OPTIMIZATION OF WATER USE IN SEEDLING PRODUCTION OF ARBOREAL SPECIES

ABSTRACT The quantification of the hydric requirement during the production of quality seedlings is of extreme importance and the substrate used is a mediator of this influence. However, few studies are carried out in this context, particularly on native species such as Luehea divaricata, which has great potential for lumber production and the restoration of riparian forests. The aim of this study was to characterize the survival and growth of L. divaricata seedlings in different substrates and under different irrigation schemes. The experimental design used a factorial scheme composed of four formulations of substrate (100T: 100% turf (peat); 80T: 80% peat and 20% carbonized rice husk - CRH; 60T: 60% peat and 40% CRH; 40T: 40% peat and 60% CRH) and six irrigation schemes. Survival, height, stem diameter, aerial dry matter, root and total leaf area, and Dickson Quality Index were evaluated. We observed elevated survival, height, stem diameter, aerial dry matter, and leaf area under an irrigation of 16 mm. day-1 with substrates 100T and 80T. The dry matter and Dickson Quality Index, independent of the irrigation, resulted in greater carbon accumulation. Thus, we concluded that substrates based on peat, mixed with up to 20% CRH, allowed greater seedling growth, facilitating earlier hardening and expedition, under an irrigation scheme of 16 mm.day-1. L. divaricata is a native species that can be considered to have high hydric demand during the seedling production phase.

摘要 优质苗木生产过程中的需水量量化研究至关重要，而栽培基质是调控该过程的核心介质。然而，当前该领域相关研究较为匮乏，尤其是针对*Luehea divaricata*这类兼具木材生产与河岸森林修复极高应用潜力的乡土树种的相关研究。本研究旨在探究不同基质配方与灌溉制度下，*Luehea divaricata*苗木的存活与生长表现。本实验采用析因设计，包含4种基质配方（100T：100%泥炭（peat）；80T：80%泥炭与20%碳化稻壳（carbonized rice husk, CRH）；60T：60%泥炭与40% CRH；40T：40%泥炭与60% CRH）与6种灌溉制度。测定指标涵盖苗木存活率、株高、茎粗、地上干物质质量、根系干物质质量、总叶面积以及迪克森质量指数（Dickson Quality Index）。研究结果显示，当灌溉制度为16 mm·d⁻¹且采用100T与80T基质时，苗木存活率、株高、茎粗、地上干物质质量与叶面积均显著提升。无论采用何种灌溉制度，苗木干物质质量与迪克森质量指数均表现出更高的碳积累水平。综上，在16 mm·d⁻¹的灌溉制度下，以泥炭为基础并混合最高20%碳化稻壳的基质配方，可有效促进苗木生长，便于提早开展炼苗与出圃作业。*Luehea divaricata*作为乡土树种，在苗木生产阶段具有较高的需水量。