EFFECT OF SPLIT APPLICATION OF NITROGEN AND POTASSIUM TO SK2047 HYBRID RICE

Abstract

Two field experiments were conduced at Rice Research and TrainingCenter, Sakha Kafr El-Sheikh, Egypt in 2007 and 2008 summer seasons to study the effect of split application of N and K to SK2047 hybrid rice [IR70368A/Giza 178R]. One level of N fertilization was used, 165 kg N/ha in the form of urea applied in three different times (N1) as two splits [2/3 incorporated into dry soil before transplanting + 1/3 before panicle initiation), (N2) as three equal splits [1/3 incorporated into dry soil before transplanting + 1/3 at mid tillering + 1/3 before panicle initiation], (N3) as three splits [1/2 incorporated into dry soil before transplanting + 1/4 at mid-tillering + 1/4 at panicle initiation]. One level of potassium (60 kg K2O/ha) was applied. All amount was applied as follow: (K1) without potassium (control), (K2) the total amount was applied as basal (100% B), (K3) one half as basal and one half at panicle initiation (50% B + 50% PI), (K4) one half as basal and other half in two equal splits; at mid-tillering and at panicle initiation (50% B + 25% T + 25% PI) and (K5) in four equal splits: basal, mid-tillering, panicle initiation and heading (25% B + 25% MT + 25% PI and 25% at heading). The main results could be summarized as follows: Three equal split applications of nitrogen (N2); [1/3 B + 1/3 MT + 1/3 PI) was superior in dry matter (DM), flag leaf area (FLA), leaf area index (LAI), N and K shoot content, panicle number, % of filled grains/panicle, panicle weight, 1000-grain weight, harvest index (HI) and grain yield. Potassium applications increased growth characters, grain yield and its components and N and K shoot content compared with the control. While, split-applied potassium with three doses (K4); 50% B + 25% MT + 25% PI, gave the highest values of studied parameters without any significant differences with those produced by (K5); 25% B + 25% MT + 25% PI + 25% heading in rice grain yield. The interaction between split application of N and K was significant for filled grains percentage and K shoot content in 2007 season. It could be concluded that for raising hybrid rice productivity, both nitrogen and potassium should be applied in the following formulas; 1/3 basal (B) + 1/3 at mid tillering stage (MT) + 1/3 at panicle initiation (PI) and 50% basal (B) + 25% at mid tillering stage (MT) + 25% at panicle initiation (PI) for nitrogen and potassium respectively.