Growth and production of crisphead lettuce cultivars in protected cultivation and high temperatures

Abstract

The objective of this study was to evaluate the effects of shading nets under lettuce in Juazeiro-BA from September to December 2017. To this end, a field experiment was set up with eight cultivars: Raider Plus, Balsamo, Irene, Rafaela, Iron Wood, Winslow, Great Lakes and Delícia in four production environments covered with red, chromatinet®, black shading nets, and under full sun, with the a randomized blocks design in a 4 x 8 factorial scheme. The harvest was at 45 days after transplanting and the following was determined: head formation index, leaf length and width, plant height, stem length, head diameter, total and commercial fresh matter, total and commercial yield. Data were subjected to analysis of variance, and means were compared by the Scott-Knott test at 5%. Significant effect was observed for the studied environments and cultivars, in addition to the interaction for all the studied variables. Shading altered the microclimatic conditions of the environments. The global solar radiation range from 17.6 to 19.5 MJ m-2 day-1 was ideal for lettuce production. The cultivars that reached the highest commercial yields were Balsamo and Delícia, in an environment covered with the chromatinet® net.