Silicon fertilization in sugarcane and water stress tolerance: influence on soil, uptake and biometric, physiological and biochemical parameters

Abstract

There is few information about Si on reducing water stress in sugarcane. This information will be useful to new areas of sugarcane cultivation, where are located sandy and loam-sand soils prone to water stress due to most of sugarcane varieties in Brazil do not show good performance in these conditions. The objectives are: a) evaluate the effects of silicon fertilization in drought tolerant and susceptible sugarcane varieties growing water stress in two periods (3 and 6 months) using biometric, physiological and biochemical attributes; available Si and water use efficiency will be also evaluate (phase 1). These data will provide information about recovery capacity of plants after water stress in function of stage of development and understand the role of Si in this mechanism; b) evaluate the effect of silicon and water stress given at summer and winter season in drought tolerant and susceptible cultivars on Si uptake and its relationship among biometric, physiological and biochemical attributes (phase 2) in order to verify the effect of temperature and water stress and understand the role of Si in this mechanism;. In the phase 1 two experiments will be set up in pots under greenhouse conditions, using the same design in randomized blocks, two sugarcane varieties (tolerant -RB867515; susceptible-RB855536), Si rates (0; 560 kg ha-1 Si), with and water stress (100% and 60% of water content in field capacity). In the first experiment the water stress will be provided at initial growing (3 months) and the second will be given at maximum growing (6 months). In the phase 2, two experiments will be done in pots using randomized blocks, without and with Si (0; 800 kg ha-1 Si), four sugarcane varieties (2 tolerant and 2 susceptible) in low Si content soil and 4 repetitions. The first experiment will be set up in summer and the second in winter. It will be evaluate height, number of green leaves and tillers, lenght of internodes, diameter, water use efficiency, yield, quality, Si uptake, soil fertility evaluation and soluble Si, SPAD index, chlorophyll content, leaf relative water content, water potential, leaf area, antioxidant enzimes (superoxide dismutase, catalase, ascorbate peroxidase , peroxidase), proline, H2O2 and lipid peroxidation on leaves before and after water stress will be also evaluated. (AU)