source-sink relationship in wheat (triticum aestivum and t. durum) and triticale (triticale hexaploid lart.) genotypes under ahvaz conditions

in order to study the sink-source physiological relationship, current photosynthesis, contribution and remobilization of assimilates to grain yield in wheat and triticale genotypes, a field experiment was conducted in iran, ahvaz area on 2003-4. treatments were two bread wheat (simareh and tawer), one durum wheat (showa) and two triticale (juvanillo92 and line 45) genotypes. grain weight changes determined with removal of 50% spikelet from one spike side in main stem and tillers. results indicated that the highest and the lowest grain yield were in juvanilo92 and line 45 genotypes. higher grain yield in juvanillo92 genotype was due to higher biological yield (1500 g.m-2), grain number per spike (65) floret per spikelet (2.3) and spikelet number per spike (28). in average, source limitation was 22 and 30.7% in wheat and triticale genotypes, respectively. increase in grain weight in spikelet removal treatments compared to unmanipulated spike was 22.2 and 29% for main stem and tillers, respectively. it seems that this reaction was due to remobilization of assimilates from main stems to tillers by spikelets removal from main spikes. however, in desirable conditions, high yielding genotypes of wheat and triticale could be selected on the basis of the higher spike number and grain yield which are related to increase of source limitation.