Transcript 8..Drainage requirement in tomato

Drainage Requirements
in Tomato
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Introduction:
For tomato, irrigation should be so arranged that the soil
remaining moderately moist.
Excessive moisture in soil induces the plant to
vine and drop off the blossoms.
During summer irrigation at intervals of 3-4
days is necessary while in winter 10-15 days
interval is sufficient.
Alvino et al (1986) found that high irrigation levels do
not increase the yield of tomato but depress the
quality.
Any thing above 30 cm irrigation depth
significantly reduced the yield as well as
quality.
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Rudich et al., (1977) found that frequent irrigation at the time
of fruit expansion had an adverse effect on fruit expansion
had an adverse effect on quality of tomato fruits by
significantly reducing the TSS viscosity and increasing the
acidity of fruit juice.
Just like other vegetables the
production of tomato also is limited
during rainy season due to excessive
moisture brought about by heavy rains.
Most vegetables are highly sensitive to
flooding and genetic variation with
respect to this trait is limited
particularly in tomato (Dela Pena and
Hughes 2007).
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In general damage to the crop by flooding is due to
reduction of oxygen in root zone which inhibits
aerobic process.
Flooded tomato plants accumulate endogenous
ethylene that causes damage to the plants (Drew
1979).
Low oxygen levels stimulated an increased
production of an ethylene precursor 1amino cyclo propane 1- carboxylic acid
(ACC) in the roots.
The rapid development of epinastic growth of leaves
is a characteristic response of tomatoes to water
logged conditions and the role of ethylene
accumulation has been implicated.
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The severity of flooding symptoms increases with rising
temperature; rapid death of tomato plants is usually
observed following a short period of flooding at high
temperature (Kuo et al.,1982).
In as much as generic variability for tolerance of
excessive soil moisture is limited or inadequate
to prevent yield loss in tomato, at AVRDC
Research work was taller up to screen egg
plant germ plasam for flood tolerance.
It was observed that many accessions
of egg plant are highly tolerant of
flooding (Midmore et al., 1997).
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So the centre developed grafting technique
to improve flood tolerance of tomato using
egg plant rootstocks which were identified
with good grafting compatibility with tomato
and high tolerance to excess soil moisture.
Tomato scions grafted on to egg plant
root stocks grow well and produce
acceptable yields the rainy season
(Midmore et al., 1997).
In addition to protection against
flooding some egg plant genotypes are
drought tolerant and such of those egg
plant root stocks can therefore provide
protection against limited soil moisture
stress also.
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