Journal of Horticulture

Journal of Horticulture
Open Access

ISSN: 2376-0354

+44-77-2385-9429

Research Article - (2015) Volume 2, Issue 4

Salt Stress Genotypic Response: Wheat Cultivars Relative Tolerance of Certain to Salinity

Ravi Sharma*
327/Sector 9, Avas Vikas Colony, Sikandra-Bodla Road, Agra-282 007, UP, India
*Corresponding Author: Ravi Sharma, 327/Sector 9, Avas Vikas Colony, Sikandra-Bodla Road, Agra-282 007 UP, India, Tel: 0562-6447901; 0562-4051472 Email:

Abstract

Forty two wheat (Triticumaestivum L) cultivars screened for their relative salt resistance raising seedlings in half-Hoagland solution (control) salinized with NaCl and maintained at 4, 8, 12 and 16 dsm-1 showed a wide range of salt resistance. The growth response to salinity, judged by the shoot and root lengths, ranged from a stimulation in the case of some cultivars at lower salinity levels (4 and 8 EC) to a severe suppression in most of the cultivars at higher levels (12 and 16 EC). It was further observed that the shoot growth was often suppressed more than the root growth with this a level of 12 EC also found to be critical for most of the cultivars except HD–2160 which showed good stand even at a salinity level of 16 EC. Based on these observations, cultivar IWP–72 of the 42 cultivars tested was found to have the maximum sensitivity to salt stress whereas cultivar HD–2160 showed highest salt tolerance. The remaining 40 cultivars fell between the two extremes and were categorized into salt–sensitive, moderately salt–tolerant and salt–tolerant groups exhibiting more than 60% , 40–60% and less than 40% reduction respectively in shoot length at 12 EC dsm-1 over control.

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Keywords: Wheat (TriticumAestivum L); Salt Stress; Critical Level; Salt–Tolerant; Moderately Salt Tolerant; Salt–Sensitive Genotypes

Introduction

The complexion of salt tolerance and the multitude of ways in which plants adapt to it have caused much confusion. Sodium (Na+) and chloride (Cl-) are among the most common ions found in excess in saline soils, and some plant species are especially sensitive to one or both of these ions [1-9]. A general suppression of growth is probably the most common plant response to salinity [10]. Crop plants differ greatly in their tolerance to salinity. Differences between species and varieties in regard to salt tolerance have been reported by several workers [1-20]. In saline soils [2,5,9,21-23] the control of water, the proper techniques of planting and the choice of tolerant crops are essential for their successful use in crop production. The choice of crops is based on: (1) the tolerance to salt; (2) adaptability to climatic or soil characteristics and (3) value of the crop in the individual farm activity. The chances of a crop failure are less if an adequately salt tolerant crop or its variety is selected. The key to improving salt tolerance in plants and studying its inheritance lies in finding sufficient variation within breeding populations and devising a screening procedure capable of identifying resistant or tolerant genotypes.

Further, as the period of seed germination and early seedling stage is the most crucial and important stage in the life cycle of species growing in saline environment [24] the present investigation was, therefore, undertaken to analyze the relative salt tolerance in wheat (Triticumaestivum L) at the early seedling stage and to select varieties that could withstand varying concentrations of the salts in their environment.

Materials and Methods

Forty two wheat cultivars (Triticumaestivum L) were procured from Wheat Directorate, Cummings Laboratory, Division of Genetics and Plant Breeding, Indian Agricultural Research Institute, New Delhi and Chandra Sekhar Azad University of Agriculture and Technology, Kanpur (UP), India. Screening of wheat cultivars for salt resistance was made by Garrad’s Technique [25] as modified by Sarin and Rao [26] and Sharma [2] and as per method of Sheoran and Garg [27] wherein shoot and root lengths of seedlings were recorded at definite intervals. Here test tubes of uniform size (30 ml capacity) were fitted with rolls of filter paper folded at the top into a cone to support the seeds. The tubes were filled to one-third part with the test solutions so that the solution might not come in direct contact with the growing roots, the salt solution being supplied to the roots through capillary action of the filter paper. Distilled water (represented the mean loss of water from the blanks) was added to each test tube after every 24 hr of interval in order to maintain salt concentration near the target levels throughout the germination period. The seeds were initially sterilized with 0.1% mercuric chloride (HgCl2) solution and later washed thoroughly with distilled water. Three seeds per tube were then transferred to the edge of the filter paper cone and were allowed to grow between the filter paper roll and the wall of the test tube in dark growth chamber at 25 ± 20C. Fifteen replicates (five tubes each having three seeds) were maintained for each treatment including the controls (half-strength Hoagland solution grown). Observations on the influence of salinity levels at 4, 8, 12 and 16 EC dsm-1 of salt solution and the controls on the total length of coleoptile and root at early seedling stage were recorded at 24 hr intervals from 48 hr after sowing up to the end of 120 hr under green safe light. The relative tolerance of different cultivars was evaluated on the basis of the% age reduction in shoot growth at 12 EC.

All parameters were analyzed by ‘Analysis of Variance’ (ANOVA) method as given by Panse and Sukhatme [28] wherein Critical Differences (CD at 1 and 5% probability were calculated wherever the results were significant.

Results and Discussion

The observations summarized here clearly demonstrate that exposure to salinity during early seedling stage resulted in stunting of growth of the shoot and root at higher salinity levels. This reduction in shoot and root growth is one of the most commonly observed responses to salinity [1-9,13-20,29,30].

In agreement with Richards [31] it is observed that the changes induced by addition of NaCl to the growth medium became more distinct with increasing salinity and with prolongation of the period of exposure to salinity. This is perhaps due to a higher intake of ions [2-9,14-20] which resulted in toxicity [32-34]. Osmotic effects might also have contributed to the low growth rates under saline conditions [35].

Seed lots of 42 wheat cultivars screened for salinity tolerance at the early seedling stage for shoot and root lengths under varying salinity levels (0, 4, 8, 12 and 16 dsm-1) induced by NaCl as indicated (ANOVA Table 1), all the main effects viz., variety, treatment and seedling age and their interactions (V x D, V x T, D x T and V x D x T) were highly significant at 0.01 probability with significant differences noticed in the shoot and root growth of all the cultivars studied (Figure 1).

Source of Variation DF Characters (MSS)
Shoot Length Root Length
Replication (R) 4 0.486375** 0.061000
Varieties (V) 41 45.705478** 161.962530**
Duration (D) 3 1477.620900** 5062.824300**
Treatment (T) 4 298.855950** 884.461750**
V X D 123 10.662409** 12.680032**
V X T 164 3.96484** 7.322207**
D X T 12 70.434100** 87.099666*
V X D X T 492 0.989345** 0.970510**
Error 3356 0.053137** 0.319951**

Table 1: ANOVA Table (Shoot and Root Growth in 42 Wheat Cultivars). Shoot Length: G.M. =1.259 S.Em. ± 0.231 C.V=18.310 ** P=0.01, Root Length: G.M=3.093 S.Em. ± 0.566 C.V. =18.289 ** P=0.01.

horticulture-Early-Seedling-Stage

Figure 1: Relative Shoot and Root Growths of Certain Wheat (Triticum Aestivum L) Cultivars under Salt Stress at the Early Seedling Stage.

The highest mean shoot growth (3.091 cm) was recorded in the cultivar Kharchia followed by HD-2009, Sonalika, Sharbati sonora, WL-410, HD-2236, UP-262, HS-43, IWP-503, HP-1303, HD-2177, HD-2135, WH-246, K-7634, HD-2260, Raj-1556, UP-115, WL-711, Moti, HD-2282, WL-2200, Raj-1482, HD-1980, IWP-72, CC-464, HD-2275, Raj-1409, HD-2160, HD-1593, Raj-1494, HD-2252, WL-908, HD-2267, UP-171, Raj-1493, HD-1977, HD-2204, K-7631, WL-1531, WG-1559, UP-154 and lastly WG-1558 with the lowest shoot length of 0.282 cm (Table 2). Similarly, significant differences were also noticed in the root growth of the cultivars studied. The maximum root length (5.974 cm) was observed in the cultivar Kharchia followed by HD-2009, IWP-503, Sonalika, Sharbati sonora, HS-43, WL-410, CC-464, UP-262, HD-2135, HD-2177, Raj-1556, UP-115, HP-1303, WL-2200, Moti, HD-2275, HD-2160, HD-2252, WL-711, WH-246, HD-1980, IWP-72, Raj-1494, Raj-1482, K-7634, HD-2260, HD-1593, Raj-1409, UP-171, WL-903, HD-2282, Raj-1493, HD-2236, HD-1977, HD-2267, K-7631, HD-2204, WL-1531, UP-154, WG-1558, and minimum (0.658 cm) was observed in WG-1559 (Table 2).

S No Cultivar Shoot Growth ( cm) Root Growth ( cm)
Cont 4EC 8EC 12EC 16EC Mean Cont 4EC 8EC 12EC 16EC Mean
1 HD-2236 3.768 4.279 2.142 0.433 0.211 2.167 4.502 5.004 3.783 1.017 0.581 2.977
2 WL-410 3.326 3.767 2.488 1.455 0.623 2.332 5.122 5.856 4.736 3.849 2.417 4.396
3 Sharbatisonora 3.263 2.956 2.639 1.585 1.315 2.352 5.271 5.190 5.017 4.221 3.158 4.571
4 Moti 2.171 2.063 1.441 0.248 0.217 1.228 5.075 4.463 3.591 1.886 1.501 3.303
5 Sonalika 3.406 2.947 2.409 1.641 1.472 2.375 5.945 5.661 5.319 4.813 3.965 5.140
6 HD-2160 1.069 1.017 0.974 0.911 0.883 0.970 3.627 3.432 3.038 2.814 2.582 3.098
7 HD-2135 2.790 2.052 1.452 0.992 0.276 1.512 6.451 5.287 4.232 2.783 1.843 4.119
8 IWP-503 3.135 2.527 1.869 0.921 0.437 1.778 7.118 6.626 5.745 4.340 2.266 5.219
9 HS-43 2.710 2.509 1.557 1.191 0.793 1.792 6.012 5.568 4.517 3.555 2.454 4.421
10 UP-262 3.374 2.647 2.003 0.977 0.275 1.855 6.630 5.683 4.429 2.969 1.735 4.289
11 HD-2177 2.948 2.329 1.719 0.841 0.198 1.607 5.019 5.482 4.488 2.790 1.853 3.926
12 WG-1559 0.748 0.623 0.193 0.153 0.070 0.357 1.442 1.211 0.293 0.227 0.095 0.653
13 HD-2267 1.516 1.358 0.745 0.180 0.125 0.785 3.658 2.891 1.039 0.619 0.105 1.662
14 IWP-72 2.430 2.015 0.950 0.190 0.125 1.142 4.119 3.496 2.006 0.607 0.240 2.093
15 HD-2282 1.613 1.543 1.445 0.927 0.568 1.219 3.046 2.902 2.844 2.007 1.719 2.503
16 WL-711 1.537 1.429 1.373 1.098 0.709 1.229 3.678 3.586 3.259 2.756 1.999 3.055
17 Raj-1482 1.711 1.654 1.229 0.660 0.554 1.161 3.909 3.762 3.072 1.893 1.729 2.873
18 HD-2260 1.935 1.491 1.406 1.360 0.443 1.327 3.470 3.213 3.096 2.692 1.395 2.773
19 WH-246 2.069 1.909 1.227 0.903 0.702 1.362 3.811 4.353 2.964 2.152 1.904 3.036
20 WL-2200 1.644 1.028 1.850 0.767 0.580 1.174 3.934 3.342 4.148 2.796 2.370 3.318
21 K-7634 1.583 1.533 1.465 1.272 0.826 1.336 3.449 2.941 3.132 2.776 2.046 2.869
22 Raj-1556 1.895 1.542 1.267 1.002 0.835 1.308 4.855 3.957 3.618 2.901 2.704 3.607
23 UP-154 0.420 0.381 0.319 0.255 0.208 0.316 1.196 1.092 1.034 0.898 0.821 1.008
24 HD-1977 0.744 0.620 0.409 0.320 0.301 0.479 2.842 2.506 1.556 1.366 1.178 1.889
25 WG-1558 0.409 0.388 0.292 0.177 0.144 0.282 0.988 1.290 1.191 0.645 0.428 0.908
26 HD-2204 0.681 0.447 0.524 0.292 0.238 0.436 1.716 1.332 1.573 1.068 0.954 1.328
27 WL-1531 0.490 0.445 0.412 0.348 0.162 0.371 1.384 1.265 1.105 0.926 0.566 1.049
28 K-7631 0.560 0.410 0.385 0.315 0.265 0.387 1.834 1.411 1.338 1.164 1.080 1.365
29 Raj-1409 1.824 1.263 0.849 0.711 0.323 1.006 4.377 3.571 2.583 1.952 1.223 2.741
30 Raj-1493 1.104 0.839 0.716 0.561 0.295 0.703 3.599 2.636 2.415 2.189 1.335 2.427
31 Raj-1494 2.095 0.925 0.825 0.594 0.235 0.935 5.685 3.311 2.393 2.013 1.265 2.933
32 WL-903 1.172 0.883 0.797 0.700 0.455 0.801 3.187 2.969 2.711 2.222 1.825 2.583
33 UP-171 1.355 1.116 0.814 0.233 0.198 0.743 4.435 3.592 2.643 1.693 1.245 2.722
34 HD-2275 1.760 1.463 1.127 0.453 0.305 1.021 4.840 3.869 3.138 2.085 1.828 3.152
35 HD-1593 2.148 0.665 0.986 0.596 0.321 0.943 5.365 2.390 3.030 1.870 1.098 2.750
36 HD-2252 1.139 1.216 0.858 0.749 0.403 0.873 3.830 4.189 2.935 2.736 1.637 3.065
37 HP-1303 2.640 2.275 1.504 1.430 1.032 1.776 4.886 3.869 3.366 3.288 2.054 3.493
38 UP-115 1.775 1.523 1.289 1.181 0.713 1.296 4.808 4.312 3.934 2.803 2.050 3.581
39 HD-1980 1.634 1.536 0.987 0.889 0.725 1.154 4.335 4.048 2.534 2.295 1.760 2.994
40 CC-464 1.931 1.103 0.985 0.905 0.465 1.078 6.199 4.515 4.293 3.835 2.968 4.362
41 HD-2009 4.077 3.627 2.583 2.337 1.514 2.824 7.755 6.441 5.383 4.891 3.909 5.675
42 Kharchia 5.291 3.661 2.610 2.277 1.616 3.091 7.838 7.070 5.522 5.110 4.332 5.974
  Means 1.997 1.666 1.267 0.834 0.527 1.259 4.315 3.799 3.167 2.416 1.767 3.092
  CD at 5% P=0.064S.Em. ± 0.023 CD at 5% P=0.351S.Em. ± 0.126

Table 2: Shoot and Root Growth of Forty two Wheat Cultivars at Different Salinity Levels.

As indicated in the Table 3 only 11 cultivars showed less than 60% reduction in shoot growth while majority of the 31 cultivars had more than 60% reduction at 16 EC. This is in contrast with root growth (Table 3) where almost a reverse trend was noticed, i.e, out of the 42 cultivars only 15 showed more than 60% reduction at 16 EC whereas 27 had less than 60% reduction. This clearly showed that the shoot is more to salinity than the root growth. This differential response of shoot and root growth is shown in Table 4 and Figure 2 where the mean shoot growth was found to be more adversely affected than the root growth. Thus, it was interesting to find that not all plant parts were equally affected. In spite of the fact that the roots were directly exposed to the saline environment it seemed significant that shoot growth was affected more adversely than the root growth. With this also 12 EC was found to be a critical level for most of the cultivars. Thus, shoot growth seemed to be better criterion for relative salt tolerance of the cultivars of the same species at early seedling stage. Based on these observations all the 42 wheat (Triticumaestivum L) cultivars were categorized into three groups viz., salt–tolerant, moderately salt–tolerant and salt–sensitive, showing <40% , 40–60% and >60% reduction in shoot growth at 12 EC over respective controls (Table 3). Further, the different rates of shoot growth of the three groups (Figures 3 and 4) as affected by increasing level of salinity showed a gradual decline in both the salt–tolerant and moderately salt–tolerant cultivars. On the other hand, the salt–sensitive cultivars had a sharp decline in growth with increasing salt concentrations.

S.No. Cultivar Shoot Growth Root Growth
4EC 8EC 12EC 16EC 4EC 8EC 12EC 16EC
1 HD-2236 113.561* 56.847 11.491 05.599 111.150* 84.029 22.589 12.905
2 WL-410 113.259* 74.804 43.746 18.731 114.330* 92.463 75.146 47.188
3 Sharbatisonora 90.591 80.876 48.574 40.300 98.463 95.181 80.079 59.912
4 Moti 95.025 66.374 11.423 09.995 87.940 70.758 37.162 29.576
5 Sonalika 86.523 70.728 48.179 43.217 95.222 89.470 80.958 66.694
6 HD-2160 95.135 91.113 85.219 82.600 94.623 83.760 77.584 71.188
7 HD-2135 73.548 52.043 35.555 09.892 81.956 65.602 43.140 28.569
8 IWP-503 80.606 59.617 29.346 13.939 93.087 80.710 60.972 31.834
9 HS-43 92.583 64.833 43.948 29.261 92.614 75.133 59.131 40.818
10 UP-262 78.452 59.844 28.956 08.150 85.716 66.802 44.781 26.168
11 HD-2177 79.002 58.310 28.527 06.716 109.224* 89.420 55.588 36.919
12 WG-1559 83.288 25.802 20.454 09.358 83.980 20.319 15.742 6.588
13 HD-2267 89.577 49.142 11.873 08.245 79.032 28.403 16.921 02.870
14 IWP-72 82.921 39.094 7.818 05.144 84.874 48.701 14.736 05.826
15 HD-2282 95.600 89.584 57.470 35.213 95.272 93.368 65.889 56.434
16 WL-711 92.973 89.329 71.437 46.128 97.498 88.607 74.932 54.350
17 Raj-1482 96.668 71.829 38.573 32.378 96.239 78.587 48.426 44.231
18 HD-2260 77.059 72.661 70.284 22.894 92.593 89.221 77.579 40.201
19 WH-246 92.266 59.304 43.644 33.929 114.221* 77.774 56.468 49.960
20 WL-2200 62.530 112.530 46.654 35.279 84.951 105.439* 71.072 60.244
21 K-7634 96.841 92.545 80.353 52.179 85.271 90.808 80.487 59.321
22 Raj-1556 81.372 66.860 52.875 44.063 81.503 74.521 59.752 55.695
23 UP-154 90.714 75.952 60.714 49.523 91.303 86.454 75.083 68.645
24 HD-1977 83.333 54.973 43.010 40.456 88.177 54.750 48.064 41.449
25 WG-1558 94.865 71.393 43.276 35.207 130.566* 120.546* 65.282 43.319
26 HD-2204 65.638 76.945 42.878 34.948 77.622 91.666 62.237 55.594
27 WL-1531 90.816 84.081 71.020 33.061 91.401 79.841 66.907 40.895
28 K-7631 73.214 68.750 56.250 47.321 76.935 72.955 63.467 58.887
29 Raj-1409 69.243 46.546 38.980 17.708 81.585 59.013 44.596 27.941
30 Raj-1493 75.996 64.855 50.815 26.721 73.242 67.101 60.822 37.093
31 Raj-1494 44.152 39.379 28.353 11.217 58.240 42.093 35.408 22.251
32 WL-903 75.341 68.003 59.726 38.822 93.159 85.064 69.720 57.263
33 UP-171 82.361 60.073 17.195 14.612 80.992 59.594 38.173 28.072
34 HD-2275 83.125 64.034 25.738 17.329 79.938 64.834 43.078 37.768
35 HD-1593 30.959 45.903 27.746 14.944 44.547 56.477 34.855 20.465
36 HD-2252 106.760* 75.329 65.759 35.381 109.373* 76.631 71.436 42.741
37 HP-1303 86.174 56.969 54.166 39.090 79.185 68.890 67.294 42.038
38 UP-115 85.802 72.619 66.535 40.169 89.683 81.821 58.298 42.637
39 HD-1980 94.002 60.403 54.406 44.369 93.379 58.454 52.941 40.599
40 CC-464 57.120 51.009 46.866 24.080 72.834 69.253 61.864 47.878
41 HD-2009 88.962 60.902 57.321 39.097 83.056 69.413 63.068 50.406
42 Kharchia 69.192 49.329 43.035 30.542 90.201 70.451 65.195 55.269

Table 3: Shoot and Root Growth of Forty two Wheat Cultivars at Different Salinity Levels (Data expressed as percentage over control).

  Interaction Duration Interaction Treatment
  Seedling Age (hr) Salinity Level dsm-1
  48hrs 72hrs 96hrs 120hrs Control 4EC 8EC 12EC 16EC
Shoot 0.192 0.562 1.419 2.863 1.997 1.666 1.267 0.835 0.529
  CD at 5% P=0.048SEm ± 0.017 CD at 5% P=0.022SEm ± 0.008
Root 0.693 2.122 3.759 5.798 4.314 3.799 3.167 2.147 1.767
  CD at 5% P=0.020SEm ± 0.007 CD at 5% P=0.054SEm ± 0.020

Table 4: Relative Shoot and Root Growth (cm) of Certain Wheat Cultivars at Varying Salinity Levels (dsm-1).

horticulture-Cultivars-Under-Salt-Stress

Figure 2: Relative Shoot And Root Growths Of Certain Wheat (Triticum Aestivum L) Cultivars Under Salt Stress At The Early Seedling Stage.

horticulture-Effect-varying-salinity

Figure 3: Effect of varying salinity levels on progressive shoot and root growth (cm) of certain wheat (Triticum aestivum L) cultivars at the early seedling stage (Treatment × Duration) [36].

horticulture-Relative-Salt-Tolerance

Figure 4: Relative Salt Tolerance of Three Groups (Salt-Tolerant; Moderately Salt-Tolerant and Salt-Sensitive Wheat (Triticum Aestivum L) Cultivars Under Salt Stress at the Early Seedling Stage (Data Expressed As percentage Over Control).

A significant reduction in shoot and root growth with increasing salinity levels was observed irrespective of cultivars and seedling age (Table 4 and Figure 2). The reduction was more pronounced after 8 EC salinity level. It was observed that the cultivars showed the first sign of germination at 48 hr after sowing irrespective of salinity level and thereafter shoot growth increased significantly with seedling age till 120 hr (Table 4 and Figure 2).

In the significant interaction of varieties with treatment the cultivars showed a decrease in shoot growth with salinity levels; however, the varietal variations were quite evident. All the cultivars except HD-2160, Sharbati sonora, Sonalika, WL-171, K-7634, Raj-1556, UP-154, HD-1977, K-7631, UP-115, and HD-1980 showed more than 60% reduction in shoot growth at 16 EC salinity level (Table 3). Like shoot growth, salinity in general, resulted in a reduction in root growth irrespective of cultivars and duration. This decline in root growth was significant at all EC levels. On the other hand, root growth increased significantly with the age of the seedling (Table 5 and Figure 3). Further, it was observed that the cultivars differed significantly in their response to increasing salinity levels and all other cultivars except HD-2160, UP-154, Sonalika, and WL-2200 showed less than 60% root growth at 16 EC level (Table 6).

  Seedling Age (hr) Salinity Level dsm-1
    Control 4EC 8EC 12EC 16EC
Shoot 48 0.280 0.236 0.184 0.145 0.114
  72 0.901 0.741 0.531 0.372 0.266
  96 2.263 1.905 1.417 0.922 0.588
  120 4.544 3.783 2.935 1.903 1.148
CD at 5% P=0.044SEm ± 0.016
Root 48 1.065 0.868 0.697 0.486 0.347
  72 3.083 2.653 2.152 1.571 1.148
  96 5.192 4.674 3.848 2.934 2.148
  120 7.915 7.002 5.972 4.675 3.425
CD at 5% P=0.039SEm ± 0.108

Table 5: Relative Shoot and Root Growth ( cm) of Certain Wheat Cultivars at Varying Salinity Levels (dsm-1) (Treatment × Duration).

  Group I Salt-tolerant (Less than 40% reduction) Group II Moderately Salt-tolerant (40–60% reduction) Group III Salt-sensitive (More than 60% reduction)
CULTIVARS HD-2160
K-7634       
WL-711
WL-1531
HD-2260
UP-115      
HD-2252
UP-154
WL-903
HD-2282
HD-2009
K-7631
HD-1980
HP-1303
Raj-1556
Raj-1493
Sharbati Sonora
Sonalika
CC-464       
WL-2200
HS-43
WL-410
WH-246
WG-1558
Kharchia
HD-1977
HD-2204
Raj-1409
Raj-1482
HD-2135
IWP-503
UP-262
HD-2177
Raj-1494
HD-1593
HD-2275
WG-1559
UP-171
HD-2267
HD-2236
Moti
IWP-72

Table 6: Showing Relative Tolerance of Certain Cultivars of Wheat Based on the% Reduction in Coleoptile Growth at 12 EC (dsm-1) Salinity Level.

The relative comparisons of seedling growth between different wheat cultivars indicated better performance of HD–2160 at almost all levels of salinity when compared with controls. It showed highest tolerance to salinity (i.e., 82.60% shoot growth at 16 EC over control) and IWP–72 showing highest inhibition in shoot growth (i.e., only 5.14% growth at 16 EC over control). The next cultivars which were relatively lesser tolerant but close to HD–2160 were K–7634, WL–711, WL–1531, HD–2260, UP–115, HD–2252 and UP–154. Based on these growth responses other cultivars of wheat followed a sequence of decrease as shown in Table 3 as far as their resistance to salt stress was concerned.

On the other hand, all the cultivars showed an increase in shoot growth with seedling age. It was evident that the different cultivars exhibited marked differences in their early seedling growth with increasing age of the seedling and that with advancement of seedling age the effect of salt declined and that, in general, tolerance to salinity increased. It was observed that root length increased with age of the seedlings in all the 42 cultivars studied irrespective of the salinity levels. This table also shows that the cultivars differed significantly in their relative root growth. Like shoot, it was observed in the present investigation that irrespective of the cultivars studied the seedlings exhibited increase in salt tolerance with the advancement of age (Tables 4 and 5 and Figures 2 and 3).

A stimulation observed in growth of some cultivars as shown in Table 3 marked with asterisk (*) at moderate levels of salinity (4 and 8 dsm-1) confirmed similar observations of [2,5,10,16-20,36,37] In certain crop plants. Poljakoff-Mayber and Gale [38] reported that Na+ and Cl-ions play important roles in the life of the plant within the range of suitable concentrations. The stimulation in growth might be attributed to the nutritional supplementation at low concentrations of the salt [2-5,14-20,39].

Thus, it is clear from the data that the cultivars differed in their ability to grow as seedlings under high salinity levels. That wheat showed fairly large varietal differences to salt stress had also been reported earlier by Bhardwaj [40], Sarin and Narayanan [41], Sharma, et al. [2], Sharma, et al. [5], Sharma and Baijal, et al. [3,4,15,16], Yadav [18]. Varietal differences to salt stress were also reported in other agricultural crops by several workers [2,5,13,16-20,34,41-47].

Conclusion

The observations recorded clearly indicated that the shoot is more sensitive to salt stress than the root and that shoot growth is a better index of relative salt tolerance of different cultivars of the same species at early seedling stage with this also 12 EC salinity level was found to be a critical level for majority of the cultivars. Thus, on the basis of the% reduction in shoot growth at 12 EC salinity level over respective control all the cultivars were categorized into three groups viz., salt-tolerant, moderately salt-tolerant and salt-sensitive, showing less than 40% , 40–60% and more than 60% reduction respectively.

Acknowledgements

Author is indebted to Dr BD Baijal (Retd Professor Plant Physiology Department of Botany Agra College, Agra) for expert comments and to the Principal K R College, Mathura for providing necessary facilities.

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Citation: Sharma R (2015) Salt Stress Genotypic Response: Wheat Cultivars Relative Tolerance of Certain to Salinity. J Horticulture 2: 158.

Copyright: © 2015 Sharma R. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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