Identification of Teak Genotypes Resistant to the Lasiodiplodia theobromae Fungus
Tectona grandis , Teak Cancer, Selection, Genetic Resistance, REML/BLUP
The teak tree, native to the tropical forests of the Indian Subcontinent and Southeast Asia, has adapted well to equatorial and tropical climates. In Brazil, teak production is increasingly growing, with financial returns in 25 years. Therefore, it is necessary to minimize losses during cultivation as, despite teak's good resistance characteristics to biotic and abiotic factors, certain phytosanitary factors can compromise production. An example is teak cancer, which causes bark detachment, especially near the pruning area and exudation of the vessels, presenting a protuberance. The recurring problems of this fungus in Brazil require more in-depth studies. Hence, this work aims to identify different teak genotypes resistant to the Lasiodiplodia theobromae fungus. The study was conducted at the experimental field of UNEMAT – Cáceres Campus, where the studied population was obtained from an in vivo germplasm bank of the Teak Resources Company. The plants were produced via cuttings in polyethylene tubes and transplanted after approximately 15 days into individual pots. They were kept in a shaded area covered with 70% shade cloth and watered by a drip irrigation system for 150 days until inoculation. For inoculation, isolate 102 was used, being the most aggressive isolate of Lasiodiplodia theobroma, from the mycology collection of the LMGV (Laboratory of Plant Genetic Improvement) of UNEMAT. It was cultivated in MYEA culture medium (2% malt extract, 0.2% yeast extract, 2% agar) in Petri dishes for 20 days until full colonization. After 150 days of inoculation, the plants will be harvested, removing all the bark to reveal the lesion area. The experimental design will be a completely randomized block, consisting of 167 treatments (teak genotypes), three blocks, with two plants per plot, totaling 1002 plants. The lesion area data will be subjected to analysis of variance and then, the average values of the variable will be analyzed by Selegen -REML/BLUP (restricted maximum likelihood/best linear unbiased prediction).