biologia plantarum

Biologia plantarum 38:519, 1996 | DOI: 10.1007/BF02890599

Soil salinity effects on transpiration and net photosynthetic rates, stomatal conductance and Na⁺ and Cl^- contents in durum wheat

S. K. Sharma¹

¹ Division of Crop Improvement, Central Soil Salinity Research Institute, Karnal, India

Leaf gas exchange, plant growth and leaf ion content were measured in wheat (Triticum durum L. cv. HD 4502) exposed to steady- state salinities (1.6, 12.0 and 16.0 dS nr^-1) for 8 weeks. Salinity reduced leaf area and number of tillers, and increased Na⁺ and Cl^- concentrations in leaves. Leaf- to- leaf gradients of these ions were observed. The oldest leaf contained 6 to 8 times more Na⁺ and Cl^- than the flag leaf. Net photosynthetic rate (P_N), transpiration rate (E) and stomatal conductance (g_S) were the highest in flag leaf, declined in the middle and fully expanded leaves, and were minimum in the oldest leaves. These processes were reduced by salinity with similar leaf- to- leaf gradients. Intercellular CO₂ concentrations in the older leaves were higher than in the flag leaf in non-saline plants, and increased similarly with salinity. Leaf age was the major factor in reducing P_N, and senescence processes were promoted by salinity.

Keywords: growth rate; leaf age; senescence; Triticum durum

Received: October 25, 1995; Accepted: March 6, 1996; Published: December 1, 1996  Show citation