Effect of saline water and shading on dragon fruit (‘pitaya’) seedling growth

ABSTRACT ‘Pitaya’ (Hylocereus undatus) is a fruit-bearing, climbing cactus with great food potential for the semiarid region. This study aimed to evaluate the production of ‘pitaya’ seedlings irrigated with low and high salinity water and grown in different light intensities. The experiment was conducted in a completely randomized design, in a 2 × 2 factorial arrangement, with two electrical conductivities of irrigation water: S1 - 0.3 dS m-1 (low salinity) and S2 - 5.0 dS m-1 (moderate salinity) in two environments: A1 - black net with 50% shading, and A2 - full sun, with ten replicates. The variables evaluated were plant height, main cladode diameter, above-ground biomass, root biomass, total plant biomass, number of secondary cladodes, root length, and length of secondary cladodes. The 50% shading (black net) promoted higher plant height, number of secondary shoots, and root length of the ‘pitaya’ plants. The irrigation with moderate saline water (5.0 dS m-1) reduced the number of secondary cladodes, length of root, and length of secondary cladodes. The ‘pitaya’ seedlings grown under 50% shading (black net) showed greater root dry biomass when irrigated with low-salinity water. Greater values of diameter of the primary cladode, above-ground dry biomass, and total dry biomass were observed under full sunlight and elevated saline stress.

摘要：‘火龙果’（*Hylocereus undatus*）是一种结果型攀援仙人掌，在半干旱地区具备极高的食用开发潜力。本研究旨在评估不同盐度灌溉水与光照强度条件下火龙果幼苗的生长表现。本试验采用完全随机设计，设置2×2析因试验方案，共包含2个灌溉水电导率梯度：S1（0.3 dS·m⁻¹，低盐度）与S2（5.0 dS·m⁻¹，中盐度）；2个光照环境：A1（50%遮光率黑色遮阳网）与A2（全光照），每个处理设置10次重复。本试验测定的指标包括株高、主肉质茎直径、地上部生物量、根系生物量、植株总生物量、次级肉质茎数量、根系长度以及次级肉质茎长度。试验结果表明：50%遮光（黑色遮阳网）可显著提升火龙果幼苗的株高、次级肉质茎数量与根系长度；采用中盐度灌溉水（5.0 dS·m⁻¹）灌溉则会降低次级肉质茎数量、根系长度以及次级肉质茎长度。在低盐度灌溉条件下，50%遮光环境培育的火龙果幼苗根系干生物量更高。全光照且高盐胁迫条件下，火龙果幼苗的主肉质茎直径、地上部干生物量以及植株总干生物量均表现为更高水平。