Drought | drought in india | effect of drought | classification of drought | causes of drought | types of drought | effect of drought in india

DROUGHT

drought

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Low rainfall or lack of monsoon rains are a recurring feature in India. This was responsible for drought and famine. The word drought that it generally denotes is called water shortage in a region.

■ Although aridity and drought are due to insufficient water dryness, it is a permanent climatic feature and is the culmination of a series of long-term processes; however, drought is a temporary condition that occurs for a short time due to low rainfall from the vegetation. river flow, water supply and human consumption.

■ Drought is due to an anomaly in the atmospheric circulation.

Microsystem of irrigation

Water use efficiency

Evapotranspiration, mulches and antitranspirants

Problems of crop production in dryland

hydrological drought

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DEFINITION OF DROUGHT

There is no universally accepted definition of drought.

1. Itinerary defined by the first worker as an extended period without rain.

2. According to Ramdas 1960, drought is a situation in which actual seasonal rainfall is deficient by more than twice the mean deviation.

3. The American Meteorological Society defined drought as an abnormally dry period of time long enough for lack of water to cause severe water imbalance in the affected area.

4. Prolonged lack of soil moisture adversely affects crop growth, indicating the incidence of agricultural drought. It is the result of the imbalance between soil moisture and the need for evapotranspiration from an area for a long enough period to cause damage to a standing crop and reduce yield. 5. The Irrigation Commission of India defines drought as a situation that occurs in an area where annual rainfall is less than 75% of normal rainfall.

SUBSEQUENT CLASSIFICATIONS

Drought can be classified according to the duration, the nature of the user, the time it occurs and using some specific terms:

ACCORDING TO THE DURATION

A. Permanent drought: - This is a characteristic of the desert climate where sparse vegetation that grows adapts to drought and agriculture is only possible through irrigation during the growing season.

B. Seasonal drought: - It is found in climates with well-defined rainy and dry seasons. Most arid and semi-arid attitudes fall into this category. The duration of the crop variety and the sowing date should be such that the growing season falls within the rainy season.

C. Potential drought: - This implied an abnormal lack of rain. It can occur almost anywhere, especially in more humid or subhumid climates. It is usually short, regular, and usually affects only a small area.

D. Invisible drought: - It can also occur if there is frequent rain in an area. When rainfall is inadequate to cover evapotranspiration losses, the result is a limiting water shortage in the soil which results in less than optimal performance. This generally occurred in humid regions.

BASED ON RELEVANCE TO USERS (NATIONAL AGRICULTURE COMMISSION, 1976)

A. Metrological drought: - It is defined as a condition in which the annual precipitation is lower than normal above and the area for an extended period (month, season, year).

B. Atmospheric drought: - It is due to the low humidity of the air, often accompanied by hot and dry wind. It can also occur and a condition of sufficient soil moisture available. It refers to a condition where the plant shows symptoms of wilting during the hot part of the day when transpiration exceeds temporary absorption for a short time. When absorption keeps pace with perspiration, the plant is reborn.

C. Hydrological drought: - Metrological drought, when the result is prolonged in a hydrological robot with depletion of surface water and consequent emptying of the water tank, etc. It results in water scarcity for the entire industry that uses water. This is based on the water balance and how it affects irrigation as a whole to bring the crop to maturity.

D. Agricultural drought (soil drought): - It is the result of soil moisture and stress due to the imbalance between the movement of the available soil and the evapotranspiration of a crop. It is usually gradual and progressive. Therefore, the plant can adapt, at least partially, to the increased water stress of the soil. This situation occurs as a consequence of low rainfall or a uniform distribution in both space and time.

■ The relevant definition of agricultural drought appears to be a period of drought during the growing season, strong enough to negatively affect yield. The extent of a loss depends on the growth phase of the crop, the degree of stress and the end point, it's not begging when it rains, he says, but actually only comes when the plant's root can't get moisture from the soil quickly. in a replacement. losses due to evapotranspiration.

BASED ON THE TIME OF NEED

A. Early Season Drought: - Occurs due to the late onset of the monsoon or due to a prolonged period of momentum after early sowing.

B. Mid-Season Drought: - Occurs due to a long interval between two successive brains and restored movement becoming insufficient during the long dry period.

C. Late drought: - Occurs due to the early cessation of rains and water stress of crops as a stage of maturity.

ANOTHER TERM TO DESCRIBE THE DROUGHT

A. Relative drought: - Drought for one crop may not be drought for another crop, this is due to the mismatch between soil moisture conditions and crop selection. For example, a condition might be a drought situation for korma rice cultivation, but the same situation might not be a drought situation for peanut cultivation.

B. Physiological drought: refers to a condition where crops cannot absorb water from the soil even when water is available due to the high osmotic pressure of the soil solution due to increased oil consumption such as in saline and alkaline soils. it is not due to a shortage of water supply.

■ water is the most abundant substance in the living organism and makes up about 70% or more of its total body weight. In both natural and agricultural conditions, plants are constantly exposed to water. Water shortage occurs when the transpiration rate exceeds the water absorption rate, this may be due to excessive water loss, reduced water absorption, or both. Depending on the degree of internal water shortage, temporary incipient and permanent wilt can be distinguished. A small loss of turgor Insufficient wilting is a common feature that results from hot, dry weather and produces no visible symptoms of wilting. More severe loss of turgor causing leaf drop reduces plant growth. If the region of the plant is turgid when the water supply is installed, this is referred to as temporary wilting. on the other hand, a longer period of dehydration causes permanent wilting when the plants do not regain their turgor even in a saturated atmosphere. Humidity does not affect all aspects of plant growth and development in the same way, some processes are strongly affected while others are less affected. Drought is basically a metrological term, which indicates a lack of rainfall over a long period of time. However, a plant physiologist refers to a situation where the transpiration rate exceeds the absorption rate exceeds the plant's experience under stressful conditions.

HORTICULTURAL CROPS:-

Cinnamon (Daalchinni)

Mustard

coriander

Types of coffee

SEQUENTIAL EFFECTS OF WATER DEFICITY ON PLANTS

- Slatyer (1967) describes the sequential effect of water deficit in the plant. Reporting the first effect in response to doubt is closer to the estimate or for much of the day, resulting in reduced sweating and even CO2 uptake. The temperature of the leaves increases significantly. Most metabolic processes, including breathing, slow down. Photosynthesis and dry matter production become practically nil. Disruption of normal cellular metabolism is a component of protein and carbohydrate breakdown that results in increased amino acid creation and sugar content. Leaf Phosphorus and nitrogen migrate from the leaf to the stem. Finally, hydration of the protoplasm will lead to hydration of individual cells and particular tissues in the hair root. In some cases, the top of the plant dies before the root, in others the opposite happens.

- The sequential effect of the water deficit in the system is presented below. Soon:-

- Stomatal closure> reduction of sweating and CO2 absorption> increase in leaf temperature> reduction of photosynthesis and respiratory growth.

- EFFECT OF DRYNESS

Water shortage negatively affects plant growth and has affected different levels of plants. These can be summarized as follows: Morphological changes: - At the level of the entire plant:

1. The stature of the whole plant is reduced.

2. There is waste in the accumulation of dry matter.

3. Seedling vigor and crop settlement opponent were affected. The productivity of the crop is reduced. The crop survivor becomes difficult in case of severe water shortage.

At the organ level: -

1. There is a reduction in the elongation of the stem: the vapor is transformed into phyloclade (cactus).

2. . Lyf enlargement is reduced: the leaf becomes a thorn or thorn (cactus)

3. The fruit / necessity has not developed to its full size.

4. There is bad nodulation.

At the cellular level: -

1. Cell division is negatively affected.

2. There is a reduction in cell elongation.

3. Cell differentiation is poor

Anatomical changes: -

1. Stem and leaf covered with bark and wax respectively.

2. Development of sunken stomata.