chilling stress, chilling and freezing stress

chilling stress, how to protect plant from chilling stress, what is damaging in plant due to chilling stress, what is main objective to protect the plant from the chillinng stress, what is morphological changes come due to chilling stress, how to protect the plant from chilling stress, what is chill stress, Why the chilling stress, what is the merit and demerit from the chilling stress

1. Presentation on Chilling stress Pradyum Maurya Ph.D . Dept. of Genetics and Plant Breeding Banda University of Agriculture & Technology, Banda

2. Introduction Stress in physical terms is defined as mechanical force per unit area applied to an object. In response to the applied stress, an object undergoes a change in the dimension, which is also known as strain. Stress is an adverse force or a condition which inhibits the normal functioning and well being of a biological system such as plants. Various types of stress are such as Freezing, chilling, heat, drought, flood, salinity, etc

3. Low Temperature Stress Chilling stress – When plants are exposed to a low temperature above 0°C. Freezing stress – When plants are exposed to a low temperature below 0°C.

4. Physiological Reaction of Plant to Low Temperature Each plant has its unique set of temperature requirements, which are optimum for its proper growth and development Water content - Total water content decreases, bound water increases. Unsaturated fatty acid increase in membrane and saturated on decreases. ABA increases, GA decreases, dormancy appears.

5. Metabolism disorder :- Uptake of solutes by root decreases and water balance disturbed Transpiration is more as compare to the water absorption due to that the plant loss water and leaf curls. Photosynthetic rate become low - Due to low temperature the rate of photosynthesis become low and the rate of respiration is increases. Aerobic respiration decreases and anaerobic respiration increases Cytolyses activity decreases, electron transport and phosphorylation activities decreases Organic substance degrades - Protein, RNA, ATP decrease

6. Chilling Injury Symptoms Cellular changes : Changes in membrane structure and composition, decreased protoplasmic streaming, plasmolysis. Altered metabolism : Increase or reduced respiration, depending on severity of stress, production of abnormal metabolites due to anaerobic condition

7. Common Symptoms : Reduced plant growth and death Surface lesions on leaves and fruits Abnormal curling, lobbing and crinkling of leaves Water soaking of tissues Cracking, splitting and dieback of stems Internal discoloration Increased susceptibility to decay Failure to ripen normally Loss of vigour

8. Mechanism of Chilling Stress Chilling is a common environmental stress in nature that can directly affect the physiological functions of chloroplasts. First, chilling can change the lipid membrane state and enzyme activities in chloroplasts. Then, the efficiency of photosynthesis declines, and excess reactive oxygen species (ROS) are produced.

9. Methods to Increase the Resistance to Low Temperature Select and use chilling tolerant species/ cultivars Low temperature hardening . Chemical control ABA, CCC, PP330, Amo-1618. Others - Proper planting dates Artificial covers Proper soil moisture Plant growth regulators as ABA

10. CONCLUSION Chilling stress may affect seed germination, and cause injury to seedlings and root systems . Chilling injury is related to membrane phase transition, metabolic disturbance, water absorption and other physiological activities etc . Low temperatures can result in poor growth. Photosynthesis is slowed down at low temperatures. Since photosynthesis is slowed, growth is slowed, and this results in lower yields.

11. Thank You...