On the basis of these indices, 'Sitta', 'Fareed' and 'FD-83' were classified as drought tolerant, 'Sarsabz' and 'Nesser' as moderately tolerant and 'Inqalab-91' as sensitive genotypes. Collectively, results suggested that selection by combining seedling survivability, growth response, RWC and leaf water potential can be efficiently used for rapid evaluation of drought tolerance in wheat breeding.
  • Authors:
    • Nachit, M. M.
    • Mori, M.
    • Inagaki, M. N.
  • Source: Cereal Research Communications
  • Volume: 38
  • Issue: 4
  • Year: 2010
  • Summary: The drought stress in the rain-fed regions of West Asia and North Africa strongly depends on residual soil water available for the reproductive plant growth. The water uptake ability (i.e. water consumption per unit dry matter per day) of three synthetic-derived bread wheat genotypes, SYN-8, SYN-10 and SYN-15, and their parental variety Cham 6 were examined under controlled conditions. In addition, yield performance was compared under one artificial environment with supplemental irrigation and ten rain-fed environments at two locations over five cropping seasons. Large differences were found in water uptake ability among the four wheat genotypes; SYN-8 had the highest and SYN-10 the lowest ability. These differences were reflected in decrease of soil water content and increase of leaf temperature after irrigation. Under field conditions of supplemental irrigation, there were no significant differences in grain yield among genotypes Cham 6, SYN-8 and SYN-10; however, SYN-15 had lower grain yield due to low harvest index. Significant differences of the grain yield were found between SYN-8 and SYN-10 grown in rain-fed conditions. Lower water uptake ability was associated with higher grain yield; this speculates that intensive extraction of water from soil during vegetative growth might increase biomass production, but leave inadequate available soil moisture for reproductive growth and grain production. The balancing of water consumption by plants with stored soil moisture over the whole growing period is a major attribute of drought adaptation in these synthetic-derived wheat genotypes.
  • Authors:
    • Kumar, S. N.
    • Byjesh, K.
    • Aggarwal, P. K.
  • Source: Mitigation and Adaptation Strategies for Global Change
  • Volume: 15
  • Issue: 5
  • Year: 2010
  • Summary: Climate change associated global warming, rise in carbon dioxide concentration and uncertainties in precipitation has profound implications on Indian agriculture. Maize ( Zea mays L.), the third most important cereal crop in India, has a major role to play in country's food security. Thus, it is important to analyze the consequence of climate change on maize productivity in major maize producing regions in India and elucidate potential adaptive strategy to minimize the adverse effects. Calibrated and validated InfoCrop-MAIZE model was used for analyzing the impacts of increase in temperature, carbon dioxide (CO 2) and change in rainfall apart from HadCM3 A2a scenario for 2020, 2050 and 2080. The main insights from the analysis are threefold. First, maize yields in monsoon are projected to be adversely affected due to rise in atmospheric temperature; but increased rainfall can partly offset those loses. During winter, maize grain yield is projected to reduced with increase in temperature in two of the regions (Mid Indo-Gangetic Plains or MIGP, and Southern Plateau or SP), but in the Upper Indo-Gangetic Plain (UIGP), where relatively low temperatures prevail during winter, yield increased up to a 2.7°C rise in temperature. Variation in rainfall may not have a major impact on winter yields, as the crop is already well irrigated. Secondly, the spatio-temporal variations in projected changes in temperature and rainfall are likely to lead to differential impacts in the different regions. In particular, monsoon yield is reduced most in SP (up to 35%), winter yield is reduced most in MIGP (up to 55%), while UIGP yields are relatively unaffected. Third, developing new cultivars with growth pattern in changed climate scenarios similar to that of current varieties in present conditions could be an advantageous adaptation strategy for minimizing the vulnerability of maize production in India.
  • Authors:
    • Kalungu, J. W.
    • Monteiro, R. O. C.
    • Coelho, R. D.
  • Source: Ciência Rural
  • Volume: 40
  • Issue: 10
  • Year: 2010
  • Summary: This paper reviews various irrigation technologies in both South Africa and Kenya that enable improvements in their socio-economic conditions. The two countries are located in semi-arid areas that experience extreme fluctuations in the availability of rain water for plant growth. Population growth exceeds the ability to produce food in numerous countries around the world and the two countries are not an exception. This experiment examined the constraints that farmers face and the role of government and nongovernmental organization in the uptake of modern technologies for irrigation. Detailed mechanisms and options to secure sustainable irrigation which are economically viable are considered. Despite the higher production of cereals and grains, fruits, and flowers also thrive in the two countries. Total irrigated area, crops grown and irrigation systems used in the two countries are discussed.
  • Authors:
    • WCI
  • Volume: 2010
  • Year: 2010
  • Summary: Welcome to the Western Climate Initiative (WCI). The WCI is a collaboration of independent jurisdictions working together to identify, evaluate, and implement emissions trading policies to tackle climate change at a regional level. This is a comprehensive effort to reduce greenhouse gas pollution, spur investment in clean-energy technologies that create green jobs and reduce dependence on imported oil.
  • Authors:
    • Butterbach-Bahl, K.
    • Yao, Z.
    • Wu, H.
    • Sutton, M. A.
    • Han, X.
    • Dannenmann, M.
    • Chen, W.
    • Brüggemann, N.
    • Zheng, X.
    • Wolf, B.
  • Source: Nature
  • Volume: 464
  • Issue: 7290
  • Year: 2010
  • Summary: Atmospheric concentrations of the greenhouse gas nitrous oxide (N2O) have increased significantly since pre-industrial times owing to anthropogenic perturbation of the global nitrogen cycle, with animal production being one of the main contributors. Grasslands cover about 20 per cent of the temperate land surface of the Earth and are widely used as pasture. It has been suggested that high animal stocking rates and the resulting elevated nitrogen input increase N2O emissions. Internationally agreed methods to upscale the effect of increased livestock numbers onN2Oemissions are based directly on per capita nitrogen inputs. However, measurements of grassland N2O fluxes are often performed over short time periods, with low time resolution and mostly during the growing season. In consequence, our understanding of the daily and seasonal dynamics of grassland N2O fluxes remains limited. Here we report year-round N2O flux measurements with high and low temporal resolution at ten steppe grassland sites in Inner Mongolia, China. We show that short-lived pulses of N2O emission during spring thaw dominate the annual N2O budget at our study sites. The N2O emission pulses are highest in ungrazed steppe and decrease with increasing stocking rate, suggesting that grazing decreases rather than increases N2O emissions. Our results show that the stimulatory effect of higher stocking rates on nitrogen cycling and, hence, on N2O emission is more than offset by the effects of a parallel reduction in microbial biomass, inorganic nitrogen production and wintertime water retention. By neglecting these freeze-thaw interactions, existing approaches may have systematically overestimated N2O emissions over the last century for semi-arid, cool temperate grasslands by up to 72 per cent.
  • Authors:
    • Lynd, L. R.
    • Gunderson, C. A.
    • Borsuk, M. E.
    • Davis, E. B.
    • Wullschleger, S. D.
  • Source: Agronomy Journal
  • Volume: 102
  • Issue: 4
  • Year: 2010
  • Summary: Fundamental to deriving a sustainable supply of cellulosic feedstock for an emerging biofuels industry is understanding how biomass yield varies as a function of crop management, climate, and soils. Here we focus on the perennial switchgrass (Panicum virgatum L.) and compile a database that contains 1190 observations of yield from 39 field trials conducted across the United States. Data include site location, stand age, plot size, cultivar, crop management, biomass yield, temperature, precipitation, and information on land quality. Statistical analysis revealed the major sources of variation in yield. Frequency distributions of yield for upland and lowland ecotypes were unimodal, with mean (+/-SD) biomass yields of 8.7 ± 4.2 and 12.9 ± 5.9 Mg ha-1 for the two ecotypes, respectively. We looked for, but did not find, bias toward higher yields associated with small plots or preferential establishment of stands on high quality lands. A parametric yield model was fit to the data and accounted for one-third of the total observed variation in biomass yields, with an equal contribution of growing season precipitation, annual temperature, N fertilization, and ecotype. The model was used to predict yield across the continental United States. Mapped output was consistent with the natural range of switchgrass and, as expected, yields were shown to be limited by precipitation west of the Great Plains. Future studies should extend the geographic distribution of field trials and thus improve our understanding of biomass production as a function of soil, climate, and crop management for promising biofuels such as switchgrass.
  • Authors:
    • Antle, J.
    • Ogle, S.
    • Paustian, K.
    • Basso, B.
    • Grace, P. R.
  • Source: Australian Journal of Soil Research
  • Volume: 48
  • Issue: 8
  • Year: 2010
  • Authors:
    • Grace, P.
    • Kiese, R.
    • Butterbach-Bahl, K.
    • Rowlings, D.
    • Rochester, I.
  • Source: Soil Solutions for a Changing World: proceedings of the 19th World Congress of Soil Science
  • Year: 2010
  • Authors:
    • Van Zwieten, L.
    • Kimber, S.
    • Rowling, D.
    • Grace, P. R.
    • Scheer, C.
  • Source: Soil Solutions for a Changing World
  • Year: 2010
  • Summary: An intensive field campaign was performed from April to June 2009 to assess the effect of biochar amendment on the emission of soil-borne GHGs from a sub-tropical pasture on acidic ferrosol. Over the whole measurement period high emissions of N2O and high fluxes of CO2 could be observed, whereas a net uptake of CH4 was measured. Only small differences in the fluxes of N2O and CH4 from the biochar amended plots (35.33 ± 4.83 μg N2O-N/m2/h, -6.76 ± 0.20 μg CH4 -C/m2/h) vs. the control plots (31.08 ± 3.50 μg N2O-N/m2/h, -7.30 ± 0.19 μg CH4 -C/m2/h) could be observed, while there was no significant difference in the fluxes of CO2. However, it could be observed that N2O emissions were significantly lower from the biochar amended plots during periods with low emission rates (< 50 μg N2O-N/m2/h). Only during an extremely high emission event following heavy rainfall N2O emissions from the biochar amended plots were higher than from the control plots. Our results demonstrate that pastures on ferrosols in Northern NSW are a significant source of GHG and that the amendment of biochar can alter those emissions. However, more field and laboratory incubation studies covering prolonged observation periods are needed to clarify the impact of biochar amendment on soil microbial processes and the emission of soil-borne GHGs.