EFFECTS OF ARTIFICIAL SHADING AND IRRIGATION WITH BRACKISH WATER ON THE INITIAL DEVELOPMENT OF Anadenanthera colubrina (Vell.) Brenan PLANTS

Abstract

The use of management strategies or changes in the cultivation environment can reduce the impacts of irrigation water salinity on plant development. Therefore, in this research, physiological responses, initial growth, and plant quality of Anadenanthera colubrina (Vell.) Brenan (Angico Branco) were evaluated under different levels of shading and electrical conductivity of the irrigation water, seeking to identify the most favorable conditions for the development of this species using brackish water. The experiment was carried out in randomized blocks with split plots and four replications. The plots were formed by four environments with different shading levels: 0 (full sun), 30, 50, and 70%, and the subplots, formed by five increasing levels of electrical conductivity of the irrigation water: 0.4, 1.6, 2.8, 4.0, and 5.2 dS.m−1. The following variables were evaluated: substrate electrical conductivity, leaf gas exchange, plant height, biomass production, and Dickson quality index at 40 days in a nursery. The use of artificial shading favored plant development and photosynthesis rate, even when irrigated with moderate and high salinity water. The DQI showed that A. colubrina plants presented higher quality index when produced under intermediate shading (30% and 50%), with yield losses below 20% when irrigated with water with electrical conductivity up to 2.8 dS.m−1.

Physiological responses of the beet crop under agricultural environment and saline stress

“…In an attempt to regulate or reduce the loss of water to the atmosphere due to saline and thermal stress, plants reduce the opening of the stomata, through hormones generated by branches and roots, limiting the net photosynthetic rate and the influx of CO2 necessary for the assimilation process (Taiz et al, 2017;Pereira et al, 2019;Muhammad et al, 2021). Thus, the decrease in stomatal conductance in the full sun environment in water of higher Ecw is possibly related to the sensitivity of the stomata of C3 plants, such as beetroot, to the increase in the vapor pressure deficit (VPD) (Pinho et al, 2022); and the high concentration of salts in the irrigation water, making it difficult to supply CO2 to rubisco, consequently, the photosynthetic machinery will increase energy dispersion (Chaves et al, 2009).…”

“…The increase in the concentration of salts in the soil caused a decrease in osmotic potential, driving plants to use a strategy to decrease water loss to the environment, since the transpiration rate is higher than water uptake by plants (Silva et al, 2019). Linked to the strategy of reducing water loss to the environment, the reduction of transpiration in saline environments decreases the absorption of salts; consequently, the translocation to part of the area occurs (Pinho et al, 2022). In studies with sugar beet, Tahjib-UI-Arif et al (2019) and Zou et al (2019) found that under high salt stress conditions there was a decrease in plant transpiration.…”

“…The shading, partial or total, emerges as an alternative to minimize the damaging effects caused by salts on plants, due to the maintenance of photosynthetic mechanisms, CO2 assimilation and increased chlorophyll content (Aras et al, 2021;Gálvez et al 2020). Similarly, Nojosa Lessa et al (2022 on passion fruit and Pinho et al (2022) in the culture of Anadenanthera colubrina (Vell.) verified positive effects of shading nets on seedling establishment and physiological responses of cultures, especially under salinity conditions.…”