Effect of seeding rates and weed management on growth, yield and yield components of Mungbean (Vigna radiate L.)

Mungbean [Vigna radiata (L.)Wilczek] is the most important source of protein in south and southeast Asia. This plant, have the most important sources of protein in arid and semiarid regions and played a major role in the economy of the regions. Seed mung bean has 51% carbohydrate, 26% protein, 10% moisture, 4% mineral and 3% vitamin. This crop can be successfully grown on marginal lands where other crops perform poorly. Legumes, have mainly poor competition against weeds. Yield decrease in crops due to the presence of weed, depending on the area and specific weed species its area. Raman & Krishnamoorthy (2005) reported that mungbean yield decreased in infested treatment to weeds to 35 percent. Optimum plant population density is an important factor to realize the potential yields as it directly affects plant growth and development. The sowing rate of 20 kg h-1 usually recommended for small to medium seed varieties might be too low to obtain optimal yield. Barary et al. (2002) observed the effect of row and plant spacing on seed yield but it was not significant. Among the yield components, number of pods plant-1 and number of grains pod-1 and 1000 seed weight decreased with increasing seed rate. Determining the optimum plant density is very important to obtain maximum quantity and quality of economic yield. Reports show that the suitable density range of mung bean depends on the distance between plants. This study was conducted to investigate the effect of density on the morpho-physiologic traits and seed yield of the mung bean and to determine the optimum planting density on weed management in the Khorramabad. Field experiments were conducted at Lorestan Agricultural and Natural Resources Research Center, Khorramabad, Iran (48.36° E, 33.48° N, altitude), 1,125 m above the sea level with annual average precipitation and temperature of 471.5 mm and 17.7 C˚, respectively. The fields were in fallow in the preceding year of the experiments. The soil at the test sites were a clay-silt with a pH of 7.7 and organic matter of 1.0% in 2014. Prato cultivar has a 1000-seed weight of approximately 25 g. Layout system was randomized complete block design (RCBD) with factorial arrangements, with 8 treatments in 3 replications. Weed factor with two levels (controlled and uncontrolled) and seed rate per unit area (25, 50, 75 and 100 kg. h-1) equivalent (6, 12, 18 and 24 plant m-2) was calculated for each plot. In this experiment, after sowing mapping, evaluated treatments were randomly assigned to experimental plots and any density considered on the 6 lines with 6 meters length, rows spacing of 60 cm and 5 cm sowing depth. Seeds planting was done by hand in June 12, 2014. Irrigation was done immediately after planting. Due to climatic conditions, farm irrigation was carried out flooding until the end of the growing season (every 10 days). In the plots of interference treatment no operations performed against the weed control. Assessing the density and weeds biomass were randomly at flowering time of crop with samples of the two frame 0.5× 0.5m per plot. Density and dry matter of weeds were counted and measured. At the end of the growing season after physiological maturity with marginal effects deletion (half a meter from the beginning and end of each row) area of 6 m-2 from 4 central rows of each plot was measured to estimate biomass, yield and seed yield by 14% seed moisture. Determining of morphological traits and yield components was selected 10 plants from each plot at final harvest. The traits measured, including biological and seed yield, plant density, pod number per plant, seed number per plant and seed weight per plant. Analysis was done by analysis variance and by using SAS 9.1. For comparing regression coefficient and latitude of origin two treatments consisting weed free and weed infested in level of seed amount was used. The experimental maximum yield (2011 kg. h-1) was achieved for weed control treatment with crop density of 25 kg. h-1, while, the lowest yield (672.7 kg. h-1) was related to weedy plots with crop density of 100 kg. h-1. The study revealed that crop density of 25 kg. h-1 mung bean (Vigna radiate) (equivalent to 60 plant. m-2) is optimum to obtain maximum mung bean yield. Results also indicated mung bean yield increased by 82.7 by weed control, the importance of weed interference in reducing mung bean yield and necessity of weed control to achieve higher yields. Among the yield components, number of pods plant-1 and number of grains pod-1 and 1000 seed weight decreased with increasing seeding rate. It seems that seeding rate of 25 kg.h-1 reduced mung bean density in area unit, and increased weed growth probably due to abundance of resources. However, seed rate of 100 kg. h-1, the Generally, the results of this research showed that selecting mung bean varieties with runner type and optimum density performance used against weeds can increase competitive pressure. Weeds management by weeding out, not only makes more seed yield but also prevented environmental damage and will help environmental sustainability.