Effect of Plant Density on Seed Yield and Morphological Characteristics of Some Guilan Local Bean Lines

  Grain legumes, as a protein-rich food, play an important role in human nutrition, especially in developing countries. Common bean, being a leguminous and short duration crop, may be used as a soil improving crop in rotation and in cropping system. Among the various factors that contribute to the attainment of potential yield of common bean, optimum plant spacing or plant population is one of the important factors. Optimization of plant density for highly new yielding lines by following suitable inter as well as intra row spacing is essential. This study aimed to evaluate the effects of plant density on yield and agronomic traits of some Guilan local bean lines. This field experiment was carried out in split plot based on randomized complete block design with three replications in 2014-2015 growing season at Guilan Agricultural and Natural Resources Research and EducationCenter. The main factor was plant density at three levels (33, 16 and 11 plants per m2) and the split factor was five Guilan local bean lines (Gd91-7, Gd91-8, Gc91-9, Gd91-15 and Gd91-18). Analysis of variance showed that the effect of plant density was significant on dry seed yield, dry seed yield to pod yield ratio and biological yield per unit area. The effect of line was significant on plant height, pod length, seed length, pod yield per unit area, dry seed yield per plant, dry seed yield to pod yield ratio, harvest index and 100-seed weight. The interaction effect of the two factors was significant on the pod lenght, pod yield per unit area, dry seed yield per plant and 100-seed weight. The highest value of seed yield (11.44 g plant-1) was obtained in Gd91-8 at the density of 33 plants per m2. The highest (316.5 g m-2) and lowest (67.42 g m-2) values of dry seed yield was obtained at the density of 33 plants per m2 and 11 plants per m2, respectively. The highest values of green pods yield (1101.84 g m-2) was obtained in Gd91-15 at a density of 33 plants per m2. The reduction of dry seed yield per plant in 33 plants per m2 density in comparison to 16 plants per m2 for Gd91-18 and Gc91-9 and in 11 plants per m2 for Gd91-7 seems to be due to restricted access to the sun radiation or dietary lemitations and genotypic characteristics. Other reasons for the decrease of grain yield per plant at high densities can be the reduction of the number of pods per plant, number of seeds per pod, pod length and 100 seed weight. Gd91-8 as a superior line according to triats such as plant height, number of pods per plant, pod length, dry seed yield and green pod yield and can be used for breeding programes as a suitable line