More MEJA MOJO Study study
Jasmonic acid (JA) is regarded as endogenous regulator that plays important roles in regulating stress responses, plant growth, and development. Salicylic acid (SA) has been identified as an important signaling element involved in establishing the local and systemic disease resistance response of plants after pathogen attack. A field experiment was conducted to assess the foliar applications effect of JA and SA on quantity and quality yields of essential oil of lemon balm (
Melissa officinalis L.). Experimental treatments were:
I) water foliar application;
II) water + 1% ethanol foliar application (as a solvent);
III-V)
JA at 0.05–0.40 mg L−1; VI-IX) SA at 0.14–14.00 g L−1. notice micro-dosing
n the present research the effect of preharvest metyil jasmonate (MeJA) treatment on the ripening process and fruit quality parameters at harvest was evaluated, for the first time, in two table grape cultivars, ‘Magenta’ and ‘Crimson’, during two years, 2016 and 2017. MeJA treatments (applied when berry volume was ca. 40% of its final one, at veraison and 3 days before the first harvest date) affected grape ripening process and vine yield differently depending on applied concentration. Thus,
MeJA at 5 and 10 mM delayed berry ripening and decreased berry weight and volume as well as vine yield, in a dose-dependent way, in both cultivars, although the effect on ‘Crimson’ was more dramatic than in ‘Magenta’. However, treatments with MeJA at 1, 0.1 and 0.01 mM accelerated ripening and increased total phenolics and individual anthocyanin concentrations, the major effects being obtained with 0.1 mM concentration. In addition, total soluble solids (TSS) and firmness levels were also increased by these MeJA treatments.
These results might have a great agronomic and commercial importance since fruit with higher size and harvested earlier would reach higher prizes at markets and berries with higher firmness and TSS would be more appreciated by consumers. Moreover, MeJA treatments increased the content of antioxidant compounds, such as phenolics and individual anthocyanins, leading to enhance the homogeneous pigmentation of the whole cluster, with additional effects on increasing the health beneficial effects of grape consumption.
Another case of less does more? And the timing of foliar treatments.
Two plum (
Prunus salicina Lindl.) cultivars ‘Black Splendor’ (BS) and ‘Royal Rosa’ (RR) were treated with methyl jasmonate (MeJA) at 3 concentrations
(0.5, 1.0 and 2.0 mM) along the on-tree fruit development: 63, 77 and 98 days after full blossom (DAFB). On a weekly basis, fruit samples were taken for measuring fruit size and weight and parameters related to quality.
Results revealed that MeJA was effective in increasing fruit size and weight, the 0.5 mM being the most effective for BS cultivar and 2.0 mM for RR. At harvest, those fruit treated with 0.5 mM MeJA had the highest firmness and colour Hue values.
notice different strains different results
Glutathione is a tripeptide involved in diverse aspects of plant metabolism. We investigated how the reduced form of glutathione, GSH, applied site-specifically to plants, affects zinc (Zn) distribution and behavior in oilseed rape plants (
Brassica napus) cultured hydroponically. Foliar-applied GSH significantly increased the Zn content in shoots and the root-to-shoot Zn translocation ratio; furthermore, this treatment raised the Zn concentration in the cytosol of root cells and substantially enhanced Zn xylem loading
. Notably, microarray analysis revealed that the gene encoding pectin methylesterase was upregulated in roots following foliar GSH treatment. We conclude that certain physiological signals triggered in response to foliar-applied GSH were transported via sieve tubes and functioned in root cells, which, in turn, increased Zn availability in roots by releasing Zn from their cell wall. Consequently, root-to-shoot translocation of Zn was activated and Zn accumulation in the shoot was markedly increased.
Can foliar spray encourage other root to shoot translocation?
Long-distance water transport in plants relies on negative pressures established in continuous water columns in xylem conduits. Water under tension is in a metastable state and is prone to cavitation and embolism, which leads to loss of hydraulic conductance, reduced productivity and eventually plant death. Experimental evidence suggests that plants can repair embolized xylem by pushing water from living vessel-associated cells into the gas-filled conduit lumina. Most surprisingly, embolism refilling is known to occur even when the bulk of still functioning xylem is under tension, a finding that is in seemingly contradiction to basic principles of thermodynamics. This review summarizes our current understanding of xylem refilling processes and speculates that embolism repair under tension can be envisioned as a particular case of phloem unloading, as suggested by several events and components of embolism repair, typically involved in phloem unloading mechanisms. Far from being a challenge to irreversible thermodynamics, embolism refilling is emerging as a finely regulated vital process essential for plant functioning under different environmental stresses.
Transport of atrazine (ATR), 2,4-dinitrotoluene (DNT), and 1,2,3-trichlorobenzene (TCB) from roots to shoots via xylem of wheat and tomato seedlings was measured following a 24-h exposure of plant roots to hydroponic solutions of these organic compounds. Transport of the compounds from roots to shoots reached equilibrium within 24 h, consistent with an earlier finding. Low concentrations of TCB were detected in the final external solution and the xylem efflux of control wheat seedlings. This suggested that there was a fast foliar uptake of TCB and its downward movement via phloem of the wheat seedlings. Concentrations of DNT, ATR, and TCB in xylem effluxes of wheat and tomato increased significantly with increases of their external concentrations. Stuff goes up fast.
The xylem is one of the two long distance transport tissues in plants, providing a low resistance pathway for water movement from roots to leaves. Its properties determine how much water can be transported and transpired and, at the same time, the plant's vulnerability to transport dysfunctions (the formation and propagation of emboli) associated to important stress factors, such as droughts and frost. Both maximum transport efficiency and safety against embolism have classically been attributed to the properties of individual conduits or of the pit membrane connecting them. But this approach overlooks the fact that the conduits of the xylem constitute a network. The topology of this network is likely to affect its overall transport properties, as well as the propagation of embolism through the xylem, since, according to the air-seeding hypothesis, drought-induced embolism propagates as a contact process (i.e., between neighbouring conduits). Here we present a model of the xylem that takes into account its system-level properties, including the connectivity of the xylem network. With the tools of graph theory and assuming steady state and Darcy's flow we calculated the hydraulic conductivity of idealized wood segments at different water potentials. A Monte Carlo approach was adopted, varying the anatomical and topological properties of the segments within biologically reasonable ranges, based on data available from the literature. Our results showed that maximum hydraulic conductivity and vulnerability to embolism increase with the connectivity of the xylem network. This can be explained by the fact that connectivity determines the fraction of all the potential paths or conduits actually available for water transport and spread of embolism. It is concluded that the xylem can no longer be interpreted as the mere sum of its conduits, because the spatial arrangement of those conduits in the xylem network influences the main functional properties of this tissue. This brings new arguments into the long-standing discussion on the efficiency vs. safety trade-off in the plants’ xylem.