Boron concentrations of dicotyledonous plants are several orders of magnitude higher than those of monocotyledonous plants. A study was taken to investigate the effect of different levels of boron application contributing to sunflower yield and oil production. This experiment was conducted during 2016-17 at ZARS, University of Agricultural Sciences, GKVK, and Bengaluru by taking sunflower as test crop in Alfisol. Experiment was designed as randomized complete block replicated thrice with five levels of B (2, 4, 8, 12 and 16 kg B ha-1) including control andonly NPK treatments, where boron was applied as borax (Na2B4O7.10H2O) to soil at the time of sowing with required NPK+FYM.The data showed that the highest seed yield (32.89 q ha-1) and dry matter yield (20.77 q ha-1) were observed where 2 kg B ha-1was applied and it significantly reduced with increase in B application rate. The yield reduction was to the tune of 5 to 60 per cent from 4 kg B to 16 kg B ha-1. Boron toxicity was seen at 4 and 16 kg B ha-1 application in the sunflower plant, and the toxic effect of B was more pronounced at 16 kg B ha-1. The B toxicity might be due to direct effect of B on pollen viability, fertility and seed set which increases with increase in B concentration in plant. The seed B concentration increased with the increase in B application which ranged from 21.17 per cent (T3: 2 kg B ha-1) to 27.00 per cent (T7: 16 kg B ha-1). However, the total uptake was higher in T2(1444.08 mg kg-1) and it significantly decreased in T7 (941.93 mg kg-1) as the B concentration increased to 16 kg B ha-1. Higher B application (16 kg B ha-1) resulted in toxic effect, where many cellular activities were partially inhibited, roots which could prohibit the nutrient uptake and plant growth which in turn lower plant growth and yield reduction of sunflower crop. Application of B had significant effect on the seed potassium content, dry matter N and P content. Major nutrients in post-harvest soil did not differ significantly, however B content linearly increased from 0.94 to 3.06 mg kg-1. The oil content and oil yield of sunflower was significantly affected by B. The higher oil content (42.06 %) was observed in 2 kg B ha-1 applied plot and lowest was observed in 16 kg B ha-1 (23.41 %) applied plot. The oil yield has decreased to the tune of 78 per cent with addition of 16 kg B ha-1 to soil. The higher oil content might be due to higher N uptake by seed and decreased as a result of less N uptake. Application of 2 kg B ha-1 significantly increased the grain yield and nutrients in sunflower which in turn directly effect on growth and yield of sunflower. As the B application rate increases the relative B toxicity affected on the dry matter, seed yield and oil production by sunflower crop.
Take away notes:
• Through my presentation, audience will understand how the higher doses of boron will affect the crop growth and production, and also know the optimal dose of boron nutrient. Audience will also understand the concentration of
boron in sunflower crop without any toxicity symptoms even at higher doses of boron, except reduction in growth and yield. This will be helpful to adopt it in their field or experimental stations for better crop productivity and precautions will be taken to avoid unnecessary application of higher doses of boron nutrient.