Nitrogen and Zinc Interaction Improves Yield and Quality of Submerged Basmati Rice (Oryza sativa L.)

Nitrogen (N) and zinc (Zn) are the two major yield-limiting factors of flooded rice cultivation systems. Both nutrients interact and affect availability of the other in alkaline calcareous soils. In order to evaluate the interactive effects of N and Zn on yield and quality of Basmati rice, a field study was conducted at Sheikhupura (Site I) and Sargodha (Site II), Pakistan. Nitrogen treatments (0, 40, 80, 120 and 160 kg/ha) were kept in main blocks while zinc levels (0, 8, 10, 12 and 14 kg/ha) were kept in sub blocks. The main effects of N and Zn levels were significant for grain yield and yield attributes. N and Zn interaction significantly improved the grain yield, yield components and all kernel quality parameters, except kernel amylose contents. Combined application of 120 kg N/ha and 14 kg Zn/ha produced the maximum grain yields at both sites (6.12 and 5.78 t/ha). This combination also yielded the maximum kernel lengths and widths, water absorption ratio and kernel protein contents. There was a significant positive correlation between grain yield and total dry matter, panicle-bearing tillers, spikelets panicle, grain weight, and harvest index. Application of 160 kg N/ha was detrimental to yield and quality attributes and reduced the agronomic efficiency of N use at both sites. Site comparison showed that soil pH and soil nutrient contents play a significant role in determination of the optimum nitrogen and zinc fertilizer doses for maximum yields.