Evaluation of rough lemon (Citrus jambhiri Lush.)as rootstock for salinity tolerance at seedling stage under in vitro conditions

Abstract

In vitro approach was adopted to study the effect of salinity on survival and growth of rough lemon (Citrus jambhiri Lush.) seeds. North-West (Punjab) part of India has been facing a major problem of soil salinity for citrus orchards. Therefore, it is logical to study the salinity tolerance of common citrus rootstock, rough lemon (Citrus jambhiri Lush.), grown in the region. The seeds were treated with nine different doses of sodium salt. In all the treatments, leaves of rough lemon seedlings showed severe injury symptoms of chlorosis and necrosis while the seeds cultured in control did not show any injury. There was a significant decrease in seed germination, seedling height, internodal length, and subsequently plant weight with increasing concentration of salt. In contrast to the above characteristics, the length of primary roots increased proportionally with the increase in salt concentration in the culture media. As under stress conditions, the in vitro grown seedlings tend to increase the root length for its survival. In comparison to the control, salt treatments showed increased level of Na⁺ and Cl^- ions in the seedlings and also resulted in a decrease of K⁺/Na⁺ ratio. Tolerance index was found minimum (100) in control and maximum in 154mM NaCl treatments after 4 and 8 weeks.

Key words: Citrus, salt, sensitivity, chlorosis, sodium chloride.