Response of Hybrid Rice to Time and Method of Potassium Application

TWO FIELD experiments were carried out at the experimental farm of the Rice Research and Training Center, Sakha, Kafrelshiekh, Egypt, during 2009 and 2010 seasons, to study the response of hybrid rice (Egyptian Hybrid1) to methods (soil addition and foliar spray (S)) and time of potassium application. Eleven combinations were studied as follow applications times: (T1) without k fertilizer , (T2) 24+0+0, (T3) 8+8+8, (T4) 8+8+S, (T5) 12+12+S, (T6) 8+ S +S, (T7) 12+ S +S, (T8) 24+ S +S, (T9) 0+ S +0, (T10) 0+ 0 +S and (T11) 0+ S +S kg K2O/fed. (feddan = 0.42 hectare) at basal (B), med tillering (MT) and panicle initiation (PI) stages, respectively, as well as (11) without K fertilizer.
The results revealed that basal application of K or foliar spray twice each at MT and PI stages resulted in a significant increase in plant height and dry matter accumulation (g.m-2) compared with control in both seasons. Soil or foliar application of K, separately or together, resulted in a significant increase in number of panicles m-2, panicle weight, panicle length, number of filled grains per panicle, 1000-grain weight, grain yield and nutrients uptake (N, P, K and Zn) in grains compared with control treatment in both seasons.
Split application of 24 kg K2O/fed in three equal doses was found to better grain yield, yield attributes and nutrients uptake in grains than entire basal application or foliar spray at MT or PI stages alone.
The integration of basal application and either top dressing or foliar K in MT and PI stages did not differ from splitting K in three equal doses in the most mentioned traits in both seasons. However, basal application of 24 kg K2O/fed alone or along with foliar spray at MT and PI produced the highest straw yield and nutrients uptake (N, P, K and Zn) in straw in the two seasons. There was no significant difference in straw yield among foliar application of potassium and control treatment. The treatment containing soil application of K twice at basal and MT stage, or entire basal application alone were insignificant with entire basal along with the foliar application of K at MT and PI stages in N, P, K and Zn uptake in straw in both seasons. The correlation among each of nutrient content and grain and straw yields were significantly positive.
The present study concludes that splitting 24 kg K2O/fed in three equal doses, i.e. 8+8+8 or the combination of top dressing (kg K2O/fed) and foliar spray (S), 8+8+S, 12+S+S and 8+S+S at basal, MT, and PI stages are a viable nutrient management package for getting higher grain yield of hybrid rice (Egyptian Hybrid1) at Kafrelshiekh Governorate.