Comparative Investigation of Salinity-induced Drastic Effects on Leaf Water Status, Physiological, Enzymatic, and Ionic Attributes of Salt-tolerant and Salt-sensitive Okra Cultivars

Tuesday, July 23, 2013: 5:15 PM
Springs Salon A/B (Desert Springs J.W Marriott Resort )
Muhammad Aslam Pervez , University of Agriculture, Faisalabad, Pakistan
Tahira Abbas , Institute of Horticultural Sciences,, Department of Horticulture, Faculty of Agriculture, University of Sargodha, Sargodha, Pakistan
Muhammad A. Shahid, Assistant Professor , Department of Horticulture, University of Sargodha, Sargodha, Pakistan
C.M. Ayub, Associate Professor , University of Agriculture, Faisalabad, Pakistan
Muhammad Rashid Shaheen, PhD Scholar , University of Agriculture, Faisalabad, Pakistan
A pot experiment was executed with the objective to observe the response of four okra cultivars under saline regime with respect to leaf water status, physiological, enzymatic, and ionic attributes. Sand culture was employed with Hoagland solution as nutrient medium to replenish the nutrient requirement of emerging seedlings of two salt-tolerant (OH-713 and OH-139) and two salt-sensitive (Sitara-9101 and Okra-7080) okra cultivars. After 20 days of growth, the seedlings were subjected to various saline levels (2, 4, 6, and 8 dS·m-1) along with control. Salinity induced reduction in leaf water potential, leaf osmotic potential, leaf turgor potential, and relative water content in all the tested okra cultivars. This reduction was observed to be highest in sensitive cultivars (Sitara-9101 and Okra-7080) while the tolerant cultivars (OH-713 and OH-139) maintained less reduction in water relations. Similarly, the physiological attributes (photosynthetic activity, transpiration rate, and stomatal conductance) also showed a significant reduction in response to salt stress. The cultivars i.e., OH-713 and OH-139 confirmed their highest salinity tolerance potential by exhibiting minimum decline above indicated  physiological attributes with respect to sensitive ones. Salt stress markedly elevated the water use efficiency (WUE) of the investigated okra cultivars, but this increse was more prominent in tolerant ones. Nitrate reductase activity (NRA) and nitirte reductase activity (NiRA) was also inhibited by salinity in both tolerant and non-tolerant okra plants. The ionic behavior of okra cultivars with respect to magnesium and potassium content revealed a continuous reduction as compared to non-saline control. The tolerant cultivars accumulated maximum contents of magnesium and potassium in their leaves as compared to roots. However, the sensitive cultivars maintained high ratios of magnesium and potassium content in their roots as compared to leaves. This varied pattern in magnesium and potassium of roots and leaves of salt-tolerant and salt-sensitive okra cultivars suggests adaptation of tolerant ones to withstand saline conditions.