Response of Rice (Oryza sativa L.) to Soil and Foliar Application of Nano-ZnO and Bulk Zn-fertilizer in Red Acidic Soil of West Bengal, India

In cereal crops Zinc (Zn) deficiency has become a major problem which causes reduction in yield and nutritional quality of the cereal grain, thus affecting human health. Being an essential micronutrient for the production of rice crop, Zn deficiency appears to be an acute problem for the human population whose staple food is rice. Small increase in the nutritive value of rice can thus contribute to the human nutrition. Thus, increasing the micronutrient content of a food crop with the help of enriched fertilizers appears to be an effective way. During two successive growing seasons (wet season, 2017 and dry season, 2018) at the experimental farm of Palli Siksha Bhavana, Visva-Bharati, West Bengal, India, field experiments were carried out to assess the potential of Zn fertilizer on plant height, grain quality, leaf chlorophyll and leaf Zn content of rice plant (Oryza sativa L.) variety MTU-1010 by application of foliar Nano-ZnO (Zinc oxide) and soil ZnSO4.7H2O (Zinc Sulphate Hepta Hydrate). In both seasons, each experiment was conducted in a randomized block design (RBD) with three replicates. Soil Zn as ZnSO4.H2O applications were assigned in the plots at the rate of 5 kg/ha and 0.30% nano-ZnO were assigned as foliar Zn spray along with the basal doses of 80 kg nitrogen (N), 40 kg phosphorus (P2O5) and 40 kg potassium (K2O)/ha as per the treatment details. After 15 days, 30 days, 45 days from transplanting and at the time of flowering as well as post-flowering chlorophyll (a, b, a+b) and Zn in rice plant leaves were determined. Plant heights were recorded after 30 days, 60 days and 90 days from transplanting and at the time of harvest. Quality parameters such as amylose, starch and crude protein content of the grain samples were determined at harvest stage. The results obtained from present assessment showed that, application of soil as well as foliar Zn resulted in significant increase in leaf Zn content, chlorophyll content, grain crude protein and plant height compared to the control. No significant effect on starch and amylose was recorded with Zn fertilization. Foliar spraying with 0.30% nano-ZnO at the time of flowering and post flowering showed a significant augmentation in leaf Zn concentration, chlorophyll content, plant height and quality of rice grain compared to the treatments receiving soil Zn application. Therefore it is considered as a more beneficial treatment in the cultivation of rice plants to promote plant growth and quality.