Agriculture Reference
In-Depth Information
Cold resistant cultivars could be planted earlier in the season leading to an
earlier harvest. Unlike cultivated tomatoes, wild tomato species such as
S.
habrochaites
S. Knapp & D.M. Spooner,
S. chilense
(Dunal) Reiche and
S.
peruvianum
L., recover rapidly after exposure to suboptimal temperatures.
These genotypes can be grown at low temperature at high elevation where
temperature remains below 10
o
C. Wild species have been used for con-
structing genetic maps and identifying genes of agronomic importance.
Through backcrosses and selection assisted by molecular markers, cold
resistant genes from wild species can be bred into cultivated tomato variet-
ies (Goodstal et al., 2005). Following strategies can be used.
• These wild genotypes can be introgressed in cultivated by somatic
and sexual hybridization as well as chloroplast exchange. The cul-
tivated tomato (
L. esculentum)
is used as female in crosses due to
inability of
esculentum
to fertilize ovules of most of the wild species
(unilateral incongruity).
• Evaluate the off springe for chilling tolerance.
• Identify the chromosome regions which may be associated with
chilling tolerance in the wild species.
With development of chilling tolerant tomato the tomato growing sea-
son can be extended and produced round the year and area of adaptation
may be broaden for glass house production, cold tolerant genotype may
reduce the energy consumption in horticulture and contribute a reduction
in CO
2
emissions and greenhouse effect on global warming, in general
cold tolerant genotypes have earliness, water use efficiency, adaptability
and high yield when grown under suboptimal temperature. Physiological
traits of chilling tolerance in tomato are as follows.
• Thin stem, short dense glandular hairs and narrow leaflets (
L. peru-
vianum
)
• Densely hairy stem, leaves and fruits (
L. hirsutum
), high photosyn-
thetic rate and seedling can survive at 0oC temperature.
•
L. chilense
can survive on rock as having deep root system and toler-
ate moisture stress.
8.3.11.3 SALINITY
• Selection of salt tolerant crops and varieties may be an effective
strategy to overcome the problem of salinity. Cucumbers, eggplants,
