Responses of macropropagated Musa plantlets to transient moisture stress in six nursery substrates

Moisture stress causes serious devastating effects on crops ranging from retarded growth, tissue desiccation, and severe yield drop to outright death. In this study, the efficacy of six nursery substrates formulated in varying volume ratios of composted plantain fruit/bunch wastes (PFW), sawdust (SD), poultry manure (PM) and topsoil (TS) were evaluated on growth and moisture stress tolerance of macropropagated banana plantlets in the nursery. Un-amended topsoil was evaluated alongside five other substrates including PFW:SD (3:3), PFW:SD:PM (2:2:2), PFW:SD:PM:TS (1½:1½:1½:1½), SD:PM (3:3) and TS:PM (3:3) in a 6×2 factorial in completely randomized design (CRD) of ten replications. Two uniform sets of 10-week-old plants were used in the study. Watering was withdrawn on one set for 2 weeks, while the other set (watered daily throughout the study period) served as the control. The 2-week moisture stress was followed by a 4-week rehydration period, and thereafter, a second cycle water stress was induced for 3 weeks after which the plants were sampled for growth and dry matter accumulation. Results showed significant (p < 0.05) variability in plant growth and dry matter yield (DMY) across the nursery substrates, vis-à-vis the induced moisture stress. Plant growth and DMY were superior in PFW:SD:PM and PFW:SD:PM:TS, and were comparably good in most other media that contained PM and or PFW. The deleterious effects of the induced moisture stress were most severe in plants raised in un-amended topsoil. In addition to poor growth and reduced DMY observed in the stressed plants, these plants allotted a greater proportion of the accumulated dry matter to the underground components. It was evident from the study that inclusion of composted organic materials in nursery substrates supports the efficient utilization of available water by the plants. The use of organic substrates therefore holds promise for moisture stress management in nurseries. Irrigation (interval or volume) could be regulated to save labour, cut cost and optimize crop water use.Keywords: Nursery media, sucker plantlets, water stress, banana