Interaction between nitrogen doses and alfalfa (Medicago sativa L.) incorporation in lettuce (Lactuca sativa L.) production

Abstract

Objective: Determine the optimal dose of nitrogen in combination with the incorporation of alfalfa in the growth, yield and concentration of ions in the sap of the lettuce leaf.

Design/methodology/approach: The experimental design used was completely randomized with a 2x5 factorial arrangement with nine repetitions in each treatment. The treatments consisted of five doses of nitrogen (200, 250, 300, 350 and 400 Kg ha^-1) and two soil conditions (with and without alfalfa).

Results: Shoot fresh weight (PFA), shoot dry weight (PSA), polar diameter (PDC) and equatorial diameter of bud (DEC), weight of bud (PC) and yield were higher when a dose of 200 to 300 Kg of N ha^-1 with alfalfa. This effect was similar to the dose of 300 kg of N ha^-1 without the addition of alfalfa. The concentration of nitrates (NO₃^-) in the sap decreased with the addition of alfalfa and with 200 Kg of N ha^-1, the concentration of potassium (K⁺) was higher with or without the addition of alfalfa and 250 Kg of N ha^-1. While the concentration of calcium (Ca²⁺) was higher in the plants that were developed with or without alfalfa but, at a dose of 400 Kg of N ha-¹.

Limitations on study/implications: One of the limitations of this research was not determining the nitrogen available in the soil, due to the lack of equipment.

Findings/conclusions: The incorporation of alfalfa into the soil is a good alternative to improve lettuce production and reduce the use of nitrogenous fertilizers.

Keywords: Growth, quality, yield, nitrate reduction.