Physiological quality evaluation of Piptadenia stipulacea (Benth.) Ducke seeds by tetrazolium test

ABSTRACT The tetrazolium test is one of the promising alternatives to determine the viability of dormant, recalcitrant and slow-germinating seeds. The objective of this study was to adapt the tetrazolium test methodology to estimate the viability and vigor of Piptadenia stipulacea (Benth.) Ducke seeds. For this, a sample of seeds was classified into three sublots using round sieves, corresponding to six, five and four millimeters in diameter, respectively. Moisture content, imbibition curve, germination, emergence, germination and emergence speed indices, mean germination time and seedling emergence were initially evaluated. The second stage was conducted using a completely randomized experimental design, in 3 x 9 factorial scheme, corresponding to three sublots and nine combinations between concentrations and time of immersion in tetrazolium salt (0.05%/2 h; 0.05%/4 h; 0.05%/6 h; 0.075%/2 h; 0.075%/4 h; 0.075%/6 h; 0.1%/2 h; 0.1%/4 h; 0.1%/6 h), totaling twenty-seven treatments with four replicates of 25 seeds, evaluated separately at 35 and 40 °C. For each treatment, the seeds were divided into four classes: viable and vigorous seeds (class I), viable and non-vigorous (class II), unviable (class III) and dead (class IV). The period of 8 h of pre-imbibition and 4 h of staining in tetrazolium solution at 0.075%, under 35 or 40 °C, is adequate to estimate the viability and vigor of P. stipulacea seeds.

摘要 四唑测定法（tetrazolium test）是测定休眠、顽拗性及慢萌发种子生活力的极具应用前景的替代方法之一。
本研究旨在适配四唑测定法的操作流程，以估算柱荚合欢（Piptadenia stipulacea (Benth.) Ducke）种子的生活力与活力水平。
为此，研究人员采用圆孔筛将种子样品划分为3个亚批，对应直径分别为6 mm、5 mm及4 mm。
首先测定了种子含水量、吸胀曲线、发芽率、出苗率、发芽速率指数、出苗速率指数、平均发芽时间及幼苗出苗情况。
第二阶段试验采用完全随机试验设计，设置3×9因子组合，即3个种子亚批与9种四唑盐（tetrazolium salt）浸种浓度-时间组合（0.05%/2 h；0.05%/4 h；0.05%/6 h；0.075%/2 h；0.075%/4 h；0.075%/6 h；0.1%/2 h；0.1%/4 h；0.1%/6 h），共计27个处理组，每组设置4次重复，每次重复包含25粒种子，并分别在35 ℃与40 ℃条件下开展评估。
针对每个处理组，将种子划分为4个等级：具有生活力且高活力种子（等级I）、具有生活力但低活力种子（等级II）、无生活力种子（等级III）以及死亡种子（等级IV）。
试验结果表明，在35 ℃或40 ℃条件下，采用8 h预吸胀+0.075%四唑溶液染色4 h的操作方案，可有效估算柱荚合欢种子的生活力与活力水平。