Quantification of the contribution of component technologies of the system of rice intensification and PalayCheck to productivity in lowland rice

The performance of lowland rice was evaluated using the different component technologies of the System of Rice Intensification (SRI) and PalayCheck rice production system singly and in various combinations at the UPLB Central Experiment Station during the wet season of 2009. The study was conducted to determine the basis and quantify the contribution of each and combinations of production technologies to rice productivity. Three replications in strip-split plot design were used with nutrient source (organic vs. inorganic fertilizer) and water management (unflooded vs. flooded) as the main strips; and seedling age at transplanting (8 days after sowring (DAS) vs. 21 DAS) and planting distance (25cm x 25cm vs. 20cm x 20cm) were the subplots. Crop growth rate and leaf area index, but not net assimilation rate, were significantly affected by nutrient source, water management, seedling age and planting distance. Low values were recorded for CGR, LAI and NAR due to the low solar radiation associated with cloudiness during rainy season and submergence of the crop during peak of flowering. Inorganic fertilizer gave significantly higher grain yield than organic fertilizer. Eight-day old seedling gave higher yield than 21-day old seedlings due to higher tiller production/hill. The tillering ability of young seedlings can be further enhanced with the use of inorganic fertilizer. Close planting distance also gave higher yield than wide spacing and this was associated with higher number of productive tillers per unit area. Flooded and unflooded treatments did not differ significantly in terms of grain yield its components except for spikelet number and spikelet fertility. Significant differences due to water management however were observed for plant height, tiller number, total dry matter and physiological parameters. Highest grain yield was obtained from 8-day old seedlings with inorganic fertilization planted at 20cm x 20cm distance. This was significantly higher than the rest of the treatment combinations. Using a mathematical model, the contribution to grain yield of different production technologies and their combination(s) were calculated by substitution of the actual value(s) obtained for the component production technologies. The contributions of the following production technologies were obtained: water management (flooded), 0.528 t/ha (15% increase), seedling age, 0.357 t/ha (10% increase), and planting distance, 0.254 t/ha (7% yield reduction). The highest contribution of 1.356 t/ha (39% yield increase) was obtained from the combination of inorganic fertilizer in unflooded field using 8-day old seedlings planted at 20 x 20cm spacing. The mathematical model could still be fine-tuned through collection of data in experiments conducted in different seasons, locations, and using different varieties.