Agriculture Reference
In-Depth Information
21.2.2 INDIRECT EFFECTS
Soil erosion and increased leaching of nutrients, increased reproduction
rate, rise in severity of infestation and extension of geographical range of
insect pests and pathogens apart from outbreak of new pests, salinization
of fresh water resources, ground water depletion, changes in social system
due to urbanization, migration, land use change like deforestation, shifting
of cropping zones, land degradation, etc.
21.3 IMPACTS ON INDIVIDUAL CROPS WITH SPECIAL
REFERENCE TO BIHAR
21.3.1 RICE
In rice, decline in rice productivity with increasing temperature under cur-
rent management is predicted. In Bihar, present productivity can be main-
tained with proper agronomic interventions up to middle of twenty-first
century as indicated by simulation studies. Increase in crop duration by
increasing temperatures during reproductive phase (>30°C) is a possibil-
ity in rice as indicated in studies. Long duration varieties are most affected
(Haris et al., 2010). Simulation studies show that 22% decline possible
in later half of the century. Spikelet sterility and lesser grain filling are
primary reasons.
21.3.2 WHEAT
Significant decline in productivity with increasing temperature is predicted
under current management in India. Decline in duration (reduced biomass
accumulation), reduction in Kernel number (4% per degree centigrade
rise in the range of 14°C-22°C) and reduced kernel weight (2-5% decline
per degree centigrade increase) is a possibility at higher temperatures. In-
creased respiration and loss of chlorophyll after anthesis is observed under
warmer conditions. High night temperatures reduce grain number. Simula-
tion studies points to 4 to 28% decline in yield at different time periods.
