Search

The main objective of soil improvement by drying is water balance regulation in the sense of decreasing water reserves, with the help of a group of agricultural and engineering reorganizing measurements. The man, in his daily work, often comes up against the need of modifying or remaking some natural—climatic, hydrological and soil conditions, among others. Some lands are naturally leveled, they have natural drainages and deep plough layers, they consist of naturally-blended clay soils with an appropriate amount of sand, they can be naturally-irrigated grasslands or covered by a loam layer; others should be leveled and require artificial drainages, the arable layer should be artificially deepened, the right proportion of clay and sand must be artificially created, that is, they are grasslands without natural irrigation that should be modified by working on it, to achieve the same conditions of other improved soils through water improvement by drying. [ABSTRACT FROM AUTHOR]

The experiment was developed under semicontrolled conditions in Los Palacios Rice Research Station for three years (2005-2007) applying a randomized complete experimental design, two treatments and five replicates. The study consisted of using a water evaporation retardant (stearilic alcohol) making a monolayer on the free water surface, which prevented big water losses by evaporation; the treatment with retardant reduced losses up to 14.97 mg.min-1.cm-2, whereas the treatment without it reached the biggest water losses: 30.27 mg.min-1.cm-2; thus, the retardant is very effective, since its application proved to reduce significantly water losses. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa) is the most important crop for human consumption, providing staple food for more than half of the world's population. Rice is conventionally grown under flooded conditions for most of its growing cycle. However, about half of the rice area in the world does not have sufficient water to maintain optimal growing conditions and yield is reduced by drought. One possible way to increase rice production in order to meet the rice demand is to improve its drought tolerance by means of the arbuscular mycorrhizal (AM) symbiosis. Thus, AM and non-AM rice plants were maintained under well-watered conditions or were subjected to moderate and severe drought stress for 15d. After that, half of the plants from each treatment were harvested, while the other half were allowed to recover from drought for additional 25d. The results showed that rice can benefit from the AM symbiosis and improve their long-term development after a drought stress period. In fact, at each watering level, AM plants showed about 50% enhanced shoot fresh weight as compared to non-AM plants. The AM symbiosis enhanced the plant photosynthetic efficiency under stress over 40%, induced the accumulation of the antioxidant molecule glutathione and reduced the accumulation of hydrogen peroxide and the oxidative damage to lipids in these plants. Thus, these combined effects enhanced the plant performance after a drought stress period., (Copyright (c) 2010 Elsevier GmbH. All rights reserved.)