Effects of Hexaconazole on Growth and Antioxidant Potential of Cucumber Seedlings under UV-B Radiation

Abstract

The present study was conducted to determine the effect of hexaconazole (HEX), a triazole fungicide, on the growth, yield, photosynthetic response and antioxidant potential in cucumber (Cucumis sativus L.) plants subjected to UV-B stress. UV-B radiation and HEX were applied separately or in combination to cucumber seedlings. The growth parameters were significantly reduced under UV-B treatment, however, this growth inhibition was less in HEX treated plants. HEX caused noticeable changes in plant morphology such as reduced shoot length and leaf area, and increased leaf thickness. HEX was quite persistent in inhibiting shoot growth by causing a reduction in shoot fresh and dry weight. HEX noticeably recovered the UV-B induced inhibition of biomass production. Significant accumutation in anthocyanin and flavonoid pigments in the leaves occurred as a result of HEX or UV-B treatments. HEX permitted the survival of more green leaf tissue preventing chlorophyll content reduction and higher quantum yield for photosystemⅡ under UV-B exposure. HEX treatment induced a transient rise in ABA levels in the leaves, and combined application of HEX and UV-B showed a significant enhancement of ABA content which activates H2O2 generation. UV-B exposure induced accumulation of H2O2 in the leaves, while HEX prevented UV-B induced increase in H2O2, indicating that HEX serves as an antioxidant agent able to scavenge H2O to protect cells from oxidative damage. An increase in the ascorbic acid was observed in the HEX treated cucumber leaves affecting many enzyme activities by removing H2O2 during photosynthetic processes. The activities of antioxidant enzymes including catalase(CAT), ascorbate peroxidase(APX), superoxide dismutase(SOD) and peroxidase(POD) in the leaves in the presence of HEX under UV-B stress were higher than those under UV-B stress alone. These findings suggest that HEX may participate in the enhanced tolerance to oxidative stress. From these results it can be concluded that HEX moderately ameliolate the effect of UV-B stress in cucumber by improving the components of antioxidant defense system.

Morphogenesis, pigment content, phytohormones and productivity of sweet pepper under the action of gibberellin and tebuconazole

“…We showed that under the action of EW-250 the content of GA3 and IAA in the stems and leaves of pepper decreased, and the content of ABA in the leaves increased against the background of inhibited stem growth and increased mass of crude matter of all vegetative organs. The obtained data complement our results of anatomical-morphological and physiological-biochemical studies of eggplant plants (Rogach et al, 2020) as well as the work of other authors on the effects of triazolederived retardants of paclobutrazole shown for magnolia plants (Shi et al, 2021), uniconazole -for winter barley plants (Bakheta & Hussein, 2014) and hexaconazole -for cucumber plants (Tae-Yun & Jung-Hee, 2012).…”

“…Under the action of the retardant, the growth of soybean stems was inhibited (Kim et al, 2018), but branching was intensified and more leaves were laid in Magnolia wufengensis plants (Shi et al, 2021). As a result of slowing down the linear growth of the stem, plastic substances were directed to the formation of new leaves in cucumber plants (Tae-Yun & Jung-Hee, 2012).…”

“…Rapeseed plants were treated with uniconazole at doses of 0.5, 1.0, 1.5 and 2.0 mg/L, which led to a fall in GA3 and IAA and a rise in cytokinins and ABA in roots and shoots (Zuo et al, 2020). Another triazolederived inhibitor of gibberellin, hexaconazole, at a dose of 100 ppm, almost doubled the ABA content in cucumber leaves (Tae-Yun & Jung-Hee, 2012).…”

The impact of growth stimulators and retardants on the utilization of reserve lipids by sunflower seedlings

“…У практичному плані для оптимізації ростових процесів і продуктивності рослин застосовують синтетичні регулятори росту, в тому числі ретарданти (Ramburan and Greenfield, 2007;Kumar et al, 2012;Tae-Yun and Jung-Hee, 2012;Pavlista, 2013;Yan et al, 2013;Sang-Kuk and Hak-Yoon, 2014;Sardoei et al, 2014;Yan et al, 2015;Panyapruek et al, 2016;Wang et al, 2016). Разом із цим, значно менше інформації про функціонування цієї системи в гетеротрофну фазу розвитку рослини (період проростання насіння, бульб, кореневищ, цибулин).…”