The Application of a Commercially Available Citrus-Based Extract Mitigates Moderate NaCl-Stress in Arabidopsis thaliana Plants

Relationship between the roots of Hippophae rhamnoides at different stump heights and the root microenvironment in feldspathic sandstone areas

Background

To solve the withering of Hippophae rhamnoides plantation in the feldspathic sandstone areas of Inner Mongolia and to promote the regeneration, rejuvenation, and sustainability of H. rhamnoides forests.

Methods

We stumped aging H. rhamnoides trees at the ground heights of 0, 10, 15, and 20 cm (S1, S2, S3, and S4, respectively) and utilized unstumped trees as the control (CK). We then analyzed the effects of the different stump heights on the roots and the root microenvironment of H. rhamnoides and the relationship between the roots and the root microenvironment in the stumped H. rhamnoides.

Results

The root fractal features, root branching rate, root length, root soluble proteins, soil moisture content, and soil nutrients among the different treatments were ranked as S3>S2>S1>S4>CK (P < 0.05). The root topological index, root proline, and malondialdehyde among the different treatments were ranked as S3<S2<S1<S4<CK (P < 0.05). The topological indices of S1, S2, S3, S4, and CK were 0.80, 0.86, 0.89, 0.94, and 0.98, respectively, and all were near 1. This result indicated a typical fishtail-shaped branching structure. The root length and root fractal dimensions were primarily affected by the positive correlation of the soil moisture content and the soil organic matter, and the root topological index was primarily affected by the negative correlation of the root proline. Root nutrients were dominant in the changes in the root architecture, while soil moisture and nutrients played supporting roles. These results indicated that stumping can promote plant root growth and root nutrient accumulation, thereby improving soil moisture and the soil nutrient distribution, and the S3 treatment had the greatest impact on the H. rhamnoides roots and root microenvironment. Therefore, the 15 cm stump height treatment should be implemented for withering H. rhamnoides in feldspathic sandstone areas to promote vegetation restoration.

Flavonoids and Devosia sp SL43 cell-free supernatant increase early plant growth under salt stress and optimal growth conditions

Salt stress is a major threat to modern agriculture, significantly affecting plant growth and yield, and causing substantial economic losses. At this crucial time of increasing climate change conditions, soil salinity will continue to develop and become an even more serious challenge to crop agriculture. Hence, there is a pressing need for sustainable techniques in agricultural production that could meet the dual challenges of crop productivity and environmental instability. The use of biostimulants in agricultural production has greatly influenced plant health and global food production. In particular, the application of bioactive materials produced by beneficial microbes is becoming a common practice in agriculture and provides numerous benefits to plant growth and resistance to stressful conditions. In this research two biostimulants; a type of plant secondary metabolite (flavonoids) and a microbe-based material (CFS: Cell-Free Supernatant) containing active compounds secreted by a novel bacterial strain isolated from Amphecarpaea bracteata root nodules (Devosia sp - SL43), have been utilized to improve the growth and stress resistance of two major oil seed crops; canola and soybean, under optimal and salt stress conditions. Our findings suggested significant improvements in crop growth of canola and soybean following the application of both biostimulants. Under optimal growth conditions, soybean growth was significantly affected by foliar spray of flavonoids with increases in shoot fresh and dry weight, and leaf area, by 91, 99.5, and 73%, respectively. However, soybean growth was unaffected by flavonoids under salt stress. In contrast, CFS with a meaningful capacity to mitigate the negative effects of salinity stress improved soybean shoot fresh biomass, dry biomass, and leaf area by 128, 163 and 194%, respectively, under salt stress conditions. Canola was less responsive to both biostimulants, except for canola root variables which were substantially improved by flavonoid spray. Since this was the first assessment of these materials as foliar sprays, we strongly encourage further experimentation to confirm the findings reported here and to determine the full range of applicability of each of these potential technologies.

Foliar spray of commercial seaweed and amino acid-derived biostimulants promoted phytoremediation potential and salinity stress tolerance in halophytic grass, Puccinellia distans

Plants pretreatment with various chemicals has often been used to diminish salinity stress impact on plants. An experiment was carried out to determine the effect of foliar spray of two commercially available biostimulants (Algabon® [0.5 g/l] and Bonamid® [2 g/l]) on the growth and tolerance of halophytic grass, Pucccinellia distans under non-salinity condition (NSC) and salinity condition (SC). The greenhouse experiment was set up in a completely randomized design with three treatments repeated three times. Our results showed that biomass, leaf relative water content, chlorophyll content, K+ content, K+/Na+ ratio, and protein and N contents were all negatively affected by 300 mM NaCl. The results obtained in the present study showed the beneficial effects of the pretreatments of two biostimulants on P. distans seedlings under non-salinity stress conditions with respect to increasing plant biomass, photosynthetic pigments, K+ content, the content of proteins, and nitrogen percentage. The results suggested that foliar spray of Bonamid® could partly diminish NaCl-caused stress on P. distans seedlings, probably due to higher accumulation of shoot biomass, photosynthetic pigments, K+/Na+ ratio, protein and N contents, phytoremediation potential, as well as upregulation of Na+/H+ antiporters located in plasma membranes and vacuoles. The highest phytoremediation potential (PP) of shoots and total biomass was detected in the plants sprayed with Bonamid® by 50.8 and 42.7% respectively, relative to that in salinity-stressed control plants. Interestingly, foliar spray with two biostimulants decreased osmoprotectants and antioxidant compounds content of shoots under salinity stress conditions. Collectively, it could be concluded that a noticeable feature of pretreatment of P. distans seedlings with Algabon® and Bonamid® is the increase in growth under NSC, whereas under SC only pretreated plants with amino acid-derived biostimulant (Bonamid®) can (partly) diminish the NaCl-induced deleterious effects in P. distans seedlings through the compartmentalization of salts in vacuoles (by upregulation of Na+/H+ antiporters).

Towards a Better Understanding of the Potential Benefits of Seaweed Based Biostimulants in Vitis vinifera L. Cultivars

Globally, 7.4 million hectares of arable land is planted with grapevine with a farm gate value of $68.3 billion. The production of grapes faces growing pressure associated with challenges such as climate change, diminishing resources as well as the overuse of chemical fertilizers and synthetic pesticides, which have an impact on sustainability. Consequently, viticulture has over the years embraced and implemented various practices such integrated pest management, organic and biodynamic farming to curb the high chemical inputs typically used in conventional farming. Biostimulants and biofertilizers are considered environmentally friendly and cost-effective alternatives to synthetic fertilizers and plant growth regulators. Seaweed is of particular interest because of its availability globally. It was reported that brown seaweed (Ascophyllum spp.) improves plant growth and agricultural productivity, hormonal signalling, and an improved secondary plant metabolism. It also provides an alternative to soil supplementation, avoiding some of the negative effects of fertilizers through the leaching of nutrients into groundwater sources. This review aims to provide a summary of the use of seaweed extracts in grape production and their influence on grapevine physiology and stress adaptation mechanisms.