IMPROVING EFFECT OF EXOGENOUS NICKEL NITRATE APPLICATION ON PHYSIO-BIOCHEMICAL FEATURES, NITROGEN METABOLISM AND EARLY GROWTH OF RICE.

High Ni²⁺ levels are toxic to plant growth; however, being a micro-nutrient, its application and/or presence in low concentration may improve plant growth. Present study investigated the effects of exogenous Ni application on morpho-physiological attributes of two rice cultivars in China i.e., Yuxiangyouzhan and Meixiangzhan 2. Nickel was applied exogenously to 11 days old seedlings as Ni(NO₃)₂ in a solution form in the following concentrations: 0.1 mM (Ni1), 0.2 mM (Ni2) and 0.5 mM (Ni3). The seedlings without Ni²⁺ application were taken as control. Results showed that exogenous Ni²⁺ application improved the early growth of seedlings in terms of seedling length, basal diameter, biomass accumulation and seedling index. Substantial improvements were also observed regarding chl a, chl b, total chl contents and carotenoids in plants under Ni²⁺ application compared to CK. Furthermore, all Ni²⁺ treatments decreased the content of Malondialdehyde (MDA). Among all applied concentrations, Ni2 proved better regarding its promotive effects, however further research is needed to explore the molecular basis of Ni-induced modulations in seedlings of both rice cultivars. [ABSTRACT FROM AUTHOR]