Loofah and coconut fiber substrates interaction with growth promoting bacteria on Cattleya harrisoniana and Cattleya granulosa

J.M. Jasmim, N.E. Manhães, F.L. Olivares, B.B. de Castro, A.P.R.C. Erthal
Orchids are very popular in the horticultural market worldwide. Cattleya harrisoniana Bateman ex Lindley and C. granulosa Lindley are attractive Brazilian orchids: the first one occurs in the southeastern hot, humid lowlands from Espírito Santo to Vale do Paraíba; the latter is an endangered species endemic to the northeastern coast of the country from Rio Grande do Norte to Alagoas. Two experiments were carried out in randomized blocks with three replications and 5 plants plot-1. Experiment 1 was in a factorial scheme (2×2) to evaluate the influence of substrate and inoculation with plant growth-promoting bacteria (PGPB) on the growth of C. harrisoniana: Substrate 1 (S1) consisted of pinus bark + coconut chip + charcoal + coconut fiber, and Substrate 2 (S2) was a mixture of pinus bark + coconut chip + charcoal + loofah fiber, in which plants were either inoculated or not inoculated with PGPB. Substrates were analyzed prior to the experiment establishment. Bacterial inoculum (108 cells mL-1) consisted of a mixture of Serratia marcescens strain 22, Burkholderia silvatlantica strain 103 and Herbaspirillum seropedicae strain HRC 54. Experiment 2 was a factorial (2×2×2) evaluating the effect of substrate, PGPB and fertilization levels on C. granulosa growth. Substrate and PGPB treatments were as described for Experiment 1; fertilization treatments consisted of either 50 or 75% of the reference dose (1 g L-1) of Peters® (20-20-20). Plant height (H), leaf length (LL) and leaf number (LN), number of sprouts (NS) and number (NPB) and diameter (DPB) of pseudobulbs were evaluated. C. harrisoniana plants grown in S2 had the longest LL; NPB in inoculated plants grown S2 were superior to those of plants in S1. Cattleya granulosa plants inoculated with PGPB under 75% of fertilization in S1 had a greater NL than those in S2; NPB of inoculated plants was higher in S1 than in S2.
Jasmim, J.M., Manhães, N.E., Olivares, F.L., de Castro, B.B. and Erthal, A.P.R.C. 2017. Loofah and coconut fiber substrates interaction with growth promoting bacteria on Cattleya harrisoniana and Cattleya granulosa. Acta Hort. (ISHS) 1168:55-62
orchids, Orchidaceae, diazotrophic bacteria, Herbaspirillum seropedicae, Luffa cylindrical

Acta Horticulturae