Comparative growth studies of crop species with special reference to harvest index as a criterion of the yielding ability of a genotype
Material type:
TextLanguage: English Publication details: Melbourne (Australia) : University of Melbourne, 1979Description: 130 pagesSubject(s): Summary: A large increase in yield during the history of crop improvement has been achieved as a consequence of selection, both deliberate and non-deliberate, by man for improved yield. Probably, without exception, present-day crop cultivars greatly outyield their ancestors. An analysis of the physiological basis of yield improvement indicates that it comes not so much from increased efficiency of the photosynthetic apparatus or plant size (kg dry matter per hectare) but through more efficient allocation of dry matter within the plant. Recent research has been directed towards investigating how the plant distributes photosynthate amongst different plant parts; that is, the partitioning of assimilates. Efficiency of distribution is summarized in the agricultural term “harvest index” which is defined as the weight of the economically valuable part of the plant (e.g. grain, tuber, fibre, etc.) expressed as a proportion of the total weight. There is good ground for thinking that harvest index is heritable, being made up of a number of components, some of which have high heritability. Therefore, it might be expected that harvest index could be bred and selected for by plant breeders and could be used as a criterion in predicting the relative performance of genotypes and in estimating their potential for producing high yields. It is not clear how consistent harvest index is. Does it vary much when small changes in environmental conditions cause absolute yield to vary? If so, its value for deliberate improvement is limited. There is a need for more investigation of the consistency of harvest index under different environments. In this study the effect of environmental factors (namely, plant density, nutrient and water status of the soil and plant growth characters) on the partitioning of assimilates, in particular on harvest index, are examined. Harvest indices of different species and cultivars within species are compared. An attempt is also made to relate change in harvest index to evolutionary development of wheat.
| Item type | Current library | Collection | Call number | Copy number | Status | Barcode | |
|---|---|---|---|---|---|---|---|
| Thesis | CIMMYT Knowledge Center: John Woolston Library | Thesis Collection | Look under author name (Browse shelf(Opens below)) | 1 | Available | 623868 |
Thesis (M. Sc.)
A large increase in yield during the history of crop improvement has been achieved as a consequence of selection, both deliberate and non-deliberate, by man for improved yield. Probably, without exception, present-day crop cultivars greatly outyield their ancestors. An analysis of the physiological basis of yield improvement indicates that it comes not so much from increased efficiency of the photosynthetic apparatus or plant size (kg dry matter per hectare) but through more efficient allocation of dry matter within the plant. Recent research has been directed towards investigating how the plant distributes photosynthate amongst different plant parts; that is, the partitioning of assimilates. Efficiency of distribution is summarized in the agricultural term “harvest index” which is defined as the weight of the economically valuable part of the plant (e.g. grain, tuber, fibre, etc.) expressed as a proportion of the total weight. There is good ground for thinking that harvest index is heritable, being made up of a number of components, some of which have high heritability. Therefore, it might be expected that harvest index could be bred and selected for by plant breeders and could be used as a criterion in predicting the relative performance of genotypes and in estimating their potential for producing high yields. It is not clear how consistent harvest index is. Does it vary much when small changes in environmental conditions cause absolute yield to vary? If so, its value for deliberate improvement is limited. There is a need for more investigation of the consistency of harvest index under different environments. In this study the effect of environmental factors (namely, plant density, nutrient and water status of the soil and plant growth characters) on the partitioning of assimilates, in particular on harvest index, are examined. Harvest indices of different species and cultivars within species are compared. An attempt is also made to relate change in harvest index to evolutionary development of wheat.
English
9704
Thesis Collection
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