Effect of plant density and kaolin on yield and biochemical traits of wheat (Triticum aestivum L.) cultivars under rainfed condition

In order to investigate the effect of plant density and foliar application of kaolin on rainfed wheat cultivars, a factorial-split plot study was conducted in a RCBD with four replications under rainfed conditions in Koohdasht. Plant density factor viz. 350, 500, 650 and 800 plants per square meter and cultivar factor including three dryland wheat cultivars Karim, Kuhdasht and Qaboos as factorial in main plots and kaolin foliar application in two levels of non-application and application of Kaolin was placed in sub-plots. The results showed that with increasing plant density, the amount of polyphenol oxidase and peroxidase antioxidants (26.2% and 9.1%, respectively) and grain carbohydrates (11.9%) increased, but the amount of grain protein (4.3%) decreased, at the highest density compared to the control. The amount of nitrogen, potassium and iron in the grain decreased with increasing plant density. The highest amount of phosphorus, zinc and grain protein belonged to Qaboos cultivar, so that in Qaboos cultivar the amount of phosphorus was 6.4% and 1.9%, respectively, the amount of zinc was 4.6% and 1.3%, respectively, and the amount of protein was 2.5% and 0.3%, respectively, more than Karim and Kuhdasht cultivars. Foliar application of kaolin increases the uptake of all essential elements studied in the shoot and the amount of nitrogen, phosphorus, iron, zinc and carbohydrates in the grain; but reduces the antioxidants of the shoot and the amount of potassium and protein in the grain compared to the non-use of kaolin. In total, Qaboos cultivar at a density of 500 plants per square meter with the use of kaolin was recommended as the best treatment for grain production and enrichment at Kuhdasht region.