Rice root growth and physiological responses to SRI water management and implications for crop productivity |
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Authors: | Abha Mishra Vilas M Salokhe |
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Institution: | (1) School of Environment, Resources and Development, Asian Institute of Technology, P. O. Box 4, Klong Luang, Pathumthani, 12120, Thailand;(2) Kaziranga University, Jorhat, Assam, India |
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Abstract: | This paper reports on several research findings on rice root responses, in terms of growth and physiology, manifested when
applying System of Rice Intensification water management principles under semi-field and field conditions, in conjunction
with variations in plant density and microbial density in the soil. The research aimed to learn about causal relationships,
if any, between rice root and shoot growth at different growth stages of the rice plant’s development and their cumulative
effect on yield, which is affected by both biotic and abiotic influences. It was seen that greater root length density and
a higher rate of root activity affected the yield-contributing parameters in all of the trials, whether conducted under semi-field
or field conditions. At the same time, both root parameters were significantly affected by the water regime, soil microbial
density, and planting pattern, the three main factors considered. The most important finding observed under semi-field conditions
was that enhanced microbial density in the soil improved the sink capacity of the rice plants under all water regimes evaluated.
Positive correlations were found between the chlorophyll content of the flag leaf and the duration of grain filling, between
the chlorophyll content of plants’ lower leaves and their roots’ oxidizing activity rate, and the roots’ oxidizing activity
rate at later growth stage and the available soil nitrogen. These relationships can significantly improve rice plants’ physiological
efficiency and hence grain yield, provided that soil nutrients are not a limiting factor and when source–sink demand is maintained
simultaneously. To realize the highest crop yield per hectare, both planting pattern and spacing are factors that need to
be optimized. This paper in its conclusion considers the relevance of exploiting roots’ potential for plasticity to enhance
crop productivity in the context of impending water constraints and climate-change effects. |
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