Bio fortification of rice (Oryza sativa) with zinc under organic and integrated nutrient management practices

Abstract

An investigation entitled “Biofortification of rice (Oryza sativa) with zinc under organic and integrated nutrient management practices” was carried out in Regional Agricultural Research Station (RARS), Pilicode during June to October 2018. The study was conducted in rice variety Uma (MO 16). The main objective of this research was to check the zinc nutrient content under organic and integrated nutrient management practices (INM). The field experiment was laid out under Randomized Block Design (RBD) with nine treatments and one control each replicated three times. The treatments consisted of soil application of Zn and combined soil and foliar application of Zn under organic (Organic Package Of Practice) and INM practices (Package Of Practice Kerala Agricultural University). Zn was applied as zinc sulphate (ZnSO4) at the rate of 1 per cent and 20 kg ha-1 as foliar application and soil application respectively. Foliar application of ZnSO4 was done at three growth stages of rice viz tillering, panicle initiation and flowering stage. Single foliar application of Zn was done at only tillering stage. Double foliar application of Zn was done at tillering and panicle initiation stages and triple foliar application of Zn was done at all the three growth stages. The effect of different treatments significantly influenced plant growth attributes like plant height, number of tillers per hill and panicles per hill. At harvest stage, the highest plant height (99.9 cm) was recorded in T8 (POP KAU + soil application of Zn + triple foliar spray of Zn) which was on par with T7. The minimum plant height was recorded in control (92.3 cm). Similarly, the maximum number of tillers per hill (15.5) and maximum number of panicles per hill (15.5) was recorded in T8 at harvest stage. Soil and foliar application of Zn along with soil application of NPK fertilizers as per POP KAU significantly improved the grain yield and other crop yield attributes. The treatment that recorded the highest grain yield was T8 (6.7 t ha-1) which was superior as compared to other treatments. The treatments that recorded the highest straw yield (6.5 t ha-1) and highest 1000 grain weight (27.1g) was with treatment T7. 127

The nutrient content in the plant samples (shoot and straw) analyzed at different growth stages of paddy was studied. The results revealed that nutrient content of N, K and Zn was highly improved in treatments under INM practices. At the harvest stage, treatments T7 recorded the highest N (0.62 %) and K (1.9 %) whereas Zn (85.7 mg kg-1) content in straw was highest with treatment T8. However, the nutrient content of P in plant samples declined with the increase in the number of foliar application of Zn. The treatment that recorded the lowest P content (0.19 %) in the straw at harvest was T5 (Organic POP + soil application of Zn + triple foliar application of Zn). The effect of treatments on Zn and P content in rice grains were also studied. Grain analysis results revealed that the treatment that recorded the highest Zn content (55.8 mg kg-1) was in T8 and the lowest Zn content (18.2 mg kg-1) was recorded in T10 (control). Similarly, P content was also analyzed in rice grains to study the interaction between Zn and P. The treatment that recorded the highest P content (0.61 %) in the grain was T2 and lowest P content (0.44%) was recorded in T5.