Efficiency of cover materials in preventing evaporation in drought-stressed soybeans grown in pots

Abstract

ABSTRACT:There are few studies in the specific literature on the use of cover materials to control evaporation in drought-stressed plants grown in pots under greenhouse conditions. The use of these materials is of great importance to ensure that water loss occurs only through transpiration. Thus this study aimed to investigate the efficiency of different cover materials -polyethylene, marble, polystyrene, and polyvinyl chloride (PVC) -in controlling evaporation in black and in silver pots cultivated with the soybean cultivar BR 16 and subjected to drought under greenhouse conditions. The plants were kept at 100% field capacity until they reached the V 3 stage. The different cover materials were then applied to the substrate surface, irrigation was suspended, and the plants were evaluated with regard to water loss and temperature of leaf and substrate for nine consecutive days. The experiment was repeated without plants to assess evaporation. Substrate water potential was measured on the last day in both experiments. Although all the cover materials showed uniformity between the replicates with respect to water loss, polyethylene and PVC presented higher substrate water potential and leaf turgor after nine days of suspended irrigation; however, PVC led to soil compactions, restricting its use. Therefore, among the materials tested, polyethylene is the most suitable to control evaporation in pots cultivated with soybean plants subjected to drought, with no influence of pot color. (Oya et al., 2004;Stolf et al., 2009). The effect of the external color of pots -black or silver -was also investigated with respect to water loss through evaporation. RESUMO: Materials and MethodsThe experiments were conducted under greenhouse conditions. Soybean cultivar BR 16 seeds were previously treated with carboxin + thiram (200 g L -1 ) and phypronyl (250 g L -1 ) and then allowed to germinate for 96 h at 25 °C on Germitest  paper moistened with water (2.5-fold volume relative to the weight of the dry paper) (Brasil, 2009). Thereafter, the seedlings were inoculated with Bradyrhyzobium japonicum (Nitro-Super F-45 Premium  ) and planted in 1 L pots (dimensions: 15 cm external diameter × 10 cm base × 11 cm height) filled with substrate (soil/sand/organic compounds, 3:2:2), so that each pot contained one seedling. The greenhouse temperature was set at 28 ± 1 °C, with cooling system actuation when temperature reached 29 °C, and heating system actuation when temperature reached values below 16 °C. The internal temperature and relative humidity (RH) were recorded in a thermohygrograph (Hobo U14-002, Onset  ) every 5 min. The vapor pressure deficit (VPD) was obtained from the Equation 1: The saturated vapor pressure (e s ) was calculated using the psychrometric chart available at http://physics.holsoft.nl/physics/ ocmain.htm. The partial vapor pressure (e a ) was obtained according to Rodrigues et al. (2011) from the Equation 2:s a RH 100x e e = (2)The experimental design was completely randomized with a 2 × 5 (pot color × cover mate...

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“…One day before the water deficiency was induced (at the end of the afternoon), all pots were saturated with water and the excess water was allowed to drain overnight. On the following morning, the pots were wrapped in polyethylene bags and the central region of the pots was covered with cotton around the stem base to prevent water loss by evaporation, as described by Ferreira et al (). The control plants were well hydrated, whereas irrigation was withheld from the water deficiency group.…”

Application of electronic nose and machine learning used to detect soybean gases under water stress and variability throughout the daytime

“…A study carried out by Ferreira et al (2015) would have tested the covering of vessels with varied materials considering soybean and demonstrated that the isolation is effective in causing water losses to be the result only of transpiration, which was crucial to this experiment. Therefore, the soil was isolated with aluminum foil to reduce gas exchange between the medium of interest and the rhizosphere, and irrigation was administered directly into the ground.…”