Rice ( Oryza sativa ) is the most of import harvest in the universe after wheat, with more than 90 % presently grown in Asia. Rice is the grain that has shaped the civilizations, diets and economic systems of one million millions of Asians. For them, rice is more than nutrient ; rice is life. About 120,000 assortments are grown across the universe in an extended scope of climatic dirt and H2O status. It is grown on an country of 149.151 million hectares ( hour angle ) giving 550.193 million dozenss of Paddy with a output of 3689 kg ha-1 ( Alam et al. , 2001 ) . In Asia, China is the major rice bring forthing state followed by India, Indonesia and Bangladesh. However, output per hectare is highest 6.1 dozenss in Japan, followed by 5.1 dozenss ha-1 in China. Rice breeders have used familial variableness to bring forth cultivars that have high output potency and that resist disease and insect harm and that tolerate cold, drouth, and even inundations. But apart from some sporadic work in Sri Lanka and India, small has been done until late to place any breed/cultivars adaptable to adverse dirt conditions such as salt. Salinity is a major menace to harvest productiveness in the southern and south-western portion of Bangladesh, where it is developed due to frequent inundation by sea H2O of the Bay of Bengal and on the other manus debut of irrigation with saline Waterss. In Bangladesh, there are about 2.85 million hour angle of coastal dirts ( Ponnamperuma, 1977 ) which occur in the southern parts of the Ganges tidal flood plain, in the immature Meghna estuarine flood plain and in tidal countries of the Chittagong coastal field and offshore islands ( Brammer, 1978 ) . About one million hour angle of land of these coastal and seaward countries are affected by changing grades of salt. These coastal saline dirts are distributed unevenly in 64 thanas of 13 coastal territories covering 8 agroecological zones ( AEZ ) of the state. The bulk of the saline land ( 0.65 million hour angle ) exists in the territories of Satkhira, Khulna, Bagerhat, Barguna, Patuakhali, Pirojpur and Bhola on the western seashore and a smaller part ( 0.18 million hour angle ) in the territories of Chittagong, Cox ‘s Bazar, Noakhali, Lakshmipur, Feni and Chandpur. Harmonizing to the study of Soil Resource Development Institute ( SRDI ) of Bangladesh, approximately 0.203 million hour angle of land is really somewhat ( 2-4 dSm-1 ) , 0.492 million hour angle is somewhat ( 4-8 dSm-1 ) , 0.461 million hour angle is reasonably ( 8-12 dSm-1 ) and 0.490 million hour angle is strongly ( & A ; gt ; 12 dSm-1 ) salt affected dirts in southwesterly portion of the coastal country of Bangladesh. Large fluctuations in salt degrees over clip are besides observed at about all sites in these parts. The common tendency is an addition in salt with clip, from November- December to March-April, until the oncoming of the monsoon rains. The electrical conduction ( EC ) of the dirts and H2O are lowest in July-August and highest in March-April at all sites. Soil salt, at any clip, is maximal in the surface beds ( 0-15 centimeter ) , the salt gradient being vertically downwards. The salt in undersoil is normally much lower than that in the top dirt. The belowground H2O within 1-2 metres below the dirt surface at all locations is reasonably to strongly saline in the dry season. The composings of the soluble salts in these saline dirts can bespeak possible direction schemes for harvest production. Sodium has been found to be the dominant cation, and Cl- the dominant anion species. Next in importance are Mg2+ and SO42- . Hence the salts are of the sodium-magnesium and chloride-sulphate types. A really of import facet of the soluble salt composing of the belowground H2O is the big surplus of Mg relation to Ca. Thus proper steps to keep ionic balance may be needed for good works growing even under low salt conditions. There is a general lacking of suited salt tolerant modern assortment ( MV ) of rice to suited different AEZ in the coastal countries of Bangladesh. The scarceness of good quality irrigation H2O is a major job in these countries. The surface H2O resources are deficient and irrigated agribusiness is mostly dependent on land H2O resource. The usage of such H2O for irrigation without proper direction may render the irrigated dirts as salt affected and accordingly harvest production may be hindered.
For centuries, husbandmans have salt-tolerant cultivars on the saline dirts of India, Burma, Thailand, Indonesia, the Philippines and Vietnam. But, because of housing and susceptibleness to disease and insect harm, outputs are about fifty ton ha-1. Recognition of the potency of saline lands for rice production in the dumbly populated states of South and southeast Asia prompted the inclusion of salt tolerance as a constituent of the programme of the International Rice Research Institute ( IRRI ) . Of the inauspicious dirt conditions, salt received most attending, because of its widespread happening in current and possible rice lands. Salt tolerance surveies are normally conducted in growing Chamberss and nursery, with workss raised in plastic trays or in little pots. The salt tolerance of any harvest is normally expressed as lessening in output associated with a given degree of dirt salt as compared with output under non-saline conditions. The primary salt factors act uponing works growing are the sort and concentration of salt nowadays in the dirt solution. Salt concentration in dirt is normally determined by mensurating EC of a dirt impregnation infusions ( ECe ) obtained from the active root zone. Recently, simple, rapid and dependable instruments such as salt detectors and four electrode investigations, have been developed for measuring of electrical conduction of dirt H2O ( ECsw ) .
Rice is the most suitable harvest for saline dirts because it can digest standing H2O, which is necessary for renewal of saline dirts. Dirts are considered saline if they contain soluble salts in measures sufficient to interfere with the growing of most harvest species. Therefore, the standard for separating saline from non-saline dirts is arbitrary ( Marschner, 1995 ) . Harmonizing to the definition, a saline dirt has an electrical conduction ( EC ) greater than 4 milli mhos cm-1 or 4 micro Siemens cm-1 or deci Siemens Garand rifle and an exchangeable Na per centum ( ESP ) and pH of less than 15 and 8.5, severally. The saline soils with an ESP & A ; gt ; 15 and pH & amp ; gt ; 8.5 are termed as saline-alkaline or saline-sodic dirts. However, many different units have been used for salt degree look. These are molar concentration ( M ) , milli molar concentration ( millimeter ) ( based on molecular weight of the salt ) ; milli siemens cm-1 ( mmhos cm-1 ) ; micro Siemens cm-1 ( µS cm-1 ) , deci Siemens Garand rifle ( dS Garand rifle ) ( based on electrical conduction ) and % salt ( based on percent concentration of the salt ) . Among these, millimeter, dSm-1 and % salt concentrations are most normally used. Approximately 58.5 mgL-1 NaCl = 1mM solution of NaCl and 640 mgL-1 NaCl is tantamount to 1 mmhos cm-1 ( = 1 dSm-1 ) EC ( Shannon et al. , 1998 ) . Therefore, 1 dSm-1 salt is tantamount to about 11 millimeters salt solution.
The present population of Bangladesh is about 140 million and rice is the chief nutrient point of its population. The dismaying growing of population and loss of cultivable land due to urbanisation are chief causes of concern for happening ways and agencies for augmenting nutrient production peculiarly rice. The possibility of increasing nutrient production by increasing land country is rather out of inquiry in Bangladesh. The lone executable option is to increase the arable land countries by conveying salt affected dirts under cultivation with high giving salt tolerant rice cultivars. The deficiency of an effectual rating method for salt tolerance in the showing of genotypes is one of the grounds for the limited success in conventional salt tolerant genteelness. Two output parametric quantities, tiller figure per works and spikelet figure per panicle, have proved most sensitive to salt and are extremely significantly correlated to concluding seed output in rice cultivar under salt emphasis ( Zeng and Shannon, 2000 ) .
Salt in dirt or H2O is one of the major emphasiss, can badly restrict harvest production ( Shannon, 1998 ) . The hurtful effects of salt on works growing are associated with ( I ) low osmotic potency of dirt solution ( H2O emphasis ) , ( two ) nutritionary instability, ( three ) specific ion consequence, or ( four ) a combination of these factors ( Ashraf, 1994a ; Marschner, 1995 ) . All these do inauspicious pleiotropic effects on works growing and development at physiological and biochemical degrees ( Munns, 2002 ) and at molecular degree ( Mansour, 2000 ) . It is frequently non possible to measure the comparative part of these major restraints to growing suppression at high substrate salt, as many factors are involved. These include ion concentration, continuance of exposure, works species, cultivar and root stock ( excluder and includer ) , phase of works development, works organ and environmental conditions. So, to get by with the above restraints, salt stressed workss chiefly adopt three mechanisms for salt tolerance such as ( I ) osmotic accommodation, ( two ) salt inclusion/ exclusion and ( three ) ion favoritism ( Volkmar et al. , 1998 ) .
Plant growing was earnestly affected due to salt which reduced turgor in spread outing tissues and osmoregulation ( Steponkus, 1984 ) . Alam el Al. ( 2001 ) stated that the critical EC degree of salt for seedling growing was about 5 dSm-1. They observed that dry affair, seedling tallness, root length and outgrowth of new roots of rice decreased significantly at an electrical conduction value of 5-6 dSm-1 and during the early seedling phase, more higher salt caused peal and atrophy of foliages, Browning of leaf tips and finally decease of seedlings. They especulated that both osmotic instability and Cl- was responsible for suppress of the growing. These writers maintained that the shoot growing was more suppressed than that of root and salt hurt was more terrible at high temperature ( 35oC ) and low humidness ( 64 % ) due to increased transpiration and consumption of H2O and salt by rice workss. At the generative phase, salt depressed grain output much more than that at the vegetive growing phase ( Alam et al. , 2001 ) . These writers maintained that at critical salt degrees straw output was normal but produced small or no grain. The lessening in grain output was found relative to the salt concentration and the continuance of the saline intervention. When the workss were continuously exposed to saline media, salt affected the panicle induction, spine formation, fertilisation of flowerets and sprouting of pollen grains hence caused an addition in figure of unfertile flowerets. The greatest deleterious consequence was on the panicle. Salinity badly reduced the panicle length, figure of primary subdivisions per panicle, figure of spine per panicle, seed puting per centum and panicle weight and reduced the grain output. The weight of 1000 grains was besides reduced. Salt hurt resulted in the production of little grains in grain length, breadth and thickness. Most rice cultivars were badly injured in submersed dirt civilizations at EC of 8-10 dSm-1 at 25o C ; sensitive 1s were hurt even at 2 dSm-1. At comparable EC ‘s hurt was less in sea H2O than in solutions of common salt, in impersonal and alkaline dirts than in acid dirts, at 20oC than at 35oC and in 2-week old seedling than in 1-week old seedlings. Since rice works is susceptible to salt at transfering and additions tolerance with age, they advised that aged seedlings ( 6 hebdomads old ) be planted in saline Fieldss.
Salt affected rice during pollenation, decreased seed scene and grain output ( Maloo, 1993 ) . Finck ( 1977 ) suggested that lack of K and Ca elements might play a important function in works growing depression in many saline dirts. Girdhar ( 1988 ) observed that salt delayed sprouting, but did non impact the concluding sprouting up to the EC of 8 dSm-1 by measuring the public presentation of rice under saline H2O irrigation. In normal conditions, the Na+ concentration in the cytol of works cells was low in comparing to the K+ content, often 10-2 versus 10-1 and even in conditions of toxicity, most of the cellular Na+ content was confined into the vacuole ( Apse et al. , 1999 ) .
Abdullah et Al. ( 2001 ) performed an experiment on the consequence of salt emphasis ( 50 millimeter ) on flowered features, output constituents, and biochemical and physiological properties of the sensitive rice assortment IR-28. The consequences showed important lessening in panicle weight, panicle length, primary subdivisions per panicle, filled and unfilled grain, entire grains and grain weight per panicle, 1000-grain weight and entire grain weight per hill. They further ascertained important decrease in both chlorophyll a and chlorophyll B content in different parts of the rice leaves at saline status. In another experiment, Abdullah et Al. ( 2002 ) studied the consequence of salt on photosynthate translocation in panicle subdivisions and developing spines, carbohydrate content of different vegetive parts and suggested that decrease in grain figure and grain weight in salinized panicles was non simply due to decrease in pollen viability and higher accretion of Na+ and less K+ in different flowered parts but besides due to higher accretion of photosynthates ( sugar ) in primary and secondary panicle subdivisions, panicle chief chaff and panicle root coupled with decreased activity of amylum synthetase in developing grains.
Gypsum ( CaSO4, 2H2O ) is widely used for bettering saline/sodic dirts due to its inclination of replacing its Ca2+ with exchangeable Na+ on the dirt composite. In add-on, gypsum application to saline/sodic dirts better output of Paddy and eatage grasses in waterless and semi waterless parts due to the effects of Ca2+ on works composing such as lessening in the concentration of Na and better plant-tissue concentrations of P, K, Zn, Cu, Mg and K: Na ratio ( Rengel, 1992 ) . The add-on of auxiliary Ca to the root environment was a agency of heightening works tolerance to salt emphasis ( Epstein, 1998 ) . This might favor the addition of Na+ inside the cells, alteration enzyme activity ensuing in cell metabolical changes ; perturbation in K+ consumption and breakdown in the cells, and throughout the works that might even impact stomatous gap, thereby, impairing the ability of the works to turn. This writer assumed that the add-on of Ca2+ to the root environment of salt stressed workss would keep or heighten the selective soaking up of K+ at high Na+ concentrations and forestall the hurtful effects of the surplus of Na+ . Another function attributed to auxiliary Ca2+ add-on was its aid in osmotic accommodation and growing via the sweetening of compatible organic solutes accretion ( Girija et al. , 2002 ) . Under salt emphasis conditions there was a lessening in the Ca/Na ratio in the root environment which affected membrane belongingss, due to displacement of membrane-associated Ca2+ by Na+ , taking to a break of membrane unity and selectivity ( Cramer et al. , 1985 ; Kinraide, 1998 ) .
Aslam et Al. ( 1993 ) observed important decrease in shoot and root fresh weights by different types of salt such as NaCl entirely, NaCl + CaCl2, Na2CO3 entirely and a salts mixture. On the works growing, NaCl entirely was found to be the most toxic, Na2CO3 entirely was the least harmful, and NaCl + CaCl2 and the salts mixture were intermediate. They found similar consequences in both solution civilization experiment and the experiments conducted in salinized dirts. They considered the better root growing under high salt status as the capacity of the tolerant genotypes to battle the inauspicious consequence of salt. Aslam et Al. ( 2001 ) investigated the consequence of auxiliary Ca on rice growing and output in solution and dirt civilizations, and in of course salt affected field. In solution civilization, Ca was applied at 5, 10, 20, 40, 80 and 160 µg/mL with 80 millimeters NaCl and without NaCl and in soil civilization 0, 50, 100 and 200 kilograms Ca ha-1 was applied to unnaturally prepared salt ( EC 9 dSm-1 ) . Three cultivars, differing in salt tolerance, were used, viz. K8-282 ( salt tolerant ) , BG 402-4 ( reasonably tolerant ) and IR-28 ( salt medium ) . Application of Ca at 20-40 µg/mL improved stooling capacity, shoot and root length, shoot and root weights in solution civilization in the presence of NaCl. Shoot Na+ and Cl- decreased, whereas K+ concentration and K+/Na+ ratio increased because of Ca supply to saline medium. Grain and straw outputs, works tallness and panicle length were significantly higher in saline compared to saline sodic dirt. Application of 200 kilograms Ca ha-1 proved statistically superior to the control in regard of panicle length, Numberss of tillers, grain and straw outputs under both saline and saline sodic dirt every bit good as in of course salt-affected field. Seed scene was improved in all cultivars because of external Ca supply to saline and saline sodic dirts. Aslam et Al. ( 2003 ) stated that an addition in K and K+/Na+ ratio was an indicant of salt tolerance due to the application of extra Ca in both salt tolerant and susceptible rice cultivars under saline environment. These writers maintained that salt affected dirts showed an betterment in the paddy output of both salt tolerant and salt sensitive rice cultivars due to Ca application as gypsum at the rate of 25 % of gypsum demand of dirt.
Franco et Al. ( 1999 ) studied the consequence of auxiliary CaCl2 on growing and osmoregulation in NaCl stressed cowpea seedlings. They found that salt inhibited the length of root and shoot of black-eyed pea but the repressive consequence could be ameliorated by the add-on of Ca2+ . The concentration of organic osmoregulators ( proline, soluble saccharides, soluble amino-nitrogen, and soluble proteins ) increased in root tips of seedlings grown in salt-stressed status with auxiliary Ca. They indicated that Ca2+ could hold a protective consequence in root tips, which is of cardinal importance for the care of root elongation in NaCl stressed cowpea seedlings.
Considerable betterments in salt tolerance have been made in harvest species in recent times through conventional choice and genteelness techniques ( Shannon, 1998 ; Ashraf, 1994a ; 2002 ) . Most of the choice processs have been based on differences in agronomic characters, which represent the combined familial and environmental effects on works growing and include the integrating of the physiological mechanisms confabulating salt tolerance. Typical agronomic choice parametric quantities for salt tolerance are yield, biomass, works survivality, works tallness, leaf country, leaf hurt, comparative growing rate and comparative growing decrease.
Many scientists have suggested that choice is more convenient and operable if the works species possesses typical indexs of salt tolerance at the whole works, tissue or cellular degree ( Ashraf, 2002 ; Epstein and Rains, 1987 ; Jacoby, 1999 ; Munns, 2002 ) . Physiological standards are able to provide more nonsubjective information than agronomic parametric quantities or ocular appraisal while testing for component traits of complex characters ( Yeo, 1994 ) . There are no chiseled works indexs for salt tolerance that could practically be used by works breeders for betterment of salt tolerance in a figure of of import agricultural harvests. This is partially due to the fact that the mechanism of salt tolerance is so complex that fluctuation occurs non merely amongst species but, in many instances, besides among cultivars within a individual species ( Ashraf, 1994a ; 2002 ) . During the class of works growing, the signifier and maps of assorted variety meats undergo important alteration and the ability of the works to respond to salinity stress depend on those cistrons that are expressed at the phase of development during which the emphasis is imposed ( Epstein and Rains, 1987 ) . The mechanism of salt tolerance becomes even more complicated when the response of a works besides varies with the concentration of saline medium and the environmental conditions in which the works is grown.
Osmotic accommodation in workss subjected to salt emphasis can happen by the accretion of high concentration of either inorganic ions or low molecular weight organic solutes. Although both of these play a important function in higher workss grown under saline conditions, their comparative part varies among species, among cultivars and even between different compartments within the same works ( Ashraf, 1994a ) . The compatible osmolytes by and large found in higher workss are of low molecular weight sugars, organic acids, aminic acids, proteins and quaternate ammonium compounds.
Harmonizing to Cram ( 1976 ) , of the assorted organic osmotica, sugars contribute up to 50 % of the entire osmotic potency in glycophytes capable to saline conditions. The accretion of soluble saccharides in workss has been widely reported as response to salt or drouth, despite a important lessening in net CO2 assimilation rate ( Popp and Smirnoff, 1995 ; Murakeozy et al. , 2003 ) . Ashraf and Tufail ( 1995 ) determined the entire soluble sugars content in five sunflower accessions differing in salt tolerance. They found that the salt tolerant lines had by and large greater soluble sugars than the salt sensitive 1s. Ashraf and Harris ( 2004 ) suggested that considerable fluctuations in the accretion of soluble sugars in response to salt emphasis were apparent at both inter-specific and/or intra-specific degrees and even among lines of which all were salt tolerant.
Several salt-induced proteins have been identified in works species and have been classified into two distinguishable groups such as ( I ) salt emphasis proteins, which accumulate merely due to salt emphasis and ( two ) emphasis associated proteins, which besides accumulate in response to heat, cold, drouth, water-logging and high and low mineral foods ( Pareek et al. , 1997 ; Ali et al. , 1999 ; Mansour, 2000 ) . Proteins that accumulate in workss grown under saline conditions may supply a storage signifier of N that is neutralized when emphasis is over and may play a function in osmotic accommodation ( Singh et al. , 1987 ) . A higher content of soluble proteins has been observed in salt tolerant than in salt sensitive cultivars of barley, helianthus ( Ashraf and Tufail, 1995 ) and rice ( Lutts et al. , 1996 ; Pareek et al. , 1997 ) . Pareek et Al. ( 1997 ) besides suggested that emphasis proteins could be used as of import molecular markers for betterment of salt tolerance utilizing familial technology techniques.
Amino acids have been reported to hold accumulated in higher workss under salt emphasis ( Ashraf, 1994b ; Mansour, 2000 ) . The of import amino acids are alanine, arginine, glycine, serine, leucine and valine, together with the imino acid – proline and the non-protein amino acids- citrulline and ornithine ( Mansour, 2000 ) . Lutts et Al. ( 1996 ) found that proline did non take portion in osmotic accommodation in salt stressed rice and its accretion seemed to be a symptom of hurt instead than an index of salt tolerance. On the contrary, Garcia et Al. ( 1997 ) reported that exogenously applied proline exacerbated the hurtful effects of salt on rice. The salt tolerant rice cultivars Nona Bokra and IR 4630 accumulated less proline in their foliages than the salt sensitive Kong Pao and IR 31785 ( Lutts et al.,1996 ) . These contrasting studies on the function of proline in salt tolerance and its usage as choice standard for salt tolerance in rice has been questioned.
Regulation of ion conveyance is one of the of import factors responsible for salt tolerance of workss. Membrane proteins play a important function in selective distribution of ions within the works or cell ( Ashraf and Harris, 2004 ) . Harmonizing to Du-Pont ( 1992 ) the membrane proteins involved in cation selectivity and redistribution of Na+ and K+ . These proteins are: ( a ) primary H+-ATPases which generate the H+ electrochemical gradient that drives ion conveyance, ( B ) Na+/H+ antiports in the plasma membrane for pumping extra Na+ out of the cell, ( degree Celsius ) Na+/H+ antiports in the tonoplast for squeeze outing Na+ into the vacuole and ( vitamin D ) cation channels with high selectivity for K+ over Na+ . It is good established that Na+ moves passively through a general cation channel from the saline growing medium into the cytol of works cells ( Marschner, 1995 ; Jacoby, 1999 ; Mansour et al. , 2003 ) and the active conveyance of Na+ through Na+/H+ antiports in works cells is besides apparent ( Shi et al. , 2003 ) . Salt tolerance in workss is by and large associated with low consumption and accretion of Na+ , which is mediated through the control of influx and/ or by active outflow from the cytol to the vacuoles and besides back to the growing medium ( Jacoby, 1999 ) . Energy-dependent conveyance of Na+ and Cl- into the apoplast and vacuole can happen along the H+ electrochemical potency gradients generated across the plasma membrane and tonoplast ( Hasegawa et al. , 2000 ) . The tonoplast H+ pumps ( H+-ATPase and H+-pyrophosphatase ) besides play a important function in the conveyance of H+ into the vacuole and coevals of proton ( H+ ) which operates the Na+/H+ antiporters ( Mansour et al. , 2003 ; Blumwald, 2000 ) .
In the past few decennaries, works breeders in Bangladesh have achieved small success in developing some salt tolerant harvests specially rice through conventional genteelness techniques, with comparatively little/no direct input from physiologists or biochemists. Mutation genteelness, a modern technique for making variableness has besides played a critical function for bring forthing new valuable cultivars of rice. Incorporation of mutant programme for accomplishing a coveted character ( s ) in a assortment can therefore cut down the clip required to engender an improved assortment with the conventional hybridisation method. Several cultivars derived from direct use of induced mutations have shown that traits such as short straw, earliness and opposition to certain diseases, can be introduced in otherwise well-adapted assortments without significantly changing their original properties. Study on the response of rice to salt emphasis may be helpful in engendering salt tolerant cultivars by placing physico-chemical potency of salt tolerance such as accretion of toxic Na+ and Cl- in the older parts of the works, higher photosynthetic efficiency of the foliages, get awaying ability to uptake Na+ and Cl- . The direct usage of mutant is a valuable attack particularly when the betterment of one or two easy identifiable characters is desired in an otherwise well-developed assortment. In order to develop operable schemes for choosing salt tolerant rice mutants/lines/genotypes adaptable in coastal belt of Bangladesh notably during boro season, elaborate information demands to be gathered on the alterations in physiological and biochemical facets due to salt emphasis are attributable against damaging effects of salt emphasis.
In add-on to the development of salt tolerant cultivars, better apprehension of nutritionary upsets in the context of works alimentary consumption and physiological every bit good as biochemical mechanisms of salt tolerance in rice workss may propose some schemes for works breeders and agriculturists for developing salt tolerant assortments and direction patterns for cultivation in saline countries. There have been few such surveies available in the state or elsewhere on rice for tolerance mechanism created particularly in mutant genotypes. This research programme has been, hence, planned with the purpose of happening out the bio-chemical causes and possible dirt betterment programme in cultivating the rice mutations in the coastal saline dirts of Bangladesh.
Keeping the above thoughts, in head, the present work has hence, been designed and planned with the following aims:
– look intoing the consequence of salt on some bio-chemical facets and growing of different rice genotypes at different growing phases,
– determination out the mechanism of salt tolerance of selected rice genotypes ; and
– suggest possible renewal programme for better growing of rice under saline status.