|Author:||Haefele, S. M. ; Jabbar, S. M. A. ; Siopongco, J. D. L. C. ; Tirol-Padre, A. ; Amarante, S. T. ; Sta Cruz, P. C. ; Cosico,W. C.|
|Book Group Author:||NA|
Water and nutrient availability are two major constraints in most rice-based rainfed shallow lowland systems of Asia. Both stresses interact and contribute to the low productivity and widespread poverty in this environment. The objective of this study was to improve the understanding of interaction between the two factors and to identify varietal characteristics beneficial for productivity in a water- and nutrient-limited rice environment. For this purpose, we screened 19 rice genotypes adapted to different rice environments under two water and two nutrient treatments during the wet season of 2004 and 2005 in southern Luzon, Philippines. Across all genotypes tested and in comparison with the irrigated control, rainfed conditions reduced grain yield of the treatment without N application by 69% in 2004 and by 59% in 2005. The mean nitrogen fertilizer response was highest in the dryer season of 2004 and the rainfed treatment, indicating that water stress had no effect on fertilizer response. Nitrogen application reduced the relative yield loss to 49% of the irrigated treatment in 2004 and to 52% of the irrigated treatment in 2005. Internal efficiency of N (IEN) and recovery efficiency of applied N (REN) were significantly different between genotypes, but were not affected by water availability (REN) or by water and nutrient availability (IEN). In contrast, grain yield and total N uptake were affected by cultivar, N and water availability. Therefore, germplasm for rainfed environments should be screened under conditions of limited and good nitrogen and water supplies. The four best cultivars, CT6510-24-1-2, IR55423-01, IR72, and IR57514-PMI5-B-1-2, performed well across all treatments and both years. Except for IR72, they were all characterized by medium height, medium duration, high early vigor, and a moderate level of drought tolerance. This combination of characteristics seems to enable the optimal use of limited water and nutrient resources occurring in many shallow rainfed lowlands. We also concluded that moderate drought stress does not necessarily affect the response to moderate N rates, provided that drought does not induce high spikelet sterility and that fertilizer N is properly managed.
|Pages:||137 - 146|
|Journal:||Field Crops Research|
application rates, drought, drought resistance, genotypes,irrigation, nitrogen fertilizers, plant nutrition, plant waterrelations, rice, use efficiency, variety trials, water stress,Philippines, Oryza, Oryza sativa, Oryza, Poaceae, Cyperales,monocotyledons, angiosperms, Spermatophyta, plants, eukaryotes, SouthEast Asia, Asia, Developing Countries, ASEAN Countries, droughttolerance, paddy, watering, Field Crops (FF005) (New March 2000), PlantBreeding and Genetics (FF020), Plant Nutrition (FF061), Plant WaterRelations (FF062), Fertilizers and other Amendments (JJ700), Soil WaterManagement (Irrigation and Drainage) (JJ800) (Revised June 2002)[formerly Soil Water Management]