Optimal temperature for growing green crops in greenhouses

In the conditions of Irkutsk Province, the greens and vegetable crops produced in greenhouses is considered the effective source of vitamins. To optimize temperature for cultivation, we studied plant growth, development and yield influenced by day and night temperatures in phytotron. The following varieties were investigated: lettuce Moskovskii parnikovyi, radish Zhara, leaf mustard Volnuch, daikon Klyk slona, dill Lesnogorskii, parsley Sakharnaya, shallot Sprint, dwarf Alp onion strain 525, schnitt Chemal. Plants were grown at 15, 22, 29 °С daytime temperatures and 5 °С nighttime temperature, and at 5, 10 и 15 °С nighttime temperatures and 22 °С daytime temperature. Phenological patterns and morphometric parameters (plant height, leaf length and leaf number) were examined, and the dates of harvesting and the green mass yield were estimated. In shallot, leaf mustard, lettuce and dill, the day and night temperatures of 29 °С and 15 °С, respectively, maximized the rate of green mass increase, whereas in dwarf Alp onion and schnitt they were 22 и 10 °С, and 22 и 5-10 °С, respectively. When the daytime and nighttime temperatures dropped to 15 and 5 °С, respectively, the rate of leaf growth and root formation slowed at least 2 times, and the ripening occurred 7-10 days later.