Performance of salicylic acid in modulating morpho-physiological, biochemical and ionic attributes of potato (Solanum tuberosum L.) under different saline regimes

Hafiz Nazar Faried, . (2015) Performance of salicylic acid in modulating morpho-physiological, biochemical and ionic attributes of potato (Solanum tuberosum L.) under different saline regimes. Doctoral thesis, University of Agriculture, Faisalabad.

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Potato is a prime crop in ensuring food security locally as well as globally in the face of changing world demographic scenario as it provides more energy per unit of land and time (216 MJ/ha/day) than any other main staple food crop. However, potato crop is not as productive in subtropical areas as it is in temperate climate. This is attributed to abiotic (e.g. salinity) stress factors which are further aggravating by urbanization, industrialization, climate change and use of underground saline water for potato production due to shortage of freshwater in most of arid and semi-arid regions of the globe. Therefore, a pot culture study, comprised of four experiments was conducted to investigate the role of SA on morpho-physiological, biochemical, enzymatic and ionic attributes that can be used for characterization of salinity tolerance in potato cultivars. Tubers were planted in plastic pots, using fine sand as growth medium and half strength Hoagland solution was applied to plants as nutrient medium. In first experiment, screening of 13 different potato cultivars for salinity tolerance was carried out on the basis of morphological and ionic attributes against six salt (NaCl) stress concentrations (0, 2.5, 5.0, 7.5, 10 and 12.5 dS m-1). Cultivars were categorized into tolerant and sensitive ones on the basis of their performance in 1st experiment. One most tolerant (N-Y LARA) and one most sensitive (720-110 NARC) cultivar were selected for further study. Moreover, in 2nd experiment, effect of different salt (NaCl ) stress levels (0, 2.5, 5.0, 7.5, 10 and 12.5 dS m-1) was investigated on physiological, biochemical, enzymatic and ionic attributes of salt sensitive and salt tolerant potato cultivars (screened out in first experiment). Furthermore, an optimization experiment (3rd) was carried out to identify the best salicylic acid (SA) concentration among various SA levels (0.0, 0.25, 0.5, 0.75, 1.0 and 1.25 mM) by foliar spray under saline (5 dS m-1) environment to test salt tolerance potential of sensitive and tolerant potato cultivars (identified in first study). Additionally, salt tolerance potential of tolerant and sensitive potato cultivars was evaluated under saline (5 dS m-1) and non-saline environment without and with foliar spray of optimized concentration of SA (0.5 mM) vis-à-vis various physiological, biochemical, ionic and antioxidant attributes. Results of 1st and 2nd experiments depicted that salt stress significantly reduced shoot length (SL), root length (RL), shoot fresh weight (SFW), root fresh weight (RFW), shoot dry weight (SDW) and root dry weight (RDW), potassium contents (K+), photosynthetic activity (Pn), transpiration rate (E), water use efficiency (WUE), stomatal conductance of CO2 (gs), substomatal CO2 (Ci), water potential (?w), osmotic potential (??), turgor potential (?p), total chlorophyll contents (Chl.), and total soluble protein content's attributes. However, mean emergence time (MET), sodium contents (Na+), Na+: K+, melondialdehyde contents (MDA), proline contents, total phenolic contents, superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activities increased with increase in salt stress severity against six salt stress levels. From 3rd experiment, 0.5 mM salicylic acid (SA) concentration proved to be the best for inducing salt tolerance in both the potato cultivars. Furthermore, findings of 4th experiment clearly indicated that SA (0.5 mM) significantly enhanced salt tolerance potential of both the potato cultivars by alleviating drastic effects of salt stress on ionic, water relations, physiological, biochemical and enzymatic attributes as mentioned in 2nd experiment. Overall, it can be extracted that salt stress is injurious for potato growth and productivity and exogenous application of SA (0.5 mM) proved effective for enhancing salt tolerance potential of potato. However, SA effect was more pronounced on N-Y LARA than 720-110 NARC reflecting that former one was tolerant to salt stress while the latter one was susceptible. Besides, one can establish that ?p, LRWC, Pn, E, WUE, gs and protein might directly be linked with growth and tuber yield attributes as they are negatively affected by salt stress in the same way as salt stress affected growth attributes in experiment one (Table-4.1.19) and tuber's yield in experiment four (Table-4.4.1), respectively. In view of salt resistance potential of N-Y LARA and efficacy of low concentration of SA (0.5 mM) to further mitigate salt stress effect, cultivation of N-Y LARA along-with foliar application of SA (0.5 mM) may be recommended in saline soil.

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: salicylic,modulating,physiological,biochemical,potato
Subjects: S Agriculture > SB Plant culture
Depositing User: Ms Maryam Saeed
Date Deposited: 26 Oct 2017 07:37
Last Modified: 26 Oct 2017 07:37

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