فصلنامه زراعت و اصلاح نباتات
سال شانزدهم شماره 2 (تابستان 1399)

In order to investigation of the effects of planting delay on yield and grain yield components of wheat cultivars, this research was done as split plot in randomized complete blocks design with three replications. the main factor with planting dates, including: November 7 (control), November 27, December 17 and January 6 and the sub-factor included three types of bread wheat cultivars: Setareh, Mehregan and Chamran2 (control). The results showed that between planting dates in terms of grain yield, biological yield, harvest index, number of spikes per spike, number of seeds per spike, number of spikes per m2, spike length and 1000-seed weight were statistically at the level of 1% and between Cultivars were significant in terms of grain yield, biological yield, harvest index, number of spikes per spike, number of seeds per spike, 1000 seed weight and spike length at 1% probability level and number of spikes per m2 at 5% level. The interaction effect of planting date and cultivar on grain yield, harvest index, number of spikes per spike, number of seeds per spike, number of spikes per m2 at 5% level. The highest seed yield was related to the planting date of November 7 and Chamran2 (control) cultivar with 6444 kg/ha and the lowest was related to the planting date of January 6 and Mehregan cultivar with 1519 kg/ha. As a result, planting of Chamran2 cultivar on November 7 and November 27 is recommended due to the increase in yield components and its effect on increasing grain yield.

Chilling stress is an abiotic stress including meteorological dynamics that happens at low temperatures. Chilling stress was introduced as the most important limiting factor in tropical and subtropical plants. In antioxidant activity, catalase, malon di-aldehyde and peroxidase enzymes were treated at temperatures of 20 ° C (control), zero degrees and 5 ° C in three Thymus vulgaris, Thymus daensis and Thymus kotschyanus thyme cultivars. The composite analysis was carried out with 3 replications. The results showed that there was a significant variation among the Thymus cultivars in terms of how to respond to temperature stresses, and the rate of enzyme changes in each of 3 significant factors justifying the role protecting them against environmental changes. Only in the amount of activity of catalase activity, the interaction of cultivars with treated temperatures was not particularly significant at 20 ° C (control) and zero degree, indicating the equality of the mode of reaction of thyme cultivars to the two treated temperatures.