Spike changes associated to six cycles of recurrent selection in bread wheat (Triticum aestivum L.)

Abstract

Eighty-four S-derived families (12 per cycle) and 12 wheat (Triticum aestivum L.) commercial varieties were evaluated to assess the effects of 6 cycles of recurrent selection (RS) on 11 spike characters. A random spike sample per family was divided into thirds for determination of seed number and weight per spikelet. Also, spikelet and seed number per spike, seed weight, and spike index were estimated. Significant differences between cycles of RS mean values were observed in 4 of the analyzed characters. The weight increased 11% at the 3rd cycle. With respect to the spikelet number per spike, a 7.8% increase was noticed after 6 cycles of RS. The higher spikelet number per spike of the sixth cycle of RS did not generate more seeds per spike. As the fertile flower number per spikelet was observed to be invariable, the diminution of spikelet fertility could be related to the suboptimal environmental conditions of cultivation during the critical period of grain number determination.