Agriculture Reference
In-Depth Information
a large majority of the weeds in agriculture, they pose a growing threat
to food production. Alien invasive plants like
Parthenium
,
Lantana
, etc.
often replicate faster by wider spread of seeds and multiplication through
vegetative means (roots, shoots and stolon's etc) and are usually more
responsive to increases in atmospheric CO
2
concentrations (Hedayetullah
et al., 2011).
19.2.6 CROP-WEED COMPETITION
Weed invasion is one of the major biotic stresses in agriculture causes yield
loss up to 33% (Vision, 2050). Majority of the crops are C
3
plants whereas
most of the weeds are C
4
plants which have better adoptability and growth
under elevated CO
2
concentration due to climate change. It is observed
that CO
2
enriched environment, weeds transfer significantly more carbon
to roots and rhizomes than to shoots.
This improves their root growth and
increases their chances of survival. More vigorous roots lead to more vi-
able plants and higher reproduction with more seeds. Weeds with stronger
roots are more competitive and more difficult to control with traditional
weed management techniques or herbicide which attack the foliage rather
than the roots. Hence, climate change is expected to promote proliferation
of new weed species in the composition of weed flora and causes invasion
over agricultural crops. This is important since the dynamics of crop-weed
competition ultimately decides crop yield. The higher genetic diversity in
weeds gives them flexibility to adapt to new environments through quickly
responding to the changes with higher rates of growth and reproduction. A
larger number of weed species are found associated with respective major
crops as well as minor crops. Often the worst weeds of crops are their wild
relatives, for example, red rice is a weed in rice cultivation and Johnson
grass a close relative of sorghum is a weed in sorghum fields.
19.2.7 CROP PRODUCTIVITY
The impact of climate change on agriculture especially in crop productiv-
ity is observable. According to the IPCC, the next few decades of climate
change are likely to bring benefits to higher latitudes through longer grow-
ing seasons, but in lower latitudes, even small amounts of warming will
tend to decrease yields. The regional inequality in food production resulting
