<i>In Vitro</i> Priming of Sugarcane Varieties (RB966928 and RB867515)

Abstract

Sugarcane, as a glycophyte, shows sensitivity to saline soils at various stages of its growth. The aim of this study was to evaluate the in vitro priming response in two sugarcane varieties (RB966928 and RB867515). Micropropagated plants, from meristems, received priming treatments by adding the salts (NaCl and KCl) in different concentrations (0.0; 12.5; 25.0 and 50.0 mM), in the MS medium. Subsequently, the plants were cultivated in rooting medium without addition of salts, acclimatized and submitted to gradient ex vitro saline stress with 20  40 and 60 mM, of each salt, for 30 days. The analyzed variables were dry matter of shoot and root, number of tillers and estimation of chlorophyll content. The experiment was carried out in a 2 × 2 × 4 factorial arrangement, in a completely randomized experimental design. Twenty replicates were used throughout the experiment. Data were submitted to analysis of variance and regression and the means were compared by Tukey's test, at a 5% probability level. The priming treatments presented a significant effect, with triple interaction, in the chlorophyll index. In the treatment with NaCl, the variety RB966928 showed an increase in the chlorophyll index with the increase of treatment levels, up to an optimal limit of 31.47 mM. On the other hand, the variety RB867515 showed decreasing in chlorophyll index. In contrast, in KCl treatment, the variety RB867515 presented the increase at the chlorophyll index with the maximum point of 25 mM. For the variables, shoot dry matter (SDM) and root dry matter (RDM) there was a significant difference (p < 0.05 and p < 0.01, respectively) only between the varieties. The variety RB966928 presented higher SDM and RDM in relation to the variety RB867515. Studies are recommended with increasing the duration of the priming treatments and more detailed study of the culture throughout its productive cycle.