Effect of Planting Date and Biological and Chemical Fertilizers on Phenology and Physiological Indices of Peanuts

IntroductionPeanut (Arachis hypogaea L.) is an annual herbaceous plant in Fabaceae which grown in tropical to temperate regions worldwide for extracting its seed oil and nut consumption. Select the optimum planting date is one of the most important agricultural techniques that comply with the seed yield is maximized . For instance, delay planting date can reduce the number of fertile nodes and the number of pods per plant. The delay in planting date reduces total dry matter (TDM), leaf area index (LAI), crop growth rate (CGR) and yield in bean (Phaseolus vulgaris L.). Daneshian et al., (2008) reported that the delay in planting date reduced sunflower (Helianthus annuus) yield due to high temperatures in early growth which shortened flowering time and reduced solar radiation. On the other hand, due to increase importance of environmental issues has been attending biofertilizers to replace chemical fertilizers. Biofertilizers has formed by beneficial bacteria and fungi that each of them are produced for a specific purpose, such as nitrogen fixation, release of phosphate, potassium and iron ions of insoluble compound. The use of nitrogen fertilizer with slow-releasing ability stimulated shoot growth in soybean (Glycine max) and be created more LAI in the reproductive process, particularly during grain filling stage and finally increased seed yield . Therefore, this study was conducted in order to evaluate the interaction of biological and chemical fertilizers in the purpose of achieving sustainable agriculture with emphasis of the effects of various planting dates on physiological parameters and growth of peanut in Hamadan.
Materials and MethodsIn order to investigate the effects of planting date on important physiological indices of peanuts (Arachis hypogaea L.) under the influence of biological and chemical fertilizers. A field experiment was conducted in the research farm of Bu-Ali Sina University, Hamedan during 2013 growing season. This study was done as a split plot experimental design based on randomized complete block with three replications. Peanut cultivar was Fleury Spanish which was prepared by the Research Center of Guilan. Three planting date included 22 May, 31 May and 10 June were used as main plot and four levels of fertilizers included 50% nitrogen chemical fertilize nitrogen biofertilizer complete phosphorus chemical fertilizer, 50% phosphorus chemical fertilizer phosphorus biofertilizer complete nitrogen chemical fertilizer, 50% nitrogen chemical fertilizer and 50% phosphorus chemical fertilizer nitrogen -phosphorus biofertilizers, and 100 % chemical fertilizer were tested as sub plot. In order to evaluate the effect of planting date and various fertilizer application on changes trend of LAI, CGR and TDM, different models (1, 2, 3) were fitted to the data.
Statistical analysis was performed using the SAS; ver. 9.1 software and mean comparison was done through Duncan test.
Results and DiscussionThe result of analysis of variance indicated that, the main effects of planting date and biofertilizer for traits such as days to flowering, days to podding, days to maturity were significant at the 1% level. However, their interaction was not significant. For mentioned traits, the 22 May planting date was better than the other planting dates. It seems that in the third planting date, plant flowering was occurred earlier than the first date. High temperature with delayed planting shortened the peanut growing season and it accelerated flowering period. Moreover, complete chemical fertilizers (100%) was highest for mentioned traits and combine using of chemical fertilizer and nitrogen phosphorus biofertilizers had the least difference compared to complete chemical fertilizer. Nitrogen-fixing bacteria help the plant to absorb more nutrients which causes increasing plant growth and the number of lateral branches in plant. Plants inoculated with Pseudomonas illustrated an increase in the amount of leaf chlorophyll content compare to plants without inoculation after 45 days which it can be attributed to the increased availability of iron in the siderophore production by Pseudomonas. Results indicated that the interaction between planting date and bio-fertilizers in maximum leaf area index, maximum crop growth rate and maximum total dry weight was significant at the %1 level. Changes in leaf area and crop growth rate and total dry matter in all planting dates had a similar trend.The highest growth index was obtained from the first planting date (22 May) with application of 100% chemical fertilizer and also combine using of chemical fertilizer and nitrogen phosphorus biofertilizers. Increasing CGR during the growing season can be attributed to the increasing of leaf area or less reduction of leaf net photosynthesis. The delay in planting date reduces the length of growing season and simultaneous occurrence of reproductive stages and late season heat stress caused the reduction in dry matter accumulation. Azospirillum with the ability to nitrogen fixing, improved root growth and increase the rate of absorption of water and nutrients and thus it causes the increase of leaf area and crop growth rate . The ccombined use of humic acid and Pseudomonas putida increased soil pH that with phosphorus availability it will make further increase soybean yield. The delay planting date has been reduced the maximum leaf area index and leaf area. Although biological nitrogen fertilizer alone could not increase the leaf area duration as much 100% chemical fertilizer, biological nitrogen fertilizer in combination with phosphorus biofertilizer increased leaf area for the 22 May and 31 May planting date. Plant yield had a direct correlation with growth duration. Whatever growth duration is longer; the amount of radiation absorption by plant increased and causes the increase crop yield. Accumulation of organic matter by bacteria in the soil increased the nutrient availability, which caused more significant increase in the number of seeds per pod and seed weight and grain yield.
ConclusionsThe results revealed that the 22 May planting date had the highest growth and yield compare with the other planting dates. In addition, using a combination of biological and chemical fertilizers decreased application of 50% chemical fertilizers. Therefore, in order to achieve sustainable agriculture and reducing environmental pollution, combination of biological and chemical fertilizers can be a viable alternative to reduce the application of nitrogen and phosphorus chemical fertilizers for peanut production in Hamedan condition.