Effect of water deficit and nitrogen timing on growth and water relations of lowland rice.
1988
Siopongco J.D. | Ingram K.T. | Castillo E.G. | Buresh R.J. | De Datta S.K.
The low and rather stagnant yields for rainfed drought-prone lowland rice (Oryza sativa L.) have been attributed to drought and inefficient utilization of N fertilizer. A field experiment was conducted in Pila, Laguna [Philippines] to assess the effects of water deficit timing and N fertilizer timing on crop growth. Three N timing treatments: control, no applied N; early N application, 80 kg urea-N/ha, 1/2 broadcast and incorporated into mud before transplanting + 1/2 broadcast into 5-cm floodwater at 37 days after transplanting (DT); and late N application, 80 kg urea-N, 1/2 broadcast into floodwater at 11 DT + 1/2 broadcast into 5-cm floodwater at 65 DT were subjected to three water regimes: continuously flooded; vegetative phase water deficit, not irrigated from 15 to 35 DT; and reproductive phase water deficit, not irrigated from 41 to 63 DT. Vegetative phase and reproductive phase water deficits reduced leaf area index, stomatal conductance, root length, and grain yield. The vegetative phase water deficit had a more detrimental effect on crop growth and yield than the reproductive phase water deficit. Nitrogen fertilization increased grain yield even under water deficit. Early N application resulted in significantly greater grain yields than delayed N application. This result was attributed to greater leaf area index and hastened root growth with early N application.
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