Microclimatic modifications and productive responses of the Iceberg lettuce (Lactuca sativa) in protected environments

Abstract

-Experiments were carried out in Ponta Grossa -PR, Brazil, in the winter and spring/summer periods with iceberg lettuces cultivars Lucy Brown and Raider Plus. The objectives were to assess the lettuce productive responses and the intensity of the microclimate modifications in five cropping systems as under shade nets Aluminet 40-O ® (AL) and ChromatiNet Vermelha ® 40 (CR), a low tunnel covered with transparent polyethylene (TU), direct cover white nonwoven (NW) and natural conditions (NT). A complete randomized design was used for both the experiments with five treatments placed in a 5x2 factorial arrangement (cropping systems x cultivars) and four replications. The photosynthetically active radiation and air temperature were monitored by installing probes in a datalogger system. In the winter both cultivars under NW and TU produced 21 days earlier compared to the other environments but they presented fresh commercial head similar to NT at the end of the cycle and superior to CR and AL. In the spring/summer there was no difference in the lettuce cycle regardless of the cultivar and the cropping systems. The Lucy Brown cultivar presented smaller sized heads for the winter cropping but did not differ from Raider Plus during the spring/summer. The mean air temperature of the air under NW was higher than in the other environments in both experiments. The use of the different covering materials reduced the photosynthetically active radiation available to the plant but did not prevent commercial head production of Iceberg lettuce.

Microclimatic changes in cultivating systems for the production of Collard greens baby leaf

“…The precocity of collard greens plants grown under PT is related to the average air temperature values more suitable to the plant development (Figure 1-A), accelerating the metabolic reactions and thus the vegetative growth. Although working with lettuce plants until the end of the cycle, Otto et al (2013) also found that the cultivation under the PT and NW environments had precocity of 21 days in harvesting, in both cultivation systems, compared to cultivation in natural environment and on screen environments with Aluminet 40-O®, red ChromatiNet® 40. According to the authors, the shading materials provided envi-ronments with better levels of radiation and thermal regimes appropriate to favor the metabolism of lettuce plants grown within these environments.…”

Produtividade, custo e rentabilidade de couve produzida sob túnel baixo

“…Among the covering materials used, agrotextiles had the lowest acquisition cost, and a useful life of five months. This material has been used previously with positive results in terms of production and protection against pests (Seabra Júnior et al, 2019, Dantas et al, 2010, Otto et al, 2013, Ponce et al, 2021. Organza is a material intended for confection, which, due to its transparency, lightness, exchange of heat and humidity with the external environment, and ease of acquisition, can be an interesting substitute for other fabrics.…”

Características Comerciais De Alface Rosabela E Robusta Em Ambiente Com Malha Foto Conversora Vermelha

“…A complexidade e importância em estudos com diferentes malhas, culturas, regiões e épocas do ano é apresentado por Otto et al (2013). Os pesquisadores realizaram estudo com duas cultivares de alface americana em diferentes ambientes de cultivo e épocas do ano.…”