Effect of Seed Priming and Encrusting Coating on Yield and Yield Components of Two Rice Cultivars

Rice (Oryza sativa L.) is one of the most important staple food crops in the world. However, rapid increase in world population and adverse effects of climate change, such as prolonged drought, has resulted in challenges in food security. One of the important factors in reducing rice yield can be the emergence and poor establishment of seedlings in the field. Seed treatment before sowing is the foundation for activation of seed resources that in combination with external ingredients could contribute to the efficient plant growth and high yield. Various physiological and non-physiological techniques are available for enhancing seed performance as well as to combat environmental constraints. Pre-sowing seed treatment such as seed coating and seed priming could improve the seed germination and vigor particularly under unfavorable environmental conditions.

In order to investigate the effect of priming and seed coating on emergence characteristics, yield and yield components of rice, a field experiment was conducted in the 2020 growing season, Rice Research Institute of Iran (RRII). The experiment was performed as a factorial in a randomized complete block design with three replications. Experimental factors include rice cultivars (Hashemi and Gohar) and treatment of rice cultivars in seven levels including 1- Priming with calcium chloride (-1.25 MPa in 24 hours), 2- Priming with potassium chloride (1.25 MPa in 24 hours), 3- Priming with zinc sulfate (concentration of 0.5 mM in 12 hours), 4- Hydropriming (48 hours) + Coating the seeds with calcium chloride, 5- Hydropriming (48 hours) + Coating With potassium chloride, 6- Hydropriming (48 hours) + coating with zinc sulfate and 7- Hydropriming (48 hours as control).

The results showed that the highest emergence percentage with 87% and 94% and the emergence rate with 0.17 and 0.19 (1.day-1) were obtained in Hashemi and Gohar cultivars, respectively. From these results, it is inferred that Gohar cultivar has higher genetic potential and physiological quality than Hashemi cultivar. The results of mean comparison showed that the highest height of rice plant with 147 and 143 cm was observed in coating and priming with potassium chloride in Hashemi cultivar, respectively. The results of this study attributed the increase in height to the effect of pretreatment on increasing the rate of emergence and better establishment of seedlings due to better plant use of related resources. The results showed that seed pretreatment with calcium chloride, potassium chloride and zinc sulfate increased the panicle length by 27, 24 and 12% under priming and 37, 34 and 17% under seed coating, respectively. The results of the mean comparison table showed that the highest panicle weight with 1.35 and 1.32 g was observed by seed coating with potassium chloride and calcium chloride, respectively. However, priming with calcium chloride, potassium chloride and zinc sulfate also increased the cluster weight by 12, 17 and 5%, respectively, compared to the control treatment. The results showed that the highest 1000-seed weight was obtained among the two cultivars with 24.63 g in Gohar cultivar. Also, the findings of this study showed well that pretreatment of rice seeds can increase the 1000-seed weight. Pretreatment of rice seeds with calcium chloride, potassium chloride and zinc sulfate 10, 12 and 5% under priming and 18, 22 and 10% under seed coating, respectively, increased 1000-seed weight. The results of mean comparison showed that grain yield in Hashemi and Gohar cultivars were 3046 and 4929 kg.ha-1, respectively. Pretreatment of rice seeds with calcium chloride and potassium chloride 14 and 20% under priming and 19 and 23% seed coating respectively, increased rice grain yield. In general, the increase in grain yield can be due to the improvement of antioxidant properties, proper establishment and optimal use of environmental factors such as light, soil moisture and nutrients.

According to the results of this study, priming and seed coating treatments with calcium chloride and potassium chloride in rice cultivars can increase rice yield by improving seedling characteristics. Therefore, farmers can be advised to use a simple and inexpensive crop management method to pre-treat seeds with calcium chloride and potassium chloride.