Relationship between Temperature and Heat Duration on Large Crabgrass (Digitaria sanguinalis), Virginia Buttonweed (Diodia virginiana), and Cock's-Comb Kyllinga (Kyllinga squamulata) Seed Mortality

Abstract

Thermal heat has been utilized for nonselective weed control methods. These methods are highly variable in application and efficacy. One effective weed–seed-control determining factor is achieving the thermal death point of targeted weed seeds. The thermal death point varies by weed species, temperature, and exposure time. Our objective was to determine the thermal death point of large crabgrass, cock's-comb kyllinga, and Virginia buttonweed at short thermal exposure periods. Studies conducted utilized 5 and 20 s exposure periods for incremental range, 60 to 250 C temperatures. Sigmoid regression curves were used to predict weed seed mortality by temperature and exposure time. A significant interaction between exposure period and temperature occurred for each weed species. Weed species increased in susceptibility to 20 s thermal heat as follows: Virginia buttonweed < cock's-comb kyllinga < large crabgrass. Increasing thermal exposure time from 5 to 20 s reduced thermal temperature by 21 C to achieve 50% mortality for large crabgrass and by 10 C for cock's-comb kyllinga. Virginia buttonweed achieved 50% mortality at 99 C for 5 and 20 s exposure periods. These data indicate that at least 50% weed seed mortality can be achieved at 99 and 103 C for 20 and 5 s exposure periods, respectively, for these weed species.

Abiotic Factors Affecting Seed Germination and Early Seedling Emergence of Large Crabgrass (Digitaria sanguinalis)

“…Mature seeds were gently shaken into a labeled envelope. The seeds were air dried for 7 d and then stored at 10 o C and 50% relative humidity (RH) prior to use (Hoyle and Scott McElroy, 2012). The 100-seed weight value was 52.20±0.99 mg.…”

“…Zhang et al (2011) studied the effect of salinity and temperature on the germination of Chloris virgata, and Digitaria sanguinali. Hoyle and Scott McElroy (2012) reported the relationship between temperature and heat duration on seed mortality of large crabgrass. However, other environmental factors such as light, pH, seed burial depth, and crop residue can also affect seed germination (Chachalis and Reddy, 2000;Koger and Reddy, 2004;Chauhan and Johnson, 2008;Chachalis et al, 2008;Wang et al, 2015;Fernando et al, 2016).…”

Assessment of the Weed Incidence and Weed Seed Bank of Crops Under Different Pedological Traits

“…The soil texture had the impact on weed seed distribution in different soil layers. In light-textured soil (I experiment) in the depth of 0-10 cm, the number of weed seeds was lower than in the depth of [10][11][12][13][14][15][16][17][18][19][20] Janicka (2006) indicate that the greatest seed reserves were in the surface layer of the soil (0-5 cm). Although, during the investigation, 41 weed species were found in crops and 35 species in the seed bank, only a few of species were spread.…”

“…Other researches suggests, that significant interactions occurred between weed species and soil texture, weed species and planting depth and soil texture and planting depth. For all weed species and soil textures, emergence decreased as planting depth increased with the greatest percent emergence at the soil surface (Hoyle et al, 2013).…”

Alkylresorcinol in Portulaca Oleracea (Purslane) Seeds as a New Source of Dietary Phenolic Lipid

“…Wild purslane is comprised of smooth and fleshy small leaves in alternate formation on a cylindrical stem contained close to the ground ( As one of the most prevalent weeds in the world, puslane is specifically deemed as a cosmopolitan weed characterized by its ability to withstand harsh climactic conditions in various regions . As such, purslane (PA) has been reported on individual counts as originating in South America, North Africa, Eastern Asia and Europe (Hoyle & Mcelroy, 2012).…”