Testing the role of allelochemicals in different wheat cultivars to sustainably manage weeds

Background

Selecting wheat varieties with allelopathic potential or high competitiveness against weeds is a sustainable solution for organic farming to eliminate the use of synthetic herbicides. Wheat is one of the most economically important crops. This study focuses on screening the allelopathic or competitive potential of four wheat cultivars, Maurizio, NS 40S, Adesso and Element, on two weeds of interest due to acquired herbicide resistance, Portulaca oleracea and Lolium rigidum, through germination and growth bioassays and the identification and quantification of benzoxazinoids (BXZs) and polyphenols (phenolic acids and flavonoids).

Results

The different cultivars showed different abilities to manage surrounding weeds and different capacity to exude or accumulate specialized metabolites in the presence of those weeds. Furthermore, each cultivar behaved differently depending on the weed present in the medium. The most efficient cultivar to control the tested monocot and dicot weeds was Maurizio, as it effectively controlled germination and growth of L. rigidum and P. oleracea while exuding large amounts of benzoxazinones through the roots, especially the hydroxamic acids 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one and dihydroxy-2H-1,4-benzoxaxin-3(4H)-one. By contrast, NS 40S, Adesso and Element showed the potential to control the growth of just one of the two weeds through allelopathy or competition.

Conclusion

This study reveals that Maurizio is the most promising wheat cultivar for sustainable weed control, and that the screening of crop varieties with allelopathic potential, which results in the displacement of synthetic herbicides, is an immediate solution in ecological and sustainable agriculture. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Disruption of responses to pheromone by (Z)-11-hexadecenyl trifluoromethyl ketone,an analogue of the pheromone,in the cabbage armyworm Mamestra brassicae

The effects of (Z)-11-hexadecenyl trifluoromethyl ketone (Z11-16:TFMK) a fluorinated pheromone analogue, on the responses to sex pheromone of the male cabbage armyworm, Mamestra brassicae, have been investigated in an actograph and by electroantennography (EAG). In spite of its structural proximity with the natural pheromone, Z11-16:TFMK was poorly active in EAG, and not active on male behaviour. When permeated in the air, Z11-16:TFMK reversibly inhibited the electroantennographic responses to (Z)-11-hexadecenyl acetate (Z11-16:Ac), the main component of the sex pheromone. In the actograph, the latency of the activation was increased and the intensity of the behavioural activity of males in response to Z11-16:Ac was significantly reduced in the presence of Z11-16:TFMK. These results, along with others previously reported by us, provide new pointers to the possible use of Z11-16:TFMK in pest-control strategies.     

Infectivity and Effectivity of Some Frankia Strains from the Rhamnaceae Family

The nodulation ability was determined of native Frankia strains (ChI1, ReI4, ReI6, TtI42, and TqI15) isolated from rhamnaceous species indigenous to Chile. All strains tested nodulated other Rhamnaceae host species within one or more genera, i.e., TtI42 nodulated seedlings of Trevoa trinervis, Retanilla ephedra, and Talguenea quinquenervia. Trees from other families such as Casuarina (Casuarinaceae) were not nodulated by the Frankia strains mentioned above. These results suggest that the five strains isolated from rhamnales could belong to the same cross inoculation group because they exhibited the same level of promiscuity. The effectivity of Frankia for nitrogen fixation was established by measurement of acetylene reduction activity in planta. Two strains (ReI6 and TtI42) were found more effective than the others and improved the total dry weight and shoot height of Retanilla ephedra seedlings. These studies may facilitate the choice of selected rhamnaceous Frankia pairs for arid soil afforestation, since these plants are naturally adapted to this environment in Chile.     

Impacts of the loss of neotropical highland forests on the species distribution: a case study using resplendent quetzal an endangered bird species

We evaluated the impacts of land-cover changes of evergreen cloud forests on the distribution of quetzals in the four mountain regions of Chiapas, Mexico. The land-cover changes were estimated comparing satellite images of 1970 and 2000. We also simulated the amount of remnant forests 50 years in the future. The past and the current distributions of quetzals were based on literature records and recent field surveys. Our results showed that in 1970 the forests occupied 973 km², and in 2000, 312 km², and annual loss from 3.34 to 6.85%. Our simulation suggests that 50 years from now, only one region will maintain evergreen cloud forests. In addition, we documented literature reports of 39 forests inhabited by quetzals, but in 2001 there remained 11 small-isolated forests. In order to guarantee the survival of this species, conversation efforts must be made to protect the quetzal and its habitat throughout the entire Mesoamerica region.     

Effect of exogenous fibrolytic enzyme on ruminal fermentation and digestibility of alfalfa and rye-grass hay fed to lambs

This experiment was carried out to study the effect of a directly fed exogenous fibrolytic enzyme on intake and digestion of DM, OM, protein, NDF, ADF, and hemicellulose of alfalfa and ryegrass hay by sheep. Four diets were randomly assigned to four ruminally cannulated lambs using a 4 x 4 Latin square design, repeated in time, with a factorial arrangement (2 x 2) of diets: 1) alfalfa hay; 2) alfalfa hay + exogenous fibrolytic enzymes (enzyme); 3) ryegrass hay; and 4) ryegrass hay + enzyme. Lambs consumed more DM and OM from alfalfa than from ryegrass hay (P < 0.001). The ADF intake was not different between the hays, but NDF intake was lower for alfalfa (P < 0.001). For both hays, the enzyme increased intake of DM (P < 0.01), as well as OM and CP (P < 0.05); however, NDF and ADF intake were not changed. Alfalfa hay had higher apparent digestibility of DM, OM, and CP (P < 0.001), but lower digestibility for NDF, ADF, and hemicellulose. The enzyme increased apparent digestibility of CP, hemicellulose (P < 0.05), and NDF (P < 0.10) for alfalfa. Also, for both hays, the enzyme improved N balance because lambs retained more N (P < 0.05). The enzyme increased (P < 0.05) total VFA concentration (3 and 6 h) for both hays. Results from this trial indicate that directly fed exogenous fibrolytic enzymes may change ruminal fermentation, intake, and digestibility of forages with different nutritive value.     

COX-2 and sPLA2 inhibitory activity of aqueous extract and polyphenols of Rhizophora mangle (red mangrove)

The aqueous extract of Rhizophora mangle bark and its polyphenolic fractions showed remarkable in vitro antiinflammatory activity in a preliminary study. The low molecular weight fraction exhibited cyclooxygenase-2 inhibitory activity while the total aqueous extract and the low molecular weight fraction showed secretory phospholipase A(2) inhibitory activity.     

Covadonga National Park,Asturias, Spain. Its history,conservation interest and management problems

The Covadonga National Park was the first to be established (1918) in Spain and is one of the oldest in Europe. Its fauna and flora include many species of interest and the park area is representative of the prevailing ecosystem throughout the wet zone of Spain neighbouring the Cantabrican mountain range. Its history is complex, having been influenced by different political ideologies dominant within the Government. The last few years have been particularly critical as the massive promotion of the country's tourism has led to the occupation of even the most wild and remote areas.For its future protection it would be advisable to adopt basic reforms which should include an extension of its present limits and the reintroduction of species which have recently disappeared.     

Portraiture and excavations

In a footnote to the review of M. M. Gerasimov's The Face Finder [173, 712 (1971)], the misspelling of Julius Koliman's name is erroneously attributed to a bibliography (1962) by W. M. Krogman. The error occurs in a different authority's work. Kollmann established methods (1898) for building on a skull a face recognizably correct.