Effect of plant growth regulators on manipulation of source-sink relationships in pigeonpea (cajanus cajan l.)
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Date
2013
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PAU
Abstract
Field experiments were conducted at Punjab Agricultural University, Ludhiana during kharif season
in the years 2010-11 and 2011-12 respectively with an objective to evaluate various groups of genotypes (early, mid, late and check) on the basis of pattern of growth, partitioning of dry matter, flower retention, growth efficiency and yield and to study the effect of foliar application of ethrel (100 and 200 μg ml
-1 ) and cobalt chloride (10 and 15 μg ml -1 ) applied at vegetative and flowering stages on seed yield. Various morpho-physiological, biochemical and yield characteristics were analyzed at different developmental stages. Study conducted with early, mid, late and check genotypes of pigeonpea revealed marked differences in partitioning of assimilates to vegetative and reproductive parts at different stages of growth cycle. The higher CGR, RGR, leaf area, LAI, photosynthesis, stomatal onductance, pod set percentage in mid-duration group resulted in high yield. Further, reproductive efficiency of four mid-duration genotypes (AL 1578, AL 1593, AL 1702 and AL 201) was chemically manipulated by foliar application of ethrel and cobalt chloride. The parameters determining reproductive efficiency and yield were significantly improved due to reduction in flower abscission. Ethrel (100 and 200 μg ml
-1) sprayed at vegetative stage and CoCl2(10 μg ml-1) sprayed at flowering stage efficiently improved seed yield and other biochemical traits through improved flower retention, pod formation , seed setting percentage and seed weight. Genotype AL 1578 exhibited high yield in all treatments including control as compared to all the genotypes. The leaves of treated plants exhibited higher level of chlorophyll, which provided better conditions for higher production of photosynthates to be utilized for grain yield due to larger sink resulting from increased branching and number of pods. The treatments also affected the content of
various biochemical constituents (total soluble sugars, total soluble proteins, total starch content, total free amino acids, chlorophyll content as well as the activity of various enzymes viz., nitrate reductase (NR), invertase and PEP carboxylase). Correlation analysis showed significant positive relationships between plant height, crop growth rate, leaf area, number of pods/plant, pod set percentage, seed eight/plant, 100-seed weight and harvest index. Further, path analysis revealed leaf area, specific leaf weight and number of pods/plant had significant positive direct influence on yield. Path analysis of various biochemical traits with seed yield revealed that activities of nitrate reductase, total soluble proteins and total starch content in leaves and invertase activity, total starch in seeds showed positive direct effect on seed yield. These traits should be used as target traits to improve seed yield. Protein profiling in mature seeds revealed much denser bands in treated plants as compare to control and also number of bands were higher in treated plants. A study of pedicel anatomy revealed an increase in area of conducting tissues through PGRs application. This increase could be responsible for enhanced translocation of assimilates to flowers, thereby helping in their retention.
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Keywords
Pigeonpea, partitioning, abscission, nitrate reductase, yield, protein profiling, pedicel anatomy