Seed priming com material vegetal, resíduo vítreo e luz na formação de mudas de Moringa oleifera sob estresses térmico e hídrico.

Abstract

Population growth associated with the exploitation of natural resources and climate change influences the demand for food, especially in semi-arid regions, which highlights the need for technologies for better growth and adaptation of cultivated species to agroecosystems. Additionally, the development of cultivation methodologies that use plant extracts and materials from waste sources are desirable for sustainable development. In this sense, the objective was to evaluate whether seed priming modulates germination and initial growth and induces tolerance to heat and water stress in Moringa oleifera. To evaluate the germination and initial growth of seedlings, an experiment was carried out in the laboratory and in a screened environment, in a completely randomized design in a 4 x 4 factorial scheme, consisting of four conditions of light quality - QLU (white, blue, red and far red) and four concentrations of aqueous extract of tubers of Cyperus rotundus - EAC (0, 25, 50 and 100%). To evaluate the induction of tolerance to heat and water stress in seedlings, an experiment was carried out in the laboratory and in a Fitotron-type growth chamber, in a completely randomized design in a 2 x 2 x 2 factorial scheme, consisting of seed priming (NSP - without application of seed priming and SPSi - seed priming with glass microparticles as a source of silicon under irradiation with red light), soil water replacement (W50 - 50% and W100 - 100% of crop evapotranspiration - ETc) and temperature variations (T30 ° - 30 °C day/25 °C night and T40 ° - 40 °C day/35 °C night). Seed priming with red light reduced the mean emergence time, while blue, red and far red lights associated with 50% EAC increased the initial shoot length and photosynthetic pigment accumulation. Seed priming with blue light resulted in seedlings with a shorter final seedling length, however, the application of 100% EAC reversed this. White light in combination with concentrations of 50 and 100% of EAC promoted a higher relative growth rate of the aerial part of the seedlings. The research revealed that seed priming with QLU and EAC modulates the germination and initial growth of M. oleifera seedlings. Seed priming with glass microparticles as a source of silicon under red light irradiation attenuated the effects of heat and water stress in M. oleifera seedlings through gas exchange homeostasis, leaf water status, osmotic adjustment and antioxidant mechanism.