The study of row mixed cropping in Durum wheat (Triticum durum) genotypes underwater deficiency Conditions

Durum wheat is one of the major food for human consumption in the world and its growth and production has mainly influenced by drought stress. One of the possible ways of increasing food in a sustainable agriculture is to produce higher yields in the same cropping area. Mixed cropping as one of the methods and examples of sustainable agricultural try to follow the objectives such as ecological balance, exploitation of resources, quantitative and qualitative increase of yield, reduction of damage of pests, diseases and weeds. Reduction of farmer's dependence on pesticides is one of the other main goals in sustainable agriculture. In general, the aim of this experiment is to evaluate the effect of genetic diversity of genotypes on yield and grain yield components under water deficiency conditions after flowering in durum wheat mixed systems.

This experiment was conducted as split plot based on a randomized complete block design with three replicates at Darab College of Agriculture and Natural Resources, Shiraz University, Darab. The factors included of two water regimes after flowering (normal and Water deficiency) and planting systems including pure culture of four durum wheat genotypes (pure culture of DW-92-4 , pure culture of DW-94-14, pure culture of Shabrang, pure culture of Behrang) and their binary mixed culture (mixed culture of DW-92-4+ Shabrang, mixed culture of DW-92-4+ DW-94-14, mixed culture of DW-92-4+ Behrang, mixed culture of DW-94-14+ Shabrang, mixed culture of Shabrang+ Behrang, mixed culture of DW-94-14+ Behrang and quadruple mixed culture of DW-94-14+ Behrang+ DW-92-4+ Shabrang).

According to the results of this experiment, maximum grain yield was observed in the treatment of binary mixed culture of Behrang+DW-94-14 genotypes with an average of 8815 kg ha-1, which did not have a significant difference with the quadruple mixed culture of 4 genotypes in normal irrigation conditions. The minimum grain yield observed in mixed culture of Behrang +Dw-92-4 with the average of 2233 kg ha-1 in water deficiency condition. Also, group comparison of treatments showed that the highest grain yield was obtained in quadruple culture of 4 genotypes with the average yield of 8799 kg ha -1in normal irrigation conditions. The analyses of correlation coefficient in this experiment showed that the highest positive correlation coefficient obtained between grain yield and biological yield (r = 0.76**) in water deficiency conditions. Also, the highest positive correlation coefficient was observed between grain yield and biological yield in normal irrigation conditions(r = 0.90 **).

The use of mixed cropping of different genotypes of durum wheat affected yield and yield components in this experiment. Mixed cropping of genotypes of durum wheat showed the highest yield under normal irrigation conditions compared to water deficiency conditions. Overall, it seems that mixed cropping can be recommended for higher yields potential either under normal irrigation conditions or water deficiency conditions. Keywords: Drought stress, Genetic diversity, mixed varieties