EFECTO FISIOLÓGICO DE LA DISPONIBILIDAD DE AGUA Y NITRÓGENO EN PLANTAS DE GUAYABA

Background: The water deficit and the low availability of nutrients are factors that limit the growth and productivity of cultivated plants. Objective: To evaluate the effect of nitrogen and water availability on growth, chlorophyll concentration and photosynthetic efficiency of guava plants (Psidium guajava L. var. cuban red dwarf). Methodology: A completely randomized experiment with bifactorial arrangement was designed under greenhouse conditions. Factor A was composed by two levels of nitrogen availability (N1: 1.0 g of nitrogen per plant, N0: no nitrogen application) and factor B by two levels of water availability (A400: 400 mL of water every three days and A200: 200 mL of water every three days). Results: Indicators of photosynthetic structure gain (leaves and branches per plant) were more sensitive to water and nitrogen availability from the early stages of plant development, showing the highest values in treatments with higher nitrogen supply, regardless of water availability. Stem growth was higher in the treatments with higher nitrogen and water supply at 80 ddt, similar to that observed in leaf growth and branch emission, regardless of water availability. Implications: The findings found provide new knowledge about the plasticity of cuban red dwarf guava to the conditions of water and nitrogen availability contrasting with the conditions of the experimental site. Conclusions: Guava plants respond to nitrogen and water limitations in the substrate, increasing root growth as a survival strategy in environments with scarce soil resources, while floods with higher water and nitrogen availability increase their assimilation capacity, proportionally to the chlorophyll content.