Avaliação do crescimento inicial de porta-enxertos de citros na região do Baixo Amazonas

Abstract

Brazilian citrus farming is one of the activities with great effectiveness in generating employment and income and in this context, the diversity of citrus rootstocks is necessary to minimize the impact of diseases and/or pests and enhance the productivity and quality of the fruits, resistance and/or tolerance to abiotic and biotic stresses. Therefore, the present study aimed to evaluate the initial growth of citrus rootstocks from the plant breeding program of Embrapa, in the lower Amazon. To evaluate the growth of the 14 rootstocks, the experiment was conducted in a Completely Randomized Design, with 14 treatments and 5 replicates each, in a protected environment, at the Campus Universitário de Juruti, at the Universidade Federal do Oeste do Pará (CJUR/UFOPA). The genotypes evaluated were: T1 - BRS Tabuleiro; T2 - Citrandarin Riverside; T3 - Citrandarin San Francisco; T4 - BRS N Gimenes Fernandes; T5 - BRS Bravo; T6 - BRS H Leão; T7 - Citrandarin Índio; T8 - BRS Ary S; T9 - BRS Donadio; T10 BRS Matta; T11 - BRS Cunha Sobrinho; T12 - TSKC x (LCR x TR)-073; T13 - BRS Dornelles; T14 - Citrandarin San Diego. The seeds were placed in 6-liter polyethylene bags, using a substrate in a ratio of 4:1 (4 parts soil to 1 part cattle manure). Initial growth was monitored for 216 days after sowing, with 8 measurements being taken throughout the experiment. The height, stem diameter and number of leaves of the seedlings were assessed monthly; and the leaf area was measured every 3 months. At the end of the experiment, using the destructive methodology, the variables of fresh and dry mass of the aerial part, fresh and dry mass of the root, root volume and the Dickson Quality Index (DQI) were measured. The data obtained were subjected to analysis of variance and the means compared by the Scott- Knott test, at 5% probability, using the SISVAR software. All genotypes showed good development throughout the evaluation period, and based on the IQD, all seedlings produced were of good quality. However, treatments T4, T6, T7, T8 and T9 showed better values for all variables evaluated, indicating greater vigor in development. Therefore, the study of these genotypes reinforces the importance of the adaptability of these rootstocks in different environments and/or regions.