Frequency of irrigation with saline water in sugar-apple seedlings produced on substrate with polymer

ABSTRACT The objective of this work was to evaluate the growth of sugar-apple seedlings under irrigation management with saline water in a substrate with soil amendment. Treatments were obtained from the arrangement between polymer doses (0, 0.2, 0.6, 1.0 and 1.2 g dm-3) and levels of irrigation water electrical conductivity (0.3, 1.1, 2.7, 4.3 and 5.0 dS m-1), associated with irrigation frequencies (daily and every alternate day), and two additional treatments to evaluate container volume (1.30 and 0.75 dm3), using a randomized complete block design, with four replicates. At 120 days after sowing, the variables substrate salinity, stem diameter, plant height, number of leaves and Dickson quality index were determined. Data were submitted to analyses of variance, regression and contrast. Substrate salinity increased with the increase in irrigation water electrical conductivity and polymer doses. Growth and quality of the seedlings were reduced with increasing irrigation water salinity, and highest values of the variables were obtained in seedlings under daily irrigation. Container with larger volume led to higher growth. The use of hydrated polymer at the adopted levels had no effect on growth and quality of seedlings, requiring further studies. To produce sugar-apple seedlings with better quality, irrigation frequency should be daily and water electrical conductivity should be lower than 2 dS m-1.摘要 本研究旨在评估在施加土壤改良剂的栽培基质中，采用咸水灌溉管理模式下番荔枝（sugar-apple）实生苗的生长状况。试验设置如下：以聚合物施用量（0、0.2、0.6、1.0、1.2 g·dm⁻³）与灌溉水电导率水平（0.3、1.1、2.7、4.3、5.0 dS·m⁻¹）为基础因子，结合灌溉频率（每日灌溉、隔日灌溉），并增设2组用于评估容器容积（1.30、0.75 dm³）的处理，采用随机完全区组设计，设置4次重复。播种后120天，测定栽培基质盐度、茎粗、株高、叶片数及迪克森质量指数（Dickson quality index）。采用方差分析、回归分析及对比分析对试验数据进行统计处理。栽培基质盐度随灌溉水电导率与聚合物施用量的升高而上升。灌溉水盐度升高会降低实生苗的生长与质量表现，每日灌溉处理下的各项指标均达到最高值。采用更大容积的栽培容器可促进实生苗生长。本试验所采用剂量范围内的水化聚合物施用量对实生苗生长与质量无显著影响，有待开展进一步研究。若要培育高品质番荔枝实生苗，应采用每日灌溉模式，且灌溉水电导率需低于2 dS·m⁻¹。