Does seed heteromorphism affect the critical temperature thresholds for wild mustard (Sinapis arvensis) germination? A modeling approach

Abstract

Wild mustard (Sinapis arvensis L.) is well-known as a serious weed of cultivated land, particularly in cereal crops. It produces large amounts of heteromorphic (black and brown) seeds. This study aimed to estimate the critical temperature thresholds of wild mustard heteromorphic seeds. For this purpose, a novel Weibull-based thermal time model was developed, which was applied to compare the germination characteristics of the heteromorphic seeds of wild mustard. Germination was investigated by exposing the seeds to eight constant temperatures of 7.5, 10, 15, 20, 25, 30, 35, and 37.5 °C. Over both the sub- and supra-optimal ranges, the proposed model reasonably explained the germination patterns of both seed types in response to temperature. Heteromorphic seeds of wild mustard exhibited different germination behaviors in response to temperature. Brown seeds were more cold-tolerant and could germinate rapidly to a high percentage (68%) in a wider range of temperature environments (2.78-38.05 °C); black seeds germinated at a narrower temperature range (4.99-37.97 °C), and a large proportion of seeds remained dormant (77%). These differences can lead to the temporal distribution of seed germination throughout the growing season.