Seeds of the threatened dry rainforest tree Cadellia pentastylis (Surianaceae) are non-dormant

Cadellia pentastylis (Surianaceae) is an Australian endemic threatened rainforest tree. Irregular flowering and fruiting events coupled with high rates of infertility and insect predation has meant that seed testing has not been possible for this species. Seeds were opportunistically collected from a wild population in early 2021, which allowed for the first germination tests to be conducted. In this study, the presence of physical dormancy was examined by performing an imbibition test using scarified and non-scarified seeds. We also investigated whether a 5-min heat shock treatment at temperatures ranging from 60 to 120°C improved germination success. The presence of physiological dormancy was also examined by recording germination success following a gibberellic acid or smoke-water pre-treatment. Both scarified and non-scarified seeds readily imbibed water over a 72-h period, and several seeds had germinated in both treatments after 48 h. Final germination proportion and t50 following a heat shock, gibberellic acid or smoke-water pre-treatment did not significantly differ from the controls. We conclude that C. pentastylis seeds are non-dormant. Although a palisade cell layer has been reported in the endocarp, our results suggest that this layer may not be sufficiently formed to restrict germination. We recommend that seeds are collected from populations following dispersal and propagated shortly after or stored as conservation collections in ex situ Seedbanks.

Fire-Related Cues Significantly Promote Seed Germination of Some Salt-Tolerant Species from Non-Fire-Prone Saline-Alkaline Grasslands in Northeast China

Seed germination in response to fire-related cues has been widely studied in species from fire-prone ecosystems. However, the germination characteristics of species from non-fire-prone ecosystems, such as the saline-alkaline grassland, where fire occasionally occurs accidentally or is used as a management tool, have been less studied. Here, we investigate the effects of different types of fire cues (i.e., heat and smoke water) and their combined effect on the seed germination of 12 species from the saline-alkaline grassland. The results demonstrated that heat shock significantly increased the germination percentage of Suaeda glauca and Kochia scoparia var. sieversiana seeds. Smoke water significantly increased the germination percentage of Setaria viridis and K. scoparia seeds. However, compared with single fire cue treatments, the combined treatment neither promoted nor inhibited seed germination significantly in most species. These results suggest that fire cues can be used as germination enhancement tools for vegetation restoration and biodiversity protection of the saline-alkaline grassland.

Vermicompost Leachate, Seaweed Extract and Smoke-Water Alleviate Drought Stress in Cowpea By Influencing Phytochemicals, Compatible Solutes and Photosynthetic Pigments

Drought is a major constraint for agricultural production worldwide and is likely to become aggravated by global warming. It can induce land degradation, exorbitant food prices and menace livelihoods. Approaches for retaining optimal yield, especially in rainfed staple crops such as cowpea (Vigna unguiculata) are paramount. Biostimulants; vermicompost leachate (VCL), seaweed extract [Kelpak® (KEL)] and smoke-water (SW) have exhibited effective amelioration for plants under abiotic stresses, however, research on cowpea remains scarce. Therefore, this study aimed to investigate the effects of seed priming of cowpea with VCL, KEL and SW on the growth, photosynthesis and biochemical levels in cowpea cultivated under three watering regimes. SW treatment amplified growth variables (i.e., foliage, shoot height, root length and number of flowers) of water-stressed cowpeas. KEL- and VCL-treated seeds significantly augmented shoot and nodules production by 2 and 4-fold respectively, compared to the control. Leaf carbohydrates and photosynthetic pigments in KEL- and SW-treated plants increased considerably under severe water deficits, while leaf proteins decreased by more than 3-fold. The biostimulants also lowered phenolic and flavonoid concentrations. Increasing and decreasing levels of soluble sugars, proteins, photosynthetic pigments, phenolics and flavonoids indicate stress alleviation and osmotic adjustment to water deficits. These biostimulants are a suitable alternative to improve soil fertility, growth, and yield of staple crops under water stress conditions.

Smoke-water and smoke-isolated butenolide (KAR1) induce the biosynthesis of tanshinones in endophytic fungus Trichoderma atroviride D16 isolated from Salvia miltiorrhiza

Although treatments of smoke-water (SW) have been successfully used for promoting seed germination as well as plant growth, less reports have been documented on the influence of SW on the production of secondary metabolites in endophytes isolated from medicinal plants. The study investigated the effects of SW and its active compound butenolide (KAR1) on the accumulation of lipophilic tanshinones in endophyte Trichoderma atroviride D16 isolated from Salvia miltiorrhiza. Results showed that the mycelia of T. atroviride D16 treated with SW and KAR1 displayed a significant increase (P < 0.05) in the content of tanshinone I, which was evaluated with 2.26-fold (SW) and 1.86-fold (KAR1) of the control on 20 d after treatment. Comparing with the control, the treatment of SW and KAR1 resulted in a significant increase in the content of tanshinone IIA, and the highest levels were observed to be 31.87% (SW 1:2000, v/v) and 17.77% (KAR1 at 10-9 M) on 20 d after treatment. These findings imply the possibility of using SW and KAR1 for enhancing the biosynthesis of tanshinones in T. atroviride D16, and enrich the application of smoke water in the medicinal plant field.