## 3 Effects of Plasma on Plant Vegetative Growth and Reproduction  
The life cycle of plants is divided into three distinct phases: vegetative, reproductive, and seed formation, followed by senescence. Vegetative growth is an important phase in which plants perform photosynthesis, increase their biomass, synthesize the reserve food, and prepare for reproduction. It is also a very sensitive stage because growth is influenced by environmental factors (i.e., heat, drought, pathogen, alkalinity, UV rays) and biological stimuli. Overall crop productivity depends on the vegetative growth phase, and, therefore, the regulation of vegetative growth is critical for plant development and survival [72]. Plasma can regulate the vegetative growth phase of plants, and plasma seed treatment has long-term effects on the early vegetative growth, as reported in several studies (Table 1). Plasma treatment promotes seed germination and subsequent seedling growth, increasing the length and biomass of seedlings (Table 1). As mentioned earlier, enhanced seedling growth without changes to the germination efficiency has been also observed after plasma treatment [15; 19; 41; 44; 56; 59; 64]. Plasma treatment at the seedling stage has also reported, which promoted seedling growth [10; 48; 55; 61; 63]. As for seed germination, the effects of plasma on seedling growth varies with the plasma dose, treatment time, feeding gases, and moisture. Extended plasma exposure or high power or atmospheric pressure reduced seedling growth; wheat seeds treated for 3 min had higher sprout biomass than seeds treated for 10, 20, or 40 min [13]. Milder plasma treatments (2.7 W) accelerates early growth and increases the root to shoot ratio [22]. [PERSON] et al. [31] investigated the effects of feeding gases and moisture on plasma-mediated seedling growth and found that DBD plasma-treated radish seeds had better seedling growth when air, oxygen (O\({}_{2}\)), nitric oxide (NO) (10%), and nitrogen (N\({}_{2}\)) were used as the feeding gases (rather than N\({}_{2}\), helium (He), and argon (Ar)). Additional moisture during plasma treatment also accelerated the growth enhancement effects. Compared to vegetative growth, the effects of plasma on flowering and fruit production have rarely been reported. Studies have shown that plasma seed treatment has positive effects on the reproductive stage and harvesting product of tomatoes, soybeans, and peanuts [10; 49]. A field study of okra (_Abellmoschus esculentus_) in India, found that cold low pressure plasma seed treatment improved different agronomic attributes, including the harvesting time, 50% flowering time, flower number, fruit number and weight, and okra yield [73]. Recently, [PERSON] et al. [74] reported increase in pod numbers (13.8%) and grain weight (8.2%) after priming oilseed rape plants with cold low pressure plasma at the reproduction stage. In another report, cold atmospheric pressure plasma seed priming increased the flower number (41.5%) and fresh weight (24%) in _Cichorium intybus_[51]. Cold atmospheric pressure plasma treatment alone or as a co-treatment with multi-walled carbon nanotubes increased the flower number and diameter of melons, which resulted in more melon fruits [75]. When investigating the mechanism of plasma action on seedling growth, many reports have focused on the increased nitrogen nutrient levels, changes in the amount growth hormones and other physiological processes, and the activation of growth-related gene expression. These mechanisms are likely related to the plasma-generated reactive species. Plasma-generated reactive species can produce nitrogen species, such as NO\({}_{2}\)\({}^{-}\) and NO\({}_{3}\)\({}^{-}\), after interacting with water. Plasma-treated water acts as a nitrogen fertilizer and is responsible for growth induction in seedlings [57]. Other reactive species, such as H\({}_{2}\)O\({}_{2}\) and NO, can act as growth stimulators. These reactive species may disturb redox homeostasis and trigger mild oxidative stress in plants at the vegetative and reproductive stages.