Responses of hybrids to N, P and K in different rice soils

Multi-location field experiments under Directorate of Rice Research during wet season 2002–03 and 2003–04 on responses of hybrids and inbreds to applied N, P and K revealed that the differences among hybrids/high yielding cultures and fertilizer treatments were significant at substantial number of locations while the interactions viz., varieties x fertilizer treatments were significant at majority of the centers. The paired t-test revealed that hybrids had a significant yield advantage of 0.82 t ha⁻¹ during 2002 and 1.01 t ha⁻¹ during 2003 over high yielding cultures indicating superiority of hybrids. With respect to responses of applied N, P and K nutrients, hybrids were found significantly superior to high yielding cultures for N responsiveness while response to P and K responses was not significant between hybrids and high yielding cultures. A significant positive relationship (R=0.51 to 0.57) between P availability in soils and response to applied N could be established irrespective of factors like variety and soil textural conditions and soil pH. Based on data from 9 locations in clay loam soils, no significant relationship between soil pH and response to N could be observed, while a negative relationship between soil pH and response to N could be established in clay soils. However, similar response was observed with hybrids and inbred rice varieties to applied P and K.