Irrigation management, light interception, and nitrogen in Tanzania grass cultivation

Manejo de irrigação, interceptação luminosa e nitrogênio no cultivo do capim Tanzânia

ABSTRACT

Management of nitrogen fertilization and light interception of pastures contributes to forage production in regions with low water availability. Therefore, the objective was to evaluate the effect of different nitrogen doses and light interception levels on the growth of Panicum maximum cv. Tanzania under different irrigation managements. The experiment was carried out in a greenhouse, using a factorial scheme (5 x 2 x 2), corresponding to five irrigation depths (40, 60, 80, 100, and 120% of actual evapotranspiration), two canopy light interception levels (90 and 95%), and two nitrogen doses (300 and 600 kg N ha^-1 year^-1). The highest biomass production occurs under irrigation with 120% of evapotranspiration. However, the best structural characteristics (tillering and number of leaves) occur with 100% of evapotranspiration, regardless of nitrogen dose and light interception level. Interruption of growth with 95% of incident light and fertilization with 600 kg N ha^-1 year^-1 promoted greater tillering, number of leaves and leaf length, regardless of the irrigation level. Tanzania grass management with an interruption of growth with 95% of incident light, 600 kg N ha^-1 year^-1, and irrigation with 80% of actual evapotranspiration led to tillering and number of leaves only 11% lower than the values found in the other treatments irrigated with 100% of actual evapotranspiration. Interruption of growth with 95% of incident light and fertilization with 600 kg N ha^-1 year^-1 improve the performance of Tanzania grass under deficit irrigation.

Keywords
Panicum maximum; Actual evapotranspiration; Nitrogen fertilization; Tropical grass