HYDROPHILIC POLYMER CHANGES THE WATER DEMAND IN THE IMPLEMENTATION OF A DWARF CASHEW ORCHARD

ABSTRACT Important losses of dwarf cashew seedlings during the establishment of orchards in the Brazilian semiarid are related to the relatively short rainy season. This study aimed to evaluate biochar and hydrophilic polymer as soil amendments to increase water retention and reduce plant death in the first year. An experiment was conducted at the Curu Station, Paraipaba, CE, Brazil, using the clone BRS 226. The experimental design consisted of randomized blocks, with amounts of 0.5, 1.0, 2.0, and 4.0 kg of cashew wood biochar and 20, 40, 60, 80 g of hydrophilic polymer applied per pit, as well as a control treatment (no soil amendment). Seedlings were submitted to an irrigation regime to avoid water stress (5 L water seedling−1 when the tensiometer installed at a depth of 0.15 m reached 60 kPa). The variables of plant development number of leaves, plant height, stem diameter, and canopy diameter were evaluated up to 374 days after transplanting to the field. The analysis of variance showed no treatment effect on plant development. However, minimum water consumption was observed when 29.56 g of hydrophilic polymer was applied per pit, providing 100.0% seedling survival.摘要 巴西半干旱地区新建果园过程中，矮腰果幼苗的大量死亡与雨季时长偏短密切相关。本研究旨在评估生物炭（biochar）和亲水聚合物（hydrophilic polymer）作为土壤改良剂，提升土壤保水能力并降低定植首年的植株死亡率。试验于巴西塞阿拉州（CE）帕伊帕巴市的库鲁试验站开展，供试材料为BRS 226无性系。试验采用随机区组设计，设置每种植坑施用0.5、1.0、2.0及4.0千克腰果木生物炭，以及20、40、60、80克亲水聚合物的处理组，另设无土壤改良剂的对照处理。试验采用调控灌溉制度以避免植株遭受水分胁迫：当安装于0.15米深度的张力计读数达到60千帕时，为每株幼苗灌溉5升水。在田间移栽后的374天内，对植株生长相关指标（叶片数、株高、茎粗及冠幅直径）进行测定。方差分析结果显示，各处理对植株生长无显著影响。然而，当每种植坑施用29.56克亲水聚合物时，植株耗水量最低，此时幼苗存活率可达100.0%。