Enhancing grain filling in rice using growth enhancers under water stress condition
Water stress is one of the key limiting factors in rice cultivation across the entire world. It reduces the production of rice, the income of farmers and stockpiles while increasing rice importation for drought stricken countries. Filled grain is the most affected part in rice plant especially...
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| Format: | Thesis |
| Language: | English |
| Published: |
2018
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/76941/1/IPTSM%202018%2011%20-%20IR.pdf |
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| Summary: | Water stress is one of the key limiting factors in rice cultivation across the entire
world. It reduces the production of rice, the income of farmers and stockpiles
while increasing rice importation for drought stricken countries. Filled grain is the
most affected part in rice plant especially during booting stage under water
stress. There are various approaches for mitigation of plant under water stress.
One of the approaches is through the use of growth enhancers by regulating
physiological and biochemical attributes such as stomatal aperture and
photosynthesis rate. The response of the rice plant variety MR219 subjected to
different water regimes (well watered and water stressed) were investigated
under both rain shelter and field condition. The objective of this study was to
examine growth, physiological processes, biomass partitioning and yield
determinants when rice plants were subjected to water stress condition. Biomass
partitioning, harvest index and photosynthesis were reduced by 50% under water
stress due to limitation in the efficiency of assimilate translocation. The results
from the field study during prevailing drought condition had indicated the severity
of yield losses at about 60-90% with drought imposed rice plant compared to the
control. In the following studies short term measures to minimize the detrimental
effect of water shortage on growth and rice plant development were carried out
both under rain shelter and field conditions. The efficacies of growth enhancers
(Vita-Grow®, epibrassinolide, spermine and pyroligneous acid) were evaluated
on yield production of rice plants subjected to water stress condition. Among the
growth enhancers studied, spermine was found to have the potential to mitigate
the detrimental effect of water stress on rice plant. Yield and grain filling
improvement of spermine treated plants were attributed to improved stomatal
conductance, photosynthesis rate and assimilate partitioning. The application of spermine with double spray was found to be more effective in improving growth
and development of water stressed rice plant. Following trials that were
conducted under control environment, a series of field trials were conducted to
validate the efficacy of spermine in reducing detrimental effects of water stress
on yield of rice in different locations, planting seasons and prevailing climates.
Application of spermine in three different locations representing our major
national granary areas (MADA, KADA, IADA BLS) showed consistently higher
rice yield compared to the control. Out of the three granary areas, the highest
intensity of water stress was observed in KADA. Application of spermine showed
significantly higher grain filling and yield in plant subjected to water stress
condition. A trial was conducted under control environment in an attempt to
investigate the response of spermine on sink strength and sucrose synthase
(SUS) enzyme in relation to the development of rice plant under water stress
condition in a control environment. The result suggested that higher grain filling
rate and greater grain weight of spikelets were mainly attributed to more sink
strength as a result of bigger sink size and high sink activity in spermine treatments. |
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