Occurrence of nutrients and plant hormones (cytokinins and IAA) in the water fern Salvinia molesta during growth and composting

Abstract

The aquatic fern Salvinia molesta is classified as an invasive, noxious weed in southern Africa. It has rapid growth and forms a thick mat in slow moving water bodies. It is hypothesized that S. molesta is a suitable candidate to promote as an organic fertilizer. The aims of this study were to determine the mineral content as well as the cytokinin and auxin content in S. molesta. The release of these compounds into the culture medium and upon decomposition of the air-dried plant matter was also determined. Minerals detected in the fresh plant material were N > K > P > Ca > Mg > Fe > Na > Cu > Zn while Cd, Pb and Ni were below the level of detection. The mineral concentrations changed after 14 days decomposition with there being an increase in Ca, Mg and Fe and a decrease in K. Sixteen isoprenoid cytokinins were detected in the plant material (total concentration 81.62 pmol g −1 DW) while only four cytokinins occurred at a greatly reduced concentration in the culture medium (4.31 pmol 500 ml −1 medium). The material that had been composted for 14 days showed a 17% reduction in cytokinin concentration (67.96 pmol g −1 DW) compared to the plant material. Run-off, termed leachate, collected during the composting experiment also had high amounts of cytokinin-like activity measured using the soybean callus bioassay. This activity peaked on day 7 of the composting experiment, indicating a rapid release of cytokinin-like compounds. IAA occurred in much higher concentrations than the cytokinins in the plant material (393.6 pmol g −1 DW) while very little IAA was detected in the culture medium (30.8 pmol g −1 DW). IAA concentrations were much lower in the composted material (148.1 pmol g −1 DW) with a 62% loss being recorded compared to the plant material. No auxin-like activity was measured using the mungbean rooting bioassay in the leachate collected at the start of the composting experiment. However, the leachate collected on days 7 and 14 had biological activity indicating that auxin-like compounds were released from S. molesta upon decomposition.

Endogenous cytokinins, auxins and abscisic acid inUlva fasciata(Chlorophyta) andDictyota humifusa(Phaeophyta): towards understanding their biosynthesis and homoeostasis

“…Mitchell (82 pmol g À1 DW) using the same method (Arthur et al, 2007). However, these concentrations were between 2 and 10-fold lower than cytokinin concentrations found in germinating Tagetes minuta L. achenes (Stirk et al, 2005) and germinating Pisum sativum L. seeds (Stirk et al, 2008).…”

Effect of freshwater sapropel on plants in respect to its growth-affecting activity and cultivable microorganism content

“…In contrast, increase in accumulation of both fresh and dry matter in mineral-enriched sand-grown lettuce plants was due to the growth-promoting activity of BDA substitution or other positive physiological effects. Non-nutrient stimulation of plant growth by organic fertilizers is usually attributed to humic substances (Tomati et al, 1988) and plant hormones (Arthur et al, 2007). Sapropel is a rich source of both humic substances (Klavins et al, 2003) as well as plant hormones (Szajdak, Maryganova, 2007) most probably acting as a growth stimulants on lettuce plants in the present study.…”

“…As related to different (usually low) level of mineralization in sapropel samples (ranging from 10% to 75%), their use as fertilizers for short-term effects of plants seems problematic. However, organic fertilizers can have more specific effect on plants related to plant growth stimulation through action of hormone-like substances (Arthur et al, 2007). Therefore, possible plant growth-affecting activity due to the high content of humic substances in sapropels can be beneficial (Xu et al, 2012).…”

Classifying nuisance submerged vegetation depending on ecosystem services

“…Spencer et al 2006;Arthur et al 2007;Wu and Wu 2007;O'Sullivan et al 2010;Perna et al 2012). In contrast to submerged species, floating leaved species such as Eichhornia crassipes or Trapa natans, but also emergent species such as Ludwigia spp.…”