| |
|
|
|
Abstract
Effects of atmospheric and soil drought on growth and development
of hevea brasiliensis
A field study was conducted in the severely
drought prone North Konkan region on the West coast of India where rubber
plants (clone RRIM 600) had been grown with and without summer irrigation
since 1987. After nine years, trees grown with irrigation had a 32% increase
in leaf area index and nearly twice as much sunlight interception by their
canopy as the rainfed trees. This led to 52% more shoot biomass per tree
in the irrigated treatment. Irrigated trees had thicker bark and most of
that was present as soft bark. At the end of the seventh and eighth year,
78% and 97% of the irrigated trees were ready for tapping respectively,
suggesting fast and uniform growth of the trees. The rainfed trees however
did not reach tapping stage even after nine years of growth, indicating
that water was the most important and the only limiting factor in this region.
In the traditional rubber growing region of India where there is no severe
drought stress, the rainfed trees of the same clone attained tappable girth
after nine years. Yield was significantly high in the irrigated trees grown
in the North Konkan area compared to the traditional region. Thus, the results
indicate that, with irrigation during summer, rubber cultivation is possible
and there is faster and more uniform growth, and a higher latex yield in
the non-traditional North Konkan region.
|