Trocas gasosas, massa fresca e qualidade de água no cultivo do gergelim associando cinzas do bagaço de cana-de-açúcar e água salina

Abstract

Irrigated perimeters are intended to minimize problems related to drought. In the Northeast, in line with the availability of water, some factors affect the quality of irrigation, such as salinization, which commonly occurs in water from wells located in sedimentary soil in the semi-arid region. Due to the climate and the characteristics of the aquifers, brackish or saline waters affect not only the physical and chemical parts of the soil but also the growth and development of the plant, its nutritional and physiological aspects. Therefore, it is necessary to introduce innovative management techniques aiming to maximize agricultural production and simultaneously reduce the effects of salinization. However, the use of organometallic fertilizers such as vegetable ash can reduce acidity and provide better soil fertility. Sesame is considered a salinitysensitive crop, on the other hand, the climate of the semi-arid region favors its production, making it a source of income for farmers. In this sense, the objective was to evaluate the effects of different dosages of ash from sugarcane bagasse and irrigation with saline water, evaluating gas exchange, dry matter, and water quality of sesame in the semi-arid region of Pernambuco. The study was conducted at the Federal Rural University of Pernambuco at the Serra Talhada Academic Unit (UFRPE/UAST), using the experimental design in randomized blocks in a factorial scheme ((5 x 2) +2), with 4 replications totaling 48 experimental units. The treatments consisted of five doses of sugarcane bagasse ash (0, 30, 60, 90 and 120 g.plant-1), two water qualities (A1= Public supply water (0.5 dS m -1); A2 = Artesian well water (4.1 dS m-1) and two additional controls (T1 = Recommended fertilization + public supply water; and T2 = Recommended fertilization + artesian well water. The experimental unit was represented by nine plants, but for physiological analysis, only one plant was used. The net assimilation of CO2(A), stomatal conductance (gs), the internal concentration of CO2 (Ci), and transpiration (E) were analyzed, and the readings were carried out 70 days after sowing. In addition, the water use efficiency (USA) and carboxylation efficiency were determined. At 90 DAS, the harvest was carried out and the fresh plant matter was measured. pH and electrical conductivity of the soil saturation extract. The data were submitted for analysis of variance by site F at 1 and 5% probability. Due to the rains during the experiment, it was not possible to state whether the ash dosages could affect the effects of salinization on gas exchange in sesame. The highest ECs were found in soil irrigated with brackish water and the use of mineral fertilizer provided a higher yield of fresh matter than treatments that received only ash from sugarcane bagasse as a source of fertilization.