Alterações na morfologia e no crescimento in vitro de Piper nigrum L . submetidas ao filtrado de cultura de Fusarium solani f. sp. Piperis Alb.

Abstract

The cultivars of black pepper (Piper nigrum L.) in use in Brazil are susceptible to the fungus Fusarium solani f. sp. piperis. However, susceptibility levels are not yet known. The aim of this study was to evaluate the susceptibility through changes in morphology and in vitro growth of the cultivar Bragantina and the intraspecific hybrid (Apra x Guajarina) of black pepper subjected to culture filtrate of Fusarium solani f. sp. piperis. Previously rooted shoots were transferred to MS medium with 3% sucrose, MS vitamins, 0.2% phytagel, 0.05 mg L-1 naphthalene acetic acid and culture filtrate at doses of 0, 20, 30 40 and 50% (v/v). Plants were grown in a growth chamber with a 16h photoperiod and 3000 lux illuminance at 25 ± 3 ° C. The experimental design was a completely randomized factorial design of 2x5 (2 genotypes and 5 doses of filtrate) and, at 45 days of cultivation, changes in morphology and reduced growth of shoots and roots were observed and evaluated on both genotypes. Data were submitted to analysis of variance and regression. The hybrid had the highest means for the number and length of roots, as well as higher average accumulation of fresh and dry weight of roots. The mean stem and internode length were higher for Bragantina, however, the average accumulation of fresh and dry weight of the stem, as well as the average number of buds, were higher for the hybrid. The average number of leaves, total leaf area, senescent leaves and accumulation of fresh and dry weight in the leaves were higher for the hybrid. The fungus culture filtrate in the medium causes more evident changes in the morphology and the growth of cultivar Bragantina than in the hybrid and it is an in vitro alternative to quantify the levels of susceptibility of genotypes of Piper nigrum L. to toxins produced by the pathogen.