Agriculture Reference
In-Depth Information
• Long root length which has good ability to uptake water and nutri-
ents from the soil surface.
• Short life span which help to minimize the temperature effect on
plant.
• Hairiness which provide partially shade to cell wall, cell membrane
and repel sun rays.
• Small leave size that resist evaporation due to shortening of stomata.
• Leaf orientation enhances the photosynthetic activity and produce
tolerance against heat stress.
• Leaf glossiness and waxiness which repel sunlight.
With the improvement through conventional breeding two cultivars
which both desire characters i.e. heat tolerance and high yielded genes are
selected and hybridized for selection of desirable plants from segregating
generation. However molecular and biotechnological strategies are also
used for the purpose of heat tolerance in tomato by using such techniques
i.e. use of genetic engineering for transfer of heat tolerant gene in plant
cell which have all other desirable characters. High temperature tolerance
has been genetically engineered in plants mainly by overexpressing the
heat shock protein genes or indirectly by altering levels of heat shock tran-
scription factor proteins. Apart from heat shock proteins, thermo tolerance
has also been altered by elevating levels of osmolytes, increasing levels
of cell detoxification enzymes and through altering membrane fluidity. It
is suggested that HSPs may be directly implicated in thermo tolerance
as agents that minimize damage to cell proteins. Tissue culture technique
may be used to make plant from transformed cell. Molecular / genetic
marker used to identify the gene in plant cell or in F
2
generation that has
ability to tolerance against high temperature. Now a day's biotechnology
contributed significantly to better understanding of heat tolerant gene and
heat tolerance mechanism in tomato plants.
8.3.11.2
LOW TOLERANCE
Many vegetable viz. broccoli, Brussels sprout, cabbage, kale, knol-khol,
onion, mustard, parsley, spinach, turnip which can tolerate very low tem-
perature can be grown in frost/chilling sensitive area successfully. Com-
mercial cultivated tomatoes are planted in the field at later dates to avoid
excessively low temperatures and minimize the risk of chilling damage.
