Studies on plant tolerance to salinity
Abstract: The present research work was conducted to find out a relation between plant salt tolerance and its chemical composition especially its content of proline amino acid which is thought to take part in increasing tolerance of plant against salinity of plant growth media. Such approach is very important and urgent to improve plant growth under conditions of shortage of water available for leaching salts out of the growth media and/or the absence of an adequate drainage system to carry the leached salts out of the plant root zone. To fulfill the purposes of this investigation, a series of pot experiments were conducted on different varieties of sunflower under different types of four salinities i.e. nonsaline-nonsodic (normal), saline-nonsodic, nonsaline-sodic and saline sodic conditions. The used soils samples were taken from Dammitta governorate at a depth of 0-30 cm. Polyethylene pots were packed with the soils under investigation at a rate of 10 kg per each in a complete randomized block with twelve replicates. Each pot received basal applications of N, P and K corresponding to 0.4g N, 0.3 g P2O5 and 0.48 g K2O in the forms of ammonium sulfate (20.6% N), superphosphate (15% P2O5) and potassium sulfate (48% K2O), respectively. Eight seeds of each of the used sunflower varieties which are Fedok, Iroflor and Giza 2 were planted in each pot, thinned after 7 days from seed emergence to 4 seedlings pot-1. The pots were watered weekly to maintain their moisture content at 70% of the water holding capacity. The growing plants were sampled at the vegetative, flowering and fruiting stages. Some growth parameters i.e. stem diameter, yield of seeds, disc diameter, 1000 seed weight were recorded. Subsamples of the dried plant materials were digested. Na, Cl, N, P, K, Fe, Mn, Zn, and Cu were determined in the digests. Likewise, free proline amino acid was determined. Seeds contents of oil and N, P, K, Fe, Mn, Zn, and Cu were determined. The obtained results could be summarized in the following-
The dry matter yields of the different varieties of sunflower plant were adversely affected by salinity and/or sodicity of soil, however, sodicity seemed to be more negative effect on dry matter yield than salinity especially at the fruiting stage. At all stages of growth, dry matter yield of Giza 2 was less affected by salinity and/or sodicity than Iroflor and Fedok. On the other hand, Fedok variety gave higher dry matter yield than Iroflor and Giza 2 when the plants were grown on normal soil. Such a finding illustrates that dry matter yield of relatively salt resistant plants was less affected by salinity than relatively salt-sensitive ones.
Fedok variety gave higher stem diameter, plant height and leaf area index than the other two varieties when the plants were grown on the normal soil. These parameters were adversely affected by salinity and/or sodicity, however sodicity had a more obvious effect. Yet, it is worthy to indicate that Giza 2 gave higher values for these parameters than Iroflor and Fedok varieties when they were grown in salt-affected soils. This finding was true at the different stages of growth.
Contents of Na+ and Cl- in different varieties of sunflower plants at the different stages of growth increased in the salt-affected soils to values higher than the corresponding areas of the plants grown on the normal soil. Na and Cl contents of Fedok and Iroflor varieties were higher than that of Giza 2 at all the studied stages of growth in all the studied soils. However Na and Cl contents under saline and/or sodic conditions were higher than those under normal conditions. Na and Cl concentrations in Fedok and Iroflor varieties were usually higher than that in Giza 2 variety at all growth stages. The relatively salt-sensitive varieties (Fedok and Iroflor) had more Na and Cl than the relatively salt-resistant one (Giza 2).
Proline content in the sunflower plant varieties grown on the salt affected soils, especially the sodic ones was higher than the corresponding proline content of the plant varieties grown on the normal soil. It was higher in the relatively salt-tolerant variety (Giza 2) than in the relatively salt-sensitive ones (Fedok and Iroflor).
Values of N and P content and uptake by the plants grown on the salt-affected soils were lower than the corresponding values of the plants grown on the normal soil. Fedok and Iroflor varieties were affected by the depressive effect of salinity on N content and uptake than Giza 2 variety. This was true at all the plant growth stages.
A general depressive effect of salinity and/or sodicity (with sodicity being more effective) was noticed on K content and uptake by the plants grown on the salt-affected soils. The effect was more pronounced in the sodic soils. This was true at all stages of growth. Moreover, values of K content and uptake were higher in the relatively salt, tolerant varieties than the salt-sensitive one.
A depressive effect of salinity and/or sodicity on values of the micronutrients (Fe, Mn, Zn and Cu) content and uptake was noticed at all stages of growth of all the studied varieties of sunflower plants. The effect of sodicity seemed to be more obvious than that of salinity. These effects were more noticeable on Fedok and Iroflor varieties than Giza 2.
Values of seeds yield of all grown varieties decreased due to salinity and/or sodicity with sodicity being of higher effect than salinity. However, it is importance to indicate that Giza 2 variety was less affected with salinity and/or sodicity than Fedok and Iroflor.
Taking into consideration, yield components i.e. disc diameter, 1000 seed weight and seed oil content, it was noticed that they were the highest values in Fedok variety grown on the normal soil. However, values of yield components of the three varieties decreased due to salinity or sodicity. Sodicity seemed to be more depressive effect on these values than salinity. Giza 2 variety was affected to a lesser extent with salinity and/or sodicity than other two varieties. Upon grown sunflower plants on the normal soil, N, P and K contents in seeds of Fedok variety were slightly higher than their contents in Iroflor or Giza 2, however the differences among the studied varieties were not significant. Under conditions of the saline and saline-sodic soils N, P and K contents of Giza 2 variety exceeded slightly the corresponding ones of Fedok and Iroflor varieties. The superiority of Giza 2 variety over the other two varieties with regard to seeds contents of N and K was more obvious than in case of the sodic soil.
Soil salinity or sodicity was accompanied with a decrease in Fe, Mn, Zn and Cu contents in seeds of all the investigated sunflower plant varieties as compared with the corresponding contents of these varieties when they were grown on the normal soil. The plants contents of the micronutritive elements were more depressed in the plants grown on the sodic soils than the saline ones. The depressive effect of salinity and/or sodicity was more obvious on Fedok and Iroflor varieties than in Giza 2
Publication year 2005
Availability location كلية الزراعة بمشتهر - جامعة بنها(معهد بحوث الاراضى والمياه والبيئة)
Availability number
Organization Name
Country Egypt
Department Improvement and Conservation of Cultivated Soils Research
Author(s) from ARC
Agris Categories Soil erosion, conservation and reclamation
AGROVOC
TERMS		 Saline soils. Salt tolerance. Sodic soils. Sunflower seed.
Proposed Agrovoc Salt affected soil;
Publication Type PhD Thesis
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