Effect of plant nutrition on crop growth and water balance elements in rainfed lowland rice (Oryza sativa L.)
2007
Priyadarshani, S.H.R., Philippines Univ. Los Banos, College, Laguna (Philippines)
In rainfed lowlands, the total water supply and its distribution in space and time are mainly determined by the distribution and amount of rainfall, and the topomorphology. The fraction of total water supply available to the crop can vary considerably and is strongly dependent on interactions of crop management factors and soil characteristics. Although the data from field trials in this interaction for rice are very limited. The study was conducted to have a better understanding of principles of crop growth in water-limited rainfed lowland rice. Specifically it aims to estimate the main water balance elements for rainfed lowland rice and to study the relationship between water balance elements and crop growth. The field experiment was conducted in the experimental farm of the International Rice Research Institute, Los Baños, Laguna Philippines in the wet season 2006. The experiment was laid out in a randomized complete block design with five different fertilizer treatments and three replications. The initial soil properties, field water status, soil moisture parameters, rainfall, evapotranspiration, percolation, crop growth performances were collected and analyzed. The plant growth parameters such as plant height, tiller number, above ground dry matter, leaf area index, crop growth rate, yield and yield contributing parameters were significantly affected by nitrogen, phosphorus and potassium (NPK) application. The NPK levels did not affect the field soil water storage in rainfed lowland condition. The components of water balance, total rainfall, irrigation, potential evapotranspiration, percolation during the season were 713mm, 58mm, 547mm, and 112mm, respectively. The total water input, output and storage during the season were 770 mm, 659 mm and 138 mm, respectively. The total biomass production and cumulative transpiration were highly correlated (R2 = 0.94) and transpiration efficiency was 2.2g per liter of water transpired. The improved crop nutrition can contribute significantly to improve water use efficiency in rainfed environment, mainly by reducing evaporation and increasing transpiration.
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