Leaf turgor pressure in maize plants under water stress

Abstract

Maize grown is affected by water stress reducing photosynthetic rate and availability of water in its tissues, decreasing plant yield. Monitoring plant water potential is an important indicator of the degree of water stress. With the new magnetic probe for determining leaf turgidity, it is possible to evaluate the water status of the plant and, in some cases, to indicate the optimal relative tolerance to water stress. The union of new and old approaches gives us a better knowledge of water relations in plats. Therefore, the aim of this study was to understand the behavior of maize plants subjected to water stress, using novel and conventional approaches. Maize plants were grown in pots in a greenhouse for 45 days. After this period, plants were subjected to water stress, where turgor measurements expressed by the variable Pp (patch pressure) were monitored. In addition, the leaf water potential, stomatal conductance, CO2 assimilation, transpiration rate, and variable growth (height, leaf area and dry weight) had been monitored for 30 days. Two treatments were conducted, one in which the plant was irrigated and the other one in which irrigation was fully suspended for a period of time and monitored the water status. As the days passed, the plants showed the first visual signs of stress like leaf rolling. During this period, we observed fluctuating Pp values throughout the day, but with a recovery of turgor at night. There were significant differences between treatments for stomatal conductance, water potential, photosynthesis, and Pp, mainly before irrigation. After each irrigation, there has been a rapid recovery in all parameters. There was five periods of stress and it is possible to see a pattern of decreasing and increasing the Pp as the advance of stress, mainly in the last two. Maize plants had a big resilience in water stress conditions, due to mechanisms of water loss mitigation, like leaf rolling and possibly osmotic adjustment. Thus, it was concluded that Pp introduced a new approach to study plants subjected to water stress and it is a complement to other variables as CO2 assimilation rate, stomatal conductance, transpiration rate, and leaf water potential.