Correlation between the soil seed bank and weed populations in maize fields

Abstract

Annual weed populations establish every year from persistent seed banks in the soil. This 3 year study investigated the relationship between the number of weed seeds in the soil seed bank and the resultant populations of major broadleaf and grass weeds in 30 maize fields. After planting the crop, 1 m 2 areas were protected from the pre-emergence herbicide application. Soil samples were collected soon after spraying to a depth of 100 mm and the weed seeds therein were enumerated. The emerged weed seedlings in the field sampling areas were counted over the following 8 weeks. Up to 67 broadleaf species and five grass weeds were identified, although not all were found at every site and some were specific to a region or soil type. For the most abundant weeds in the field plots, on average 2.1-8.2% of the seeds of the broadleaf species and 6.2-11.9% of the seeds of the grass weeds in the soil seed bank emerged in any one year, depending on the species. Overall, the results showed a strong linear relationship between the seed numbers in the soil and the seedling numbers in the field for all the grasses and for most broadleaf weeds. For some species, like Trifolium repens, only a weak relationship was observed. In the case of Chenopodium album, which had the largest seed bank, there was evidence of asymptotic behavior, with seedling emergence leveling off at high seed numbers. An estimate of the soil seed bank combined with knowledge of the germination and behavior of specific weed species would thus have good potential for predicting future weed infestations in maize fields.Keywords: broadleaf weeds, grass weeds, maize, soil seed bank, weed emergence, weed seed bank.The weed seed bank as a reservoir of weed seeds in the soil largely determines the potential density and species composition of weeds that subsequently interfere with crops during the growing season (Forcella 1993). In this respect, an estimate of the seedbank population in the soil, combined with knowledge of the germination and behavior of specific weed species, presents practical opportunities to develop integrated and environmentally sound weed management programs. Some bioeconomic weed management models now use seedbank estimates to predict weed population dynamics and competitiveness (Lybecker et al. 1991). Grundy (2003) has recently reviewed the current state of research using the methodologies presently available to predict weed emergence.The likely density and composition of weed plants arising after cultivation could, in most instances, be deter-

Characteristics and control of dicamba‐resistant common lambsquarters (Chenopodium album)

“…All the samples were air‐dried and then the viable common lambsquarters seeds were counted by both the seed extraction and seedling emergence methods (Rahman et al . ). The seed viability was determined by crushing the seeds and only those containing undecayed endosperm were recorded as potentially viable (Sawma & Mohler ).…”

Diversity in weed seed production and the soil seed bank: Contrasting responses between two agroecosystems

“…) and there are fewer reports in relation to tropical countries (Rahman et al . 1998; 2006). In the Indian tropical region, few authors have paid attention to the weed flora and soil seed bank of agroecosystems (Saxena & Ramakrishnan ; Tripathi & Yadav ; Misra et al .…”

Cover crops and compost prevent weed seed bank buildup in herbicide‐free wheat–potato rotations under conservation tillage

“…The weed seed banks up to 15 cm depth generally correlate with the aboveground weed community (Dessaint et al, 1997;Rahman, James, & Grbavac, 2006) and can therefore be used to assess the efficiency of weed management systems. However, in the short term, specific crop management strategies, such as cover cropping, can lead to lower weed biomass than in systems without cover crops despite initially larger weed seed banks (Moonen & Bàrberi, 2004).…”