The effect of salt stress under the two salinity levels and control (0, 100mM, 150mM) on three varieties of wheat SASSUI, SEHAR, MARVI was conducted. The data showed that the NaCl salinity stress significantly affected the growth of wheat seed arrtibutes by reducing the shoot and root length. Regarding the germination, the maximum germination was found in genotype SASSUI in different salt stress treatments. The germination data reading is 24 hours 48 hours and 72hours. At the 72 hours, the values for seed germination increased in all wheat seed germination and 150mM is comparatively less than other 100mM. according to biochemical analysis, proline increases with increasing salinity level and decrease the protein content in physiologically active leaves with different treatments on wheat varieties.
Introduction
Wheat (Triticum aestivum) is one of the staple food for more than one-third of the world. Since earliest times, wheat played a major role in the development of civilization. It contributes 13.1% to the value added in agriculture and 2.8% to GDP. The size of wheat crop provisionally estimated 23.5 million tons, 11.8% more than last year crop. In Sindh province of Pakistan wheat is planted on 9062 thousand hectares with a production of 23421 tons and 2585kg/ha yield (Agriculture Statistics of Pakistan 2013 2014). In Pakistan, spring wheat is cultivated as a Rabi crop. It is planted on 8169.8 kg/ha thousand hectares with a production of 17002.4 thousands of tons. The average yield of wheat is 2081 kg/ha (Agriculture Statistics of Pakistan 2013-2014).
Wheat is one of the most important crops in Pakistan and it's extensively grown, produced and consumed in the country, readily stored and transported and easily processed to give highly refined raw food. It contributes more calories and more proteins to the world are diet than any other food crop. In Europe and Russia, over 10% of the calories come from wheat. The per capita consumption of wheat, while in the United States exceeds that of any other single food staple (Elias, 2003). Wheat compares well with other cereals in nutrient values. Its proteins content is higher than that of rice, maize, and sorghum and about equal to that of other cereals. Protein improvement has rarely been a major objective of wheat because wheat protein has usually been considered adequate for human nutrition. The salt stress effect on the seedling growth and germination percentage in different ways depending on plant species (Ungar, 2005; Gul et a, 1999).
Many factors influence on the low yield of wheat such as low yielding varieties, the old method of cultivations, environmental and climatic conditions, amount and method of fertilizer applications, time of sowing and availability of irrigation water in time. One of the major factors which affect the yield of this crop is soil salinity. It is commonly observed in arid and semi-arid regions of the world. It is considered a serious problem of Pakistan (Rajpar et al., 2002). Soil salinity is one major effect on the plants which reduce the growth and high salinity reduced the content of the pigment in leaves ( Al-Sobhi et al, 2006 ). Crop yields start declining when the pH of the soil solution exceeds 8.5 or Electrical conductivity (EC) values go above 4dS/m. At higher EC values the crop yield is reduced so drastically that crop cultivations are not economical without soil amendments. Addition to the salt of water, lower its osmotic potential, resulting is decreased availability of water to root cell (Sairan 2002).
Excess amount of salts in the soil affect plants from germination to harvesting. It may affect the plants in two ways (a) by decreasing the rate of water entry in the plants and (b) to promoting the entry of toxic ions. Sodium-saturated soils have the problem of poor aeration and low hydraulic conductivity, both of which may creat oxygen stress to plants and the problem of leaching of disturb of nutrient balance and osmotic pressure of plants. Salinity in the arable land has an increasing impact on many irrigated, arid and semiarid areas of the world and it is a major factor in reducing crop productivity of cultivated lands. Areas affected by the soil salinity is rapidly increasing in the Middle East and North Africa. A large area of Pakistan Iran and Egypt has been rendered agriculturally unproductive.
The climate of an area also plays a significant role in the formation of salt-affected soils which is characterized by low rainfall, great fluctuations in temperature and high rate of evaporation (Almansouri, et al., 2001). Hence the present work is a planned in the study “ the Effect of Salt stress on the growth of different wheat genotypes” and benefit in deciding the right wheat variety to be grown in relation in soil salinity.
Methods and Materials
The research work reported by manuscript with attention to exploring the effect of salinity on seed germination and growth of seedling in different wheat genotype (Triticum aestivum L) (Sassui, Saher, and Marvi). The methodology adopted to conduct this research work is described under.
Effect of Salt Stress on Germination of Some Wheat Genotypes
This research on seed germination and affects of salinity were conducted on the plant physiology Laboratory, Institute Of Plant Sciences University Of Sindh Jamshoro during the year of 2018. Seeds were collected in October 2018 from Field Research Station Sindh Agriculture University Tandojam. We were collected three types of the wheat seeds form there we were given the names (Sassui, Sehar, Marvi). Seeds were sterilized by 1/4 strength Hoagland nutrient solution as growing media then washed with fresh water followed by distilled water. Germination was sterilized in Petri dishes containing filter papers and a thin layer of cotton for moisturized solution and water from seeds. The germination seed was tested in Petri dishes (size 12.5cm diameter). The salinity imposed by Sodium Chloride (NaCl) salt having three treatments control, 100mM, 150mM. Each treatment repeated three times and twenty-five seeds of each genotype were placed in filter paper, soaked with a nutrient solution of respective concentration and placed in the laboratory. The seed emergence percentage was recorded after 24, 48, 72 hours of sewing.
Effect Of Salt (NaCl) Stress At Early Seedling Stage Of Wheat Genotypes
This experiment was conducted in water cultured using 1/4th strength Hoagland Solution as growing media, the chemical combination of nutrient solution and micro nutrient solution. Healthy seeds were surface sterilized for 10 minutes with 5% sodium hydrochloride (NaOCl) and were thoroughly washed many times with distilled water. The studies of seedling growth were conducted in plastic bowls that size is (8.4 x 4.5) thirty seeds were planted on sieves of bowls containing sufficient nutrient solution (control). Two salinity treatments of 100mM and 150mM were imposed.
Effect Of Salinity On Root Length Of Wheat Seed Genotypes
The results for root length of different wheat genotypes at affected by NaCl stress. Increasing concentration of NaCl had reduced the root length of all the wheat genotypes. Maximum reduction at 150mM salt stress and under Control the maximum root length showed in SEHAR that is 11cm and minimum root length 10.2cm In MARVI. At low salinity 100mM, the maximum root length was recorded in genotype SASSUI 5.5cm followed by SEHAR 5.2cm, while minimum root length 5cm was recorded in MARVI genotype. At high salinity treatment the minimum root length was shown in SASSUI 2.5cm and high root length was recorded in MARVI that is 3.1cm.
Effect of Salinity On Shoot Length Of Wheat Seed Genotypes.
The Shoot Length Results Of Different Wheat Seed Genotypes As Affected By NaCl As Shown In Part Two. There Was A Decrease In Shoot Length With An Increase In Salinity Treatments In All Genotypes. The Decreases Shoot Length Was More In 150mm Salinity Treatment Compare With 100mm. Mean Value Of Shoot Length Were Recorded As 16.20cm, 15.82cm, 13.86cm Followed By SASSUI, SEHAR, MARVI.
Discussion
It is well determined that is the presence of soluble salts in the growing solution medium are the major factor to reduce germination in wheat. Tobe et al., 2001; Pujol et al., 2000; Rubio-Casal et al., 2003). reported that an increase in salinity by NaCl, significance effect the emergence and growth. In presence work, there were significant decreases in all the genotypes seed germination. Lowest germination was recorded at the highest salinity level (150mM NaCl). The decreases seed germination was also reported earlier (Gul et al., 1999). The decreases the germination with increases salinity might be due to the low osmotic pressure of growing media, resulting in less inhibitions of water by seeds phase under salinity.
Genotypes germination differences were also found in this study indicate the wheat genotypes varyingly under “Saline environment” wheat genotype SASSUI and SEHAR responded well having maximum germination 100% under the various concentrations of NaCl ( 0, 100mM, 150mM ) recorded after 72 hours.
Salinity also reduced vegetative growth of wheat genotypes there were decreases in root and shoot length of all three varieties of wheat genotypes with increases the salinity. This decreasing trend in wheat seed was also reported by (Mansour and Salama 1996)
Conclusion
As it can be seen from the present study data that wheat seeds, treatments and their interaction with highly significant for germination ( % ), root/shoot length, among the different genotypes, the genotypes SASSUI showed that highest germination at different salinity levels. Benefits of these treatments and causes are that usually, salts present in irrigation water and soil can hinder the most significant phase of germination in plant life. Due to the osmotic pressure created by sodium chloride NaCl water can not enter the seed coat, instead, salts enter and cause toxicity to plants.
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