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Salinity is a severe problem of horticultural crops and field crops throughout the Pakistan. The experimentwas conducted at vegetable area, Institute of Horticultural Sciences, University of Agriculture, Faisalabad under different salinity levels in plastic pots. Four salinity levels (2.91, 3.90, 1.51, and 1.45 dS m-1NaCl) to four different leafy vegetables (lettuce, spinach, coriander and fenugreek) were applied. Hoagland’s solution was used as nutrient medium. Foliar applications of five concentrations of chitosan (0, 50, 75, 100, 125 ppm) and salicylic acid (0, 69.5, 347.5, 695 ppm) were applied. The data was collected regarding mortality (%), germination (%),total dry weight (g), total fresh weight (g), number of leaves, chlorophyll contents (CCI), shoot length (cm), root length (cm), nitrogen (N) concentration (mg g-1DW) and protein contents (mg). Data of each treatment will be subjected to the statistical analysis using standard procedure. It was concluded that in leafy vegetables by increasing the levels of chitosan and salicylic acid,that total plant length, fresh weight, shoot length, root length, mortality percentage, nitrogen contents and protein contents increased.It was reported that by increasing the levels of chitosan and salicylic acid total dry weight and chlorophyll contents were decreased.
Herbaceous plants which are harvested for their leaves are known as leafy vegetables including spinach, letuce, fenugreek and coriander etc. Spinach (Spinaciaoleracea L.) is native to Asia and is high value vegetable rich in vitamins, calcium, iron and fiber contents (Knol et al., 1976).Letuce(Lactuca sativa L.) is also another highly important leafy vegetable belonging to family compositeae, having salient medicinal properties. It is an excellent source of vitamins K, C and E, carotenoids and known king of salad crops round the globe (Hunter and Burit, 2002). Fenugreek (Trigonellafoenum-graecum L.) is a flowering annual plant of fabaceae family, having autogamous flowers. It is used to stimulate the spleen and liver, relieve indigestion and to prevent constipation. It is grown all over the Pakistan for its leaves and seeds (Baloch, 2009). Coriander (Coriandrumsativum L.) is an annual plant from apiaceae family, used by people worldwide for medicinal, food and spice purposes (Carruba et al., 2006; Msaada et al., 2009).
Salinity is one of the most destructive factor of land deprivation that is the cause of less production in the whole world, mostly in semiarid and arid areas (Shomeili et al., 2011). Salinization can be defined as the accumulation of salts in root zone, it occurs as the soil is basically saline or due to insufficient drainage of water from the sub-soil (Kanber et al., 1992).Munns (2002) gave the idea of two phase growth response of plant in saline conditions. In the first phase, the growth of plant was decreased due to the osmotic effect of the saline solution outside the root, where high external salt concentration caused water deficit conditions. The second phase of growth decrease was caused by the accumulation of salt in transpiring leaves and was therefore, salt specific. High concentration of salt in cellular tissue caused changes in the structure of plasma membrane which damage cell metabolism (Hasegawa et al., 2000). This resulted in decreased activity of enzymes such as PEP carboxylase and Rubisco, which further inhibits protein synthesis and results in reduction of plant growth (Yang et al., 2003). All these factors caused adverse effects on palnt growth and devolpment at physiological and biochemical (Munns, 2002) and at the molecular level (Winicov, 1998) as well.Jamil et al., (2005) studied the result of salinity on four vegetable were treated with different concentrations of salt solution. Results indicated that salinity caused considerable reduction in germination percentage, shoot length, germination rate, fresh shoot and root weights. Linear relation was devolped to find relation between salt stress and plant growthand also between germination and rest of plant characters.Salicylic acid is an important plant hormone which acts as signaling molecule. It shows an important role in ion uptake, plant growth and transport. Salicylic acid is also involved in endogenous signaling to trigger plant defense against pathogens (Khan et al., 2003: Arfan et al., 2007), under abiotic stress conditions. The salicylic acid spray results in tolerance of plants to various abiotic and abiotic stresses contain viruses, fungi and bacteria (Delany et al., 1994). Salicylic acid was useful in inducing stress tolerance when used as soil drench (Senaratna et al., 2000) spray or seed treatment (Aldesuquy et al., 1998). Chitosan is a biopolymer, a chitin derivative, a compound which is completely safe for the environment. This compound is characterized by unique properties, such as bioactivity and biocompatibility (Dias et al. 2013). The results from the literature show that, when used in plants, chitosan can increase the yield (Mondal et al. 2012), reduce transpiration (Dzung et al. 2011) and induce a range of metabolic changes as a result of which, plants become more resistant to viral, bacterial and fungal infections (Al-Hetar et al. 2011).
Material and Methods
The research was carried out atvegetable area, Institute of Horticultural Sciences, University of AgricultureFaisalabad, during 2014-2015. The experiment was laid out according to Randomized complete block design(RCBD) with two factors factorial arrangements with 3 replications.Seeds were sown in plastic pots containing sand rinsed with distilled water. The number of seeds per pot were adjusted seven to ten and seedlings were watered according to need of plant by observing the moisture of sand. Four leafy vegetables (lettuce, spinach, fenugreek and corriandar) were grown under different salinity levels. After sowing half strength (0.5) Hoagland’s nutrient solution was applied to plants for nourishment and after two weeks of germination of seeds,NaCl was applied with following concentrations, 2.91 dSm-1, 3.90 dSm-1, 1.45 dSm-1,1.51 dSm-1. After 10 days of application of NaCl, foliar application of chitosan and salicylic acid was applied according to the following concentrations.
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Experiment was continued till four to five plant leaves stage and following parameters were studied.Following parameters were studied, germinationpercentage,mortality percentage, shoot length (cm), root length (cm), total plant length (cm), total fresh weight (g), total dry weight (g), number of leaves, Chlorophyll contents (CCI),nitrogenconcentration (mg g-1DW) and protein contents (mg). Chlorophyl contents of seedlings were measured with the help of chlorophyll meter.The quantity of N + ions was estimated in ppm by comparing the emission of Flame Photometer (Sherwood Flame Photometer Model-410) with that of standard curve.The total protein contents can be determined by multiplying nitrogen amount by factor depending on the protein types. This value is called ‘crude protein’ contents. The protein determination formula is given by;
Crude protein= N × 6.25 (AOAC, 2000
Randomized complete block design(RCBD) with two factors factorial arrangements was applied to the experiment with 3 replications. Collected data was analyzed statistically by applying analysis of variance technique and significance of treatments was tested by using LSD test (Steel et al.,1997).
Result and Discussion
The germination percentage ranged from 85.00 to 96.67%. The maximum germination percentage was observed for fenugreek in control, coriander in 75 + 139ppm chitosan + salicylic acid level, spinach in 100 + 347.5ppm chitosan + salicylic acid level and fenugreek and coriander in 125 + 695ppm chitosan + salicylic acid level. The minimum germination percentage was observed for spinach in 50 + 69.5. The maximum mortality observed for spinach in control and 50 + 69.5ppm chitosan + salicylic acid level. The minimum mortality percentage was observed for fenugreek in control, coriander in 75 + 139ppm, spinach and fenugreek in 100 + 347.5ppm and fenugreek and coriander in 125 + 695ppm levels of chitosan + salicylic acid.The maximum plant height was observed for spinach in 125 + 695ppm chitosan + salicylic acid level, followed by spinach in 50 + 69.5ppm chitosan + salicylic acid level. The minimum plant height observed for lettuce in control chitosan + salicylic acid level.The maximum number of leaves were observed for fenugreek in 125+ 695ppm chitosan + salicylic acid level, followed by fenugreek in 100 + 347.5ppm chitosan + salicylic acid level. The minimum number of leaves recorded for coriander in 100 + 347.5ppm chitosan and salicylic acid level. The application of chitosan + salicylic acid showed highly significant differences for root length. The interaction between vegetable crops and chitosan + salicylic acid was also highly significant. The root length ranged from 3.88 to 8.42cm. The maximum root length was observed for fenugreek in 125 + 695ppm chitosan + salicylic acid level followed by fenugreek in 100 + 347.5ppm chitosan + salicylic acid level. The minimum root length was observed for lettuce in control chitosan + salicylic acid level.The total fresh weight ranged from 6.24 to 26.15gm. The maximum total fresh weight observed for spinach in 50 + 69.5ppm chitosan + salicylic acid level, followed by fenugreek in 100 + 347.5ppm chitosan + salicylic acid level. The minimum total fresh weight observed for fenugreek in 100 + 347.5ppm chitosan + salicylic acid level.The interaction between vegetable crops and chitosan + salicylic acid was also significant. The total dry weight ranged from 4.53 to 14.29gm. The maximum total dry weight was observed for fenugreek in 50 + 69.5ppm chitosan + salicylic acid level, followed by fenugreek in control and 75 + 139ppm chitosan + salicylic acid level. The minimum total dry weight was observed for lettuce in control. The maximum chlorophyll contents were observed for lettuce in 100 + 347.5ppm chitosan + salicylic acid level, followed by lettuce in control chitosan + salicylic acid level.The nitrogen concentration ranged from 0.32 to 2.23 unit. The maximum nitrogen concentration was observed for lettuce in 75 + 139ppm chitosan + salicylic acid level followed by spinach in 125 + 695ppm chitosan + salicylic acid level. The minimum nitrogen concentration was observed for coriander in control chitosan + salicylic acid level.The maximum protein contents observed for lettuce in 100 + 347.5ppm chitosan + salicylic acid level, followed by spinach in 125 + 695ppm chitosan + salicylic acid level. The minimum protein contents were recorded for coriander in control chitosan + salicylic acid level.
Mean comparison of vegetable crops for different parameters
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Means sharing common letter differ non-significantly at 5% probability level
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- C.M. Ayyub (Author)Waleed Iqbal (Author)Atif Nawaz (Author)Salman Haider (Author)Touseef Ur-Rehman (Author), 2015, Role of Chitosan and Salicylic Acid in Alleviation of Salt Stress in Leafy Vegetables, Munich, GRIN Verlag, https://www.grin.com/document/309836