Quantifying the effect of rice leaf blast on leaf photosynthesis, crop growth, and final yield using ecophysiological model of crop growth
1991
Bastiaans, L. (Wageningen Agricultural Univ., Wageningen (Netherlands). Dept. of Theoretical Production Ecology)
The effect of Pyricularia oryzae Cav., the causal organism of blast of rice, on leaf photosynthesis was measured. At both high and low light intensities, leaf blast reduced photosynthesis not only through a reduction in green leaf area, but also through an effect on photosynthesis in the remaining green leaf tissue. Whole leaf dark respiration increased as a result of infection. The effect of reduced leaf photosynthesis on the growth rate of rice crop grown under favorable soil nutrient and moisture conditions was quantified, using an ecophysiological simulation model for crop growth. For moderate epidemics of leaf blast, the simulated reduction in shoot dry weight at flowering slightly underestimated the reduction observed in the field. Simulation indicated that a reduction in crop growth before flowering may affect final yield. Reduced nitrogen accumulation in an affected crop proportional to the reduction in biomass may accelerate redistribution of N from the remaining leaf tissue. Model computations showed that a reduction in leaf photosynthesis resulting from lower N content will have a marked effect on final yield. This effect will be more pronounced when N uptake after flowering is low.
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