Abstract
The Echinochloa genus contains two of the world's top five worst weeds. The persistence and weediness of Echinochloa spp. are partly due to its seed longevity and variable seed dormancy. In the USA, specifically in Arkansas, multiple species infest the same field in many cases. Persistence could vary across species and dormancy affects infestation level. Studies were conducted to evaluate the seed production potential and dormancy of Echinochloa species in the State. Ninety-four accessions were characterized in a common garden in Fayetteville, Arkansas, USA. The species were Echinochloa colona (L.) Link, E. crus-galli (L.) P. Beauv, E. muricata P. Beauv and E. walteri (Pursh). Only one accession was identified as E. walteri and was excluded from data analysis. Seeds were after-ripened for 6 months at room temperature and germinated at 32°C day/23°C night with 12-h daylength. Germination was monitored for 14 d. The Echinochloa species in Arkansas were predominantly E. colona (78%). E. colona had the highest seed production and the lowest seed dormancy among species. Dormancy within each species varied greatly, especially for E. colona, with a germination capacity (GC) of 41–99%. Only 2.7% of 73 E. colona accessions were dormant. E. crus-galli had 56–79% GC; 33% of the accessions were dormant. E. muricata had 2–39% germination, with all accessions considered dormant. E. colona had the highest fecundity, with 72,973 seeds per plant. This was 2.3- and 2.6x higher than that of E. crus-galli and E. muricata, respectively. High seed production and high germination capacity must have contributed to the dominance of E. colona among other Echinochloa species. E. muricata is expected to persist longer in the soil seedbank compared to E. colona and E. crus-galli. Seed production, dormancy and longevity will affect interspecies population dynamics in response to management tactics.
Highlights
Echinochloa species are the most problematic weed in rice fields, with E. crus-galli and E. colona recorded among the ten most common weeds in vegetable farms, rice (Oryza sativa L.), and upland row crops in Arkansas including cotton (Gossypium hirsutum L.), sugarcane (Saccharum offcinarum L.), sorghum (Sorghum bicolor L.), peanut (Arachis hypogea L.) and cassava (Manihot esculenta Crantz) (Holm et al, 1991, Dowler, 1995; Ciocarlan, 2000; Norsworthy et al, 2013)
Few studies have been conducted on the germination behavior of E. colona (Chun and Moody, 1987; Lin and Kuo, 1996; Kovach et al, 2010); one study was conducted on E. walteri; and none on E. muricata
E. colona produced the highest amount of seed (539 seeds panicle−1) and E. muricata produced the lowest (259 seeds panicle−1) (Table 1)
Summary
Echinochloa species are the most problematic weed in rice fields, with E. crus-galli and E. colona recorded among the ten most common weeds in vegetable farms, rice (Oryza sativa L.), and upland row crops in Arkansas including cotton (Gossypium hirsutum L.), sugarcane (Saccharum offcinarum L.), sorghum (Sorghum bicolor L.), peanut (Arachis hypogea L.) and cassava (Manihot esculenta Crantz) (Holm et al, 1991, Dowler, 1995; Ciocarlan, 2000; Norsworthy et al, 2013). Echinochloa Fecundity and Dormancy species are major global weeds in rice. It is important agronomically and economically to study the characteristics of these species under similar growing conditions since weedy Echinochloa can invade and dominate a crop field after only one season and cause significant yield losses (RuizSantaella et al, 2006). E. crus-galli can produce up to 1,000,000 seeds plant−1 contingent upon environmental conditions. Understanding the abundance and distribution of E. colona, E. muricata, and E. crus-galli, requires good comprehension of the dormancy behavior of these species (Bryson and Reddy, 2012). This knowledge informs long-term weed management strategies
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