Effect of irrigation regime and plant density on yield and yield components of chickpea (Cicer arietinum L.)

Legumes contain an average of 18-32% protein and are an important source of protein for low-income people (Majnoun Hussein, 2008). Chickpea (Cicer arietinum L.) Is known for its resistance to moisture changes; this plant shows physiological and morphological changes under conditions of water scarcity (Ghorbanli et al., 2001). Chickpea grows in a wide range of weather conditions from the subtropical to Mediterranean regions of western Asia, northern Africa, and southern and southwestern Europe (Toker et al. 2007). Environmental stresses are the most important factor that limits crop production of chickpea. The most critical environmental stresses that have a negative effect on crop production are water and heat stresses (Rahbarian et al. 2011). By applying the effect of different levels of irrigation and plant density on yield and yield components of chickpea, grain yield, 1000-seed weight, the number of pods per plant and harvest index decreased during drought stress (Raei et al., 2008). Severe drought stress, by reducing the water uptake by the roots, disrupts the transfer of sap in the phloem, which ultimately leads to a decrease in nutrient uptake and the activity of antioxidant enzymes (Armand et al. 2016). Plant density is one of the most important management factors on crops that will affect plant yield. When competition for growth increases, the yield will be decreased. The selection of appropriate plant density should be based on environmental factors such as cultivar, cultivation target, weed competition, seed size, soil moisture content, and plant characteristics including plant height, plant density, leaf angle, and production capacity of the growing environment (Khajehpour, 2008). According to the above, this study was conducted to investigate the effects of different levels of irrigation and planting density on some agronomic traits of white chickpea in Karaj.

To investigate the effect of water regime and plant density on some agronomical traits of chickpea (Cicer arietinum), a split-plot experiment based on randomized complete block design with three replications conducted at the College of Agriculture and Natural Resources of Karaj, Iran in 2015. The water levels included eight levels (I1 =full irrigation at all growth stages, I2 = irrigation to grain filling and then stop, I3 = irrigation to podding and then stop, I4 = irrigation to flowering and then cut, I5 = 50% of full irrigation at all growth stages, I6 = 50% of full irrigation to grain filling and then stop, I7 = 50% of full irrigation to podding and then stop, I8 = 50% of full irrigation to flowering and then stop, considered as the main factor and plant density at three levels (30, 40 and 50 plants.m-1) as subplots. Geographical characteristics of this farm include 1321 meters above sea level, longitude 51 degrees east, latitude 35 degrees and 48 minutes north. This region has a hot and dry climate with an average rainfall of 33 years, about 248 mm.

The results showed that increasing water deficit stress reduced the growth traits and ultimately the grain yield of chickpea cultivar ILC 482. Increasing plant density increased the growth traits of yield components and grain yield. The highest grain yield (2892 kg. ha-1) was obtained in full irrigation (I1), and the lowest (1075 kg. ha-1) gained from I4. The highest grain yield (2068 kg. ha-1) was acquired at 40 plants m-1.

The results of this study showed that low water stress reduced the yield of chickpeas, but since Iran has low average rainfall, it is possible to achieve a good yield by using 50% irrigation at all stages of growth.