43. Adaptation and distribution of crops 1 Adaptation Adaptation may be defined as any feature of an organism, which has survival value under the existing condition of its habitat. Such features or feature may allow the plants to make fuller use of nutrients, water, temperature or light available or may give protection against adverse factors such as temperature extremes, harmful insects and diseases. Adaptation may be morphological or physiological. Morpho holo logi gica call adaptation such as growth habit, strength of stalk, radial symmetry, or rhizomes. (a) Morp (b) Physiological adaptation, which result in resistance to parasites, greater ability to compete for nutrients or ability to withstand desiccation. However both morphological and physiological adaptation represents the expression of physiological processes. 2 Principles of Plant Distribution Environmental factors are highly influential in determining the natural distribution of plants. There are eight principles of plant distribution • Evolution • Climatic factors Climatic factors like light, temperature, moisture, wind etc. • Edaphic factors like soil, parent material, physiography • Dispersal of flora • Plant migrations • Climatic variations or change • Relative distributions of land and sea (occurrence in geological time ) and it exerts a high degree of control over distribution of flora • Biotic factors like obligate insect pollination, seed dissemination by animals and grazing by live stock directly influence the plant distribution. 3 Theories Governing Crop Adaptation and Distribution Theory of tolerance - Each plant or living organisms is able to thrive well in certain climatic conditions below which and above which the plant can’t grow, i.e., it requires optimum climatic conditions. Temperature is one of the most common limiting factors in plant distribution. Many tropical crops such as rubber, cocoa, banana will not with stand freezing temperature (0°C). In these rubber probably has the narrowest tolerance range and banana the widest range for temperature tolerance. Theory of avoidance - It may be accomplished through rapid completion of the life cycle, as in ephemerals, dormancy in seeds to avoid effects of the hottest and driest periods, dormancy in vegetative parts or roots of all the perennials, water accumulation in succulents and extremely deep root systems s ystems to avoid moisture deficiency. Theory of factors replaceability - One factor that can be replaced by another or substituted by another. For e.g. e.g.,, • Elevation can be substituted for latitude because of its temper ature temper ature effects. The climatic conditions at the latitudes of 35 – 45° 45° N resembles to that of tropical regions at elevation of 4000 – 6000 6000 ft. • The angle direction of slope may be substituted for latitude. This is also a temperature adjustment, depending on the angle of exposure to solar radiation, wind etc. • Parent materials may compensate for climate. • Rainfall may be replaced by fog and to some extent by dew. • Soil texture may be substituted for moisture.
Major Crops of Indian Sub-continent The origin, adaptation, altitude, rainfall and temperature, soil and distribution of different crops are given below. 1. Rice - In India rice is the most important food crop and it is the staple food in tropical and subtropical regions of Asia and Africa. Origin: Indo-Burma (Indo-Myanmar). Adaptation: Grown in the world between 39°S (Australia) 50°N latitude (China). In India it is grown between 8°N to 34°N latitude. latitude. Altitude: From below sea level (Kuttanad region of Kerala) to 3000 m (Jammu and Kashmir) above MSL.
Rainfall and Temperature: Rice is classified as a hydrophyte. A heavy rainfall (R.F.) of 125 cm is required during its growing period. There should be a monthly R.F. of 200 mm to grow lowland rice and 100 mm to grow upland rice respectively. Deep water rice requires one meter height of standing column of water. Rice requires high humidity and high temperature (18 – 32°C). The critical mean temperature for flowering and fertilization is 16 – 20°C. Soil: Though rice can be grown in variety of soils, ideal soil is heavy alluvial soils of river valley and delta. The best is soils with slightly acidic nature 5.5 to 6.5 pH, but rice is commonly grown in soils of 4.5 to 8.5 pH. Rice is also grown in acidic peaty soils of Kerala with pH of 3.0 and highly alkaline soils of Punjab and Haryana with pH 10.0. Distribution: Rice is widely distributed in India, Pakistan, Bangladesh, Malaysia, Taiwan, China, Japan, Australia, USA, Spain, Korea. In India rice is grown in the states of Tamil Nadu, Kerala, Bihar, Uttar Pradesh, Madhya Pradesh, West Bengal, Orissa, Andhra Pradesh etc. 2. Wheat - Wheat is the most important and widely cultivated crop in the world. In occupies a prime position in terms of production. India ranks second in production next to China. In India, wheat is the second most important food crop next to rice. Origin: Central Asia. Cultivated species Common/bread wheat – 95% production. Durum/macaroni/samba wheat – 3-4% production. Emmer wheat – 1% production Indian dwarf wheat – less than 1% production Distribution: Widely distributed in USSR, China, USA, Switzerland, France, Germany, India etc. In India wheat is grown in the states of Uttar Pradesh, Madhya Pradesh, Punjab, Rajasthan, Bihar, Haryana, Maharashtra and Gujarat. Adaptation: It can be cultivated from sea level to as high as 3,300 m above MSL. Climate: Cool winter and dry hot summer is required. Wheat requires a rainfall of 40 – 90 cm. But high temperature and high humidity are harmful. Soils: Though grown in wide range of soil, well drained loams and clay loams are better suited. It is grown in soils with pH above 5.8 and the most suitable pH is 6.5 – 7.5. Seasons Winter wheat: Long duration wheat varieties are grown in this season, which require low temperature during early growth for flowering and fruiting. It is grown from October, November to May, July. Spring wheat: These varieties do not require low temperature for flowering the fruiting. Normally grown from March, May to August, September. In India, spring wheat is grown in winter (October, November to March, April). There are two seasons for wheat in hills of Tamil Nadu (i) October – April, and (ii) May – September. Wheat zones of India 1. North Western plains, 2. North Eastern plains, 3. Central zone, 4. Peninsular zone. 3. Maize - It is a multipurpose cereal, grown in USA, Brazil, China, Mexico, India and Canada. In India it is grown in states of Uttar Pradesh, Madhya Pradesh, Bihar, Rajasthan, Punjab, Karnataka, Himachal Pradesh. It requires a mean temperature of 24°C and night temperature more than 15°C. Summer temperature below 19°C is not suitable. It requires a well distributed rainfall of 50 – 75 cm. It can be grown from sea level to 3000 m above MSL. 4. Sorghum (Jowar) - It is a cereal crop for food in underdeveloped countries and it is grown in USA, China, Nigeria, Sudan and Argentina. In India, it is grown in states of Maharastra, Andhra Pradesh, Karnataka, Gujarat, Madhya Pradesh, Tamil Nadu, Rajasthan and Uttar Pradesh. The Temperature requirement is minimum 8 to 10°C, optimum 26-29°C and maximum 35-40°C. Sorghum can tolerate high temperature throughout its life cycle better than any other cereal crops. Sorghum can tolerate drought condition. Because (a) it remains dormant during moisture stress and resumes growth when favourable condition reappear, and (b) it possesses (i) high resistance to desiccation, (ii) low transpiration rate, and (iii) largest number of fibrous roots. 5. Chick pea/Bengal gram - It is number one pulse in area, production and economic importance in India. It is grown in India, Pakistan, Ethiopia, Burma, Turkey. In India, it is grown in states of Madhya Pradesh, Uttar Pradesh, Rajasthan, Punjab, Haryana and Maharastra. It is a winter season crop but severe cold and frost are injurious to it. It requires a moderate rainfall of 60-90 cm. 6. Pigeonpea (arhar) - A pulse crop of India with high demand. It is the second most important pulse crop of India and foremost in Southern India. It is a crop with great resilience and withstands water stress and
association of short duration crops without any considerable adverse effect on yield. It is grown as pure crop, intercrop border crop etc. 7. Groundnut (peanut) - It is an introduced important oilseed crop of India. It is a tropical crop grown in India, China, U.S.A. and Brazil. In India, it is grown in the states of Gujarat, Andhra Pradesh, Tamil Nadu and Punjab. It is grown between 45°N and 30°S latitude with R.F: 370 – 600 mm, minimum temperature: 14 – 16°C and optimum temperature : 21 – 26.5°C. 8. Sunflower - It is also an important oil seed crop of India. It requires a rainfall of 380 mm in summer and 550 mm in sandy loam soils. Sunflower has a heliotropic response. It is grown in U.S.A, Argentina, Romania, Spain, Yugoslovakia, Turkey and former USSR countries. Being thermo and photo insensitive it can be grown throughout the year. 9. Mustard - An oilseed of Indian origin. It is grown in India, China, Pakistan and Bangladesh. In India, it is grown in Uttar Pradesh, Madhya Pradesh, Rajasthan, Punjab, Haryana, Bihar, Orissa, West Bengal and Gujarat. It requires cool climate and rainfall of 35 – 45 cm. 10. Cotton - It is a fibre crop of commercially important and an industrial crop. It is grown in India, U.S.A, former USSR countries, China, Brazil, Egypt, Pakistan, Mexico, Turkey and Sudan. In India, it is grown in Maharastra, Gujarat, Karnataka, Andhra Pradesh, Tamil Nadu, Punjab, Rajasthan, Haryana and Uttar Pradesh. Cotton is a heat loving plant requires a minimum rainfall of 175-200 mm (well distributed). It requires a minimum of 180 – 200 frost free days. 11. Jute - It is also a fibre crop. It is grown in India, Bangladesh, China, Thailand, Brazil, Peru, Burma, Nepal and Vietnam. In India, it is grown in West Bengal, Bihar, Orissa, Uttar Pradesh, Meghalaya and Tripura. It requires an optimum temperature of 25 – 38°C, rainfall of 150 cm/annum and relative humidity of 55 – 90%. 12. Tobacco - It is grown in India, China and USA. In India, it is grown in Andhra Pradesh, Gujarat, Karnataka, Tamil Nadu, Orissa, West Bengal, Bihar, Maharastra and Uttar Pradesh. It is a day neutral plant. It requires a rainfall of 500 mm and 90-120 frost free days. The temperature requirement is, minimum temperature 13 – 14°C, Optimum temperature 27 – 32°C and maximum temperature 35°C. 13. Sugarcane - It is an important commercial cash crop, grown in India, Cuba, Brazil, Mexico, Pakistan, China, Philippines, Thailand and USA. In India, it is grown in the states of Andhra Pradesh, Gujarat, Orissa, West Bengal, Bihar, Maharastra, Karnataka and Tamil Nadu. (It is grown in 30°N – 30°S latitude) Frost causes injury to sugarcane buds. It requires an annual rainfall of 1250 – 2500 mm. It is a short day plant, flowering can be photoperiodically controlled. It requires an optimum temperature of 26 – 32°C for growth. 14. Potato - Being a crop of temperate crop, requires a cool temperature. Ideal temperature for vegetative growth is 24°C and that for tuberisation is 18-20°C. It is susceptible to frost and requires bright sunny weather. High humidity coupled with cloudy days is injurious to potato because the crop is attacked by fungal diseases (late blight). 15. Sugar beet - It is grown in former USSR countries, USA., France, Germany, Italy, Turkey, Poland, Czechoslovakia etc. In India, it is grown in Jammu and Kashmir, Punjab, Rajasthan, Uttar Pradesh and Maharastra. It requires an optimum temperature of 20 – 22°C and maximum temperature of 30°C and the crop is highly tolerant to frost and cold. 16. Banana - It is grown in India, Taiwan, Equator, Coasto rica, Panama, Mexico, Ivory coast, Columbia and Guatemala. In India, it is grown in Tamil Nadu and Kerala. It is grown with rain fall of 1800 – 2500 mm. It requires a minimum temperature of 8 – 9°C and optimum temperature of 24 – 29°C.
