Screening of Some Cotton Varieties for Allelopathic Potential on Clover Broomrape Germination

Abstract

Research on the chemical basis of allelopathy has oft en been hindered by the complexity of plant and soil matrices, making it diffi cult to track active compounds. Well-designed bioassays under controlled environments can be useful in evaluating the allelopathic potential of plants. Th is paper describes two experiments about the allelopathic potential of cotton (Gossypium hirsutum L.). In the fi rst experiment, root exudates were collected from six common cotton (G. hirsutum L. and G. barbadense L.) varieties grown hydroponically. Th e cotton (donor plant) root exudates were tested on clover broomrape (Orobanche minor Smith), to determine which variety had the highest allelopathic potential. In the second experiment, the allelopathic potential of 22 soon-to-be-released cotton varieties was evaluated for clover broomrape using rhizosphere soil and extracts from diff erent plant parts. Th e results indicated that methanol was a more suitable reagent than distilled water for extracting germination stimulants from cotton plants. Th ere was a signifi cant positive correlation between the rates of clover broomrape germination in the rhizosphere soil treatments and those in the stem extract (r = 0.6018, P < 0.05) and the leaf extract treatments (r = 0.5540, P < 0.05). Th ere was also a signifi cant positive correlation between germination rates in the root extract treatments and the stem extract treatments (r = 0.7237, P < 0.05). In conclusion, the allelopathic potential of cotton can be assayed by observing the germination of clover broomrape seeds treated with cotton stem extracts.

Lily Cultivars Have Allelopathic Potential in Controlling Orobanche aegyptiaca Persoon

“…seed germination (Figs 3B , 5B and 6B ). However, these results were not consistent with recent studies in which allelopathic substances produced by cotton and potato root were transported upwards and retained in above-ground parts, resulting in a positive relationship between root and stem or leaf [ 13 , 20 , 47 ]. Instead, our results showed that a transition between organ types occurred at a specific turning point (i.e., leaf expansion stage), with the strongest stimulant allelopathy from the bulb to scale leaf in underground organs during lily growth ( Fig 9 ).…”

“…Actually, recent experiments have demonstrated that the function of SLs or their metabolites in the rhizosphere were synthesized in both roots and stem and transported upward in xylem for control of shoot branching. This means that SLs may have the certain mode of action and exist in some parts of plant [ 13 , 20 , 47 ]. Based on these facts, we presume that sophisticated components of the bulbous lily plant are likely the main causes of a distinct allelochemical transportation model, which should be further investigated.…”

Some Soybean Cultivars Have Ability to Induce Germination of Sunflower Broomrape

“…This is in consistent with the opinion that strigolactones are mainly synthesized in roots and transported to shoots [28]. Similar observations have been made for red clover ( Trifolium pratense L.), cotton ( Gossypium hirsutum L.), and tobacco ( Nicotiana tabacum L.) [29]–[32]. Correlation analysis confirmed significant correlation among germination rates induced by soybean roots, stem, and leaf extracts (Fig.…”

Recent research progress in combatting root parasitic weeds

“…Varietal differences were found in the germination-inducing activity [134], and germination of O. minor increased gradually with increasing ploidy levels of wheat [135]. Root exudates collected from cotton grown hydroponically, rhizosphere soil of fieldgrown cotton and plant extracts from the cotton had a germination-inducing activity to O. minor [136]. Selection and breeding of varieties with a high germination-inducing activity to O. minor would be possible in wheat and cotton.…”