Compost enriched with ZnO and Zn-solubilising bacteria improves yieldand Zn-fortification in flooded rice

摘要

Zinc (Zn) is an essential element for humans, animals andplants, however, its deficiency has been widely reported aroundthe world especially in flooded rice. Adequate amount of Zn isconsidered essential for optimum growth and development of rice.We hypothesised that management practices like Zn-mineral fertiliser,-compost, and -solubilising bacteria would improve Znavailability and uptake in flooded rice. A series of studies wereconducted to find out the comparative efficacy of Zn-enrichedcomposts (Zn-ECs) with Zn solubilising bacteria (ZnSB) vs.ZnSO4 for improved growth, yield and Zn accumulation in rice.There were six treatments viz. control, ZnSB, ZnO (80% Zn),ZnSO4 (33% Zn), Zn-EC80:20 and Zn-EC60:40. In all the treatments,Zn was applied at the rate of 5 kg ha~(-1) except the control. Thetreatment Zn-EC60:40 resulted in the maximum Zn release in soil ascompared to ZnSO4 and all other treatments during incubationstudy. The treatment Zn-EC60:40 significantly improved root dryweight, grain yield and 100-grain weight of rice by 15, 22 and28%, respectively as compared to ZnSO4. The same treatmentresulted in the maximum increase in photosynthetic rate (11%),transpiration rate (21%), stomatal conductance (17%), chlorophyllcontents (8%) and carbonic anhydrase activity (10%) while adecrease of 27% in electrolyte leakage was observed in comparisonwith ZnSO4 application. Moreover, the maximum increase ingrain quality parameters and Zn bioaccumulation was observedwith the application of Zn-EC60:40 in comparison with ZnSO4application and all other treatments. We conclude that Zn-EC60:40are not only an effective strategy to improve growth, physiologyand yield parameters of rice, but also to improve the grain qualityand Zn-bioaccumulation in rice compared to ZnSO4.