Abstract
Climate change has increased the occurrence of water deficit in regions where sugarcane and energy cane are cultivated, jeopardizing dry matter production of stems. It was hypothesized that the reasons behind this fact relate to C:N:P stoichiometric modifications in these species that impair the conversion rates of accumulated nutrients in the stems, which could be attenuated by supplying silicon (Si) to the crops. Thus, the aims of this study were to evaluate the effects of water deficit in sugarcane and energy cane ratoons in the presence and absence of Si, in the C:N:P stoichiometry of stems, in the use efficiency of these nutrients and in the accumulation of dry matter in stems. Two experiments were carried out, using sugarcane (Saccharum officinarum) and energy cane (S. spontaneum), cultivated in pots filled with a Typic Quartzipisamment. The treatments for both experiments were arranged in a factorial scheme 2 × 2, without (70% of the soil’s water retention capacity) and with (30% of the capacity) water deficit, without and with the application of Si via fertirrigation, associated with foliar pulverization, both at a concentration of 2.5 mmol L−1, arranged in randomized blocks. The reduction in dry matter production of stems in both species caused by water deficit was due to modifications of the C, N and P stoichiometric homeostasis, but the benefit of Si in these plants when increasing dry matter production was not a reflection of the change in homeostasis, thus it may be involved in other mechanisms that remain unknown and should be further studied.
Highlights
The sugar-energy industry sector is responsible for the widespread cultivation of sugarcane (Saccharum officinarum L.), which is a plant species with high concentrations of sucrose used for the production of sugar and ethanol, a biofuel that is widely used in Brazil
These studies evidenced that the injuries of water deficit in the stoichiometry result in nutritional imbalances, which could reflect in reduced dry matter production and nutrient accumulation in stems; these facts remain poorly investigated in sugarcane crops
Si application via fertirrigation associated with foliar spraying increased the concentration of this element in the stems of sugarcane (Fig 1a) and energy cane (Fig 1b), in the presence and absence of a water deficit condition
Summary
The sugar-energy industry sector is responsible for the widespread cultivation of sugarcane (Saccharum officinarum L.), which is a plant species with high concentrations of sucrose used for the production of sugar and ethanol, a biofuel that is widely used in Brazil. Silicon (Si) may attenuate the stoichiometric disturbances of C:N:P in plant tissue that are caused by stress such as water deficit This benefit of Si may be due to improved nutrient metabolism, as there are reports arguing that Si could replace part of the C in the epidermis cell wall as it binds to cellulose or hemicellulose compounds, favoring cell structuring, decreasing the demand for structural compounds such as lignin (which has a high energy cost for its synthesis)[15], favoring the plant’s energy savings, which may have an impact on the metabolism of other nutrients. According to Siddiqi and Glass[16], the efficient use of a given nutrient is the capacity to produce dry mass per unit of cumulative nutrient in the plant
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