Nutri-priming as an efficient means to improve the agronomic performance of molybdenum in common bean (Phaseolus vulgaris L.).

Microelements play important roles in improving crop productivity and quality. Two traditional methods of providing micronutrients are soil and foliar application, yet the cost involved and phytotoxicity risks poses a major challenge in most global agricultural areas. Nutri-priming represents thus a very promising and viable alternative to ensure that the plants' requirements for micronutrients are met. This paper explores the Mo-priming effects on the germination, growth and yield components of common bean (Phaseolus vulgaris L.). In order to accomplish this research objective, our study is divided in two phases. The first phase seeks to determine the effects of two durations (5 and 10 h) of Mo-priming on the germination parameters. Then, a greenhouse pot experiment was conducted with primed seeds showing better germination performance to assess the effects of Mo-priming on certain parameters related to biological nitrogen fixation and crop yield. Five seed pretreatments were studied, namely, 0, 0.025, 0.05, 0.1 and 0.2% of ammonium heptamolybdate ((NH4)6Mo7O24.4H2O). Unprimed seeds treated with or without the recommended dose through a soil application were used as controls. Hydropriming is sufficient to improve seed germination performance. However, 0.1% Mo-priming for 10 h improved the net CO2 assimilation rate, chlorophyll content and biological nitrogen fixation. Six times more nitrogen was fixed (65.8 kg ha-1) in these plants than in the controls. Additionally, grain yield increased by 115% compared to the negative control. Thus, compared to soil intake, nutri-priming was a very efficient experimental method.