Nagarathna T K, Gayithri M, Shadakshari Y G, Murali K, Puttarangaswamy K T and Punith H V
University of Agricultural Sciences, Bangalore, India
Posters & Accepted Abstracts: J Plant Pathol Microbiol
The major production constraints in sunflower are poor seed filling and seed set, lack of uniformity in open pollinated varieties leading to production instability, excessive vegetative growth and lack of photosynthetic activity at the time of seed filling and improper translocation of photosynthates. To improve the productivity, translocation of photosynthates from vegetative organs to seed is very important. To achieve higher yield, two sets of experiments were conducted in the field in two seasons to study the influence of source and sink manipulations on crop growth and yield in sunflower hybrid, KBSH- 44. In the first set of experiment, source size and sink capacity was manipulated by applying plant growth regulators, growth retardant, higher dose of nitrogen with micronutrients and source size was reduced by defoliation. In the other set, the source size was manipulated by different nitrogen levels, application of growth regulator mixture and defoliation with two plant densities. Manipulation of sink capacity by spraying 240 ppm TIBA with 120 ppm NAA and 0.2% boron improved the rate of translocation which in turn increased the productivity by 33% to 36%. Due to more biomass and yield, harvest index was also increased by 32%. Cycocel (3000 ppm) at ray floret stage increased the seed yield followed by spraying of 150 ppm BA at ray floret stage. These hormones play a major role in increasing translocation of photosynthates from source to sink especially during seed filling period. Further, increase in source size by applying 200% nitrogen combined with growth regulator mixture by maintaining recommended plant density, productivity can be increased up to 10-15%. Results from this study indicate that, seed development in sunflower is source limited which can be improved when the available source size increases. Nitrogen fertilization has a substantial influence on sunflower seed yield and high yielding sunflower hybrids have more nitrogen requirement to enhance the yield.
Email: [email protected]