Regulatory mechanism of enhancing fertilization of mango flower in response to urea application

Urea is a potent N fertilizer inducing biological process of plants. However the regulatory mechanism of enhancing fertilization in mango flower in response to urea is not clarified. In this respect, flower of Langra variety of mango were used and the enzyme urease in flower extract when treated with 100 mM urea were maximally increased. For the regulation of urease activity, role of heavy elements like arsenic (As) and mercury (Hg) and light elements like zinc (Zn) and calcium (Ca) was investigated. 10 mM Na2HAsO4 potentially prohibited the urea induced urease activity in flower than the effect of 1 mM concentration. Similar inhibitory effects were observed whenever the extract was treated with different doses of mercuric chloride (1, 10, 50, and 100 mM) and the effective concentration was 10 mM which reduces 36% of activity. On the other hand, the effects of 1, 10 and 100 mM Zn(NO3)2 were examined on urea induced urease activity where 1 and 10 mM concentrations were found to enhance 30 and 58.4% enzyme activity respectively. We also examined the effect of different doses of CaCl2 (1, 10 and 100 mM) on urea induced urease activity and declined by increasing concentration of CaCl2. However, the effective concentration of CaCl2 was 1 mM showing 103.2% increased activity. The findings indicate that calcium is more potent than zinc on increasing urease activity. To clarify the regulatory mechanism of urea induced primary amine synthesis, the flower was treated with 10 mM Na2HAsO4 which potentially reduced color pigmentation for primary amine demonstrating clearly that arsenic is involved in prevention of primary monoamine during flowering.