Vertical gradient in soil temperature stimulates development and increases biomass accumulation in barley

Abstract

We have detailed knowledge from controlled environment studies on the influence of root temperature on plant performance, growth and morphology. However, in all studies root temperature was kept spatially uniform, which motivated us to test whether a vertical gradient in soil temperature affected development and biomass production. Roots of barley seedlings were exposed to three uniform temperature treatments (10, 15 or 20°C) or to a vertical gradient (20-10°C from top to bottom). Substantial differences in plant performance, biomass production and root architecture occurred in the 30-day-old plants. Shoot and root biomass of plants exposed to vertical temperature gradient increased by 144 respectively, 297%, compared with plants grown at uniform root temperature of 20°C. Additionally the root system was concentrated in the upper 10 cm of the soil substrate (98% of total root biomass) in contrast to plants grown at uniform soil temperature of 20°C (86% of total root biomass). N and C concentrations in plant roots grown in the gradient were significantly lower than under uniform growth conditions. These results are important for the transferability of 'normal' greenhouse experiments where generally soil temperature is not controlled or monitored and open a new path to better understand and experimentally assess root-shoot interactions.

Arguments for and against self and non-self root recognition in plants

“…In Ambrosia dumosa , intraspecific water competition is thought to be the reason for growth reduction when self roots are recognized (Mahall and Callaway, 1992). Hence, local changes in the microclimate should also be taken into account; for instance, root temperature gradients affect root productivity and lead to top soil accumulation (Füllner et al, 2012). Indeed, these problems have been recognized and highly controlled experiments have been set up in which plants are grown in preconditioned liquid media (Biedrzycki et al, 2010; Caffaro et al, 2011).…”

Analyzing Lateral Root Development: How to Move Forward

“…Root developmental strategies strongly depend on both local concentrations of nutrients as well as on the nutrient status of the whole plant (Gojon et al, 2009) and on soil temperatures (Fü llner et al, 2011). We believe that the scientific community might not necessarily profit from the general use of one single growth medium, given that substantial progress has been realized using different media and different growth conditions, instead of one standardized medium.…”

“…In addition, a naturally heterogenous environment affects root system architecture at a specific point in time and space. As such, the root system also reflects previous local environmental situations (Fü llner et al, 2011). Therefore, we should be mindful that time is an important parameter when considering development of primordia and root systems.…”

The art of growing plants for experimental purposes: a practical guide for the plant biologist

“…Root damage may occur if pots are black and warm up under direct solar radiation. Moreover, soil temperature per se and even gradients in soil temperature within single pots can affect plant growth and allocation (Füllner et al 2012). Specific considerations on these issues are given in sections 4D,F,G.…”