Photosynthesis, Water Use Efficiency, and Growth Responses of Two Lettuce Cultivars to Different Cover Crop Species

A high demand for lettuce, combined with a growing appeal for the sustainability of production processes, requires changes in production techniques. In such a context, no-till practices appear as a conservation alternative. The current work evaluated the development and productivity of lettuce crops in a no-tillage system. The experiment had four treatments, i.e., conventional management, millet, sunn hemp, and a combination of covers, comprising millet and sunn hemp. Two lettuce cultivars, Pira Roxa and Valentina, were used in this research. The experimental design was set in randomized blocks, with three replications. Physiological, biometric, and productive characteristics were considered, including net photosynthetic rate, stomatal conductance, CO2 concentration, transpiration, water use efficiency, relative chlorophyll content, head diameter, fresh weight, and productivity. In the Valentina cultivar, there was an increase in the photosynthetic rate when using straw, regardless of the cover plant species. In the cultivar Pira Roxa, the photosynthetic rate was higher without the presence of straw, causing an increase in water use efficiency in the presence of straw. Higher transpiration and head diameter were found in treatments that included all cover plant species in the soil. In addition, fresh weight, leaf count, and productivity increased when using millet straw and the combination for the Valentina cultivar. Regardless of the cover crop or the arrangement between cover plants, the presence of straw on the soil increased the gas exchange capacity in plants, resulting in productive gains.

Photosynthesis, Water Use Efficiency, and Growth Responses of Two Lettuce Cultivars to Different Cover Crop Species Keywords:

Conservation management , cover plants , Lactuca sativa , minimal soil disturbance , regenerative agriculture