Mulching Affects Seed Set, Provisioning, and Offspring Performance of Vicia unijuga (Fabaceae)

Abstract

Core Ideas Seed set of V. unijuga plants can be maximized by mulching in subalpine conditions. Plastic mulching increased seed provisioning, thus improving V. unijuga seed quality. Increased seed provisioning (mass) of V. unijuga improved germination success. Large seeds/seedlings have higher competitive ability relative to small seeds. ABSTRACTOur aim was to identify the soil and environmental modifications needed to improve seed set and seed quality of the perennial forage legume perennial vetch (Vicia unijuga A. Br.) in harsh subalpine conditions. A 3‐yr field experiment was conducted in a subalpine zone of China to evaluate the effects of modified soil temperature and moisture conditions generated by no mulching (control), plastic film mulching (FM), removal of plastic film mulching at the 30% flowering stage (RM), and threshed barley straw mulching (SM) on seed set, mass, reserves, germination, and seedling growth. The FM and SM treatments were efficient in increasing seed maturation and decreasing ovule abortion at the base of the pods. There were higher 100‐seed weight (HSW) and seed nutrient reserves in the FM and RM treatments, accompanied by higher final germination percentage (FGP) and lower time to 50% germination (T50) and greater initial seedling growth than in the control, whereas the reverse was true for the SM treatment. Modified soil temperature and moisture generated by mulching improved offspring performance traits of V. unijuga through an increase in HSW. The HSW was positively correlated with FGP and seedling growth traits and was negatively associated with T50. In conclusion, the FM treatment provided adequate soil temperature and water resources to maximize seed set by V. unijuga plants. The well‐provisioned seeds from this treatment conferred the advantages of good offspring performance on high germination and seedling growth traits.