Biological responses of barley as affected by soil moisture and cationic balance in Brazil

Control of water in the soil-plant-atmosphere system is vital to assure maximization of crop yield. Nutrients uptake by the plants is considerably affected by soil moisture mainly because mineral nutrients reach out for roots as a function of mass flux and diffusion. Soil cationic balance might impinge upon calcium (Ca), magnesium (Mg) and potassium (K) uptake by the plant roots. In light of the hypothesis that soil Ca:Mg ratio more suitable for agricultural crops hinges upon soil moisture, the current research aimed to study interrelationships between soil moisture status and cationic balance in soil on biological responsiveness of barley plants. The experiment was conducted in a protected environment and a randomized complete block design was used with three replicates arranged in a 4×4 factorial scheme. Soil water treatments imposed herein were defined as a function of four fractions of maximum crop evapotranspiration (ETm): 60, 80, 100, and 120% ETm along with four ratios between calcium (Ca) and magnesium (Mg): 1:1, 3:1, 6:1, and 9:1. The parameters evaluated were: plant height, number of tillers, number of ears per plant, number of grains per ear, number of grains per plant, grain weight per plant, and thousand-grain weight. Soil cationic balance did not impinge upon agronomic performance of barley crop, whereas all of response-variables evaluated were highly governed by soil water availability. Conversely, the most adequate soil Ca:Mg ratio to promote the best biological responsiveness of barley grown under a protected environment did not depend on soil moisture levels.