Altered weed reproduction and maternal effects under low-nitrogen fertility

Abstract

The low-nitrogen status of highly weathered soils may offer a potential alternative for weed suppression in agricultural systems with N2-fixing crops. In this study, we used sicklepod as a model to evaluate weed response that might occur with managed reductions in nitrogen-soil fertility. A field study was conducted with the parental generation supplied 0, 112, 224, or 448 kg N ha−1. Decreased nitrogen fertility led to reduced shoot biomass, seed number, and total seed mass. Individual seed mass was lower, but seed % nitrogen was not affected. Analysis of seed-mass distribution confirmed that low parental fertility was associated with more small seeds as a proportion of total seeds produced. Additional experiments in hydroponics culture revealed slower growth rates of seedlings produced from small seeds when grown under low-nitrogen conditions. Competitiveness of plants from small (low nitrogen) and large (high nitrogen) seed classes was determined in a replacement-series experiment conducted in sand culture in a controlled environment at two densities and two levels of nitrogen nutrition. Plants produced from smaller seeds were less competitive in low-nitrogen fertility conditions, but plants from small and large seeds competed similarly when grown under high-nitrogen fertility. The results support the hypothesis that comprehensive management strategies to reduce nitrogen availability for weed growth in low-fertility conditions could decrease weed interference by decreasing growth and seed production of parental plants and through maternal effects that lower competitiveness of offspring.

Overcoming Weed Management Challenges in Cover Crop–Based Organic Rotational No-Till Soybean Production in the Eastern United States

“…The high biomass levels and residue quality (high C : N ratio, lignin, and hemicellulose content) of cereal rye results in very low inorganic N released to soil during residue decomposition and could contribute significantly to weed suppression by rye residue (Figure 1). Most nonleguminous weeds are highly responsive to N (Blackshaw et al 2004;Henson and Jordan 1982;Tungate et al 2006), and therefore manipulation of soil inorganic N levels could serve as a tactic for reducing weed competition in a cereal rye-mulched soybean cash crop. Frey et al (2000) demonstrated (via 15 N tracer) fungal mediated upward movement of soil N from below the soil surface into the rye mulch.…”

Acorn size is more important than nursery fertilization for outplanting performance of Quercus variabilis container seedlings

“…These differences have a strong phylogenetic basis but are also the result of opposing selective pressures related to dispersal mode, predation avoidance, and tree performance (Foster and Janson 1985;Venable and Brown 1988;Westoby et al 1992;Carlo and Yang 2011). Seed size determines short-term seedling survival and growth, especially under stress conditions such as deep shade (Ke and Werger 1999;Quero et al 2007), low soil fertility (Tungate et al 2006), and low water availability (Rice et al 1993;Ramírez-Valiente et al 2009).…”

Germination Ecology of Brachiaria eruciformis in Australia and Its Implications for Weed Management

“…For example, weeds maturing at the crop boundary seldom receive any tillage, fertilizer, or irrigation compared to those in crop fields. Such differences in management practices may select for changes in the germination characteristics of weed seeds [18][19][20][21] and need to be accounted for while making weed management decisions based on their germination ecology.…”