Assessment of planting date and seed density impact on yield and yield components of chickpea genotypes in dryland conditions of Mashhad

Chickpea (Cicer arietinum L.) is a pulse crop with high nutritional properties and is an important source for food, feed and forage. It is a drought-tolerant crop that is mainly cultivated in dryland farming and able to fix nitrogen at least 20-60 kg/ha. Nitrogen fixation and other characteristics of this crop are the reasons for expansion of chickpea cultivated land and use of this crop in rotation with other crops. It has been reported that planting date, cultivar and seed density have the important effects on quantity and quality of chickpea seed. Traditionally chickpea is planted in early spring in mostly cultivated land in Mediterranean regions and specially in our country and Khorasan Razavi province, while this crop could be cultivated in autumn or early of winter and reported that these planting dates had improved seed yield. Diverse cultivars of dryland chickpea with special characteristics have been introduced in our country that have the ability to adopt in dryland regions and increase the yield in unit area of dryland cultivation. Also has been reported that seed density affects on chickpea yield in dryland conditions. With attention to these matters, the aim of this experiment was determination of optimum planting date, introduction of proper chickpea cultivars and seed density for improvement of seed yield and developed chickpea cultivated land in dryland conditions of khorasan Razavi provinces.

In order to evaluate the effects of planting date and seed density on three cultivars and two landraces of chickpea, an experiment with split-split plot in randomized complete block design with three replications was conducted on Torogh agricultural and natural resources research station in 2015-2016. Treatments included of two planting dates, end of autumn (2015 Dec. 27) and usual planting date (2016 Mar. 8) as main plot, five genotypes of chickpea, included of Saral, Jam, Binalood cultivars and Neyshaboor and Ghouchan landraces as sub plot and two seed density of 40 and 50 seed/m-2 as sub-sub plot. After moldboard plow and disc, base fertilizer added to soil and plots determined. Each plot included of 6 row with 4 meter length and 25 centimeter row width. Weeding was made by hand and pest control was made by pesticides. Growth stages recorded weekly and in ripening stage, 5 plants harvested from each plot for determining of yield components and then whole plant of each plot harvested for seed yield determination.

Results showed that besides of yield and yield components, growth stage of studied genotype was affected by planting dates. Saral cultivar that was early maturity in first planting date, in second planting date was late. Also results showed that most of studied traits significantly were affected by planting date and with delay in planting date they significantly reduced. There was significant differences between planting dates and studied chickpea genotypes for many traits such as plant height, number of pod per plant, harvest index, biological yield, 100seed weight and grain yield. Mean grain yield of first planting date was 860 kg/ha that had significant advantage to second date (360 kg/ha). Jam cultivar and Neyshaboor landrace with mean yield of 761 and 764 kg/ha had the greater mean grain yield than other cultivars in two planting dates, but Jam and Saral cultivars and Neyshaboor landrace with grain yield of 1038, 900 and 908 kg/ha, respectively in first planting date, had the most yield and Binalood cultivar in second date with 30 kg/ha had the least seed yield among cultivars in this experiment.

 First planting date (27 Dec. 2015) improved the quantity and quality of produced grain in all cultivars and therefore is preferred to traditional planting date (8 Mar. 2016) and recommended. In the end of autumn planting date Saral and Jam cultivars and Neyshaboor landrace are best for cultivation from quantity aspect of grain production but if marketing is considered, because of small grain of Neyshaboor landrace (100seed weight was 17.7 g), Jam and Saral cultivars with 100seed weight of 25.9 and 26.8 g, respectively are appropriate for first planting date. In this study reaction of cultivars to planting date was differed and this point must be considered in selection of cultivars for each planting date. Seed density had not significant effect on the most important traits and therefore lower density will be recommended. With this considerations, chickpea has the potential as a useful crop in rotation with other dryland crops.