Seleção de porta-enxertos de citros para ‘Tahiti’ e ‘pera’ tolerantes ao estresse hídrico no cerrado.

Abstract

The Brazilian citrus industry is a highly organized and competitive sector, being one of the most outstanding activities of the country's agribusiness. As it encompasses a large number of fruit plants of socioeconomic importance, the success of the production chain depends a lot on technification and technologies adapted to the production regions. The preference for rootstocks that favor changes to the canopy variety in terms of growth, production and fruit quality, has been studied by several research centers. Although numerous rootstocks and citrus canopies are available in germplasm banks in Brazil, there are no studies that indicate alternative varieties for cultivation in the Cerrado of Tocantins. Knowledge about highly adaptable genotypes and combinations between these genotypes is important not only for the safety of the production chain, but it is also important for increasing productivity and fruit quality. The aim of this study was to select combinations of crowns / rootstocks that best adapt to the conditions of Tocantins by assessing growth and physiological responses to different levels of water availability as a function of ETc. The work was carried out in the experimental area of the Federal Institute of Education, Science and Technology of Tocantins, Campus Dianópolis. Located in the southeastern region of the state of Tocantins, municipality of Dianópolis. His conduct was guided by the study of two citrus canopy varieties, grafted under different rootstocks and receiving 5 levels of water supplementation. The citrus canopy varieties (C) were, C2 - 'Tahiti' acid lime [Citrus latifolia (Yu. Tanaka) Tanaka], selection EMBRAPA 2001 and C1 - orange 'Pêra' [Citrus sinensis (L.) Osbeck]. All variables were subjected to analysis of variance, Tukey-type averages test at a level of 5% probability, and regression analysis with treatment unfolding within each crown / rootstock combination. The results showed that the plants grafted with the canopy acid lime variety 'Tahiti' showed higher growth rates than those grafted with the orange cane variety 'Pêra' in all evaluated seasons. The citrandarin rootstock 'Riverside' provided the 'Tahiti' acidic canopy variety with the most appropriate physiological behavior, thus obtaining the greatest development within the growth variables analyzed. The orange crown variety ‘Pêra’, obtained the best results, both for physiological parameters and for development, through the Cravo Santa Cruz genotype. These canopy / rootstock combinations were the most adapted to local conditions, being the most prominent in development in the first two years of cultivation. Aiming at the efficient use of water, water availability in 75% of the ETc is recommended for the cultivation of these canopy / rootstock combinations in edaphoclimatic conditions in the Tocantins' cerrado, certain that the plants submitted to this water regime did not differ in their majority. of the plants that received water availability at 100% of the ETc.