000			03066nam a22003377a 4500
001			G63779
003			MX-TxCIM
005			20250411113406.0
008			250411s1979||||at ||||| |||| 00| 0 eng d
040			_aMX-TxCIM
041			_aeng
090			_aLook under author name
100	1		_aBamakhramah, H.S.
245	1	0	_aComparative growth studies of crop species with special reference to harvest index as a criterion of the yielding ability of a genotype
260			_aMelbourne (Australia) : _bUniversity of Melbourne, _c1979
300			_a130 pages
340			_aPrinted
500			_aThesis (M. Sc.)
520			_aA 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.
546			_aEnglish
591			_a9704
595			_aTC
650		7	_aCrop yield _2AGROVOC _91066
650		7	_aPlant growth _2AGROVOC _921209
650		7	_aHigh-yielding varieties _2AGROVOC _91147
650		7	_aPlant production _91212 _2AGROVOC
650		7	_aSelection _2AGROVOC _94749
650		7	_91134 _aGenotypes _2AGROVOC
650		7	_aPlant breeding _2AGROVOC _91203
942			_cTH _2ddc
999			_c41650 _d41650