In order to evaluate the effect of sowing date and planting pattern on yield and qualitative parameters of rapeseed (Brassica napus L.) and chickpea (Cicer arietinum L.) in intercropping, a split plot experiment was conducted based on randomized complete block design with four replications, in Hamedan, Iran, during 2014-15. The rapeseed seeds were sown on 21st September. Chickpea was sown on four sowing dates as the main factor (21 September, 10 October, 30 October and 20 November) with 20 days interval. The sub-factor was the planting pattern by replacement series including 100:0, 75:25, 50:50, 25:75 and 0:100 chickpea-rapeseed mixtures, respectively. Based on the results obtained, among chickpea sowing dates, the first and the last dates had the lowest and highest above-ground biomass and grain yield, respectively. During the late sowing date of chickpea (20 November) the field temperature was colder than the earlier dates, and therefore the freezing temperatures did not allow the seeds to germinate. However, no damage happened to seedlings with the earlier sowing dates. The highest yield was observed in sole cropping for both crops. In contrast, the highest values of land equivalent ratio were obtained in intercropping system. The highest value for land equivalent ratio was calculated as 1.23 in intercropping of 50% chickpea + 50% rapeseed.

To determine the possible protective and enhancer role of selenium foliar application on oil yield, fatty acid composition and glucosinolate content of rapeseed cultivars under late-season thermal stress, a factorial split-plot experiment based on randomized complete block design with three replications was carried out in Karaj, Iran during the two growing seasons 2014–2015 and 2015–2016. Three sowing dates (Oct. 7 as normal planting date), (Oct. 17 as semi-late planting date), (Oct. 27 as late planting date) and two selenium foliar application (non-application as control and sodium selenate as foliar application) were factorially randomized to main plots, and rapeseed cultivars were allocated to sub-plots. Plant materials were six cultivars including three hybrids and three Iranian open pollinated varieties. Late-season thermal stress caused by late planting date reduced oil yield, oil content, oleic acid, linoleic acid, palmitic acid and increased linolenic acid, erucic acid and glucosinolate content of investigated cultivars. The results of this study demonstrated that the highest amount of oil yield, oil content, oleic acid, linoleic acid, palmitic acid and the lowest amount of erucic acid and glucosinolate content were observed in L72 cultivar in both control and selenium application treatments. This study provided new important findings about the supportive and enhancer role of selenium in the form of sodium selenate on quantity and quality of oil in rapeseed plant.

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Weeds that emerge along with or immediately after crop plants usually can reduce the yield of those crops.Two randomized complete block design experiments were conducted during 2006 and 2007 in Tabriz, Iran to determine the critical period of redroot pigweed control in the green bean hybrid "Cantander".The treatments were weed-infested and weed-free plots at 2, 4, 6, 8, 10, and 14 weeks after bean emergence (WABE).The green bean biomass was affected by the early emergence of redroot pigweed, but it was not reduced when redroot pigweed emerged at 10 weeks after crop emergence, along with crop emergence, and grew with green bean until 4 WABE.The redroot pigweed biomass decreased by 2.7 g m -2 per day when weed emergence was delayed. Each 100 g m -2 of weed biomass that was produced resulted in a 1.4 kg ha -1 loss in the green bean yield. When redroot pigweed interference lasted for Ն4 weeks after green bean emergence, the green bean yield was reduced significantly. Weeds, which emerged 2 weeks after green bean and thereafter were controlled, did not decrease crop productivity significantly. The highest crop yield was obtained when the weed emerged at 14 WABE. The critical period of redroot pigweed control, considering a 10% yield loss, was between 19 and 55 days after green bean emergence. Thus, weed control practises should be begun no later than 3 WABE and should continue until at least 8 WABE in order to obtain the maximum green bean yield.