Physiological and anatomical basis of flower drop in pigeonpea (Cajanus cajan L.) in response to foliar application of mineral nutrients
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Date
2015
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Publisher
PAU
Abstract
In the present investigation, the effect of mineral nutrients viz., CaCl2 (1mM and 2mM), KNO3 (0.5% and 1%), MgCl2 (0.1% and 0.2%) and urea (1% and 2%) on growth, yield and anatomical changes in pedicel of Cajanus cajan L. were studied. Two pigeonpea varieties (PAU881 and AL201) were sown in a randomized block design and sprayed with each of these mineral nutrients at green floral bud stage of inflorescence. Foliar application of different mineral nutrients improved the vegetative growth of pigeonpea varieties. Growth efficiency parameters i.e. plant height, number of branches, CGR and RGR showed an increase with application of mineral nutrients. Leaf characteristics viz., LA, LAI and SLW also showed an improvement following mineral nutrients application. Mineral nutrient application enhanced the stomatal conductance which significantly increased internal CO2 concentration (Ci) and ultimately enhanced photosynthetic efficiency of crop. Partitioning of dry matter towards reproductive parts was significantly improved by mineral nutrient application which increased the number of flowers and their retention. Yield of pigeonpea varieties was efficiently improved with mineral nutrient application through higher flower retention, high pod set percentage, increased pod weight and 100 seed weight. Mineral nutrient application also enhanced the level of total soluble sugars, starch, soluble proteins and free amino acids in leaves and developing seeds of both the varieties. The activities of nitrate reductase, PEPC and invertase were favourably modified especially with urea and potassium application. These mineral nutrients declined the activity of hydrolytic enzymes viz., cellulase and polygalacturonase in flower pedicel and ultimately enhanced the flower retention. The area of translocatory tissues particularly phloem was greater in pedicel of treated plants which indicates better translocation efficiency of these plants as compared to control. Amongst all the treatments, 2% urea application proved to be most efficient in terms of improved growth efficiency, biochemical constituents in leaves and seeds, increased retention of flowers and pods thereby mproving yield of both the varieties. Protein profile of mature seeds showed the appearance of some new proteins as well as increase in intensity of a few protein bands in seeds of treated plants. Correlation analysis of number of branches, leaf area, CGR, photosynthetic rate, pod weight/plant, harvest index and pod set percentage showed strong positive correlation with yield. Correlation matrix of biochemical parameters viz., total soluble sugars, total starch, free amino acids, total soluble proteins in leaves and in developing seeds, PEPC and nitrate reductase activity in leaves and invertase activity in seeds showed significant positive correlation with yield. However, the activity of cellulase and polygalacturonase in pedicel were negatively correlated with yield. Further, path analysis showed that number of branches, CGR, pod weight, harvest index, total soluble sugars, free amino acids and total soluble proteins in leaves, total soluble sugars and invertase activity in seeds had higher direct contribution to yield.
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Keywords
productivity, irrigation, storage, additives, economic systems, inorganic acid salts, adsorption, preservation, biological development, acidity