Agriculture Reference
In-Depth Information
up to 48 °C, cold temperatures influence crop production. Sub-zero tem-
peratures for even a single day or few hours severely damage or even kill
the trees the trees as could be seen during the 2013 fruiting season in Luc-
know (portion of twig death) and Dehradun region of Uttarakhand where
nearly 10,000 trees have been reportedly dead. Trees manifest strong veg-
etative bias with increasing temperatures provided; water and nutrients are
not limiting (Whiley et al., 1989). They observed that the median (mean
of the maximum and minimum daily temperatures) daily temperature for
zero shoot growth of ten mango cultivars to be 15 °C which, was subse-
quently confirmed to be critical for critical daily mean temperature for
vegetative growth. Soil temperatures reportedly have a strong control on
synchronization of growth phases in the tree. The same authors found that
periodic shoot growth, changing between phase of activity and dormancy,
occurred when soil temperatures were held at 27 °C or 32 °C for 120 days
but at 21 °C an extended dormant period developed. Temperature also
influenced the number and size of leaves. An average of 7.1 leaves that
developed on shoots at 20/15 °C increased to 13.6 at 30/25 °C. Dry matter
partitioning to roots was the greatest in trees growing at 15/10 °C, that is,
temperatures that suppressed shoot growth. With increase in temperatures,
partitioning to roots declined but correspondingly increased for stem and
leaves. In '
Irwin
,' there was a greater allocation of dry matter to roots at
higher temperatures of 25/20 °C and 30/25 °C, a reflection of its reduced
flushing and semidwarf architecture (Table 5.1).
TABLE 5.1
Competence of Important Phenophases in Respect of Key Vulnerable
Physiological Attributes in 'Dashehari' to Weather Dynamics
Type of shoot/stage
Rate of photosynthesis (PN)
(µ mol m-2 s-1)
Leaf water potential (Ψw)
(MPa)
Vegetative growth
9.25
-7.36
Reproductive growth
-
-
a) FBD
7.61
-7.95
b) Flowering
6.25
-8.46
c) Fruit set
7.27
-6.50
