Adaptive changes in root morphological traits of Gramineae and Leguminosae seedlings in the ecological restoration of the semiarid region of northwest China

Abstract

Gramineae and Leguminosae forages are widely grown in the semiarid region of northwest China. To understand the changes in root morphology in forage seedlings under drought stress, a nursery experiment was conducted with and without water stress using four Gramineae species (Bromus inermis, Agropyron mongolicum, Lolium perenne, and Bothriochloa ischaemum) and four Leguminosae species (Lespedeza bicolor, Medicago sativa, Astragalus adsurgens and Melilotus suaveolens). The forages were grown in rhizoboxes under drought stress (15% polyethylene glycol stress) and well-watered (85% of field capacity) conditions. The results showed that the root length, root area, and specific root length of the Gramineae species were higher than those of the Leguminosae species at the 30-60 cm soil depth. The fine roots of eight species in the 0~0.5 mm diameter class had the largest total root length and total root area, and the total root volume and root tips in the 0.5~1.0 mm diameter class were the highest. Based on the subordinate function method results, B. inermis had the highest comprehensive score, while M. suaveolens had the lowest. Our results implied that Gramineae seedlings distributed more roots than Leguminosae seedlings in the 30-60 cm soil layer under drought stress. Under drought stress, fine roots in the 0~0.5 mm and 0.5~1.0 mm diameter classes were the main organs sustaining the growth of the eight species when suffered drought stress. Among the eight species, B. inermis had the strongest drought tolerance and could act as an optimal ecological restoration forage in the semiarid region of northwest China.

Comparing Water Use Characteristics of Bromus inermis and Medicago sativa Revegetating Degraded Land in Agro-Pasture Ecotone in North China

“…Nevertheless, root traits of Bromus inermis are different from that of Medicago sativa. Root length and root surface area of Bromus inermis with fibrous root system are higher than that of Medicago sativa with taproot system, while root volume of Bromus inermis is lower than that of Medicago sativa [51,52].…”

“…The dichotomization of water uptake patterns from July to September between Bromus inermis and Medicago sativa may be explained by different root allocation modes. Bromus inermis was prone to exploiting deep soil water and groundwater, which was largely a consequence of its deeper root distribution with greater root mass, root length, root tips and root forks in the subsoil layer than in the topsoil layer [52][53][54]. At the same time, Medicago sativa was reversely apt to consume shallow soil water in the rainy wet season, which probably resulted from its larger proportion of root surface area, root tips, root length and root volume of lateral and fine roots (with diameters no more than 2 mm) being located in the topsoil layer than in the subsoil layer [52,55].…”

Effects of two water regimes on morphological traits, nutritive value and physiology of three Bituminaria bituminosa varieties from the Canary Islands

“…The roots of each layer were then split into thin roots (<0.5mm) and thick roots (>0.5mm) and immediately frozen. This threshold was chosen to explicitly emphasise more absorptive roots (Wang et al., 2020). A representative subsample of thin roots from the first layer and all thick roots from the three soil layers of four WW plants per variety were split and independently scanned (EPSON 1,640 XL).…”

Grass-Legume Seeding: A Sustainable Approach Towards Reclamation of Coalmine Degraded Lands in India

“…The branching fibrous roots of grasses lowers the bulk density of compacted mine soil which accelerates the recovery of soils physical conditions at surface 10 cm depth [48]. Under drought stress conditions, root length and root area of grasses are more than legumes at the 30-60 cm depth of soil, therefore grass-legume mixture having different water use strategies can be opted for restoration of fragile areas [49]. The aggressive taproot system of legume species penetrates to a depth of 6-8 feet into soil.…”