Crop rotational diversity can mitigate climate-induced grain yield losses.

Diversified crop rotations have been suggested to reduce grain yield losses from the adverse climatic conditions increasingly common under climate change. Nevertheless, the potential for climate change adaptation of different crop rotational diversity (CRD) remains undetermined. We quantified how climatic conditions affect small grain and maize yields under different CRDs in 32 long-term (10-63 years) field experiments across Europe and North America. Species-diverse and functionally rich rotations more than compensated yield losses from anomalous warm conditions, long and warm dry spells, as well as from anomalous wet (for small grains) or dry (for maize) conditions. Adding a single functional group or crop species to monocultures counteracted yield losses from substantial changes in climatic conditions. The benefits of a further increase in CRD are comparable with those of improved climatic conditions. For instance, the maize yield benefits of adding three crop species to monocultures under detrimental climatic conditions exceeded the average yield of monocultures by up to 553 kg/ha under non-detrimental climatic conditions. Increased crop functional richness improved yields under high temperature, irrespective of precipitation. Conversely, yield benefits peaked at between two and four crop species in the rotation, depending on climatic conditions and crop, and declined at higher species diversity. Thus, crop species diversity could be adjusted to maximize yield benefits. Diversifying rotations with functionally distinct crops is an adaptation of cropping systems to global warming and changes in precipitation.

Selective Inhibition of Wild Sunflower Reproduction with Mugwort Aqueous Extract, Tested on Cytosolic Ca2+ and Germination of the Pollen Grains.

Wild sunflower (Helianthus annuus L.) is an invasive species widely distributed in several regions of the world, where it shares a large area with domesticated sunflower. The imidazolinone-tolerant sunflower enables the control of problematic weeds (such as Xanthium spp., Brassica spp., wild sunflower) with imidazolinone herbicides (Clearfield® production system) in cultivated sunflower crops, but could facilitate the gene transfer of herbicide resistance, from cultivated sunflower to wild sunflower, generating hard-to-control weed biotypes or herbicide-resistant populations. The development of new practices that involve the selective inhibition of reproduction structures, such as pollen granules, could be an innovative strategy to minimize outcrossing and the origin of weed-crop hybrids in Clearfield® production systems. In this study, the effects of mugwort (Artemisia vulgaris L.) aqueous extract on cytosolic Ca2+ and the germination of pollen grains collected from conventional, wild and IMI-tolerant sunflower were tested. The results showed that mugwort deregulated Ca2+ homeostasis and markedly reduced the germination of conventional and wild sunflower pollen, but not IMI-tolerant pollen. The HPLC analysis revealed the presence of phenolic acids belonging to the hydroxycinnamic and benzoic classes in the mugwort extract. Hydroxycinnamic acids (caffeic and ferulic) deregulated the cytosolic Ca2+ of conventional and wild sunflower pollen, but not those which were IMI-tolerant, similar to mugwort extract. Selective inhibition of wild sunflower pollen in the Clearfield® sunflower crop contributes to a possible new weed management strategy, reducing the wild sunflower reproduction by seed, minimizing the potential risks of outcrossing with the formation of weed-crop hybrids. The Ca2+ selective chelating activity of caffeic or ferulic acids provides elements to be investigated for their possible use as an alternative to mugwort extract.

Phytodepuration of Nitrate Contaminated Water Using Four Different Tree Species.

Water pollution by excessive amounts of nitrate (NO3-) has become a global issue. Technologies to clean up nitrate-contaminated water bodies include phytoremediation. In this context, this research aimed to evaluate four tree species (Salix alba L., Populus alba L., Corylus avellana L. and Sambucus nigra L.) to remediate nitrate-contaminated waters (100 and 300 mg L-1). Some physiological parameters showed that S. alba L. and P. alba L. increased particularly photosynthetic activity, chlorophyll content, dry weight, and transpired water, following the treatments with the above NO3- concentrations. Furthermore, these species were more efficient than the others studied in the phytodepuration of water contaminated by the two NO3- levels. In particular, within 15 days of treatment, S. alba L. and P. alba L. removed nitrate quantities ranging from 39 to 78%. Differently, C. avellana L. and S. nigra L. did not show particular responses regarding the physiological traits studied. Nonetheless, these species removed up to 30% of nitrate from water. In conclusion, these data provide exciting indications on the chance of using S. alba L. and P. alba L. to populate buffer strips to avoid NO3- environmental dispersion in agricultural areas.

Use of two grasses for the phytoremediation of aqueous solutions polluted with terbuthylazine.

The capacity of two grasses, tall fescue (Festuca arundinacea) and orchardgrass (Dactylis glomerata), to remove terbuthylazine (TBA) from polluted solutions has been assessed in hydroponic cultures. Different TBA concentrations (0.06, 0.31, 0.62, and 1.24 mg/L) were chosen to test the capacity of the two grasses to resist the chemical. Aerial biomass, effective concentrations (to cause reductions of 10, 50, and 90% of plant aerial biomass) and chlorophylls contents of orchardgrass were found to be more affected. Tall fescue was found to be more capable of removing the TBA from the growth media. Furthermore, enzymes involved both in the herbicide detoxification and in the response to herbicide-induced oxidative stress were investigated. Glutathione S-transferase (GST, EC. 2.5.1.18) and ascorbate peroxidase (APX, EC. 1.11.1.11) of tall fescue were found to be unaffected by the chemical. GST and APX levels of orchardgrass were decreased by the treatment. These negative modulations exerted by the TBA on the enzyme of orchardgrass explained its lower capacity to cope with the negative effects of the TBA.

Nitrogen concentration estimation in tomato leaves by VIS-NIR non-destructive spectroscopy.

Nitrogen concentration in plants is normally determined by expensive and time consuming chemical analyses. As an alternative, chlorophyll meter readings and N-NO(3) concentration determination in petiole sap were proposed, but these assays are not always satisfactory. Spectral reflectance values of tomato leaves obtained by visible-near infrared spectrophotometry are reported to be a powerful tool for the diagnosis of plant nutritional status. The aim of the study was to evaluate the possibility and the accuracy of the estimation of tomato leaf nitrogen concentration performed through a rapid, portable and non-destructive system, in comparison with chemical standard analyses, chlorophyll meter readings and N-NO(3) concentration in petiole sap. Mean reflectance leaf values were compared to each reference chemical value by partial least squares chemometric multivariate methods. The correlation between predicted values from spectral reflectance analysis and the observed chemical values showed in the independent test highly significant correlation coefficient (r = 0.94). The utilization of the proposed system, increasing efficiency, allows better knowledge of nutritional status of tomato plants, with more detailed and sharp information and on wider areas. More detailed information both in space and time is an essential tool to increase and stabilize crop quality levels and to optimize the nutrient use efficiency.