High level of salinity adversely affects growth, productivity as well as quality of vegetable crops by reducing photosynthetic capacity, enzyme activities, and by enhanced production of reactive oxygen species (ROS). These ROS cause peroxidation of membrane lipids leading to disintegration of cell membrane with the leakage of electrolytes. All these detrimental effects ultimately contribute to the crop with reduced yield and low nutritive value. The present investigation was carried out to test salt tolerance capacity of ten genotypes of tomato on the basis of growth, physiological and biochemical characteristics. The results show that all the ten tested genotypes of tomato responded differently to 200 mM NaCl stress. Regarding growth parameters, BL-1076 gave higher values, while Queen gave the lowest values for most of the parameters (plant height, number of leaves, leaf area, shoot and root fresh weight and dry weight). Regarding physiological and biochemical parameters, BL-1076 gave higher values for the activities of carbonic anhydrase and nitrate reductase, leaf chlorophyll content, relative water content, and activities of antioxidant enzymes (superoxide dismutase, peroxidase and catalase). However, genotype Queen gave the lowest values for these parameters. On contrary, the least membrane damage (TBARS content) was registered in BL-1076, while the highest in Queen. Overall assessment of results leads to the conclusion that the genotype BL-1076 was found salt tolerant while Queen salt sensitive. The ten genotypes may be arranged on the basis of their salt tolerance capacity in decreasing order as: BL-1076 > Trust > Imperial > Tanshet star > PakmoreVF > L 26 > Plitz > Bonus F1 > Grace > Queen.
Tomato fruits are one of the important horticultural crops grown across the globe. Tomatoes are an excellent source of antioxidants, dietary fiber, minerals, and vitamins [
Surface sterilized healthy seeds of ten genotypes of tomato (Lycopersicon esculentum Mill.), namely BL-1076, Trust, Imperial, Tanshet star, PakmoreVF, L 26, Plitz, Bonus F1, Grace and Queen were sown in seedling trays. 30 days after sowing (DAS), seedlings were transplanted to 10 cm diameter plastic pots, filled with acid-washed sand. In each pot ten seedlings were established. Later on, thinning was performed and 5 healthy plants were maintained in each pot. Plants grown in pots were kept under natural illuminated conditions (General climatic conditions such as humidity, day/night temperature were recorded during the experiment). To fulfill nutrient requirement of growing plants, all the pots were supplied with 50 mL of Raukura’s nutrient solution [
Response of plants to salt stress was assessed at 60 DAS in terms of growth parameters viz. plant height, fresh weight, dry weight, number of leaves, leaf area per plant (LA); and physiological and biochemical parameters viz. carbonic anhydrase activity, nitrate reductase activity, leaf chlorophyll content (Chl), leaf relative water content (LRWC), lipid peroxidation, and activities of antioxidant enzymes [superoxide dismutase (SOD), peroxidase (POX), and catalase (CAT)].
Growth of plants in response to NaCl was assessed in terms of plant height, fresh weight, dry weight, number of leaves, and leaf area per plant (LA). Dry weight was recorded by drying the plants at 80˚C for 24 h.
The leaf area of about 10% of leaves (LA1) was measured by tracing the leaves on a graph paper and dry weight of these leaves was recorded (W1). Leaf dry weight of total leaves per plant (W2) was registered. Leaf area per plant was calculated using the following formula [
The activity of CA (E.C. 4.2.1.1) was measured using the method as described by Dwivedi and Randhawa [
Lipid peroxidation was estimated by the content of thiobarbituric acid reactive substances (TBARS) as described by Cakmak and Horst [
Leaf tissues were homogenized with three volumes (w/v) of an ice-cold extraction buffer (50 mM Tris-HCl, pH 7.8, 1 mM EDTA, 1 mM MgCl2 and 1.5% (w/w) polyvinyl pyrrolidone). The homogenate was centrifuged at 15,000 g for 20 min at 4˚C. The supernatant was used as the crude extract for the assay of enzyme activities.
Activity of SOD (E.C. 1.15.1.1), POX (E.C. 1.11.1.7) and CAT (E.C. 1.11.1.6) was determined according to Beauchamp and Fridovich [
Each pot was considered as one replicate and the treatment for each genotype was repeated three times. The data were analyzed statistically with SPSS-17 statistical software (SPSS Inc., Chicago, IL, USA). When F value was found to be significant at 5% level of probability, least significant difference (LSD) was calculated. Values were expressed as means ± standard deviation (SD).
In the present experiment response of ten genotypes to 200 mM NaCl was tested to evaluate salt tolerant and salt sensitive genotypes. Perusal of the data show that the tested genotypes responded differently to NaCl stress (
Genotypes | Parameters | ||
---|---|---|---|
Plant height (cm) | Number of leaves | Leaf area per plant (cm2) | |
BL-1076 | 76.5 ± 1.31 | 11 ± 1.38 | 124.7 ± 2.96 |
Grace | 72.0 ± 0.93 | 10 ± 1.52 | 119.8 ± 2.15 |
Queen | 92.4 ± 0.88 | 7 ± 1.10 | 86.5 ± 1.41 |
Tnshet star | 89.6 ± 1.06 | 8 ± 1.29 | 93.7 ± 3.09 |
Trust | 91.5 ± 1.14 | 8 ± 0.96 | 91.2 ± 2.38 |
Imperial | 81.2 ± 1.23 | 9 ± 1.51 | 103.8 ± 2.17 |
L 26 | 93.7 ± 1.07 | 7 ± 1.20 | 89.5 ± 1.82 |
PakmoreVF | 94.1 ± 2.16 | 9 ± 1.47 | 107.2 ± 1.09 |
Bonus F1 | 88.6 ± 1.12 | 9 ± 1.39 | 99.5 ± 2.10 |
Plitz | 95.2 ± 1.83 | 7 ± 1.15 | 88.2 ± 1.69 |
LSD at 5% | 3.65 | 2.64 | 5.91 |
Average of three determinations is presented with LSD at 5%; ± indicating S.D.
Genotypes | Parameters | |||
---|---|---|---|---|
Shoot fresh weight (g) | Shoot dry weight (g) | Root fresh weight (g) | Root dry weight (g) | |
BL-1076 | 6.08 ± 0.51 | 1.97 ± 0.093 | 1.82 ± 0.015 | 0.89 ± 0.006 |
Grace | 5.85 ± 1.10 | 1.06 ± 0.024 | 0.96 ± 0.008 | 0.68 ± 0.002 |
Queen | 3.59 ± 0.87 | 0.74 ± 0.032 | 0.58 ± 0.003 | 0.14 ± 0.001 |
Tnshet star | 3.72 ± 0.39 | 0.88 ± 0.051 | 1.09 ± 0.015 | 0.21 ± 0.006 |
Trust | 3.86 ± 0.91 | 0.85 ± 0.040 | 1.06 ± 0.021 | 0.28 ± 0.008 |
Imperial | 4.42 ± 1.18 | 1.17 ± 0.621 | 1.27 ± 0.016 | 0.31 ± 0.005 |
L 26 | 3.94 ± 0.79 | 1.04 ± 0.036 | 0.71 ± 0.002 | 0.19 ± 0.001 |
PakmoreVF | 3.82 ± 0.88 | 1.21 ± 0.051 | 1.28 ± 0.036 | 0.31 ± 0.003 |
Bonus F1 | 5.49 ± 1.05 | 1.29 ± 0.071 | 1.02 ± 0.017 | 0.39 ± 0.006 |
Plitz | 4.86 ± 0.82 | 1.04 ± 0.010 | 1.07 ± 0.005 | 0.21 ± 0.007 |
LSD at 5% | 1.27 | 0.18 | 0.07 | 0.08 |
Average of three determinations is presented with LSD at 5%; ± indicating S.D.
of NaCl in the growth medium significantly decreases growth attributes of tomato. As shown by the results, 200 mM NaCl caused highest reduction in the activities of CA and NR enzymes (
revealed that the genotypes had a wide range of variability for all plant growth traits (Alsadon et al., 2013).
Salt tolerance capacity of the selected genotypes was also tested in terms of physiological and biochemical parameters. The results exhibit that genotype BL-1076 gave highest values for the activities of CA and NR enzymes under 200 mM NaCl stress. However, Queen gave lowest values for these two enzymes (
Present investigation was carried out to evaluate salt tolerant and salt sensitive genotypes of tomato through assessing growth and physio-biochemical attributes. The results show that all the ten tested genotypes exhibited a wide range of variability in growth, physiological and biochemical attributes in response to salinity. Genotype BL-1076 exhibited higher values of antioxidant enzymes that assisted plants in maintaining optimum activities of CA and NR enzymes, leaf chlorophyll content and leaf relative water content. All these together contributed to improved growth of the plants of BL-1076 genotype. However, reverse is true for the genotype Queen which exhibited lower activities of antioxidant enzymes coupled with lower values of growth, physiological and biochemical characteristics. Thus, the results confirm that BL-1076 was salt tolerant while Queen salt sensitive. Variation in the performance of tested genotypes under salinity leads to the conclusion that these parameters were governed by the genetic makeup of the genotypes. To put all in a nut shell the genotypes can be arranged in the following order of their decreasing salt tolerance capacity: BL-1076 > Trust > Imperial > Tanshet star > PakmoreVF > L 26 > Plitz > Bonus F1 > Grace > Queen. As in the present investigation a genetic variability within a species was recorded which was considered as a valuable tool for plant breeding studies. Therefore, the evaluated genotypes can be used for plant breeding projects of tomato to improve fruit yield, quality and resistance to salt stress.
The financial support (Project no. S-0105-1436) by Deanship of Scientific Research (DSR), University of Tabuk, Saudi Arabia is gratefully acknowledged. The author would also like to thank the Head of the Department of Biology, Faculty of Sciences, University of Tabuk for providing necessary facilities and thanks are also to Saudi Digital Library and University Library for providing relevant and updated literature.
M. NasirKhan, (2016) Growth and Physiological Attributes of Tomato (Lycopersicon esculentum Mill.) Genotypes as Affected by NaCl Stress. American Journal of Plant Sciences,07,453-460. doi: 10.4236/ajps.2016.73039