Effect of maternal environment on seed germination and seed yield components of Thlaspi arvense

Abstract

Thlaspi arvense has attracted great attention due to its high oilseed content and potential use as biomass for biofuel production. However, seed dormancy and low seed yield of wild T. arvense difficulties its cultivation and efficient use. Knowledge on seed germination, seed yield (SY) and their response to maternal environmental conditions is needed for the development of less dormant, high yield accessions, but this information is limited. Here, fresh seeds of a low altitude population (LAP) from Xiahe, and a high altitude population (HAP) from Maqu, both located in central China, are compared for germination and dormancy characteristics, including germination percentage, germination rate and dormancy-release. In a pot experiment, the effect of soil moisture content and shading of maternal plants on seed germination, their response to gibberellin, SY and SY components were determined. Germination of freshly collected mature seeds from HAP (0.89%) was higher than that of LAP (7.33%). The difference in seed germination between the two populations also was reflected by the gibberellin requirement for dormancy-release, in which GA50 was 0.135 and 0.012 mmol/L for LAP and HAP seeds, respectively. In addition, drought stress and light decreased the sensitivity of dormancy-release to gibberellin (improved GA50). The GA50 of LAP was 0.123, 0.133, 1.781, and 0.069 mmol/L for seeds matured under low, moderate, and severe drought stress and shade conditions, respectively; while for HAP this values were of 0.034, 0.041, 0.056, and 0.016 mmol/L. Drought stress reduced SY of T. arvense through a direct and indirect negative effects on height, biomass, reproductive branches per plant, siliques per branch, seeds per silique and 1000-seed weight. However, shade treatment increased SY by improving height and biomass. These results suggest that T. arvense populations with different dormancy levels can be selected from wild germplasm resources for domestication, according to breeding objectives. On the other hand, results also indicate that different quality and yield of seeds can be obtained by adjusting the environmental conditions during plant growth. Moreover, reproductive branches per plant and siliques per reproductive branch contributed the most to seed yield of T. arvense both in drought stress and shade condition. Thus, reproductive branches per plant and siliques per reproductive branch should be prioritized in a breeding program to improve SY of T. arvense.