Volume of cells on trays influences hydroponic lettuce production

ABSTRACT Lettuce seedlings used on hydroponic cultivation (NFT) are usually produced in trays with small volume, requiring two transplants: from tray to nursery and then to the definitive place. The aim of this study was to verify lettuce performance under NFT system, using seedlings produced in trays with several cell volumes (50, 40, 35, 31, 30, 29, 27, 20 and 10 cm³ cell-1). The tray volumes are considered treatments. The experimental design was completely randomized blocks, with four replicates. Seedlings were transplanted directly to the definitive profile, except those ones produced in 10 cm³ cell-1. Two harvests were performed, at 22 and 29 days after transplant (DAT). We evaluated number of senescent leaves, total number of leaves, shoot fresh mass, root fresh mass, shoot dry mass, stem length and productivity. The best performance was obtained using seedlings produced in trays with higher volume per cell. The nursery phase was not necessary and it was possible to obtain reduction from two to one transplant, corresponding to trays of 20 to 50 cm³ cell-1. Seedlings produced in trays with 40 and 50 cm³ cell-1 made the early harvest possible, at 22 DAT of cultivation under hydroponic NFT system.摘要：用于NFT（Nutrient Film Technique，营养膜技术）水培栽培的生菜幼苗通常在小体积育苗盘中培育，需经历两次移栽：从育苗盘转移至育苗圃，再定植至最终种植位点。本研究旨在探究NFT水培体系下，采用不同单细胞体积育苗盘（单细胞体积分别为50、40、35、31、30、29、27、20及10 cm³·cell⁻¹）培育的生菜幼苗生长表现。本实验以育苗盘体积为处理因素，采用完全随机区组设计，设置4次重复。除单细胞体积为10 cm³的幼苗外，其余幼苗均直接定植至最终种植位点。分别于移栽后22天（days after transplant, DAT）和29天开展两次收获。测定指标包括衰老叶片数、总叶片数、地上部鲜重、根系鲜重、地上部干重、茎长及产量。结果显示，采用单细胞体积更大的育苗盘培育的幼苗生长表现最优；对于单细胞体积为20~50 cm³的育苗盘，可省去育苗环节，将两次移栽流程缩减为一次；采用单细胞体积40和50 cm³的育苗盘培育的幼苗，可在NFT水培栽培体系中实现移栽后22天的早期收获。