Effects of Glyphosate Application on Physiologically Integrated Clones of the Invasive Plant Carpobrotus edulis

Management of invasive alien species is a high priority for biodiversity conservation. Here, we studied the effects of glyphosate application, at 0.06 g/m2 concentration, on physiologically integrated basal and apical ramets of the invasive clonal plant Carpobrotus edulis. Physiological integration allows the transport of resources and other substances between connected ramets in clonal plants. We found a significant reduction of growth and photochemical efficiency both in basal and apical ramets of C. edulis after glyphosate application. Interestingly, we also observed a significant growth reduction in untreated basal ramets when they remained connected to apical ramets treated with glyphosate. This result was interpreted as a cost for basal ramets due to supporting severely stressed apical ramets. Therefore, local application of glyphosate to apical ramets of C. edulis can negatively affect not only their own growth, but also the growth of their interconnected, untreated basal ramets. Our results suggest that glyphosate effectiveness can be maintained when applied only to one part of the clone so that the amount of herbicide used in eradication programs can be greatly reduced, which can minimize the negative impact of chemical herbicides on ecosystems.

Functional Ecology of Iceplant Taxa and Their Role in Eco-restoration of New Zealand Sand Dunes

<p>Biological invasion by non-native plant species has often been cited as a cause of native biodiversity loss. While the outcome of species invasions depends on interactions between exotic and resident native species, most studies of biological invasions have focused solely on the direct negative impacts of non-indigenous species on native biota. Although investigations of the role of competition in shaping natural plant communities were dominant in the previous generations and are still popular, more recent experimental research has uncovered the striking influence of facilitation on community dynamics. This thesis aims to investigate competitive and facilitative influence of the invasive South African iceplant (Carpobrotus edulis) on Spinifex sericeus, a native foredune grass species, with particular reference to implications of these interactions for dune restoration in New Zealand. It further explores the growth rates, substrate preferences and mating systems of the exotic and native iceplant taxa found in New Zealand. I begin by briefly outlining the influence of competition and facilitation on natural plant communities with reference to the role of facilitation in eco-restoration. I also give a few examples where exotic species have been found to facilitate native ones. Secondly, a neighbour removal experiment was conducted on coastal sand dunes with the main aim of studying the effects of Carpobrotus edulis on establishment of Spinifex sericeus at the foredune region. Finally, I compared the growth rates of the most widely distributed iceplant taxa in New Zealand in different substrates and the breeding systems of the exotic Carpobrotus. Examples abound in literature of exotic plant species facilitating native ones especially in forestry. In the neighbour removal study, Carpobrotus edulis protected Spinifex seedlings against storm erosion, sandblasting and salt sprays while at the same time suppressing its leaf production. Suppression of Spinifex leaf production was more pronounced at top of the dune where stress elements is presumably more benign. There was no evidence of allelopathic suppression of Spinifex by C. edulis. Only Carpobrotus chilensis displayed some level of substrate preference by putting on relatively lower biomass in gravel. The exotic Carpobrotus spp. put on greater dry matter content than the native Disphyma australe and the Carpobrotus-x-Disphyma hybrid. The hybrid displayed a faster vegetative growth rate whereas D. australe allocated relatively more biomass to the roots than the shoot. Both Carpobrotus spp. are self compatible and highly capable of intrageneric and intergeneric hybridisation. Mass removal of the existing exotic iceplant stands from foredunes along high energy coasts is not advisable as they serve as useful stabilisers. The intergeneric hybrid is sexually sterile with sparsely spread stolons that could allow co-occurrence with other species and therefore is more suitable for foredune stabilisation. However, more research needs to be conducted on the ecology of the intergeneric hybrid.</p>

Functional Ecology of Iceplant Taxa and Their Role in Eco-restoration of New Zealand Sand Dunes

<p>Biological invasion by non-native plant species has often been cited as a cause of native biodiversity loss. While the outcome of species invasions depends on interactions between exotic and resident native species, most studies of biological invasions have focused solely on the direct negative impacts of non-indigenous species on native biota. Although investigations of the role of competition in shaping natural plant communities were dominant in the previous generations and are still popular, more recent experimental research has uncovered the striking influence of facilitation on community dynamics. This thesis aims to investigate competitive and facilitative influence of the invasive South African iceplant (Carpobrotus edulis) on Spinifex sericeus, a native foredune grass species, with particular reference to implications of these interactions for dune restoration in New Zealand. It further explores the growth rates, substrate preferences and mating systems of the exotic and native iceplant taxa found in New Zealand. I begin by briefly outlining the influence of competition and facilitation on natural plant communities with reference to the role of facilitation in eco-restoration. I also give a few examples where exotic species have been found to facilitate native ones. Secondly, a neighbour removal experiment was conducted on coastal sand dunes with the main aim of studying the effects of Carpobrotus edulis on establishment of Spinifex sericeus at the foredune region. Finally, I compared the growth rates of the most widely distributed iceplant taxa in New Zealand in different substrates and the breeding systems of the exotic Carpobrotus. Examples abound in literature of exotic plant species facilitating native ones especially in forestry. In the neighbour removal study, Carpobrotus edulis protected Spinifex seedlings against storm erosion, sandblasting and salt sprays while at the same time suppressing its leaf production. Suppression of Spinifex leaf production was more pronounced at top of the dune where stress elements is presumably more benign. There was no evidence of allelopathic suppression of Spinifex by C. edulis. Only Carpobrotus chilensis displayed some level of substrate preference by putting on relatively lower biomass in gravel. The exotic Carpobrotus spp. put on greater dry matter content than the native Disphyma australe and the Carpobrotus-x-Disphyma hybrid. The hybrid displayed a faster vegetative growth rate whereas D. australe allocated relatively more biomass to the roots than the shoot. Both Carpobrotus spp. are self compatible and highly capable of intrageneric and intergeneric hybridisation. Mass removal of the existing exotic iceplant stands from foredunes along high energy coasts is not advisable as they serve as useful stabilisers. The intergeneric hybrid is sexually sterile with sparsely spread stolons that could allow co-occurrence with other species and therefore is more suitable for foredune stabilisation. However, more research needs to be conducted on the ecology of the intergeneric hybrid.</p>

Evaluation of Growth Parameters on Carpobrotus edulis, Kalanchoe daigremontiana and Kalanchoe tubiflora in Relation to Different Seaweed Liquid Fertilizer (SLF) as a Biostimulant

The aim of this research was to evaluate the biofertilization capacity of five different species of algae, representative of the three main groups of macroalgae selected from Lake Ganzirri in Messina, Venice Lagoon and Norwegian coasts. The experiments, started in January 2021, were conducted in the greenhouses of CREA-OF in Pescia (Pt), Tuscany, Italy (43°54′N 10°41′E) on Carpobrotus edulis, Kalanchoe daigremontiana and Kalanchoe tubiflora from seed. The test showed a significant increase in the agronomic parameters analysed in plants treated with algae extracts on succulents cultivated. The test also showed increased control of the pathogen Pythium debaryanum in seedlings where the algae extracts were introduced and also an increase in the percentage of seed germination and a reduction in the average germination time. This research work has shown that algal species have great potential for use in the development of biofertilisers in sustainable agriculture in terms of cost-effectiveness, ecological role, possible reduction of synthetic fertilisers and plant protection products, increased soil fertility and microbiological diversity.

Therapeutic Role of Leaf Pulp of Carpobrotus edulis on Chromium VI Induced Toxicity in Wistar Rats

The leaf pulp of Carpobrotus edulis has antibacterial, antifungal, and tissue regeneration abilities. Chromium is a ubiquitous contaminant that has raised a major concern due to its level of toxicity. This study investigated the therapeutic role of leaf pulp of Carpobrotus edulis on chromium VI-induced toxicity in male Wistar rats. Thirty rats were divided into five groups of six rats, each comprising group 1 (control group), given 0.5 mL of de-ionized water. Group 2 was pre-treated with 0.5 mL of the leaf pulp for seven consecutive days, and afterward, 5 mg/kg potassium dichromate (K2Cr2O7) was administered for another seven days. Group 3 was given 5 mg/kg K2Cr2O7 for seven days and 0.5 mL of the leaf pulp after that. Group 4 was given only 5 mg/kg K2Cr2O7 for 7 days, and group 5 was treated with 0.5 mL of the plant leaf pulp for 14 days. The rats were sacrificed under mild diethyl ether anesthesia twenty-four hours after the last treatment. The blood, liver, and kidney were collected and used for hematological, biochemical, and morphological analyses. Significant increases (p<0.05) were observed in WBC, NEUT, and MON while significant decreases were observed in RBC, PCV, and hemoglobin in group 4 compared to the control. In the pre-treated (group 2) and the therapeutic (group 3) groups administered leaf pulp of Carpobrotus edulis, the hematological parameters were increased compared to the control. The levels of MDA, SOD, GST, and catalase in the liver and kidney were significantly (p<0.05) depleted in group 4 when compared to control, whereas these parameters were significantly (p<0.05) elevated in the group treated with the leaf pulp only. The levels of AST, ALT, and ALP showed a significant (p<0.05) decrease in group 4 when compared to the control; however, no significant (p<0.05) change was observed in all the other groups. There was a significant increase (p<0.05) in the urea level in group 4, while creatinine level showed no significant change. Other biochemical parameters such as LDL, TRIG, Total and direct bilirubin showed no significant change in group 4 compared to the control. Similarly, there was no significant change in the electrolyte parameters. There was a significant decrease in HDL and CHOL levels in group 2 when compared to the control. Summarily, the leaf pulp of C. edulis appears to reverse the toxicity caused by chromium VI probably through its antioxidative effects and its ameliorative effect on the liver and kidney functions. This may partly justify the folkloric use of the leaf juice of the plant.