IONS ACCUMULATION, PROLINE CONTENT AND JUICE QUALITY OF SUGAR BEET GENOTYPES AS AFFECTED BY WATER SALINITY
A. H. Mari1*, I. Rajpar1, Zia-ul-Hassan1, S. Tunio1 and S. Ahmad2
1Department of Soil Science, Sindh Agriculture University Tandojam, Pakistan
2National Sugar & Tropical Horticulture Research Institute, Thatta
*Corresponding author: firstname.lastname@example.org
In arid and semiarid regions salinity affects physiology of most of the plants. Under salt stressed conditions, plants do not uptake required quantity of nutrient elements from soil solution; they rather uptake and accumulate larger quantity of toxic ions like Na+, Cl-, etc. Plants have various mechanisms to tolerate soil salinity. Among these mechanisms, K+/Na+ discrimination and synthesis of osmo-protectants is recognized as most effective ways to cope with salt-stress environment. However, variation exists among these genotypes. The goal of this study was to stress ten sugar beet (Beta vulgare L.) genotypes with 4, 8, 12 and 16 EC (dS m-1) levels of saline water in field plots up to maturity and determine variations in Na+, K+ and Cl- concentrations in the sap of fully mature leaves, proline (osmo-protectant) content of leaf tissues and juice quality. The genotypes included in the study were: California, Ernestina, Magnolia, Mirabella, Sandrina, SD 12970, SDPAK 03/06, SDPAK01/07, SDPAK 07/07 and SDPAK 09/07. The results indicated that the plants grown on soil receiving saline water of EC 4, 8, 12, and 16 (dS m-1) salt solutions accumulated more Na+ and Cl- and less K+. Hence they displayed lower K+/Na+ ratio in their leaves. Under salt-stress environment of soil receiving saline water of EC 8 and 16 (dS m-1), sugar beet plants have synthesized more proline in their leaves. Among the 10 genotypes included in the study, four (California, SD PAK 09/07, SD PAK 03/06 and SD PAK 01/07) were found with less Na+, more K+ and lower K+/Na+ ratio, these genotypes were also able to exhibit more proline in leaves, under salt-stress environment, possibly to counter the osmotic effect of salts.
Keywords: Sugar beet, genotypes, proline, Na+, K+, K+/Na+.