Abstract: Salt stress is a big problem for whole world including developed or developing countries. It is of prime importance to have awareness that how different attributes of plants are affected by salt stress. As an agricultural country salinity problem is a great challenge for Pakistan, and there is a need to explore the means by which plants can tolerate the adverse effects of salinity. To assess these mechanisms, vegetables of winter and summer have been selected as they are rich source of many ingredients required for our body. There will be four vegetables, two winter [Cauliflower (Brassica oleracea var. botrytis) and Carrot (Daucus carota)] and two summer and Okra (Hibiscus esculentus)]. Two cultivars of each of the four vegetables will be utilized in this project. All vegetables will be grown in sand culture using Hoagland’s nutrient solution. Sodium chloride induced salinity will be applied along with full strength Hoagland’s nutrient solutions. In addition to growth, water relations, gas exchange and mineral nutrients, various osmoprotectants like glycinebetaine, proline, and ascorbic acid, activities of enzymatic and non-enzymatic antioxidants like catalase, peroxidase, superoxide dismutase and glutathione reductase, total phenolics and vitamin E (alpha, gamma and delta tocopheroles) will also be analyzed. All these attributes will be helpful in understanding the salt tolerance mechanism and for optimizing breeding programs to enhance the salt tolerance of vegetables using some of the biochemical attributes as selection indicators.

Problem statement: Pakistan is basically an agricultural country. Agricultural production is severely affected by abiotic stresses like drought stress, salt stress, temperature stress etc. Most of the cultivated area of Pakistan is salt affected. Keeping this in view this problem this project was devised make some solutions against this problem.

Objectives:

• The primary objective of this study is to elucidate the mode of accumulation of various organic substances like vitamins, phenolics and osmoprotectants like glycinebetaine, proline, ascorbic acid and activities of various antioxidant enzymes i.e. catalase, peroxidase, superoxide dismutase, and glutathione reductase.
• To draw the relationship of these determinants with salt tolerance of winter and summer vegetables
• To recommend some of the biochemical compounds as potential indicators for breeding programs entailing enhancement of salt tolerance in the prospective vegetables.

Methodology: Salt tolerance in the two winter and two summer vegetables will be examined at the vegetative and the flowering stages in various experiments. In each experiment, 20 seeds of each cultivar will be sown per plastic pot each containing 10 kg dry river sand. After two weeks of germination, plants will be subjected to four NaCl treatments (0, 50, 100 and 150 mmol L-1) in Hoagland’s nutrient solutions. Similar, levels will also be applied in solution culture. Data will be collected after four weeks of treatment application both at vegetative and flowering stages. After measurement of growth parameters, gas exchange characteristics will be determined with infra-red gas analyzer. Water use efficiency will be determined by the ratio of net rate of photosynthesis and rate of transpiration. Water potential will be measured with a pressure chamber, while osmotic potential with a vapor pressure osmometer. Glycinebetaine will be determined by the method of Colmer et al. (2000), while free proline using the method of Bates et al. (1973). Total phenolics will be determined using Folin–Ciocalteau reagent (Julkenen-Titto, 1985). Alpha, gamma and delta tocopherols will be determined using HPLC by the methods of Catignani (1983) and Miller et al. (1984). Antioxidants i.e. catalase, peroxidase (Chance and Maehly (1955), SOD (Giannopolitis and Ries, 1977) and glutathione reductase will be determined spectrophotometrically. Protein concentration will be determined following Bradford’s method (1976).

Results and Discussions: As this is the first year of the project, so various experiments are in progress. After recording the data, the results of all attributes will be displayed.

Conclusions: Conclusions will also be drawn after obtaining the results of the experiments.

Recommendations: Recommendations will also be made in accordance with findings of this project.