Temperature Effects on Vegetative Growth of Round-Leaved Mallow (Malva pusilla)

Abstract

Vegetative growth response of round-leaved mallow to various day/night temperature regimes was studied under controlled-environment conditions to predict its potential geographic distribution and to develop an effective control program. Round-leaved mallow dry matter production was greatest with day temperatures of 18 to 26 C. Dry matter accumulation was reduced by a night temperature of 6 C but was minimally affected by night temperatures ranging from 12 to 24 C. Regression analysis predicted minimal vegetative growth at mean daily temperatures below 8 C and above 30 C, with optimum growth at 20 C. Partitioning of round-leaved mallow biomass in leaves, stems, and roots was affected by temperature. Maximum leaf weight ratio occurred at low temperatures, 10 C day and 6 C night. Stem weight ratio was greatest at a day temperature of 26 C, with night temperature having little effect. Maximum root biomass occurred with a day temperature of 18 C. Results are discussed in terms of environmental conditions that allow round-leaved mallow to be an effective competitor with crops and potential approaches for its control.