Flag Leaf and Awns Ablation and Spike Shading Effects on Spike Yield and Kernel Weight of Durum Wheat (Triticum Turgidum L. Var. Durum) Under Rainfed Conditions

Abstract

The present study was undertaken with the objective to investigate the photosynthetic contribution of flag leaf blade, awns and spike to the grain filling under semi-arid conditions. A field experiment including 13 durum wheat (Triticum turgidum L. var. durum) varieties and breeding lines was conducted at the Agricultural Research Station of the Field Crop Institute (ARS-ITGC) of Setif (Algeria) during the 2009-2010 cropping season. Source limitation treatments including a control, flag leaf blade ablation, awns removal and spike shading were applied at heading. Ten main stems were tagged per genotype and treatment in a random design with three replications. Grain yield and yield components were determined from two rows, one meter length per replicate. Compared to the control, the removal-shading treatments, averaged over varieties, induced significant declines of 14.7%, 21.7% and 8.0 % in the number of grains per spike, spike grain yield and kernel weight, respectively. The means of the control treatment were 46.8 kernels, 2.3 g per spike and 48.8 mg per kernel, for the number of grains per spike, spike grain yield and kernel weight, respectively. The differences between removal-shading treatments were not significant as indicated by the contrast analysis. The magnitude of the induced-declines, caused by the source limitation treatments, varied among the assessed varieties suggesting that compensation among plant organs was differential operating within the tested plant material. The analysis of the relationships between main stem traits and traits measured on an area basis suggested that genotypes with high number of fertile tillers/m² and those characterized by a high thousand-kernel weight had the ability to minimize declines due to source limitation through compensation among plant organs.