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.     

Salinity-induced changes in biometric,physiological and anatomical parameters of Passiflora edulis Sims plants propagated by different methods

ABSTRACT

Salinity is one of the most important abiotic stresses limiting agricultural production worldwide. Here, we investigated the biometric, physiological and anatomical changes of Passiflora edulis plants propagated from seeds, cuttings and grafts and exposed to salt stress (0.3 – control and 6.3 dS m^?1). Saline stress significantly reduced plant height, the number of leaves, total chlorophyll, stomatal conductance, shoot dry weight, total dry weight, total water consumption and root volume. Among the propagation methods evaluated, plants propagated from seeds were more sensitive to salinity, while plants propagated from cuttings showed smaller alterations when subjected to salinity. Similar behavior was observed for anatomical characteristics, since plants propagated from seeds presented more pronounced anatomical alterations, such as greater thicknesses of the leaf mesophyll, upper epidermis, lower epidermis, palisade parenchyma and spongy parenchyma and also was observed presence of calcium oxalate crystals in the form of druses in greater quantity in the root cortex, in comparison to plants propagated from cuttings. The approach used in this study allowed identifying the type of yellow passion fruit propagation (cuttings) that was best for physiological and anatomical adaptation to salt stress and will be potentially useful in programs for improvement of the crop.     

Biochemical modulations in açaí palm (Euterpe oleracea Mart.) under vegetative stages in an agroforestry system of the Amazon

Background : The açaí palm (Euterpe oleracea Mart.) is a species native to the Amazon region, where the largest stock of these palms is located in the state of Pará, Brazil. This species occurs predominantly spontaneously in the plateau and plains areas of the Amazonian estuary. Water deficit is the main limiting factor of plants, negatively regulating the growth, metabolism and productivity of crops. Aim : This study aimed to deepen the ecophysiological and biochemical responses of Euterpe oleracea Mart. to a water deficiency condition in agroforestry systems. Methods : The study was carried out in a defined period of lowest rainfall in the region, which runs from July to October, averaging 58.6 mm for those months, such as location, age, uniformity, health, development, height and diameter of the stipe, in order to determine the biochemical variables. Responses to biochemical components under water deficit such as starch, sucrose and carbohydrates increased for rachis and fruits. Results : The concentrations of ammonia and proteins increased in stems and fruits. For amino acids, the structures that accumulated these organic compounds were fruits and arrow. One of the most representative amino acids against water deficiency is proline, and its increase in plant tissues is due to osmoprotein function, especially for structures such as rachis, fruit and petioles + rachis. Conclusions : Therefore, Euterpe oleracea Mart. presents excellent physiological plasticity to deal with stressful conditions as well as adaptive behavior to overcome this deficiency.     

Sorption-desorption of flucarbazone and propoxycarbazone and their benzenesulfonamide and triazolinone metabolites in two soils

Sorption-desorption interactions of pesticides with soil determine the availability of pesticides in soil for transport, plant uptake and microbial degradation. These interactions are affected by the physical and chemical properties of the pesticide and soil and, for some pesticides, their residence time in the soil. While sorption-desorption of many herbicides has been characterised, very little work in this area has been done on herbicide metabolites. The objective of this study was to characterise sorption-desorption of two sulfonylaminocarbonyltriazolinone herbicides, flucarbazone and propoxycarbazone, and their benzenesulfonamide and triazolinone metabolites in two soils with different physical and chemical properties. K(f) values for all four chemicals were greater in clay loam soil, which had higher organic carbon and clay contents than loamy sand. K(f-oc) ranged from 29 to 119 for the herbicides and from 42 to 84 for the metabolites. Desorption was hysteretic in every case. Lower desorption in the more sorptive system might indicate that hysteresis can be attributed to irreversible binding of the molecules to soil surfaces. These data show the importance of characterisation of both sorption and desorption of herbicide residues in soil, particularly in the case of prediction of herbicide residue transport. In this case, potential transport of sulfonylaminocarbonyltriazolinone herbicide metabolites would be overpredicted if parent chemical soil sorption values were used to predict transport.     

Diversity of endophytes across the soil-plant continuum for Atriplex spp. in arid environments

Endophytes are hypothesized to be transferred across the soil-plant continuum, suggesting both the transfers of endophytes from environment to plant and from plant to soil. To verify this hypothesis and to assess the role of locality, we evaluated the similarity of microbial communities commonly found both in soils and endophytic communities in three arid regions, i.e. the Jornada LTER(Long Term Ecological Research) site in New Mexico, USA, and the research station of Jordan University of Science and Technology(JUST) and Khanasri research station in Badia region of Jordan. Rhizosphere and non-rhizosphere soils, leaves and seeds of Atriplex spp. were sampled. Diversity and distribution of bacteria and fungi across the soil-plant continuums were assessed by tag-encoded FLX amplicon pyrosequencing and sequence alignment. Of the total bacterial OTUs(operational taxonomic units), 0.17% in Khanasri research station, 0.16% in research station of JUST, and 0.42% in Jornada LTER site were commonly found across all the plant and soil compartments. The same was true for fungi in two regions, i.e. 1.56% in research station of JUST and 0.86% in Jornada LTER site. However, in Khanasri research station, 12.08% of total fungi OTUs were found in at least one soil compartment and one plant compartment. Putative Arthrobacter, Sporosarcina, Cladosporium and members of Proteobacteria and Actinobacteria were found across all the soil-plant continuums. Ascomycota, mainly including Didymellaceae, Pleosporaceae and Davidiellaceae were present across all the soil-plant continuums. Microbial communities in two regions of Jordan were similar to each other, but both of them were different from the Jornada LTER site of USA. SIMPER(similarity percentage) analysis of bacterial and fungal taxa for both soil and endophyte communities revealed that dissimilarities of two bacterial genera(Arthrobacter and Sporosarcina) and two fungal genera(Cladosporium and Alternaria) are very high, so they play key roles in the soil-plant continuums. A weighed Pearson correlation analysis for the specific bacterial OTUs in the soil-plant continuums only showed high similarity between the two regions of Jordan. However, fungal groups showed higher similarities among all regions. This research supports the hypothesis of continuity of certain bacterial and fungal communities across the soil-plant continuums, and also explores the influences of plant species and geographic specificity on diversity and distribution of bacteria and fungi.     

Networks of inbreeding coefficients in a selected population of rabbits

The correlation between pedigree and genomic-based inbreeding coefficients is usually discussed in the literature. However, some of these correlations could be spurious. Using partial correlations and information theory, it is possible to distinguish a significant association between two variables which is independent from associations with a third variable. The objective of this study is to implement partial correlations and information theory to assess the relationship between different inbreeding coefficients using a selected population of rabbits. Data from pedigree and genomic information from a 200K SNP chip were available. After applying filtering criteria, the data set comprised 437 animals genotyped for 114,604 autosomal SNP. Fifteen pedigree- and genome-based inbreeding coefficients were estimated and used to build a network. Recent inbreeding coefficient based on runs of homozygosity had 9 edges linking it with different inbreeding coefficients. Partial correlations and information theory approach allowed to infer meaningful associations between inbreeding coefficients and highlighted the importance of the recent inbreeding based on runs of homozygosity, but a good proxy of it could be those pedigree-based definitions reflecting recent inbreeding.     

Evidence that severe acute stress and starvation induce rapid atresia of ovarian vitellogenic follicles in Atlantic bluefin tuna, Thunnus thynnus (L.) (Osteichthyes: Scombridae)

The effects of different stressors on the atretic degeneration of ovarian vitellogenic follicles, as well as on the ovarian mass, were examined in female Atlantic bluefin tuna, Thunnus thynnus (L.), from the Mediterranean Sea. The stressors taken into consideration were short-term starvation (up to 14 days), long-term cage rearing (1 year) and crowding-induced severe panic frenzy. Wild-caught individuals were used as a control group. Fish subjected to either severe panic frenzy or starvation exhibited a decrease in gonad mass and had significantly higher intensity of α atresia in the vitellogenic follicles (means: 78% and 58%, respectively; range: 36-100%) than either wild or long-term caged individuals (means: 32% and 30%, respectively; range: 19-44%). The extensive atresia in fish stressed by severe panic frenzy was observed as early as 24 h after the stressing event. The present study represents the first evidence of the extreme susceptibility of Atlantic bluefin tuna to severe acute stress during vitellogenesis; it also shows that starvation is associated with progressive reabsorption of vitellogenic oocytes.