Production of Pityrocarpa moniliformis (Benth.) Luckow & R.W. Jobson (Fabaceae) seedlings irrigated with saline water

ABSTRACT Saline irrigation water at high levels causes disturbance in the growth of more sensitive plants. The objective of this research was to evaluate the initial growth of Pityrocarpa moniliformis seedlings under different electrical conductivity in irrigation water through physiological and biochemical analyses. The experiment was conducted in a greenhouse with five water electrical conductivities (0.5, 2.0, 4.0, 6.0 and 8.0 dS m-1) and four repetitions of 20 plants each, arranged in a randomized block design. Application of the treatments with irrigation water containing NaCl began at 30 days after sowing. To determine the behaviour of the species, the following variables were analysed: stem diameter, plant height, number of leaves, leaf area, Dickson quality index, shoot dry mass, root dry mass and total dry mass, as well as the biochemical variables, such as the concentrations of total soluble sugars, free proline and chlorophylls a and b. The increase in irrigation water salinity hampered the growth of P. moniliformis seedlings, with electrical conductivity of 0.5 dS m-1 being the limit for maximum production. The results also indicated that the deleterious effects of salt stress on P. moniliformis seedlings variables increase in concentrations of proline, total soluble sugars and betaine glycine.摘要 高浓度盐渍灌溉水会对敏感性较强的植物生长造成干扰。本研究旨在通过生理生化分析，评估不同电导率灌溉水处理下单形盾柱木（Pityrocarpa moniliformis）幼苗的初始生长情况。本实验于温室中开展，设置5个灌溉水电导率梯度（0.5、2.0、4.0、6.0和8.0 dS·m⁻¹），每个梯度设置4次重复，每次重复包含20株幼苗，实验采用随机区组设计。含氯化钠（NaCl）的灌溉水处理于播种后30天开始实施。为明确该物种的生长响应特征，本研究分析了以下指标：茎粗、株高、叶片数、叶面积、迪克森质量指数（Dickson Quality Index）、地上部干重、根部干重及总干重；同时分析了总可溶性糖、游离脯氨酸、叶绿素a与叶绿素b含量等生化指标。灌溉水盐度升高会抑制单形盾柱木幼苗的生长，电导率0.5 dS·m⁻¹为其达到最大生物量的临界值。本研究结果还表明，盐胁迫对单形盾柱木幼苗各项指标产生的有害效应，会伴随脯氨酸、总可溶性糖及甘氨酸甜菜碱浓度的升高而加重。