Promoting seedling vigour and grain zinc accumulation in rice by priming seeds and foliar application with zinc and potassium fertiliser

Abstract

Seed priming with zinc (Zn) and potassium (K) has been suggested to improve plant growth and productivity; however, the same effects have not yet been established when a simultaneous Zn+K solution is applied. This study aimed to determine the effects of priming seed and foliar application with Zn and K solution on seedling growth, yield, and grain Zn concentration in three rice varieties (SPT1, BL and KDK). The study consisted of three independent experiments. In Experiment 1, seed germination and seedling vigour were evaluated after priming rice seeds with a solution of 0.5% ZnSO4, in combination with various concentrations (1-4%) of K, compared with a control of no Zn and K. In Experiment 2, the selected concentrations of K solution combined with Zn (Zn0K0, Zn+K0, Zn0K+ and Zn+K+) were applied for each rice variety to evaluate seedling growth and development at 7 and 21 days. In Experiment 3, foliar application with the same solution as in Experiment 2 was used to evaluate its effect on yield and grain Zn accumulation. Seed priming with Zn combined with K at concentrations of 1%, 3% and 2% resulted in the maximum seedling growth traits in SPT1, BL and KDK respectively. Seed priming with a combination of Zn and K (Zn+K+) markedly increased the dry weight of 7-day-old seedlings, for about 14-15% in SPT1 and BL varieties compared with the unprimed seeds. Moreover, foliar application with Zn+K0 and Zn+K+ increased grain yield by 16-29% in the BL variety, whereas it increased grain Zn concentration in all rice varieties by 18-27% from the control treatment. This study concluded that priming rice seed with a combination of Zn and K can be used to improve seed germination and seedling growth, whereas increasing grain yield and grain Zn concentration requires an additional foliar Zn application.