Short-Term and Long-Term Effects of Plasma and Radio Wave Seed Treatments on Red Clover Plants

Abstract

The effect of high-frequency 5.28 MHz plasma and radio wave seed treatments on red clover growth, nodule formation and isoflavonoid content has been investigated. The short-term and long-term effects of plasma and radio wave treatment of seeds were evaluated on clover plants during two years of vegetation. The response of plants to plasma treatment was increment in root growth and the nodule formation. Significant changes in the length and weight of roots were noted in the first year of vegetation. The increase in isoflavonoids content observed after plasma and radio wave treatments can be explained by the advancement in nodulation process.

Biochemical and Physiological Plant Processes Affected by Seed Treatment with Non-Thermal Plasma

“…The composition of flavonoids in root exudates of red clover plants growing from NTP treated seeds also significantly differed from the control plants, so that the amount of 7,4′-dihydroxyflavone, daidzein, quercetin, and kaempferol was increased more than twice [ 148 ]. A strong increase in daidzein and formononetin content in the roots of red clover plants grown from low-pressure CP treated seeds was reported by other authors [ 193 ], although isoflavonoid changes in the leaves were different from those obtained in another study [ 54 ]. The amounts of isoflavonoids daidzein, genistein, and daidzin were diminished 1.5–1.8 fold compared to the control (while genistin content was not affected) in the roots of soybean plants growing from DBD plasma treated seeds [ 94 ].…”

The Potential of Cold Plasma-Based Seed Treatments in Legume–Rhizobia Symbiotic Nitrogen Fixation: A Review

“…Nedved et al [65] conducted assessments on one to two trifoliate leaves of red clover over two years and found similar results, with plants obtained from CP-treated seeds showing a 2-fold higher daidzein and a 1.4-fold higher formononetin content during the second production year. However, no difference was observed in genistein content compared to the untreated control [65]. The study suggested that the higher nodule number in CP-treated plants might be attributed to increased isoflavonoid production and enhanced lateral root development [65].…”

“…These findings underscore the significance of timing and seed color/type in CP treatments. Another study demonstrated the efficacy of high-frequency plasma (5.28 MHz) at atmospheric pressure (200 Pa) for five minutes in enhancing lateral root and nodule numbers (Table 2, [65]). These experiments suggest that CP treatments can impact root development and trigger the formation of lateral roots or nodules in legumes that form indeterminate nodules.…”

“…The seven-minute CP treatment resulted in a two-to three-fold increase in the quantity of five out of nine measured flavonoids/isoflavonoids, including hesperetin, quercetin, kaempferol, daidzein, and 7,4 ′dihydroxyflavone [22]. Nedved et al [65] conducted assessments on one to two trifoliate leaves of red clover over two years and found similar results, with plants obtained from CP-treated seeds showing a 2-fold higher daidzein and a 1.4-fold higher formononetin content during the second production year. However, no difference was observed in genistein content compared to the untreated control [65].…”

“…Interestingly, research indicates that CP seed treatment has the potential to alter the release of flavonoids/isoflavonoids from legume roots [22,65]. Five-week-old seedlings cultivated from red clover seeds treated with air-generated CP for five and seven minutes exhibited higher levels of root exudate flavonoids/isoflavonoids compared to untreated controls (Table 2; [22]).…”