Abstract
ABSTRACT: Knowledge on weed biology and ecology is fundamental to provide suitable control practices in weed management systems. The objective of this research was to understand the effect of light and temperature on germination of Chamaesyce hirta, as well as to evaluate the effect of depth of seed placement in the soil in the emergence of the plant. Two experiments were conducted. In the first one, in the laboratory, the seeds were placed to germinate in plastic boxes and kept in a B.O.D. germination chamber, under constant temperatures of 20, 25, 30 and 35 ºC, either in the dark or under continuous light. Daily germination assessments were performed. The percentage of germinated seeds in the 10-day period and the germination speed index (GSI) were calculated. In the second trial, carried out in greenhouse conditions, 100 seeds were planted, under six levels of seeding depth (0, 1, 2, 3, 4 and 5 cm) and three soil cover conditions: no straw, under black oats (Avena strigosa) straw and under corn (Zea mays) straw. Daily plant emergence was counted along 30 days and total emergence and GSI were calculated. Germination of C. hirta seeds occurs both in the presence and absence of light. For the highest temperature, both increased germination and GSI were reported in the presence of light. The highest levels of emergence were obtained with the absence of plant cover and under corn straw at 0 cm depth. The presence of black oat straw on the soil reduced the emergence of C. hirta.
Highlights
The lack of knowledge about the biology and ecology of weeds is one of the biggest limitations for the development of management strategies (YAMASHITA et al, 2008)
The weed emergence flow is influenced by edaphoclimatic conditions, soil management and herbicide application, varying according to species, seed response patterns in relation to interference from environmental factors and cultural practices (ZANDONA et al, 2018)
It can be said that soil temperature, light, water and air composition with oxygen and carbon dioxide are fundamental to the seed germination and seedling emergence processes (CALADO et al, 2011)
Summary
The lack of knowledge about the biology and ecology of weeds is one of the biggest limitations for the development of management strategies (YAMASHITA et al, 2008). The knowledge of aspects related to the germination of these plants, such as temperature, light, causes of dormancy and maximum depth that allows the emergence can be fundamental for the application of viable management systems. The weed emergence flow is influenced by edaphoclimatic conditions, soil management and herbicide application, varying according to species, seed response patterns in relation to interference from environmental factors and cultural practices (ZANDONA et al, 2018). It can be said that soil temperature, light, water and air composition with oxygen and carbon dioxide are fundamental to the seed germination and seedling emergence processes (CALADO et al, 2011). Germination is controlled by the interaction of environmental conditions and the physiological state of the seeds. Each plant species requires an ideal temperature for germination, and Approved 01.28.21 Returned CR-2020-0764.R1 by the author
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