Estimate of vigour in seeds and seedlings of Bixa orellana L.

ABSTRACT Multiplication in such species as the achiote tree is limited, due to inadequate knowledge of the morphological and physiological characteristics of the seeds and seedlings, and the restricted methods for determining seed quality. The aim of this research was to study the suitability of the accelerated ageing test to estimate vigour in seeds of the achiote (Bixa orellana L.), relating the results of the test to the formation of seedlings and the differences in genotype of the genetic accessions. The achiote seeds, represented by four genetic accessions, and three lots, were evaluated for germination, first germination count, classification of seedling vigour, and seedling emergence (total and speed index). The accelerated ageing test evaluated a temperature of 41°C, and periods of 48, 72 and 96 hours of exposure of the seeds to a relative humidity of 100% (water) and 76% (saturated NaCl solution). The saturated solution reduces the amount of water absorbed by the achiote seeds under conditions of accelerated ageing, reducing seed deterioration, favouring uniformity of results and reducing the proliferation of fungi common in the germination of seeds of the achiote. The accelerated ageing test with water or saline solution for 72 or 96 hours is efficient in classifying the achiote seeds as to quality. The variation in the water content of the seeds should be between 23.6 and 28.9% (72 hours) and 29.7 and 32.9% (96 hours) when using water, and between 7.3 and 9.5% with the use of the NaCl solution.

摘要
胭脂树（Bixa orellana L.）等物种的繁殖受限，原因在于对其种子与幼苗的形态及生理特性认知不足，且种子品质检测方法有限。本研究旨在探讨加速老化试验用于评估胭脂树种子活力的适用性，并将试验结果与幼苗形成及不同遗传种质材料的基因型差异相关联。本研究以4份遗传种质材料和3个种子批的胭脂树种子为试材，对其发芽率、初次发芽计数、幼苗活力分级以及幼苗出苗情况（总出苗数与出苗速率指数）进行了评价。本试验设置的加速老化条件为：温度41℃，种子分别置于相对湿度100%（纯水环境）与76%（饱和氯化钠溶液环境）中，处理时长分别为48、72及96小时。饱和氯化钠溶液可降低胭脂树种子在加速老化条件下的吸水量，从而延缓种子劣变，提升试验结果的一致性，同时减少胭脂树种子发芽过程中常见真菌的滋生。采用纯水或饱和氯化钠溶液进行72或96小时的加速老化试验，可有效区分胭脂树种子的品质等级。采用纯水进行加速老化处理时，种子初始含水量需控制在23.6%~28.9%（72小时处理组）及29.7%~32.9%（96小时处理组）；采用饱和氯化钠溶液处理时，种子初始含水量应介于7.3%~9.5%之间。