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Biology and Biotechnology of Environmental Stress Tolerance in Plants, Volume 3

with the accumulation of different ROS (Lata et al., 2018). Water deficit

condition also affects several morphological and physiological changes like

reduced root growth, delaying flowering and fruiting, reduced seed numbers

and retard plant growth (Xu et al., 2016). Salt stress is another significant

stressor which is characterized by high salt concentration in the soil that

limits plant growth. Saline condition induces ion toxicity, reduced uptake of

phosphorus and nitrogen, decreased membrane function, suppressed cellular

metabolism, and accumulates ROS (Kumar, 2013). Rapid climate changes

contribute to the global warming which also influences plant growth and

development. High temperature rising has a direct detrimental effect on

plants. Heat stress negatively impact protein stability, metabolism, RNA, and

cytoskeleton structures (Theocharis et al., 2012). High temperature reduced

seed germination and results in impaired photosynthetic machinery. In an

experiment, it was observed that a short exposure of high temperature might

cause fatal collapse of cellular organization and could cause cell and tissue

death (Ahuja et al., 2010). Besides this, cold stress has several negative influ­

ences like membrane damage, cellular dehydration, inhibition of enzymatic

reaction, changes in structures of proteins and macromolecular interactions

(Yadav et al., 2010). Plants under the influence of heavy metal stress are

also subjected to several physiological and biochemical changes. Prolonged

heavy metal exposure to plants affects respiration, photosynthesis efficiency,

nutrients uptake and causes membrane damage (Zhang et al., 2009). It was

found that abiotic stresses significantly trigger biological, physiological,

and molecular changes in plants. Moreover, drought, salt, and temperature

stresses can initiate osmotic stresses which retards plant growth. Biotic stress

includes different pathogens belonging to different groups like bacteria,

fungi, nematodes, insects, and viruses. Uncontrolled biotic stress associated

with crop field could cause 100% yield losses. Biotic stress causes several

physiological and physical damages like root rot stem rot, plant wilt, seed

damages and also affects flowering.

3.3 PLANT RESPONSE TO EXTERNAL STRESSES

During the stress condition plant suffer from different difficulties and abnor­

malities in their body which halts growth. Abiotic and biotic stress is the main

challenge in the modern sustainable agriculture which needs to be controlled

to ensure food security in the near future. With due course of evolution,

plants have adopted different protective strategies to minimize the negative