The effect of wheat residue management and nitrogen levels on yield and yield component of mungbean (Vigna radiate)

IntroductionCrop residues are those parts of the plants that left in the field after the harvestable parts of crops (grain, tubers, roots, etc.) are removed. The recycling of crop residues has the advantage of converting the surplus farm waste into useful products for meeting nutrient requirements of crops. It also maintains the soil physical and chemical condition and improves the overall ecological balance of the crop production system. Research has shown that the return of crop residues on fragile soils improved the tilt and fertility of soil, enhance crop productivity, reduce the wind and water erosion and prevent nutrients losses by run off and leaching. Despite these advantages, farmers in Iran prefer to remove crop residues out of field to feed livestock or use them as fuel or as building construction materials and burning. Nitrogen is one of the basic compounds in plant nutrition and its deficit directly one of important growth limiting factors in plants because the need of plants to this element is much more than the other one. The aim of the present study was to evaluate the wheat residue management and nitrogen fertilizer levels to improve mungbean growth and productivity under Ahwaz conditions.
Materials & MethodsThe experiment was conducted at Agriculture Faculty Farm, of Chamran University during summer of 2014. The soil texture of the experimental site is clay loam with pH of 7.9 and EC of 2.8 ds.m-1. The experiment was conducted in randomized complete block design using split plot arrangement with three replications. Five crop residues (0, 1750, 3500, 5250 and 7000 kg.ha-1) were assigned to the main plots. While three levels of nitrogen (0, 150, 250 kg.ha-1) were applied to the sub plots. The experimental unit area was 10.5 m2 (4.2 × 2.5 m). At harvest, random samples of ten plants for each experimental unit were taken and plant height number of branches, pod per plant, seed per pod, 1000 grain weight, were recorded. Whole plot was harvested for determination of seed, straw and biological yield and harvest index. All collected data were subjected to analysis of variance procedure using the MCTATC statistical software and means were separated using Duncan method at 5% level of significance.
Results & DiscussionThe results of experiment revealed that crop residue management and interaction wheat residue and nitrogen levels had a significant effect on number of pod plant-1, number of seed pod-1 traits. Wheat residue incorporation enhanced those traits in comparison with control (No crop residue incorporation) in this respect application of 3500 kg/ha straw (50% wheat residue) produced 50.77 pod per plant and 9.75 seed per pod respectively. It is plausible that wheat residue gave the highest number of branches, consequently increased the number of plant. Application of N fertilizer significantly enhanced all yield component in this study compared with control. The highest values of number of pod per plant, number of seed per pod and 1000 kernel weight, plant height traits were obtained when N application was used at the rate of 250 kg ha-1. There was no significant difference between the mean values obtained from applying 150 or 250 kg ha-1 for number branch/plant and 1000 seed weight. The results are in agreement with that obtained by Achakzai et al., (2010) and Azadi et al., (2013). Data revealed that wheat straw rates, N fertilizer levels and their interaction had significant effect on seed yield and biological yield and harvest index. Application of wheat straw enhanced this trait in comparison with control (no crop residue) and the superiority in this respect to (3500 and 5250 kg.ha-1 wheat straw) which gave the highest values of 2611 and 6983 for seed yield and biological yield respectively. The highest values of seed yield and biological yield were obtained when N fertilizer application was used at the rate of 250 kg.ha-1, furthermore, the interaction between crop residue and N fertilizer rates had significant effect on seed yield and biological yield. The highest seed yield and biological yield were obtained from combination treatment with 50% wheat straw incorporation and 250 kg/ha with no significant differences between this interaction and obtained seed yield and biological yield from 75% wheat straw and 250 kg N.ha-1. This is to be logic since the same interaction gained the highest values of yield components and consequently seed yield. It might be due to the addition of crop residue and additional fertilization which might have improved the soil health and consequently higher uptake of available nutrients from the soil and increased the yield components, morphological and physiological characteristics which ultimately attributed to increase grain yield. Crop residue on decomposition released nutrients slowly throughout the growth period, which resulted in better plant growth and higher yields. Also biological nitrogen fixation by legumes increased by crop residue application on soil surface due to better activity of rhizobia created by relatively cooler and moist environment in the rhizosphere led to high crop growth, increased NPK uptake, and resulted into significant increase in mungbean yield.
ConclusionThe results of this experiment showed that application of 3500 kg wheat residue ha-1 and 250 kg N.ha-1 enhanced crop growth and produced the highest seed yield.