Effect of temperature on the growth, reproduction, and germination pattern of two populations of Chloris virgata

Abstract

A holistic knowledge about the growth of weed species (i.e., from germination to seed production) in response to environmental factors (e.g., temperature, sunlight, moisture, etc.) is of utmost importance to understand the intensity of infestation, especially for Chloris virgata which demonstrates year-round germinability. An experiment in naturally lit greenhouse was conducted to assess the vegetative and reproductive growth of two C. virgata populations [FTR3 (glyphosate-susceptible, GS) and FTR11 (glyphosate-resistant, GR)] at two alternating temperature regimes: 25/15°C, low temperature and 35/25°C, high temperature. The average seed production of both populations was about 78% higher (12635 seeds/plants) at 25/15°C than at 35/25°C (7117 seeds/plants), indicating that late-winter/early-summer maturing cohorts will produce more seeds compared to the cohorts that mature in mid/late summer. The germination pattern of FTR3 and FTR11 maturing at two alternating temperature regimes (25/15°C and 35/25°C) was evaluated in an incubator calibrated to deliver 30/20°C with a 12 h/ 12 h photoperiod. The seeds collected from FTR3 and FTR11, which completed the lifecycle at 35/25°C, released dormancy faster than those matured at 25/15°C, suggesting the late-winter maturing flushes will have an extended germination period. In the light of climate change, these results could aid in designing sustainable integrated management programs to effectively manage this weed species in Australian farming systems.