Climatic Adaptation and Sustainability of Rice in Bangladesh

Climatic Adaptation and Sustainability of Rice in Bangladesh
Mohammed Ataur Rahman1* and Sowmen Rahman2
1Professor, College of Agricultural Sciences and Director, Centre for Global Environmental Culture, IUBAT—International University of Business Agriculture and Technology, Uttara, Dhaka
Email: marahman@iubat.edu *Corresponding author

2 Department of Environmental Planning, University of Waikato, New Zealand.
Email: soemenurp@gmail.com

Published in IUT-JARD Vol 5 No 2, 2020 https://iutripura.edu.in/IUT-JARD-Combined-Issue-April-2019-Septembe-2019-October-2019-March-2020.pdf

Abstract
Rice is the most important grain crop of Bangladesh. There are thousands of varieties of rice were in Bangladesh. Over 5000 local rice varieties have become extinct in the country in the last few decades. To date, approximately 8,200 germplasm have been preserved by the BRRI genebank. From the available data of Digital Herbarium of Crop Plants only 135 varieties are in cultivation now. According to climatic adaptation in the tropical monsoon four Ecotypes or Landraces of rice are grown in Bangladesh. These are Aus, Aman, Boro and Jhumia which are grown in different climatic seasons of tropical monsoon. The characteristics of these landraces are studied in detail in this paper. Special emphasis was given on adaptability and sustainability; residue management and biomass recycling of rice.

Keywords: Monsoon seasons, Agroecological niches, Landraces, Sustainability, Biomass recycling

Introduction
Bangladesh is located between 20°34´ and 26°38´ North latitudes and 88°01´ and 92°41´ East longitudes. It is a part of the Ganges and Brahmaputra delta which lies to the south foothills of the eastern Himalayas; west to the Arakan and Lusai folding ranges and in the south, the Bay of Bengal. Hundreds of rivers and tributaries from the upper north, northwest and eastern zones travel towards the Bay. There are few hillocks in the central zone of Bhawal and Madhupur, Lalmai and some high flats in the Barendra region. Besides these, there are scattered patches of hills and hillocks which are mainly the extensions of Himalayas and Lusai-Arakan ranges. The remaining areas are alluvial plains, flood plains, deep and shallow depressions or wet lands. Geologically, Bangladesh is a part of the Bengal Basin and the floor consists of quaternary sediments deposited by the GBM river system, and their numerous tributaries and distributaries. Over 92% of the annual runoff with huge sediments generated in the GBM catchment area flows through Bangladesh, which is only about 7% of the total catchment (Rahman and Rahman, 2015).
The climate of Bangladesh is humid subtropical nature with warm humid summer and cool dry winter under Indian Monsoon region having distinct four seasons. The Climatic Seasons are Pre-Wet Monsoon, Wet Monsoon, Post Wet Monsoon and Dry Monsoon (Shahid 2010). The Pre Wet Monsoon starts in March and prevails in the whole May. During this season, the southwest maritime wind starts, temperature rises up to 35°C, day and night temperature variation is very high often exceeds 20°C. Windy weather with increasing humidity, often with tropical cyclones called Nor’wester or Kal-Boishakhi. The Wet Monsoon starts in June and continued throughout September with high humidity, high temperature and high rainfall. Floods often cause serious damage to lives, crops and structures. Day and night temperature difference is comparatively low, seldom exceeds 10°C. The Post-Wet Monsoon starts in October till the end of November with high day light intensity and decreasing humidity. Often causes strong cyclones especially in the coastal region. During this period, water recedes from the floodplains like Baed, Kuri and edges of the Beels. The Dry Monsoon starts from December and prevails in February, dry weather with low temperature. Temperature often drops below 10°C usually with foggy nights and mornings.
The weather condition varies with the locations. While the eastern and southern districts have more moisture availability, which in the western is comparatively less. Although the average rainfall in Bangladesh is high but its distribution over time and space is not uniform. The period from December to February is virtually dry having only 65.9 mm rainfall. Among the districts, Natore receives the lowest rainfall (1556 mm) while Sylhet the highest (3876 mm). The mean annual temperature is 24.82° C, with maximum 29.79 and minimum 14.79° C averaged from 1796 until 2015. The average solar radiation indicates that the radiation interception is only 36 – 38% of the sunshine hours during June to August owing to continuously overcast sky. Flood is a regular feature affecting rice production in Bangladesh. On an average four percent of rice are annually damaged by flood (Paul and Rasid, 1993).
The average pH of Bangladesh soils could be taken on the acidic side of the pH scale, between 5.5 and 6.5. The Gangetic alluvium soils, particularly the calcareous one, have pH greater than 7.5, reaching at times up to 8.3. These contain free carbonates and bicarbonates. Soils in plateaus, raised lands and hills are usually acidic in nature. Organic matter (OM) status of Bangladesh soil is one of the lowest in the world. About 3.7 million hectares of land contain’ 1.75% organic matter; soils of the low-lying areas contain’ 5.5% organic matter with the exception of peat soils which contains not less 20% organic matter; and rest of the soils contain medium to high amounts of organic matter (Banglapedia).
Variation of climatic factors in different seasons and undulated landscapes provided distinct wet, semidry and wet phases of soil with variable fertility. These wide spectrum of fertility status of the region, in turn, results in vegetative growth potentials in general and cropping pattern in agriculture pattern in particular, especially for rice, attributing to inherent diversity traits of the region. It is roughly estimated that during the past more than 30,000 rice cultivars were grown in the eastern and north eastern parts of India. The indigenous rice varieties cultivated by traditional farmers may contain a considerable genetic diversity that can serve as a source of germplasm for genetic improvements of cultivated varieties of rice. In general, diverse landraces traditionally cultivated by farmers around the centers of diversity and domestication of crops are considered as key natural resources important for maintaining the future food security in light of the changing climate (Pusadee et al. 2009 and Choudhury et al. 2013).
Rice is the most important grain crop of Bangladesh. There are thousands of varieties of rice were in Bangladesh. Over 5000 local rice varieties have become extinct in the country in the last few decades (Rahman, 2013). Nearly I 0,000 landraces are considered to exist in Bangladesh (Cai and Morishima 2000) and it is estimated that about 120,000 varieties of rice exist in the world (Khush 1997). To date, approximately 8,200 germplasm have been preserved by the BRRI genebank (Islam et al. 2018). These germplasms are not only the basis of providing food security but also essential for saving the biodiversity. From the available data of Digital Herbarium of Crop Plants only 135 varieties are in cultivation now; this situation is very alarming both for food security and biodiversity. The ongoing rapid changes in agricultural practices that favor agronomically improved varieties have become a serious threat for the persistence of indigenous rice varieties. Thus, conservation and management strategies are urgently needed to prevent further loss of genetic diversity inherent to indigenous rice varieties in the region. A detailed understanding of the genetic structure and diversity is needed for the planning and implementation of effective conservation, management and utilization of rice germplasm in the whole region (Choudhury et al. 2013).
Therefore, along with the genetic forced crop improvement, climatic adaptation and improvement of environmental factors through climatic manipulation and aggregate farming using multiple varieties of crops, pets and aquatics etc. are utmost essential for food and nutrient security in this climate change situation. Considering these, climatic adaptation of rice has been studied under Bangladesh condition.

Methodology
This work has been started in 2010 with a self-funded initiative to collect information from different sources like research publications, government and public research institutions, offices, books and journals, periodicals and also from the news media. Physical investigations were made visiting most part of the country meeting people of different ages and levels. Many changes are also shared from the author’s experiences at different work places and compared them by revisiting. Since, there are marked changes of landscape are found but not scientifically documented or studied, as it was less understood or overlooked in the past, so little data is available. However, this study has been done with care and given utmost importance on its scientific needs.

Ecotypes and Landraces of Rice in Bangladesh
According to climatic adaptation in the tropical monsoon four Ecotypes or Landraces of rice are grown in Bangladesh which are Aus, Aman, Boro and Jhumia.

Aus: In BRRI genebank, there are 1,500 varieties of Aus rice are available. Growing period Pre-wet monsoon (March-April) to wet monsoon (July-August) Since Aus rice group has shorter duration and capabilities to address biotic and abiotic physiologically stress condition, so this particular group is being drawn attention to rice scientist for extensive research activities. There is very limited information on the above comparative study on physicochemical properties of these selected HYV and local Aus cultivars. These cultivars are being grown in the country and may have some useful characteristics, which would be helpful for developing improved new rice varieties (Hosen et al. 2016). It is interesting to note that seeds of Aus rice do not need any pre-germination wetting or soaking. Seeds are broadcast in well-ploughed dry field and they are happy to germinate and grow in the film moisture of the soil. They have well-developed root-system penetrate deep into the soil. Heavy rainfall at the early life is harmful for the plants, stagnancy hampers root aeration even plants get rotten. Beside this, heavy competition faces with other grasses and hamper the growth. Aus rice is tolerant to drought at the vegetative stage and to high temperature at the reproductive stage.
He quoted from Khona as saying on Aus rice something like as:
“Drought in May followed by a heavy rain,
Dry stalks grow green to yield better grain”.
Generally, drying up of the growing shoots of the plant at its early vegetative stage due to the severe drought helps to break the apical dominance to regenerate new tillers profusely immediate after the monsoon rain. Though Aus rice prefers to grow better under upland conditions, the reproductive and maturity stage of the crop has to encounter the rainy season. Even in the lower topography or in the charland farmers have to harvest their Aus crop in a knee to waist deep water (Biswas 2017).
Aus allows mixed cropping, traditionally amaranth, musk melon and sesame used to grow in the Aus field. Although the yield of Aus rice is low 1.83 tons per hectare (BBS 2012) but the aggregate output is very high.
Aus is very important for maintaining the dry phase of the soil and its microflora.
Some examples of local Aus varieties are: Haitta, Kotoktara, Goria, Porangi, Kala Manik, Hasi Kalmi, Balam, Vaduri, Aguli, Begun bitchi, Rang mahal, Laxmijhota, Katar, Chiknal, Manikmendal, Baismugur, Dal Kaisha, Kali Bori, Garia, Panock , MarikMandu , Chiknal , Shoni , Ingra , Nayan Tara , LangraBeni, LalGalong, Bolium , Holat , Noroi, Kamini Sail,, Laxmilota, Mele, Saita ,GoriSaita ,Porangi , Goyal , Manikmoda , Saita, Paik juta, Kala manic, BenaFul , KoeJuri , Tepakain , Kautukmoni , Hasha , Korchamuri , Ajabbeti , Boilam , Bnamka , Parangi , Baturi , HaitaiSaeta ,MorySaita , Manikmendal RangMahal, Baismagur , LaxmiJhota , Sribalium , Pankhira (Siddique et al., 2016).

Aman: Also called Baoa in Greater Mymensingh region. Cropping period for Broadcast method: Pre-wet monsoon to late Post wet monsoon; for Transplanted: early Wet monsoon to Post wet monsoon. Usually Aman is adapted to grow in the floodplains and seasonal wetlands like Baed, Kuri and edges of the Haors and Beels. Flood free upland flats are also used by terracing to keep required water for their growth and development of Aman rice. Vegetative growth needs longer photoperiod but flowers in short days. As Aman plants are water loving they have special adaptation with the environment. Their root system is comparatively not well-developed as they do not need to search for water. Usually with the rise of water, quick elongation of internodes and develop adventitious roots in the nodes for respiration. Some of the varieties of deep water rice are highly adapted even growing in deep monsoon water especially in the Beels and Haors. There are more than 2,000 deepwater rice cultivars in Bangladesh and almost all the deepwater cultivars are strongly photoperiod sensitive (Catling 1992). Photosensitivity fixes flowering time at a favourable point in the flooding period, enables the plant to escape the adverse effect, of low temperature in the reproductive phase, and usually ensures crop maturity as soon as floods have receded. Deepwater floating rice has three special adaptations: (i) ability to elongate with the rise of water levels; (ii) develop nodal tillers and roots from the upper nodes in the water; and (iii) the upward bending of the terminal part of the plant called ‘kneeing’ that keeps the reproductive parts above the water as the flood subsides (Yamuna and Ashwini 2016). Deepwater rice grows under rainfed dry land conditions for 2-4 months before the onset of flood, when plant produces basal tillers. With inundation the plant becomes an emergent macrophyte and grows in an aquatic environment for the remaining 3-5 months of its life. Nodal roots absorb nutrients from floodwater. Stem elongation is stimulated by partial submergence; it results from cell division and elongation of cells in the intercalary meristem due to an interaction of the plant hormones, under the control of two complementary genes. There is an increase in number of elongated internodes with the increase in water depths. Majority of deepwater rice cultivars in Bangladesh is of strong elongators. Stem may reach 5-6 m in very deepwater situations (Banglapedia). Unlike Aus, from the initial period viz. germination, seedling and growing stage till flowering it needs huge water. However during the ripening season excess water delays the development of grain and hampers ripening.
A few common Aman rice are Nazir Shail, Loti Shail, Raja Shail, Balam, Binni, Kataribhog, Digha, Kartik Shail, Birui, Kali Jira, Nuinnya, Chinigura, Beti Balam, Horkhuch, Britichikon, Tilok Kajol, Chengai Dhan, Sal Kele, Bet, Bilbadai, Modhusail, Lalmota, Sadamota, Rajushail, Patnai, Nonashail, Jhingashail, Indrashail, Kataribhog, Tulsimala and Kalijira.etc. Varieties like Jotabalam, Ashfall, ghunshi and Benapol are salinity tolerant.
According to land-water availability and climatic seasons Aman rice can be grouped into three which are Sali, Asra and Bao (Ngachan et al. 2011).
Sali usually grow in flood free terraced land and temporary flooded plains like Baid and Bandha; traditionally transplanted during the Wet Monsoon July to August. The essential rainwater is usually managed by Ails or raised boundaries through opening and closing channels or Nala. With the recession of rainfall, grams and pulses are often sown as mixed crops in most of the rice fields. Black gram (Mash Kolai) and Mung bean (Mug Kolai) are in the flood free and raised terraced land and Lathyrus (Kheshari) in the temporary floodplains. The rice used to harvest in late Post Wet Monsoon November and December.
Asra is shallow water rice usually grows in 1-2 M deep water, traditional sowing season Pre wet monsoon March-April and harvesting in Post wet monsoon November-December. For transplanted one: early Wet monsoon to Post wet monsoon.
Bao is deep water of floating rice grows in 2-5 M deep water traditional sowing season Pre wet monsoon March-April and harvesting in Post wet monsoon November-December. For transplanted one: early Wet monsoon to Post wet monsoon.

Boro: cropping period starts in Dry monsoon and harvest in Pre-wet monsoon. The boro rice is commonly known as winter rice. The term boro is Bengali originated from the Sanskrit word “Borob”. Boro has traditionally been cultivated in the river basins, deltas, chaurs or saucer shaped depressions, where water accumulates during the monsoons but cannot be drained, thus providing ideal settings for boro rice cultivation during the winter season. Rainfed swampy ecologies occur in depressed land conditions where the soil remains either submerged or saturated for a substantial period of the year. These areas are generally saucer-shaped and have various levels of soil saturation or submergence – the central low-lying zone generally remaining saturated or submerged throughout the year while the periphery shows gradual moisture depletion after the monsoon finishes, making it ready for rice transplanting in December or January. Being very low-lying, swampy ecologies are chronically flood-prone during the monsoon, rendering them unusable for crop cultivation from June to November (Pathak et al. 1999).
Although, boro rice cultivation has been an old practice in deep water areas, it is only recently that it has emerged as a major breakthrough in enhancing rice productivity, not only in traditional, but also in non-traditional boro rice areas with assured irrigation and modern inputs. The credit primarily goes to the farmers’ own initiatives in adopting its cultivation in a big way. With the increased availability of irrigation facilities, boro rice technology has also moved to non-traditional flood-free irrigated areas (Singh and Singh 2000). Traditional Boro rice is adapted with low temperature and low humidity. Boro rices are photoperiod insensitive and are adapted to mild winter conditions (Zaman, 1980) and cold adaptive (Choudhury et al 2013). They are similar to transplanted Aman both in their method of cultivation and crop habit. The boro crop is sown in October -November, transplanted around December-January and harvested in the spring. Traditionally, they have only been grown on land which retains sufficient water throughout the rabi season to support crop growth. However, with improved irrigation, these high yielding varieties are increasingly being adopted by Bangladeshi farmers (Parsons et al. 1999).
Few examples of local Boro rice are: Tepi boro, Jagli Boro, Kili Boro, Nayon moni, Tere bale, Bere ratna, Ashan boro, Kajol lata, Koijore, Kali boro, Bapoy, Latai balam, Choite boro, and Sylhety boro etc .

Jhumia or Jhum rice is also called Hill Rice: Cropping period: Sowing in Pre-wet monsoon April and May and harvested in Post wet monsoon September to November. They are grown on sloppy hills mixed with other crops after slash and burn method also known as shifting cultivation. There are thousands of Jhumia landraces in Northeast India. More than 300 local Jhum rice landraces have been collected from various locations in Chittagong Hill Tracts and conserved in Bangladesh Rice Research Institute (BRRI) Genebank (Source: BRRI Genebank accession book). Jhumia rice is also cultivated on the hills of Moulvibazar and Sylhet districts but very scant information is available on genetic divergence there. This collection is an invaluable genetic resource that can be used for varietal improvement (Islam et al 2017). Both red and white sticky (glutinous) and non-sticky (non glutinous) rice are grown in Bangladesh. Jhumia rice is adapted with high humidity and they cannot tolerate standing water at any phases of their life. Jhumia show adaptations to a wide range of ecological conditions including low levels of soil moisture in areas at high altitudes reaching over 3000 m above sea level (Choudhury et al 2013). They are mostly grown on the uplands covered extensively by Ultisols characterized by acidic reaction and the dominance of variable charge clays (Kyuma 2009). Jhumia rice usually cultivated with 30-40 other alley crops viz. maize, sesame, chilli, basils, arums, ginger, gourds, cucumbers, pumpkin, melons, string bean, Marpha, cotton and banana etc. which are traditionally grown by the local people. This multiple cropping systems provides the opportunity for livelihoods of other animals like wild fowls, pigs, wildboar, Monitor lizards, deer, wild dogs, porcupines, snakes, monkeys, jackals, hares, frogs and mongoose etc.
Some examples of locally cultivated Jhumia rice are: Kamarang, Koborok, Helong, Guri chinel, Bandar Bini, Horba Bini, Horin binni, Gellong, Lonka Pora, Uttose, Laxmi binni, Dop Chodai, Guri, Tarkee, Angu, Marry, Pattiya, Modhumaloti, Mon ange, Ame dhan, Badheia, Longur dhan, Biralbinni, Binni, Sonamukhi, Meli and Jhummalati etc.

Adaptability and Sustainability of Rice
Rice has the wide adaptation ability under different agroecological niches of Bangladesh. It can be cultivated on the slope of the hill, plain lands, floodplains, semi-dry to very deep flooded areas. Widely adapted with different climatic seasons; can be cultivated throughout the year. Rice is the best-adapted cereal crop in the lowland soil in the wet season. No other crops have this ability to cope with the situation. When the vast areas of our country go under flood water for considerable time in the wet season, or when intermittent flash flood affects majority of the lowlands, or when tide water rises up and falls down twice a day, rice is the only crop option to be suited in those conditions. Thus rice enables to bring these vast areas under cultivation in unfavorable conditions (Nasim et al. 2017).
An extremely high density of human population in Monsoon Asia has been supported by paddy rice cultivation developed on exceptionally extensive lowlands that have resulted from erosions of uplifting Himalayas and erupting volcanoes under heavy monsoon rains. A native grass, Oryza Sativa, has many outstanding merits when cultivated in submerged soil, thus making paddy rice/soil system highly productive and, at the same time, highly sustainable. High productivity and high sustainability are the outstanding merits of rice cultivation, while upland cultivation in Monsoon Asia for dry footed crops has been handicapped by low soil fertility and high susceptibility to soil erosion. In the future, rice would remain as the most important crop in Monsoon Asia and further intensification of rice cultivation should be attained. To nourish the region’s increasing population, upland cultivation must also be intensified with adequate measures for soil amendment and conservation (Kyuma, 2009).
Traditionally in Bangladesh, Jhum or shifting cultivators had been paying careful attention to soil resilience by practicing short cultivation following long fallow system with minimum of disturbance to the surface soil to avoid soil erosion and to help facilitate forest regeneration thus Jhum cultivation as a means of slopeland utilization has traditionally been quite sustainable.
According to variation of climatic seasons and topography there evolved different kinds of rice with many characters and specialties. Aromatic, non-aromatic, glutinous and non-glutinous, coarse and fine grain, long medium and short grain rice with varied colors: brown, white, red and black etc.
Perhaps rice is the most sustainable food crop in the world in providing energy and nutrition, has versatile food preparations, preservation and regeneration opportunities. Comparing to vegetable crops, other grain crops, tuber and root crops and even fruit crops rice is cheaper and handy.
Rice is considered to be an auspicious symbol of life and fertility. Starch is the most important source of carbohydrates in the human diet and accounts for more than 50% of our carbohydrate intake. It occurs in plants in the form of granules, and these are particularly abundant in cereal grains and tubers, where they serve as a storage form of carbohydrates. We often think of potatoes as a “starchy” food, yet other plants contain a much greater percentage of starch (potatoes 15%, wheat 55%, corn 65%, and rice 75%). Commercial starch is a white powder (LibreTexts 2019). Although potatoes are cheaper than rice but it is one-fifth efficient to rice therefore costlier than rice.
Boiled and cooked rice, viz. Bhat, Polao, Biriani, Khichuri, fried and puffed rice: Chira, Muri, Khoi and Moa, fermented Bini Bhat, wine, bear and vinegar, rice bran oil, soup and many kinds of cakes and preparations with fruits, sugar, milk, chili and spices e.g. Pitah, Payesh, Kheer, Semai, banana leaf Puli, and bamboo Pitahs, different seasonal Pitah preparations like Taler (Palmyra palm) Pitah in Vadra, Vapa Pitah in Poush, Kolar (Banana) Pitah in Magh, Katal (Jackfruit) Pitah in Jaista and Ashar and coconut pitah throughout the year. Cooked rice is usually consumed with diverse recipes prepared with meat, fishes, prawns and vegetables and fruits as curries, Vorta and salads etc.

Residue management and biomass recycling
Residue management practices affect soil physical properties such as soil moisture content, temperature, aggregate formation, bulk density, soil porosity and hydraulic conductivity. Increasing amounts of rice residues on the soil surface reduce evaporation rates and increased duration of first-stage drying. Thus, residue-covered soils tend to have greater soil moisture content than bare soil except after extended drought (Mandal, et al. 2004). The straws are very good fodder for cattle used both green and dry conditions. Straws contain cellulose lignin and many minerals which decompose in the field or recycled via cattle through enzymatic and microbial process enriching food chain adding value with protein, fat and minerals. The cellulose is the carbohydrate like starch with similar basic unit glucose. Therefore both rice and straw are contributing in energy conversion and nutrient supply chain and in biogeochemical cycle more efficiently than any other crop.
Usually the yield of the vegetable crops is high and consumed whole plant parts; thus all nutrients are ingested by human, very little portions are recycled through involvement of other animals. As a result, short-cycled recycling of the human faeces or excreta is not easy especially from the quickly growing urban areas. Therefore, the nutrients are not getting back to their sources of origin and the soil nutrition status is declining sharply mainly from the vegetable fields. Practically in the urban and peri-urban areas, the huge faeces are remained unutilized years together in the septic tanks; the black water overflows to the rivers or wet-bodies through sewerage system. Unfortunately, most of the wet bodies are deadly polluted with the chemicals, oils and other pollutants discharged from the industries, transports, hospitals and tanneries etc. As a result, the productivity of fishes and other aquatics is also very poor from those wet bodies. On the other hand, urban green garbage is rarely recycled rather dumps for landfill. Other than the faeces, according to Waste Concern (2006), average per capita urban waste generation rate is estimated as 0.41 kg/capita/day of which food and vegetable comprises 67.65% i.e. about 0.28 kg/capita/day and for present urban 40% of the total population of the country producing 20,160 tons green waste everyday by the urban people of which a very negligible quantity is recycled. Thus the soil fertility status of the country has been declining very sharply and the farmers are becoming increasingly dependent on chemical fertilizers. Therefore rice-based home centered farming system for short cycled biomass recycling is utmost essential. The diversified landraces of rice have the ability to supply the necessary energy and nutrients to human and other animals associated in the cropping circle in this region.

Conclusion
Since rice is the most adaptive crop grown in versatile conditions like hill slopes, flatlands, floodplains, wetlands in varied weather conditions especially of monsoon regions, tropical and equatorial zones of the world providing food and nutrients to almost half of the population of the earth it should be remembered that if there is no rice to eat, the whole civilization will collapse. It must be investigated whether the flourishing Indus Valley civilization collapsed as a result of adverse climate change. Climate is of crucial importance in rice production. A change in the climate regime can cause to end a civilization. Therefore, extensive climatic research in the country with emphasis on agro-climatology (Choudhury 2011) is urgently needed. To save the biodiversity and for regaining of the soil health by enriching the soil micro and macroflora and nutrient recycling the diverse landraces of rice are essential. Large variation of its color, smell, grain-size, texture and chemical composition etc. indicate the richness of its sustainability.

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