Agriculture Reference
In-Depth Information
increasing
the
ambient temperature approximately 4°C above normal gave
consistently earlier maturity of lettuce, delayed cauliflower curd initiation
by up to 49 days and increased the final number of leaves in cauliflower
by 36. The crop like lettuce, celery, cauliflower and kiwi grown under high
temperatures matured earlier with lower harvest index than the same crops
grown under low temperatures. The increased temperatures in Sambalpur,
India, have delayed the onset of winter. As a consequence, cauliflower
yields have dropped significantly (Pani, 2008). Where growers commonly
harvested 1 kg heads, inflorescences are now smaller, weighing 0.25-0.30
kg each. Reductions in yield drive up production costs, an effect also ob-
served in tomato, radish and other native Indian vegetable crops.
Rosenzweig et al. (1996) reported decline in yield of orange cultivar
Valancia due to excessive heat during the winter which might be counter-
act by the rise in the CO
2
in the atmosphere, however fall in potato pro-
duction with increased CO
2
and changes in planting date were estimated
to have minimum compensating impacts on simulated potato yields. Mod-
erately high temperatures do not appear to limit photosynthesis and dry
matter production in potato (Midmore and Prange, 1992; Reynolds et al.
,
1990; Wolf et al.
,
1990b), but partitioning of photosynthate away from
leaves and toward tubers is likely to be decreased under these conditions
(Basu and Minhas, 1991; Krauss and Marschner, 1984; Wolf et al.
,
1990a).
Nonetheless, the potato contains considerable genetic variability and plas-
ticity, providing a basis for optimism with respect to adaptation to warmer
climates (CIP, 1991; Levy, 1986 a, b;
Manrique, 1989; Manrique et al.
,
1989; Reynolds and Ewing, 1989a, b).
Temperate horticultural crops in Himachal Pradesh were the worst
hit during heat wave in summer, 2004. About 50% reduction in green tea
leaves was noticed in April 2004 when compared to 2003 and 2005 in Hi-
machal Pradesh due to increase in maximum temperature of the order of
2.1 to 7.9°C in March (Prasada and Rana, 2006). Flowering of apple is ad-
vanced by 15 days under high temperature scenario. A large-scale flower
drops was seen in April due to acute moisture stress. Heavy rainfall during
second forth night of April accomplished by sharp fall in temperature re-
sult in poor fruit set. The optimum temperature for fruit blossom and fruit
set in apple is 24°C while the region experienced 26°C for 17 days. In con-
trast, some part of Jammu, Punjab, Harayana, Himachal Pradesh, Bihar,
Uttar Pradesh and North Eastern States experienced the unprecedented
cold wave during 2002-2003. The crop yield loss varied between 10 and
