Positive Effect Induced by Plasma Treatment of Seeds on the Agricultural Performance of Sunflower

Abstract

The need for efficient technologies to enhance productivity in agriculture strongly motivates research on plasma treatment of seeds and plants. In this study, the influence of plasma treatment on sunflower (Helianthus annuus L.) seeds was evidenced throughout the entire life span of the plants. The seeds were packed in a DBD reactor operated in air and treated in plasma for 10 min, using a sinusoidal voltage of 16 kV amplitude at 50 Hz frequency. Early growth observation of plants under laboratory conditions showed that, after a slower start, the plasma-treated seeds developed faster and produced taller seedlings with greater total mass as compared to the control samples. Results obtained from mature plants cultivated in the field revealed a positive effect of plasma exposure with respect to capitulum size, number of seeds per capitulum and mass per thousand seeds, resulting in a remarkable increase in crop yield. The plasma effect lasted for at least two weeks of seed storage; however, it was considerably affected by the sowing period.

Keywords: crop yield; dielectric barrier discharge; non-thermal plasma; seed treatment; sunflower.

Figure 1

(a) Stem lengths (from the soil up to the cotyledons) of plasma-treated and control seeds grown in organic substrate; (b) Lengths of roots, shoots and entire seedling after 30 days of incubation; (c) Fresh weight and (d) Dry weight of the whole plant and, separately, of the shoot and leaves and of the root on the 30th day (C—control/untreated seeds, P—plasma-treated seeds). Different letters indicate statistically significant differences between mean values (p < 0.05).

Figure 1

(a) Stem lengths (from the soil up to the cotyledons) of plasma-treated and control seeds grown in organic substrate; (b) Lengths of roots, shoots and entire seedling after 30 days of incubation; (c) Fresh weight and (d) Dry weight of the whole plant and, separately, of the shoot and leaves and of the root on the 30th day (C—control/untreated seeds, P—plasma-treated seeds). Different letters indicate statistically significant differences between mean values (p < 0.05).

Figure 2

(a) Plant height; (b) Number of leaves; (c) Capitulum diameter of sunflower plants grown from plasma-treated and control seeds, at approximately 2–2.5 months from sowing (C—control/untreated seeds, P—plasma-treated seeds). Different letters indicate statistically significant differences between mean values (p < 0.05).

Figure 2

(a) Plant height; (b) Number of leaves; (c) Capitulum diameter of sunflower plants grown from plasma-treated and control seeds, at approximately 2–2.5 months from sowing (C—control/untreated seeds, P—plasma-treated seeds). Different letters indicate statistically significant differences between mean values (p < 0.05).

Figure 3

(a) Capitulum diameter; (b) Number of seeds per capitulum; (c) Mass per 1000 seeds; (d) Yield, for sunflower plants grown from plasma-treated and control seeds (C—control/untreated seeds, P—plasma-treated seeds). Different letters indicate statistically significant differences between mean values (p < 0.05).

Figure 4

(a) Capitulum diameter; (b) Number of seeds per capitulum; (c) Yield, for sunflower plants grown from untreated/control seeds (C) and seeds treated by plasma on 7 April 2021 (P1) and on 21 April 2021 (P2), sown on 26 April 2021 and harvested on 30 September 2021. Different letters indicate statistically significant differences between mean values (p < 0.05).

Figure 5

Schematic drawing of the field experiment.

Figure 6

Graphic representation of the results for each data set throughout this paper.