Agriculture Reference
In-Depth Information
tivity. Plants may respond similarly to avoid one or more stresses through
morphological or biochemical mechanisms (Capiati et al.,
2006). Environ-
mental interactions may make the stress response of plants more complex
or influence the degree of impact of climate change. Measures to adapt to
these climate change-induced stresses are critical for sustainable vegetable
production. There is a need to do more research on how vegetable crops
are affected by increased abiotic stresses as a direct potential threat from
climate change. Some of the important environmental stresses, which af-
fect vegetable production at great extent, have been reviewed below.
8.3.4 HIGH TEMPERATURE
Heat stress due to increase temperature is a major agricultural problem
in many areas in the world. Exposure to elevated temperatures can
cause morphological, anatomical, physiological, and ultimately,
biochemical changes in plant tissues and as a consequence, can
affect growth and development of different plant organs (
Table
8.2).
These events can cause drastic reductions in commercial
yield. Constantly high temperature can affect the seed germination, plant
growth, flower shedding, pollen viability, gametic fertilization, fruit set-
ting, fruit size, fruit weight, etc. The optimum temperatures for tomato
cultivation are between 25 and 30 °C during the photoperiod and 20 °C
during the dark period. However only 2-4 °C increase in optimal tempera-
ture adversely affected gamete development and inhibited the ability of
pollinated flowers into seeded fruits and thus reduced crops yields (Peet et
al., 1997; Firon et al., 2006). High temperatures also interfere with floral
bud development due to flower abortion. High temperatures can cause sig-
nificant losses in tomato productivity due to reduced fruit set, and smaller
and lower quality fruits (Stevens and Rudich, 1978). High temperatures
in tomato causes bud drop, abnormal flower development, poor pollen
production, dehiscence, and viability, ovule abortion and poor viability,
reduced carbohydrate availability, and other reproductive abnormalities.
In addition, significant inhibition of photosynthesis occurs at temperatures
above optimum, resulting in considerable loss of potential productivity.
Lettuce celery and cauliflower grown under higher temperature matures
earlier than the same crops grown under lower temperature (Phelps, 1996)
