Physiological quality of forage palm seeds and seedlings associated with the level of ploidy

ABSTRACT. The forage palm is widely cultivated in semiarid regions. It has a basic chromosome number of x = 11 and polyploids are the main variation. It is propagated via vegetative reproduction, and sexual propagation is rarely used. The objective was to associate the physiological quality of seeds of different cultivars of forage palm with the level of ploidy in the genera Opuntia and Nopalea. The cultivars used were: diploids (2n = 22) ‘F8’, ‘F21’, and ‘IPA Sertânia’; tetraploids (2n = 44) ‘Clone 6 African Elephant Ear’, ‘Mexican Elephant Ear’, and ‘V19’, and octaploids (2n = 88) ‘Round’, ‘Giant’, and ‘IPA Clone 20’. Thousand seed weight, length, diameter, number of seeds per fruit, first count and emergence percentage, shoot and root length, fresh and dry mass, electrical conductivity, and length, width, and fresh and dry weight of cladodes were measured. A nested scheme design was used, with three levels of ploidy and three cultivars within each level. The ploidy level positively influenced the number of seeds per fruit and the physiological quality of the seeds. Cultivars behave differently within the same ploidy level.摘要。饲用仙人掌（forage palm）在半干旱地区广泛栽培。其染色体基数（basic chromosome number）为x=11，多倍体（polyploids）为主要变异类型。该物种以无性繁殖（vegetative reproduction）为主，极少采用有性繁殖（sexual propagation）。本研究旨在对仙人掌属（Opuntia）与麒麟掌属（Nopalea）不同饲用仙人掌品种的种子生理品质与其倍性水平开展关联分析。供试品种包括：二倍体（2n=22）品种‘F8’、‘F21’及‘IPA Sertânia’；四倍体（2n=44）品种‘Clone 6 African Elephant Ear’、‘Mexican Elephant Ear’及‘V19’；八倍体（2n=88）品种‘Round’、‘Giant’及‘IPA Clone 20’。本研究测定的指标涵盖千粒重、种子长度、种子直径、单果种子数、初次发芽计数、出苗率、芽长与根长、鲜重与干重、电导率，以及肉质茎片（cladodes）的长度、宽度、鲜重与干重。试验采用巢式设计（nested scheme design），设置3个倍性水平，每个倍性水平下设3个供试品种。结果表明，倍性水平对单果种子数与种子生理品质具有正向影响；同一倍性水平下，不同品种的表现存在显著差异。