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Author: Don Lee Keim Publisher: ISBN: Category : Wheat Languages : en Pages : 294
Book Description
Winter wheat cultivars (Triticum aestivum) were evaluated for their response to water stress and adaptability to a wide range of moisture limited environments. Grain yield was analyzed for ten cultivars at six locations across four years. Regression of the cultivar mean on the year-location mean was used as a measure of the environmental response of a particular cultivar, Plant water status (leaf osmotic potential and water potential) during the grain filling period, along with grain yield and yield components were determined at three locations for fifteen cultivars under space-planted conditions in 1972 and for ten cultivars under solid-seeding in 1973. Five cultivars were evaluated for plant water status and rates of growth during reproductive development and for final grain yield and yield components at a severely stressed location in 1973. Drought resistance, described as yielding ability under severe soil moisture stress, was found to be the result of avoidance, tolerance and escape characteristics. Plant water status influenced the components of yield when their development occurred during a period of high external stress. However, the relative importance of plant water status to final yield varied depending on the magnitude of the direct effect of spike number on yield. Drought avoidance was the ability to maintain a high plant water status when under high external stress conditions. In the cultivar Yamhill, the stable growth rate during inflorescence development and the extended period of grain filling may have resulted from the ability of this cultivar to avoid drought. These characteristics, also, may explain the large spikelet number and the high kernel weight of Yamhill. Even though Hyslop and Wanser had a moderate and high internal water stress, respectively, they were relatively tolerant of stress in terms of high growth rates during the grain filling period. The high yielding ability of Wanser and McDermid under high stress conditions was primarily related to a large number of spikes. This trait was considered an escape characteristic because tillering was established before the onset of severe stress. The club wheats neither avoided or tolerated internal water stress under solid-seeded conditions nor did they have sufficient tillering capacity to compensate for the effect of stress on the laterdeveloped components.of yield. Nugaines, Hyslop and Rew maintained a moderate internal stress during later development but differed in their yield component responses. The yield of Nugaines depended primarily on a high tillering capacity, whereas the yield of Hyslop and Rew depended on a balance of contributions from all the components of yield. Widely adapted cultivars, such as Hyslop and McDermid, not only yielded well under severe stress conditions but had the genetic potential to respond adequately to more favorable moisture conditions. Cultivars specifically, adapted to lower yielding environments, such as Yamhill and Wanser, were able to avoid, tolerate or escape drought but were limited in one or more of their yield component responses to better conditions. Conversely, cultivars specifically adapted to high yielding environments, such as Nugaines and Paha, lacked the ability to consistently yield well under high stress environments but had a high response to more favorable moisture conditions. Cultivars best adapted to dryland cultivation should have the highest yield under stress conditions as expressed through the components of yield by one or a combination of avoidance, tolerance or escape characteristics. These cultivars should also have the maximum expression in, and balance among, the components of yield for maximum response to more favorable moisture conditions. This goal may be obtained by selection in favorable as well as stressed environments and by testing throughout the range of the environments where the cultivar is expected to be grown. Because high yield under stress was found in this study to be manifested through different characteristics of the plant the breeder should be aware of traits which may contribute to drought resistance, but he should not be restricted to a particular ideotype when breeding for yield under conditions of high moisture stress.
Author: Don Lee Keim Publisher: ISBN: Category : Wheat Languages : en Pages : 294
Book Description
Winter wheat cultivars (Triticum aestivum) were evaluated for their response to water stress and adaptability to a wide range of moisture limited environments. Grain yield was analyzed for ten cultivars at six locations across four years. Regression of the cultivar mean on the year-location mean was used as a measure of the environmental response of a particular cultivar, Plant water status (leaf osmotic potential and water potential) during the grain filling period, along with grain yield and yield components were determined at three locations for fifteen cultivars under space-planted conditions in 1972 and for ten cultivars under solid-seeding in 1973. Five cultivars were evaluated for plant water status and rates of growth during reproductive development and for final grain yield and yield components at a severely stressed location in 1973. Drought resistance, described as yielding ability under severe soil moisture stress, was found to be the result of avoidance, tolerance and escape characteristics. Plant water status influenced the components of yield when their development occurred during a period of high external stress. However, the relative importance of plant water status to final yield varied depending on the magnitude of the direct effect of spike number on yield. Drought avoidance was the ability to maintain a high plant water status when under high external stress conditions. In the cultivar Yamhill, the stable growth rate during inflorescence development and the extended period of grain filling may have resulted from the ability of this cultivar to avoid drought. These characteristics, also, may explain the large spikelet number and the high kernel weight of Yamhill. Even though Hyslop and Wanser had a moderate and high internal water stress, respectively, they were relatively tolerant of stress in terms of high growth rates during the grain filling period. The high yielding ability of Wanser and McDermid under high stress conditions was primarily related to a large number of spikes. This trait was considered an escape characteristic because tillering was established before the onset of severe stress. The club wheats neither avoided or tolerated internal water stress under solid-seeded conditions nor did they have sufficient tillering capacity to compensate for the effect of stress on the laterdeveloped components.of yield. Nugaines, Hyslop and Rew maintained a moderate internal stress during later development but differed in their yield component responses. The yield of Nugaines depended primarily on a high tillering capacity, whereas the yield of Hyslop and Rew depended on a balance of contributions from all the components of yield. Widely adapted cultivars, such as Hyslop and McDermid, not only yielded well under severe stress conditions but had the genetic potential to respond adequately to more favorable moisture conditions. Cultivars specifically, adapted to lower yielding environments, such as Yamhill and Wanser, were able to avoid, tolerate or escape drought but were limited in one or more of their yield component responses to better conditions. Conversely, cultivars specifically adapted to high yielding environments, such as Nugaines and Paha, lacked the ability to consistently yield well under high stress environments but had a high response to more favorable moisture conditions. Cultivars best adapted to dryland cultivation should have the highest yield under stress conditions as expressed through the components of yield by one or a combination of avoidance, tolerance or escape characteristics. These cultivars should also have the maximum expression in, and balance among, the components of yield for maximum response to more favorable moisture conditions. This goal may be obtained by selection in favorable as well as stressed environments and by testing throughout the range of the environments where the cultivar is expected to be grown. Because high yield under stress was found in this study to be manifested through different characteristics of the plant the breeder should be aware of traits which may contribute to drought resistance, but he should not be restricted to a particular ideotype when breeding for yield under conditions of high moisture stress.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Insufficient water is the environmental factor most limiting crop productivity in the semi-arid and dry subhumid regions of Saskatchewan. This study was undertaken to establish a framework for the development of winter wheat cultivars which are less sensitive to drought stress. Five winter wheat genotypes, 'Norstar' and 'Norwin' (products of previous breeding efforts) and three more recently selected 'CDC Kestrel-type' advanced Lines were grown in 17 field environments between 1989 and 1991. This study established that the CDC Kestrel-type lines have a higher yield potential and higher average yield than Norstar or Norwin, but they do not differ in yield under most dryland conditions. The yield advantage of the CDC Kestrel type Lines was associated with conditions that favoured the establishment of yield potential. Conversely, the elimination of the CDC Kestrel-type yield advantage was associated with conditions which suppressed the establishment of yield potential. Differences in rainfall, evaporative demand, soil water depletion, evapotranspiration and aerial biomass accumulation during four periods of crop development resulted in three temporal patterns of drought stress: (1) intermittent, (2) terminal and (3) low stress. The environmental effect on grain yield was due to crop water conditions during all development periods. Crop water conditions from heading to anthesis were particularly important to grain yield. Flag leaf water content was positively related to grain yield in the dryland trials. There was no association between aerial biomass at anthesis and grain yield. Both pre- and post-anthesis ET were of similar importance to grain yield. Soil water reserves were depleted by the time the crop had headed in the dryland trials. Consequently, flag leaf water content declined. The distribution of growing season rainfall determined the timing and intensity of drought. A relatively small genotype-environment (GE) interaction for grain yield resulted in a poor co.
Author: Ellery Channing Chilcott Publisher: ISBN: Category : Wheat Languages : en Pages : 24
Book Description
"Limited rainfall is the controlling factor in crop production in the Great Plains. The average yields of a series of years can be foretold from the records of past years; but because the rainfall is fluctuating in amount and uncertain in distribution, the yields of a simple year can not be foretold with any certainty. The chances of success are, however, much better when the soil is wet to a considerable depth at seeding time than they are when the soil contains little or no available water at that time. The relation between the amount of water in the soil at seeding time and the yield is much closer with winter wheat than with other crops. This crop should, therefore, be seeded on the best-prepared land and that in which the greatest amount of water is stored. Except in the southern section, the response of winter wheat to summer tillage is greater than that of any other crop. Summer-tilled land should be seeded to winter wheat wherever this crop can be grown. The growth of corn is one of the best preparations for winter wheat, especially north of Kansas. With increase in the length of season and the time between harvest and seeding, there is an increase in the value of early preparation for winter wheat. In the northern section the crop can be replaced with spring wheat without serious loss. In the central section winter wheat has a greater advantage over spring wheat and can not be replaced by the latter without serious loss. In the southern section, winter wheat is less certain and less productive than farther north and can not be replaced by spring wheat. It is, however, profitably raised under favorable conditions of oil, season, and preparation. In this section particularly it should be recognized that the chances of producing a crop are low when it is seeded on land that does not contain water enough in storage to wet the soil to a depth of 3 feet."--Page 2
Author: Cesar Lopez Publisher: ISBN: Category : Winter wheat Languages : en Pages : 156
Book Description
The Pacific Northwest (PNW) is an important region for winter wheat production in the USA, where water deficits are often present at sowing and during grain filling. Consequently, improving the genetic adaptation of wheat cultivars to drought stress represents one of the main objectives in breeding programs. An observed biochemical response to dehydrative stress is the accumulation of a family of proteins called dehydrins, which are believed to protect membranes and macromolecules against denaturation. Seven cultivars, 'Connie', 'Gene', 'TAM105', 'Rod', 'Hiller', 'Rhode', and 'Stephens', were evaluated in four experiments under progressive drought stress to characterize the accumulation of dehydrin proteins and their association to stress tolerance at adult plant (during grain filling) and seedling stages. In the adult plant experiments, a 24 kDa dehydrin was present in all leaves sampling dates and cultivars studied. Differences in the accumulation of this dehydrin protein were observed between cultivars in the third sampling date (four days of stress). This differential accumulation was associated to stress tolerance characterized by a lower reduction in yield and in the rate of decrease in leaf water potential in Connie, TAM105, Gene and Stephens. In contrast to leaves, an increasing number of dehydrin bands were observed in grains under stress and non-stress treatments. Despite the number of dehydrins detected, there was no apparent association between drought stress and dehydrin expression in grains. A 24 kDa dehydrin was also observed in the seedling experiments on sampling dates fourth, fifth and sixth, when cultivars were subjected to stress. No dehydrins were present in the non-stress treatment. Connie, TAM105, and Gene started to accumulate dehydrins at the fourth sampling date, while other cultivars showed dehydrins only in the sixth sampling date. The presence of dehydrin proteins observed in leaves of seedlings was related to drought stress tolerance characterized by a lower reduction in the shoot dry matter production in the most tolerant cultivars Connie, TAM105, and Gene. Although the specific role of these proteins remains unknown, their association with stress tolerance suggests that dehydrins might be used to improve the adaptation to drought.
Author: Food and Agriculture Organization of the United Nations Publisher: Food & Agriculture Org. ISBN: 9789251043516 Category : Business & Economics Languages : en Pages : 120
Book Description
The rapid response of the agricultural sector to increased crop prices indicates that it is able to meet the world's overall food requirements. The problem lies more in the distribution of the agricultural output and the economic inability of a segment of the population to satisfy basic requirements. This document presents guidelines for governments on the development of fertiliser strategies. It illustrates the difference before and after the involvement of the private sector and offers solutions for improvement. The role of fertilisers in the development of agriculture is discussed with practical suggestions for decision-makers regarding production and import. The many issues involved in the efficient distribution and marketing of fertilisers are presented, together with an institutional framework for the integration of all the aspects into a comprehensive policy. There is a useful glossary.
Author: Arun K.Shanker Publisher: Elsevier ISBN: 0128160918 Category : Science Languages : en Pages : 600
Book Description
Climate Change and Crop Stress: Molecules to Ecosystems expounds on the transitional period where science has progressed to 'post-genomics' and the gene editing era, putting field performance of crops to the forefront and challenging the production of practical applicability vs. theoretical possibility. Researchers have concentrated efforts on the effects of environmental stress conditions such as drought, heat, salinity, cold, or pathogen infection which can have a devastating impact on plant growth and yield. Designed to deliver information to combat stress both in isolation and through simultaneous crop stresses, this edited compilation provides a comprehensive view on the challenges and impacts of simultaneous stresses. Presents a multidisciplinary view of crop stresses, empowering readers to quickly align their individual experience and perspective with the broader context Combines the mechanistic aspects of stresses with the strategic aspects Presents both abiotic and biotic stresses in a single volume
Author: R. H. Skinner Publisher: ISBN: Category : Languages : en Pages : 51
Book Description
Five varieties and three breeding lines of winter wheat (Triticum aestivum L.) were compared for drought resistance at the seedling stage. Emergence under a greenhouse line-source sprinkler system was compared with germination in PEG 6000 and mannitol solutions as well as with seed weight and the ability to emerge from deep planting. No significant correlation existed between line-source emergence and germination in PGE or mannitol, emergence from deep planting or seed weight. Within varieties, light seeds (average 50 seed weight 1.313 g) germinated better under moisture stress than heavier ones (average 50 seed weight = 1.991 g) but there was no significant correlation between seed weight and germination among varieties. Seedling maturation rates were measured using the Haun index while total dry weight was used to indicate productivity. Shoot weight, root weight, root/shoot ratio, leaf water potencial and plant height were compared with productivity and maturation rate. None were found to be correlated with the index. Plant height, shoot weight and root weight were all significantly correlated with total dry weight. Plant height is suggested as a convenient, nondestructive indicator of total plant productivity. No correlation was found to exist between emergence under drought conditions and the ability of seedlings to grow under moisture stress. What little relationship existed between the two was generally negative, making incorporation of drought resistance at both stages into one variety difficult.
Author: Don Lee Keim
Author: Don Lee Keim
Author: 
Author: Ellery Channing Chilcott
Author: International Rice Research Institute
Author: Cesar Lopez
Author: Food and Agriculture Organization of the United Nations
Author: Arun K.Shanker
Author: 
Author: 
Author: R. H. Skinner