Evaluation of yield components, yield and competitive power of chickpea cultivars under weed interference

Weeds are among the main limiting factors in agriculture. In fact, the problem of weeds is a basic problem in farms, which can lead to major yield loss. Weeds can decrease soil nutrients and threaten crops by competing for water and light or by their allelopathic effects. Crop yield losses due to weeds depend on a number of factors such as grown species, weed number per area, weed competitive value, and crop developmental stage. Weeds can decrease grain quality, cause unequal maturation and harvesting difficulties, and act as the hosts for pathogens and pests. In addition, environmental and human health impact of herbicides, increasing resistance to herbicides, scarce by herbicides and increased conservation agriculture were the main factors stimulating the interest in developing new weed control methods. Chickpea is a weak crop against weed. Chickpea (Cicer arietinum L.) is one of the earliest cultivated legumes and has been found in the Middle East 7500-years ago. It plays an important role in human nutrition as a source of protein, energy, fiber, vitamins, and minerals for large population sectors in the developing world and is considered a healthy food in many developed countries. 

In order to evaluate yield components, yield and competitive power of chickpea cultivars, an experiment was conducted on a sand claysoil at the Agricultural Research Station (latitude 35˚1' N, longitude 48˚31' E and 1690 m altitude), Faculty of Agriculture, University of Bu-Ali Sina, Hamedan, Iran. The long-term average air temperature and average air temperature during the growing season was 12.5˚C and 22˚C, respectively. The experiment was done within two seasons, 2013 and 2014. The same field was used in both years and the same treatments were applied to the same plots. Experiment was conducted as the factorial based on randomized complete block design (RCBD) with three replications. Experimental treatments included weeding, no weeding of weeds, and five cultivars of chickpea (Tork, Hashem, Arman, Azad and Mahali). Analysis of variance was used for statistical analyses (Version 9.2, SAS). Differences between treatments were compared by least significant difference (LSD) test at the 5% probability. 

Analysis of variance showed that the effect of weed control on all traits except harvest index was significant. The effect of cultivar on all traits except harvest index was significant. The effect of weed control × cultivar interaction was statistically significant only on grain and biological yield. The highest grain yield (136.00 g m-2) was obtained for Hashem cultivar in weeding condition. The lowest value of this trait with about 75% reduction was obseverd for Mahali cultivar under no weeding condition. Maximum biological yield (394.75 g m-2) was observed for Hashem cultivar under weeding condition and the lowest value, with about 70% reduction, was found for Mahali cultivar under no weeding condition. Maximum and minimum weed biomass (104.99 and 52.50 g m-2, respectively) and weed density (20.50 and 10.67 per m2) was found for Hashem and Mahali cultivar, respectively. Therefore, results showed that the highest ability withstand competition (52.30) was observed for Hashem cultivar, and the lowest value of this index (39.12) was for the Mahali cultivar. The results showed that increasing the biomass of chickpea plants increased the ability withstand competition index, and decreased weed density and weed biomass. Therefore, Hashem cultivar can be known as a resistant cultivar against weeds, but Mahali cultivar has the lowest ability against weed invasion. In general, the use of resistant varieties is a good solution to reduce weed damages.

The results of this experiment showed that the yield of different chickpea cultivars decreased in the presence of weeds. However, yield reduction in different cultivars was not the same. As a result, Hashem and local cultivars were identified as the strongest and weakest cultivars against weeds, respectively. By evaluating the yield of different chickpea varieties and competitiveness index, the varieties with good competitive ability in the presence of weeds can be identified. Additionally, this has the potential for weed control management without chemical herbicides.