Soil Moisture Determines Horizontal and Vertical Root Extension in the Perennial Grass Lolium perenne L. Growing in Karst Soil

Abstract

Karst regions are characterized by heterogeneous soil habitats, with shallow wide soil (SW) on hilly slopes and deep narrow soil (DN) in rocky trenches. To make full use of limited water and nutrients, plants have therefore developed a number of root extension strategies. This study investigated the effect of soil moisture on horizontal root extension in SW and vertical root extension in DN by assessing root growth responses, biomass allocation, and root distribution. A full two-way factorial blocked design of soil dimensions by water availability was followed. The perennial grass Lolium perenne L. was grown in SW and DN under high (W100%), moderate (W50%), and low (W30%) water availability, respectively. The main results were as follows: (1) The total biomass of L. perenne was not influenced either by soil habitat or by water application. Root length, root surface area, root biomass and root to shoot ratio all decreased with decreasing water application in SW, but not in DN soil. (2) With decreasing water application, the cumulative percentage of root length, root surface area and root biomass in 4 rings from the center out to 12 cm of SW soil showed a trend of W50% > W30% > W100% in SW, however, the cumulative percentage of root biomass in 4 layers from the surface to a depth of 36 cm was not significantly different between different water treatments in DN. (3) Under all three water treatments, specific root length showed an increase but root length density showed a decreasing trend from the center outward in SW soil or from the surface to bottom in DN soil. Overall, these results suggest that in SW habitat, soil moisture determines horizontal expansion of the roots in L. perenne , although the overall expansion ability was limited in severe drought. However, due to the relatively strong water retention ability, soil moisture changes were less obvious in DN, resulting in no significant vertical extension of the root system. The root response of L. perenne helps our understanding of how herbaceous plants can adjust their belowground morphology to support their growth in harsh karst soil environments.

Rapid Estimation of Water Stress in Choy Sum (Brassica chinensis var. parachinensis) Using Integrative Approach

“…The morphological characteristics of choy sum roots as quantified in this study revealed that even though reduced soil water content affects plant roots, maintaining the water content in the soil throughout the growing season improves yield and plants adaptability. It is well known that root systems can change their morphological structure in response to the soil environmental conditions such as temperature and soil water content [51]. Root development in choy sum was affected by the soil moisture content in this study.…”

“…However, many studies have reported that crop roots tend to grow deeper into the soil when the immediate soil the root occupies is deficient in water [39,[53][54][55][56][57][58] with one study reporting that root growth of plants in water stress conditions reduced root development and may cause root damage. Chung et al and Zhang et al [51,58] reported that the drought level and root growth were inversely related if the drought occurred from the onset of planting or early growth stages. Results from this study inveterate that severe water stress limits root growth throughout the choy sum growth especially during the early and flower development stages.…”

Sustainable Potato Production: A Model of Potato Production at Low Latitude Plateau in Winter, Yunnan Province, China

“…The soil cover thickness may explain the increase in soil moisture content (Fig. 5) which has greater effect on roots extension [13] which has positive impact on potato tubers development. Mulching with about 15cm soil covering depth (Fig.…”

Plant functional traits affect competitive vigor of pasture grasses during drought and following recovery

“…All three species are cool‐season C 3 perennial grasses. Phalaris and Festuca are considered deep rooted (Norton et al, 2016; Volaire & Lelièvre, 2001), while Lolium exhibits a shallower, fibrous root system (Zhang et al, 2019).…”