State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China.
Department of Biology, University of Kentucky, Lexington, KY, USA.
Physiol Plant. 2024 May-Jun;176(3):e14353. doi: 10.1111/ppl.14353.
Environmental factors, such as temperature and moisture, and plant factors, such as seed position on the mother plant, can affect seed viability and germination. However, little is known about the viability and germination of seeds in different positions on the mother plant after burial in soil under natural environmental conditions. Here, diaspores from three positions on a compound spike and seeds from two/three positions in a diaspore of the invasive diaspore-heteromorphic annual grass Aegilops tauschii were buried at four depths for more than 2 years (1-26 months) under natural conditions and viability and germination monitored monthly. Viability of seeds in each diaspore/seed position decreased as burial depth and duration increased and was associated with changes in soil temperature and moisture. Germination was highest at 2 cm and lowest at 10 cm soil depths, with peaks and valleys in autumn/spring and winter/summer, respectively. Overall, seeds in distal diaspore and distal seed positions had higher germination percentages than those in basal diaspore and basal seed positions, but basal ones lived longer than distal ones. Chemical content of fresh diaspores/seeds was related to diaspore/seed position effects on seed germination and viability during burial. We conclude that seeds in distal diaspores/seed positions have a 'high risk' strategy and those in basal positions a 'low risk' strategy. The two risk strategies may act as a bet-hedging strategy that spreads risks of germination failure in the soil seed bank over time, thereby facilitating the survival and invasiveness of A. tauschii.
环境因素，如温度和湿度，以及植物因素，如母株上种子的位置，都会影响种子的活力和萌发。然而，对于在自然环境条件下埋藏在土壤中后，母株上不同位置的种子的活力和萌发情况，我们知之甚少。在这里，我们对三个复合穗上的位置的小孢子和入侵的小孢子异型一年生草 Aegilops tauschii 的一个小孢子中两个/三个位置的种子进行了研究，将它们分别埋藏在四个深度超过 2 年（1-26 个月）的自然条件下，并每月监测其活力和萌发情况。每个小孢子/种子位置的种子活力随着埋藏深度和时间的增加而降低，这与土壤温度和湿度的变化有关。萌发率在 2cm 时最高，在 10cm 时最低，分别在秋季/春季和冬季/夏季出现峰值和低谷。总体而言，远位小孢子和远位种子位置的种子的萌发率高于近位小孢子和近位种子位置的种子，但近位种子的存活时间比远位种子长。新鲜小孢子/种子的化学含量与小孢子/种子位置对埋藏期间种子萌发和活力的影响有关。我们得出结论，远位小孢子/种子位置的种子具有“高风险”策略，而近位位置的种子具有“低风险”策略。这两种风险策略可能起到了分散风险的作用，即在土壤种子库中，种子萌发失败的风险会随着时间的推移而分散，从而促进了 A. tauschii 的生存和入侵。
