PRE and POST Herbicidal Activity of Monoterpenes against Barnyard Grass (Echinochloa crus-galli)

Abstract

Monoterpenes, the major constituents of essential oils, are known for their diverse biological activities. This study was conducted to assess the herbicidal effect of six monoterpenes viz. (R)-carvone, 1,8-cineole, cuminaldehyde, (S)-fenchone, geraniol, (S)-limonene, and (R)-linalool on barnyardgrass under laboratory and glasshouse conditions with a view to explore the possibility of their utilization for future weed management. The effect of monoterpenes on chlorophyll contents and total phenolic compounds was also evaluated. The inhibitory effects of monoterpenes on seed germination and seedling growth were tested at concentrations of 1, 2, 4, 6, and 8 mM. The results showed that geraniol and (R)-carvone caused greatest reduction of seed germination with complete inhibition at the concentrations > 2 mM. Similarly, these two compounds were the most potent inhibiters for root and shoot growth. In general, monoterpenes were less effective against seed germination than seedling growth. Furthermore, the inhibition of root growth by all compounds was greater than that of shoot growth. In foliar application treatments under glasshouse conditions, the monoterpenes reduced the fresh and dry weights, and shoot length of two-leaf stage barnyardgrass at concentrations of 1 and 2%. In addition, the tested monoterpenes caused phytotoxicity symptoms, mainly chlorosis and necrosis, followed by weed death. Complete weed control was observed in the treatments with 1 and 2% of geraniol, and 2% of cuminaldehyde. Further, a reduction of chlorophyll contents and total phenolic compounds of barnyardgrass leaves was noticed, indicating that the monoterpenes cause adverse effect on photosynthesis and weed metabolism. Based on the results of this study, it can be concluded that the monoterpenes, particularly geraniol, (R)-carvone, and cuminaldehyde, can be used as potential natural herbicides.

Herbicidal, Insecticidal and Structure-Activity Relationship Studies on Pyranopyrazole and Oxinobispyrazole Derivatives

“…In addition, all of the tested compounds had greater inhibitory effects on root growth than on shoot growth. These results are supported by our earlier studies of inhibitory effects of essential oils, sesquiterpenes and monoterpenes on seedling growth (Abdelgaleil et al, 2009 and2014;Saad et al, 2012;Gouda et al, 2016). This finding might be predictable, because it is likely that roots are the first to absorb the allelochemicals compounds from the media (Turk and Tawaha 2002).…”

Inhibitory Effects of a Variety of Aldehydes on Amaranthus tricolor L. and Echinochloa crus-galli (L.) Beauv.

“…Furthermore, in the present study, most aldehydes affected root growth more than shoot growth and all of the tested compounds had no effect on seed germination of barnyardgrass. Similarly, in 2016, Gauda and coworkers [ 30 ] conducted a study on the herbicidal activity of a variety of monoterpenes against barnyardgrass. They found that, generally, these monoterpenes were more effective against seedling growth than seed germination of the plant.…”

“…Both species were chosen as representatives of dicot and monocot plants, respectively. We selected an aldehyde chemical class since there are several reports indicating that natural and synthetic aldehydes [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ] or crude extracts containing aldehydes [ 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 ] could interrupt the germination, growth, and development of plants, algae, and microorganisms. Furthermore, numerous aldehydes are commercially available in pure form which can be directly purchased.…”

Recent advances in allelopathy for weed control: from knowledge to applications

“…Limonene, together with 1,8‐cineole, has been also tested as a pretreatment before the application of other herbicides as cuminaldehyde; showing inhibitory seed germination of barnyardgrass 9 days after sowing …”

“…77,80 Limonene, together with 1,8-cineole, has been also tested as a pretreatment before the application of other herbicides as cuminaldehyde; showing inhibitory seed germination of barnyardgrass 9 days after sowing. 81 Homoterpenes (monoterpenes with an added methylene group) have also been studied as allelochemicals. 82 These terpenoids can arise via different biosynthetic routes in a tissue-specific manner; in the case of 4,8-dimethyl-1,3,7-nonatriene, it is synthesized by degradation of the C30 triterpene diol, arabidiol, and catalyzed by the Brassicaceae-specific cytochrome P450 monooxygenase CYP705A1.…”