Impact of elevated temperature and carbon dioxide on crop-weed interactions in Wheat
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Date
2018
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CENTRE FOR ENVIRONMENT SCIENCE AND CLIMATE RESILIENT AGRICULTURE ICAR-INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI
Abstract
A field experiment was conducted with a promising wheat cultivar, HD 2967 under
ambient (400 ppm) and elevated CO2 (550 ppm) level with normal and increased
temperature of 1.5 - 3.0°C above ambient with and without weed infestation during
Rabi season 2015-16 and 2016-17 at the controlled environment facilities site of
CESCRA, IARI to assess the growth, yield and physiological response of wheat crop
grown with and without weeds to elevated temperature and carbon dioxide
concentration of air. The results indicated that most of the growth and physiological
parameters such as leaf area index, average leaf size, leaf thickness (SLW) and
photosynthetic rate and water use efficiency were enhanced by elevated CO2, while the
same were reduced by elevated temperature and weed infestation. Grain yield of wheat
crop enhanced substantially (14%) by increasing the atmospheric CO2 level from 400
to 550 ppm, while the same reduced drastically at elavated temperature of 1.5 °C (12%)
and further reduced by 20% at elevated temperature of 3.0 °C. Infestation of wheat crop
with weeds caused about 8% reduction in grain yield. Elevated CO2 up to 550 ppm had
counteracted the detrimental effect of temperature up to 1.5 °C, but the negative effect
of temperature beyond that could not be offset by the same level of CO2 in the air. It
was also recorded that the degree of yield reduction by weed infestation was invariably
higher under elevated CO2 level in air compared to ambient level of CO2. The increase
of grain yield by elevated CO2 was mainly attributed to marked enhancement in the
photosynthetic rate and area of photosynthetic surface (leaves), tillering, spikes
numbers, grains per spike and 1000 grain weight and biological yield without any
changes in harvest index. However, the reduction in grain yield under increased
atmospheric temperature and weed infestation was due to marked decline in these
growth and yield attributes. Nitrogen and phosphorus contents in wheat shoots reduced
markedly under elevated CO2, while potassium content was increased in shoots under
same environment. The rise in temperature and presence of weeds in wheat crop
showed marginal decrease in the nutrients contents of wheat shoots. The uptake of
nitrogen and phosphorus were found almost at par both under ambient and elevated
CO2 condition, while the potassium uptake was invariably higher under elevated CO2
than under ambient CO2 condition. Rise in temperature and weed infestation showed
marginal reduction in nutrient uptake of wheat crop. Thus the nitrogen and phosphorus
use efficiency of wheat crop was registered higher under elevated CO2 condition, while
potassium use efficiency was reduced under same condition. There was slight reduction
in nutrient use efficiency by increased temperature and weed infestation except. Similar
to wheat crop, both the weed species Phalaris minor and Chinopodium murale also
showed positive and negative response to elevated CO2 and temperature respectively.
Nutrient uptake by weeds was slightly lower under elevated CO2 and temperature and
the same was markedly higher in Chinopodium murale compared to Phalaris minor.
Presence of weed population in wheat crop shared about 5-8% of nutrients takenup by
the wheat and weeds together which would otherwise have gone to wheat crop for their
growth and developmant. Thus occurrence of C3 weed in C3 wheat crop showed
negative interaction especially under elevated CO2 condition and exhibited greater
degree of yield depletion compared to ambient CO2 condition.
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Key words: Climate change, Grain yield, Nutrient uptake,Nutrient use efficency
Description
t-10044
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