Effect of climatic factors on crop

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2. MASHOOQ HUSSAIN ODHANOASSISTANT RESEARACH OFFICERAGRICULTURE CHEMISTRY (SOILS) SECTIONAGRICUTLURE RESEARCH INSTITUTE TANDOJAM 3. As elevation increases, the average temperature decreases.Above a certain elevation, low temperatures make itimpossible for trees to grow, as seen here on WashingtonsMount Rainier. 4. Pakistans Resource Base LAND (in million hectare) Geographical area= 79.6 Area under cultivation = 27.6% (21.87) Crop area irrigated= 22.6% (17.99) Rainfed Agriculture area = 4.97% (21.87) Forest = 4.5% (3.61) Culturable waste = 11.7% (9.31) Range Lands= 59% (46.96) 5. Cropping Seasons Rabi November-April Wheat, Lentil, Chickpea Kharif May-October Rice, Maize, Mungbean, Cotton 6. ClimateWind,Temperature RainfallSunshine, CO2 levelSolar RadiationPhotosyntheticEvapo-transpiration (ET) ActivityCrop Water Demand Canal/groundwaterWater Availability Agriculture (Crop Yield) 7. Agricultural productivityCrop YieldWheat2262 kg/haRice 1836 kg/haMaize1768 kg/haSugarcane 48.1 t/haCotton 579 kg/haFodder22.3 t/ha 8. Climate and Food Production Weather and Climate are the key factorsin food productivity Being open to vagaries of nature, foodproduction are highly vulnerableto climate change phenomena 9. What is Crop? A crop is a volunteered or cultivated plant (any plant) whoseproduce is harvested by man at some point of its growth stage. Crops refer to plants of same kind that are grown on a largescale for food, clothing, and other human uses. They are non-animal species or varieties grown to be harvested as food,livestock fodder, fuel or for any other economic purpose (forexample, for use as dyes, medicinal, and cosmetic use). Major crops include sugarcane, pumpkin, maize (corn), wheat,rice, cassava, soybeans, hay, potatoes and cotton. While theterm "crop" most commonly refers to plants, it can also includespecies from other biological kingdoms. For example, mushrooms like shiitake, which are in the fungikingdom, can be referred to as "crops". In addition, certainspecies of algae are also cultivated, although it is alsoharvested from the wild. In contrast, animal species that areraised by humans are called livestock, except those that arekept as pets. Microbial species, such as bacteria or viruses, arereferred to as cultures. Microbes are not typically grown forfood, but are rather used to alter food. For example, bacteria 10. What is Climate? Climate is defined as an areas long-term weatherpatterns. The simplest way to describe climate isto look at average temperature and precipitationover time. Other useful elements for describingclimate include the type and the timing ofprecipitation, amount of sunshine, average windspeeds and directions, number of days abovefreezing, weather extremes, and local geography. 11. Climate Related climatic factors of Agricultural Productivity CO2 Temperature Solar Radiation Precipitation Others (Wind speed and direction, Soil Moisture,Water vapour, etc.)Basic understanding of these factors helpsmanipulate plants to meet human needs of food,fiber and shelterThe parameters also help understand impacts ofclimate change and devise adaptation/mitigationstrategies 12. Rainfall and Water Rainfall is the most common form of precipitation. It is the falling of water in droplets on the surface of the Earth from clouds. Other forms of precipitation are freezing rain, sleet or ice pellets, snowfall, and hail. The amount and regularity of rainfall vary with location and climate types and affect the dominance of certain types of vegetation as well as crop growth and yield 13. Light Light is a climatic factor that is essential inthe production of chlorophyll and inphotosynthesis, the process by whichplants manufacture food in the form of sugar(carbohydrate). Other plant processes that are enhanced bythis climatic factor include: stomatalmovement, phototropism,photomorphogenesis, translocation, mineralabsorption, and abscission. 14. Light (Contin;) Light is that visible portion of the solar radiationor electromagnetic spectrum. It is a form ofkinetic energy that comes from the sun in tinyparticles called quanta or photons, travelling inwaves. Three properties of this climatic factor that affectplant growth and development are light quality,light intensity, and day length or photoperiod. Light quality refers to the specific wavelengths oflight; light intensity is the degree of brightnessthat a plant receives; and daylength is theduration of the day with respect to the night period. 15. Temperature :The degree of hotness or coldness of a substance is called temperature. It is commonly expressed in degree Celsius or centigrade (C) and degreeFahrenheit (F) This climatic factor influences all plant growth processessuch as:Photosynthesis, respiration, transpiration, breaking of seed dormancy, seedgermination, protein synthesis, and translocation. At high temperatures thetranslocation of photosynthate is faster so that plants tend to mature earlier. In general, plants survive within a temperature range of 0 to 50 C .Enzymeactivity and the rate of most chemical reactions generally increase with risein temperature. Up to a certain point, there is doubling of enzymatic reactionwith every 10 C temperature increase But at excessively high temperatures,denaturation of enzymes and other proteins occur. Excessively low temperatures can also cause limiting effects on plant growthand development. For example, water absorption is inhibited when the soiltemperature is low because water is more viscuous at low temperatures andless mobile, and the protoplasm is less permeable. At temperatures belowthe freezing point of water, there is change in the form of water from liquid tosolid. The expansion of water as it solidifies in living cells causes the ruptureof the cell walls. The favorable or optimal day and night temperature range for plant growthand maximum yields varies among crop species. 16. Temperature 17. Air The air is a mixture of gases in the atmosphere. According to Miller(2001), about 75% of this air is found in the troposphere, theinnermost layer of the atmosphere which extends about 17 km abovesea level at the equator and about 8 km over the poles. In addition, about 99% of the clean, dry air in the troposphere consistsof 78% nitrogen and 21% oxygen. The remainder consists of argon(slightly less than 1%), carbon dioxide (0.036%), and traces of othergases. The oxygen and carbon dioxide in the air are of particular importanceto the physiology of plants. Oxygen is essential in respiration for theproduction of energy that is utilized in various growth anddevelopment processes. Carbon dioxide is a raw material inphotosynthesis. The air also consists of suspended particles of dust and chemical airpollutants such as carbon monoxide (CO), carbon dioxide (CO2),sulfur dioxide (SO2), sulfur trioxide (SO3), nitrogen oxides, methane(CH4), propane, chlorofluorocarbons (CFCs), solid particles of dust,soot, asbestos and lead, ozone and many more. However, the composition of this climatic factor is susceptible of 18. Relative Humidity The amount of water vapor that the air can hold depends on its temperature; warmair has the capacity to hold more water vapor than cold air. There is almost one-halfreduction in the amount of water vapor that the air can hold for every 10 C drop intemperature. Relative humidity (RH) is the amount of water vapor in the air, expressed as theproportion (in percent) of the maximum amount of water vapor it can hold at certaintemperature. For example, an air having a relative humidity of 60% at 27 Ctemperature means that every kilogram of the air contains 60% of the maximumamount of water that it can hold at that temperature . The amount of water vapor in the air ranges from 0.01% by volume at the frigid polesto 5% in the humid tropics. Compared to dry air, moist air has a higher relativehumidity with relatively large amounts of water vapor per unit volume of air. The relative humidity affects the opening and closing of the stomata which regulatesloss of water from the plant through transpiration as well as photosynthesis. Asubstantial understanding of this climatic factor is likewise important in plantpropagation. Newly collected plant cuttings and bareroot seedlings are protectedagainst dessication by enclosing them in a sealed plastic bag. The propagationchamber and plastic tent are also commonly used in propagating stem and leafcuttings to ensure a condition with high relative humidity. 19. Wind Air movement or wind is due to the existence of pressure gradient on a globalor local scale caused by differences in heating. On a global scale it consists ofthe jet stream flow and movement of large air masses. On the local scale onlya smaller quantity of air moves. Surface winds are lower and less turbulent atnight due to the absence of solar heating. When air that is close to the ground cools, it contracts and the pressure rises;when it warms, it expands and loses pressure. Where both cold and warm airoccur in proximity, as over a lake and its adjacent shore, the cold flows to thedirection of the warm air or from high to low pressure area to correct thepressure imbalance. This also happens in tropical Asia but in a larger and morecomplex way, as the monsoon winds. This climatic factor serves as a vector of pollen from one flower to another thusaiding in the process of pollination. It is therefore essential in the developmentof fruit and seed from wind-pollinated flowers as in many grasses. Moderate winds favor gas exchanges, but strong winds can cause excessivewater loss through transpiration as well as lodging or toppling of plants. Whentranspiration rate exceeds that of water absorption, partial or complete closureof the stomata may ensue which will restrict the diffusion of carbon dioxide intothe leaves. As a result, there will be a decrease in the rate