Growth and Physiological Responses of 'Persian' Lime and 'Mayer' Lemon to Salinity Stress

Citrus trees are one of the major fruit trees that grow in arid and semi-arid environments. Such environments are generally characterised as saline and crops grown on them often suffer from poor growth and productivity. In a greenhouse study conducted at the Universiti Putra Malaysia, the effects of salinity on the growth and physiology of two citrus cultivars 'Persian' lime and 'Mayer' lemon were evaluated. The seedlings were grown in 25x20 cm plastic bags containing 2.5 kg soil and treated with 0, 25, 50, and 75 mM NaCl. At 12 weeks of salinity treatment, the seedlings were harvested and length of shoots and roots, number of leaves, photosynthetic rate, and proline content of leaves were measured. Salinity reduced shoot and root growth of the seedlings. Similarly, the negative effect of salinity was also observed on net photosynthesis in both cultivars. Overall, 'Persian' lime was found to be more tolerant to salinity stress than 'Mayer' lemon possibility due to a better osmotic adjustment as shown by higher proline accumulation in 'Persian' lime.