Nano fertilizers for enchancing the productivity of sunflower (Helianthus annus L.)

Abstract

A study entitled ‘Nano fertilizers for enhancing the productivity of sunflower (Helianthus annuus L.) was carried out at International Crops Research Institute for the Semi-Arid Tropics, Hyderabad during early summer season of 2021 and 2022 with the objective of productivity enhancement of sunflower through nano N, P, K and nano boron fertilizer application. The research work consists of two field experiments viz., 1) Standardization of nano N P K dose for enhancing the productivity of sunflower and 2) Response of sunflower to foliar application of nano fertilizers. Both the experiments were laid out in randomized block design with three replications. Experiment I consisted of 7 treatments viz., T1-Conventional fertilizers as per recommended dose (75:90:30 Kg ha-1), T2- nano N P K at 100 Kg ha-1, T3 - nano N P K at 80 Kg ha-1, T4- nano N P K at 60 Kg ha- 1, T5- nano N P K at 40 Kg ha-1, T6- nano N P K at 20 Kg ha-1, T7-Absolute control. Among different treatments, application of nano N P K (19:19:19) @ 100 kg ha-1 recorded significantly higher plant height, number of leaves, leaf area, leaf area index and dry matter production at all growth stages except at 30 DAS and it was statistically on par with the application of nano N P K @ 80 kg ha-1. At 0 - 30 DAS & 90 DAS - harvest, both the crop growth rate and relative growth rate doesn’t show any significant difference among the treatments. At 30-60 DAS, highest crop growth rate and relative growth rate was recorded with application of nano N P K (19:19:19) @ 100 kg ha-1. Net assimilation rate doesn’t show any significant difference at different stages of sunflower except at 60-90 DAS. Yield parameters viz., head weight (g), number of seeds per capitulum, filling percentage, seed yield per plant, seed yield (kg ha-1), stalk yield (kg ha-1) and oil yield (kg ha-1) were significantly influenced by nano fertilizer treatments. Application of nano N P K (19:19:19) @ 100 kg ha-1 & 80 kg ha-1 were significantly on par and resulted an yield increment of 16.8% and 13.3 %, when compared to conventional fertilizers. Higher uptake of nitrogen, phosphorus and potassium at 60 & 90 DAS was observed with application of nano N P K @ 100 kg ha-1. The highest available soil nitrogen and phosphorus after harvest of sunflower was observed with the application of nano N P K @ 100 kg ha-1. With respect to potassium, highest available soil K was observed with the application of nano N P K @ 100 kg ha-1 in the first year. But, in the second year it doesn’t show any significant difference. Conventional fertilizer treatment recorded the lowest nutrient use efficiency in terms of partial factor productivity, agronomic efficiency and apparent recovery, when compared to nano fertilizer treatments. The result of the experiment indicated, application of nano N P K (19:19:19) @ 100 kg ha-1 & 80 kg ha-1 resulted significantly higher yield when compared to conventional fertilizers and found to be the best treatments in increasing the crop growth, productivity and yield of sunflower. Even though, higher yield was recorded in treatments with the application of nano N P K @ 100 and 80 kg ha-1, higher net returns and B:C ratio was observed in conventional fertilizer treatment because of high cost of nano fertilizers resulted in higher cost of cultivation and reduced net returns and B:C ratio. At present, nano fertilizers are not profitable to the farmers. Experiment II consisted of 12 treatments Viz., T1 - Conventional fertilizers as per recommended dose (75:90:30 Kg ha-1), T2 - Conventional fertilizers as per recommended dose + nano (19:19:19) N P K @ 0.2% as foliar spray at 30 DAS and 60 DAS,T3-Conventional fertilizers as per Recommended dose + N P K (19:19:19) @ 0.2% as foliar spray at 30 DAS and 60 DAS , T4 - Conventional fertilizers 50% as per Recommended dose + nano (19:19:19) N P K @ 0.2% as foliar spray at 30 DAS and 60 DAS; T5: Conventional fertilizers 50% as per Recommended dose + N P K (19:19:19) @ 0.2% as foliar spray at 30 DAS and 60 DAS, T6 - nano (19:19:19) N P K @ 0.2% as foliar spray at 30 DAS and 60 DAS, T7 - T2 + nano boron @ 0.2 % as foliar spray at ray floret opening (RFO) stage, T8 - T3 + nano boron @ 0.2 % as foliar spray at RFO stage, T9 - T4 + nano boron @ 0.2 % as foliar spray at RFO stage, T10 - T5 + nano boron @ 0.2 % as foliar spray at RFO stage, T11 - T6 + nano boron @ 0.2 % as foliar spray at RFO stage, T12 - Absolute control. Soil application of conventional fertilizers as per recommended dose (75:90:30 kg ha-1) + nano (19:19:19) N P K @ 0.2% as foliar spray at 30 DAS and 60 DAS + nano boron @ 0.2 % as foliar spray at RFO stage recorded significantly higher plant height and number of leaves, leaf area, leaf area index and dry matter production at all growth stages except at 30 DAS and it was statistically on par with application of conventional fertilizers 50% as per recommended dose + nano (19:19:19) N P K @ 0.2% as foliar spray at 30 DAS and 60 DAS + nano boron @ 0.2 % as foliar spray at RFO stage. All the yield parameters, seed yield (kg ha- 1) and stalk yield (kg ha-1) were significantly influenced by various foliar treatments except capitulum diameter (cm), test weight (g) and harvest index (%). An increment in seed yield of 22.71 % & 21.97 % was observed with T7 and T9 when compared to conventional fertilizer treatment (T1). Foliar application of nano (19:19:19) N P K @ 0.2% at 30 DAS and 60 DAS resulted in yield increment in the range of 2.23 to 9.68 % compared to the conventional foliar sprays. Similarly, foliar application of nano boron @ 0.2 % at ray floret opening stage resulted in yield increment in the range of 7 to 19.34% compared to the treatments without nano boron spray. At 60 and 90 DAS, higher uptake of nitrogen, phosphorus and potassium was observed with T7 and was on par with T9. At 90 DAS, highest boron uptake was recorded in T7 and was on par with treatment T9, T8 and T10. After harvest of sunflower, soil pH, EC, organic carbon and available nitrogen, phosphorus, potassium and boron doesn’t show any significant difference among the treatments. Soil application of conventional fertilizer recorded the lowest nutrient use efficiency in terms of partial factor productivity, agronomic efficiency and apparent recovery, when compared to treatments receiving foliar sprays. The result of the experiment indicated that foliar application of nano (19:19:19) N P K @ 0.2% at 30 DAS and 60 DAS + nano boron @ 0.2 % at ray floret opening stage helped to reduce conventional fertilizers as per recommended dose (75:90:30 kg ha-1) to 50% without effecting the productivity of sunflower. Even though, higher yield was recorded in T7 & T9, but higher net returns and B:C ratio was recorded with application of conventional fertilizers 50% as per recommended dose (75:90:30 kg ha-1) + nano (19:19:19) N P K @ 0.2% as foliar spray at 30 DAS and 60 DAS) because of high cost of nano boron fertilizer resulted in higher cost of cultivation and reduced net returns and B:C ratio in T7 & T9.