Organic fertilization attenuates heat stress in lettuce cultivation

Abstract

Organic or organomineral fertilization favours aeration; the distribution, storage and drainage of water through the structure of the soil favouring, in this way, the reduction in sudden variations in temperature that interrupts the of absorption of nutrients by plants. In addition, it is an important source of macro- and micronutrients essential for plant growth and development. The present study was carried out at the Olericulture Sector of the Federal University of the Valleys of Jequitinhonha and Mucuri with the aim of determining the behaviour and growth pattern of lettuce plants (Lactuca sativa L.) cv. Regina, at different levels of fertilization and variable temperature. Temperatures were 12 °C, 20 °C, 23°C and 28°C. A granulated organic fertilizer modified with conventional minerals, proposed by Geofert (a pelletized organic-mineral ((4N-17P2O5-7K2O at 5.30 g/pot) was applied, and cattle manure plus a control treatment without fertilizer. Parameters as plant height, 'head' point diameter, and leaves number/plant were measured. In addition, chlorophyll A and B contents were estimated, leaf area ratio (LAR), the specific leaf area (SLA) and leaf weight ratio (LWR). Fertilization with bovine manure and Geofert fertilizer favoured plant growth, especially at lower or higher temperatures than the recommended for this vegetable (15 - 24 ° C). Organic fertilizers were more efficient than conventional fertilization in the moderating effects of the high temperatures evaluated.