## 4 Discussion

Table 5: Chemical constituents detected in extracts from _Arachis pintoi_ by GC-MS analysis. the allelopathic impacts of the candidate plant species. To address this issue, in this study, we have presented the inhibitory effects of _A. pintoi_ against the germination and growth of several tested plants including _E. crus-galli_, natural paddy weeds, and cultivated species (_O. sativa_, _V. radiata_, and _L. sativa_) under various environments (laboratory, greenhouse, and field). Notably, among the cultivated species used in this study, _L. sativa_ was reported to be highly sensitive to allelochemicals even at low concentrations and to either stimulators or inhibitors used in allelopathic studies [17], while the major paddy weed (_E. crus-galli_) and common crops (_O. sativa_, _V. radiata_, _Medicago sativa_, etc.) are suitable as the tested plants for determining the inhibitory magnitude of the candidate plant species [27]. In laboratory bioassays and greenhouse experiments, the growth of _E. crus-galli_ and tested plants were significantly suppressed and varied based on the doses applied and the tested plant species. Remarkably, the roots of all tested plants were the most suppressed by 72.9 to 89.3% (Table 1). Our results were in agreement with the report of [PERSON] et al. [45], which indicated that the dry leaves of _A. pintoi_ at 200 mg/L remarkably reduced the radicle and hypocotyl of _L. sativa_ by using the sandwich method. At the lower doses, the tested plants were either negligibly inhibited or slightly promoted (Tables 1-3) because _A. pintoi_ contains multi-nutritive values and mineral contents, which may lead to plant growth enhancement [46; 47]. Our findings were also congruent with the previous results of [PERSON] et al. [48], who reported that _A.pintoi_ extracts exerted the elongation of pepper (_Capsicum annum_), tomato (_Solanum Lycopersicum_), and _E. crus-galli_ (barnyard grass) at low concentrations [49]. In the field trials, the magnitude of _E. crus-galli_ and natural weed biomass reduction were significant differences at doses of 100-200 g/m\({}^{2}\), indicating that the suppressive ability of weeds was directly proportional to the dose of application. The results are in agreement with those of preceding reports, in which the suppressing activity of candidate plant powders has been indicated to be dose-dependent against tested plants [17; 50]. Furthermore, candidate plants may selectively inhibit weeds without harmful effects on rice production [7; 17]. Accordingly, we found that despite a significant reduction in the total dry weight of natural paddy weeds, _A. pintoi_ did not induce any injury to rice plants; rather, it promoted rice yield by over 30% (Table 4). These results were in line with our previous studies wherein application of 1-2 tons/ha dry biomass of allelopathic plants, namely neon (_A. indica_), passion fruit (_P. edulis_), alfalfa (_M. sativa_), buckwheat (_Fagporum esculentum_), and kava (_Piper metrulticum_), dramatically minimized the growth of major rice paddy weeds including monochoria (_Monochoria vaginalis_), India toothcup (_Rotala indica_), dirty dora (_Cyperus difformis_), and _E. crus-galli_, together with an increase in rice yield by over 20% [10; 17; 18]. [PERSON] et al. [17] explained that enhanced rice yield was caused by the release of potential nutrients, such as N, P, K, Ca, and Mg, during the application of plant-derived materials. On the other hand, weeds and rice plants compete for resources, such as light, space, and nutrition, etc., which can significantly reduce rice yield. Conversely, rice plants can thrive and reach their maximum yield potential when weed growth is limited, inhibited or absent. Practically, _A. pintoi_ has been reported as a promising green manure with multiple benefits comprising soil coverage and nitrogen fixation [20; 21; 24; 25]. In addition, other studies have demonstrated that the growth and yield components of corn (_Zea mays_) and tomato (_Solanum Lycopersicum_) were significantly enhanced using a living mulch of _A.