Considerations for developing and implementing a safe list for alien taxa.

Many species have been intentionally introduced to new regions for their benefits. Some of these alien species cause damage, others do not (or at least have not yet). There are several approaches to address this problem: prohibit taxa that will cause damage, try to limit damages while preserving benefits, or promote taxa that are safe. In the present article, we unpack the safe list approach, which we define as "a list of taxa alien to the region of interest that are considered of sufficiently low risk of invasion and impact that the taxa can be widely used without concerns of negative impacts." We discuss the potential use of safe lists in the management of biological invasions; disentangle aspects related to the purpose, development, implementation, and impact of safe lists; and provide guidance for those considering to develop and implement such lists.

Micronutrient seed priming improves maize (Zea mays) early seedling growth in a micronutrient deficient soil.

Micronutrient deficiency is a major constraint to crop productivity in South Africa. Agronomic interventions such as nutrient seed priming (NSP) could significantly improve stand establishment in micronutrient deficient soils. However, the effectiveness of the technique depends on the efficacy of the priming procedures. Laboratory and glasshouse studies were carried out to determine the effects of NSP concentration of Zn, B and Mo and priming duration on maize germination and seedling emergence and early growth in micronutrient deficient soils. Five concentrations: 0.01%, 0.05%, 0.1%, 0.5% and 0% (control) and three priming durations: 24 h, 12 h and 8 h were used for the laboratory experiment whilst the 0.5% concentration and 8 h duration were excluded in the glasshouse experiment. Seed priming duration and concentration levels and their interactions had significant (P < 0.05) effects on germination percentage (GP), germination rate (GR), the coefficient of velocity of germination (CVG), days to germination (DG) and mean germination time (MGT). These parameters were improved by priming at low concentration of the micronutrients for longer. Similarly, under glasshouse conditions, NSP at the lowest concentration but for the longest duration resulted in up to 50% earlier seedling emergence over the control. Priming with 0.01% Bo reduced the number of days to seedling emergence by 94%, increased fresh and dry seedling mass and chlorophyll content index by 29%, 47% and 58% respectively relative to the control. The earlier seedling emergence could have also contributed to superior fresh and dry seedling mass as well as both higher shoot and root mass over the control. Moreover, NSP enhanced chlorophyll content index, which could have ultimately led to better shoot growth. This suggests that with optimum micronutrients concentration levels and appropriate priming duration NSP can improve germination and seedling growth and hence maximization of the yield parameters.