Enhancing the performance of direct seeded fine rice by seed priming

Higher water requirements and increasing labor costs are the major problems of the traditional rice production system. Direct seeded rice culture, growing rice without standing water, can be an attractive alternate. However, poor emergence and seedling establishment, and weed infestation are the main hindrances in the adoption of this culture. An attempt to improve the performance of direct seeded rice by seed priming was made in the present study. Priming tools employed were traditional soaking (soaking in tap water up to radicle protrusion), hydropriming for 48 h, osmohardening with KCl or CaCl2 (osmotic potential of -1.25 MPa) for 24 h, vitamin priming (ascorbate 10 ppm) for 48 h and seed hardening for 24 h. All the priming techniques improved crop stand establishment, growth, yield and quality except traditional soaking, which resulted in impaired germination and seedling establishment that ended in reduced kernel yield and lower harvest index than that of control. Early and synchronized germination was accompanied by enhanced amylase activity and total sugars. Osmohardening with CaCl2 resulted in the best performance, followed by hardening and osmohardening with KCl. Osmohardening with CaCl2 produced 2.96 t ha(-1) (vs 2.11 t ha(-1) from untreated control) kernel yield, 10.13 t ha(-1) (vs 9.35 t ha(-1) from untreated control) straw yield and 22.61% (vs 18.91% from untreated control) harvest index. Mean emergence time and emergence to heading days, germination percentage and panicle bearing tillers; plant height and straw yield, 1000-kernel weight and kernel yield, alpha-amylase activity and total sugars, kernel proteins and kernel water absorption were correlated positively.