Regulation Mechanism of Exogenous Brassinolide on Bulbil Formation and Development in Pinellia ternata

The bulbil is the propagative organ of the P. ternata, which has a great effect on the yield of P. ternata. It is well known that plant hormones play important roles in bulbil formation and development. However, there is not clear about brassinolide (BR) regulation on bulbil formation and development. In this study, we revealed the effects of BR and BR biosynthesis inhibitors (propiconazole, Pcz) application on the histological observation, starch and sucrose metabolism, photosynthesis pathway, and hormone signaling pathway of P. ternata. The results showed that BR treatment reduced starch catabolism to maltodextrin and maltose in bulbil by decreasing BAM and ISA genes expression and increased cellulose catabolism to D-glucose in bulbil by enhancing edg and BGL genes expression. BR treatment enhanced the photosynthetic pigment content and potential maximum photosynthetic capacity and improved the photoprotection ability of P. ternata by increasing the dissipation of excess light energy to heat, thus reduced the photodamage in the PSII center. BR treatment increased the GA and BR content in bulbil of P. ternata, and decreased the ABA content in bulbil of P. ternata. Pcz treatment increased the level of GA, SL, ABA, and IAA in bulbil of P. ternata. BR regulated the signal transduction of BR, IAA, and ABA to regulate the formation and development of bulbil in P. ternata. These results provide molecular insight into BR regulation on bulbil formation and development.

The Effect of The Herbicide of Glyphosate (Nphosphonomethyll Glycine) On Photosynthetic Pigments And Photosynthetic Activity of Basil (Ocimum Basilicum L.) By Laser-Induced Chlorophyll Fluorescence Spectroscopy

The aim of this study was to investigate the effect of short and long term exposure to N-(phosphonomethyl)glycine (glyphosate) on the photosynthetic activity of Ocimum basilicum L. (basil) plants. Photosynthetic pigment content, chlorophyll fluorescence, and laser-induced chlorophyll fluorescence spectra of basil plants treated for 30, 50, or 70 days with either 0,1, 2, or 3 ml/L (H2O) glyphosate were measured. The ratio of the two fluorescence intensity maxima was calculated by evaluating curve-fitted parameters. Findings revealed that after 30 days of treatment, 1 ml/l (H2O) of glyphosate stimulated, whereas 2 and 3 ml/l (H2O) of glyphosate inhibited, photosynthetic activity of basil plants. In contrast, all tested concentrations of glyphosate became inhibitory after 50 and 70 days of treatment. This study clearly showed that at high concentrations (> 1 ml/l (H2O)), glyphosate is highly toxic to basil. This finding may be helpful for determining the optimal dose of glyphosate in agricultural practices.

Optimizing Nitrogen Application in Root Vegetables from Their Growth, Biochemical and Antioxidant Response to Urea Fertilizer

Nitrogen is one of the most influencing inorganic nutrients for improved plant growth and yield in crops. However, excessive fertilizer application may have adverse impacts on the environment. Therefore, we strive to investigate in this work by examining the impact of different nitrogen (N) doses in the form of urea (46% N) on the growth, yield, photosynthetic pigment content, nitrate reductase activity, carbohydrate content, protein content, and antioxidant enzyme activity of the carrot and beetroot. A pot experiment was conducted under natural conditions with four nitrogen levels as basal treatment (Control = Nil N, U50 = 145.57 mg/kg N; U100 = 291.14 mg/kg N; U150 = 436.71 mg/kg N; U200 = 582.28 mg/kg N). Results found that U150 (436.71 mg/kg N) is the optimum N fertilizer dose at which significant (p ≤ 0.05) improvements in all the growth, yield and biochemical attributes of carrot and beetroot were observed. However, the further increment in N doses did not affect the observed parameters and, therefore, excessive N level was observed beyond U150 = 436.71 mg/kg N. The principal component analysis presented significant correlations among the various parameters observed. Two principal components account for a total of 98.86% variance (PC1 = 92.96%; PC2 = 5.90%) in carrot and 99.2% variance (PC1 = 92.64; PC = 6.56) in beetroot of the overall data variability in plants supplemented with different N treatments.

Correlation Among Phenotypic Parameters Related to the Growth and Photosynthesis of Strawberry (Fragaria × ananassa Duch.) Grown Under Various Light Intensity Conditions

The objective of this study was to investigate characteristics of phenotypic parameters such as physiology, yield, and fruit quality responses of strawberry (Fragaria × ananassa Duch.) to various light intensity conditions (VLICs), and to determine the correlations among these phenotypic parameters. Strawberry plants were cultivated in a smart greenhouse separated into four areas, three of which were completely shaded by curtains from 20:00 until 10:00 (3 hS), 12:00 (5 hS), and 14:00 (7 hS), respectively. The fourth area was a non-shaded control treatment (0 hS). The ambient light intensities during the experimental period for the 0, 3, 5, and 7 hS treatments were 1,285, 1,139, 770, and 364 mol⋅m–2, respectively. Strawberry plants grown under low light intensity conditions experienced decreases in photosynthetic rate, stomatal conductance, and sugar accumulation compared to the 0 hS. Petiole generation and fruit yield were also sharply decreased in proportion to the degree of decrease in light intensity. In contrast, photosynthetic pigment content was shown to increase under low light conditions. Organic acid contents (excluding acetic acid) and leaflet size did not change significantly under low light conditions compared to the 0 hS. Changes to light intensity are considered to induce changes to the phenotypic characteristics of strawberry plants to favor growth using the energy and carbon skeletons obtained through respiration and photosynthesis. In the 7 hS treatment, where light intensity was drastically reduced, NPQ, qP, and RFd values as chlorophyll a fluorescence parameters were significantly lowered, which could indicate their measurement as an important technique to check the stress response of plants grown in low light conditions.

Effects of copper and cadmium on physiology and antifouling defense of the marine macroalga Ulva reticulata

Heavy metals are major stressors for benthic macroalgal communities in marine ecosystems. In this study, the effects of copper and cadmium on some physiological parameters along with antifouling defense of the marine macroalga Ulva reticulata were assessed under laboratory conditions. Macroalgal samples were treated with three concentrations (1 mg l−1, 3 mg l−1 and 5 mg l−1) of copper and cadmium for 2 and 7 days. After treatment, algal samples were analyzed for chlorophyll-a, carotenoid, total polyphenol and total antioxidant capacity. Also, algal extracts were tested against biofilm-forming bacteria strains to understand differences in antifouling activity. The results indicated that exposure of U. reticulata to copper and cadmium, on the one hand, induced protective mechanisms such as total phenol production and antioxidant capacity against metal stress and, on the other hand, reduced photosynthesis. While the extract obtained from control algal samples showed a strong inhibitory effect on the growth of biofilm-forming bacteria, treatment with heavy metals resulted in reduced antibiofilm activity. In general, the results revealed that exposure of macroalgae to heavy metals can affect antifouling defense traits in addition to changes in photosynthetic pigment content.

Two-Species Forests at the Treeline of Siberian Mountains: An Ecophysiological Perspective under Climate Change

In an underexplored region of the East Sayan mountains, ecophysiological traits of two conifers, Pinus sibirica Du Tour and Abies sibírica Ledeb., have been studied. The goal was to predict which of the species co-dominating the same habitat is more vulnerable under prospective climate change. Along a transect from the treeline to the floodplain, photosynthetic pigment content and electron-transport rate (ETR) were measured in needles of neighboring trees of the species. From 570 to 1240 m a.s.l., P. sibirica does not suffer from stress factors during the growing season, while A. sibirica does. The latter is reflected in a decrease of pigment content and ETR with the increase of altitude. A stronger climate-change trend (probably to more dry and warm conditions) will likely favor the shift of P. sibirica upper in altitudes, and only under the pine shelter might the fir survive the changes.

Leaf Age-Dependent Effects of Boron Toxicity in Two Cucumis melo Varieties

Boron (B) is an essential nutrient for plant growth and development, exhibiting extremely narrow margins between deficiency and toxicity. B toxicity is devastating for productivity and apparent for a continuously increasing part of agricultural land, under the influence of on-going climate change. In this study, the effects of increased B supply (by using H3BO3) were addressed by examining critical physiological responses of young and mature leaves, which were devoid of toxicity symptoms, in two melon varieties (Armenian cucumbers, cantaloupes). B was primarily translocated through the transpiration stream, and secondarily via the active cell membrane transport system. The B distribution pattern was independent of leaf age, and remained rather unchanged under increased B supply. Armenian cucumbers, exhibiting higher leaf B levels, underwent an enhanced adverse impact on (root and shoot) growth, photosynthetic pigment content, cellular membrane integrity, and also exhibited attenuated antioxidant defense stimulation. Notably, and unlike other abiotic stressors, no evidence of B toxicity-induced systemic reaction was apparent. B toxicity greatly enhanced the transcription of the genes coding for borate influx and efflux channels, an effect that was mostly evident in mature leaves. In conclusion, shoot physiological responses to B toxicity are highly localized. Moreover, the obstruction of the diffusion and the B translocation to the aerial organs under increased B supply is genotype-dependent, governing plant physiological responses.

Facing metal stress by multiple strategies: morphophysiological responses of cardoon (Cynara cardunculus L.) grown in hydroponics

The contamination of environments by heavy metals has become an urgent issue causing undesirable accumulations and severe damages to agricultural crops, especially cadmium and lead which are among the most widespread and dangerous metal pollutants worldwide. The selection of proper species is a crucial step in many plant-based restoration approaches; therefore, the aim of the present work was to check for early morphophysiological responsive traits in three cultivars of Cynara cardunculus (Sardo, Siciliano, and Spagnolo), helping to select the best performing cultivar for phytoremediation. For all three tested cultivars, our results indicate that cardoon displays some morphophysiological traits to face Cd and Pb pollution, particularly at the root morphology level, element uptake ability, and photosynthetic pigment content. Other traits show instead a cultivar-specific behavior; in fact, stomata plasticity, photosynthetic pattern, and antioxidant power provide different responses, but only Spagnolo cv. achieves a successful strategy attaining a real resilience to metal stress. The capacity of Spagnolo plants to modify leaf structural and physiological traits under heavy metal contamination to maintain high photosynthetic efficiency should be considered an elective trait for its use in contaminated environments.

Effect of salicylic acid on some physiological indices of Chrysanthemum cv “mai vang” cut flowers

Chrysanthemum (Chrysanthemum sp.) has an important economic and medicinal value. This plant is the second most important cut flower produced in the world. Salicylic acid is a growth regulator with multifunction that is involved in plant physiology. In this works, the effect of salicylic acid at different concentrations (0.0; 0.25; 0.5; 0.75; 1.0; 1.5 and 2.0 mM, respectively) on physiological characteristics of Chrysanthemum "mai vang" cut flowers was investigated. Research results indicated that salicylic acid affected the content of photosynthetic pigments and chlorophyll fluorescence of leaves as well as anthocyanin content in the petals Chrysanthemum cv. “mai vang” cut flowers. Salicylic acid at concentrations of 0.25 - 0.5 mM increases the content of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids in leaf tissue at days 2 to 5 compared to day 1. The content of these photosynthetic pigments did not change through the experiments under influence of 0.75-1.0 mM salicylic acid. Meanwhile, salicylic acid at the concentration of 1.5 - 2.0 mM reduced photosynthetic pigment content at days 3 - 5 compared to day 1. A decrease of Fv\Fm value from day 1 to day 5 was observed in all experimental formula, the smallest reduction was found in the 0.25 and 0.5 mM treatments. Anthocyanins were higher accumulated in Chrysanthemum "mai vang" petals in all experimental formulas at days 2 to 4 than at day 1. At day 5, the anthocyanin content was still higher than at day 1 under salicylic acid treatments with concentrations of 0.25 - 0.75 mM.