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Microcystins (MCs) are one of the most prevalent cyanotoxins and pose significant risks to aquatic ecosystems and human health, particularly in lakes used as drinking water sources. However, knowledge about the MC concentrations in plateau lakes experiencing high solar radiation is scarce. This study investigated the spatial-temporal distribution of MCs in eight Yunnan Plateau lakes in China, focusing on their relationships with environmental factors. Water samples (n = 63) were collected during summer and winter seasons and analyzed for MC concentrations along with a suite of environmental variables. Results revealed significant seasonal and spatial variations in MC concentrations, with higher levels in eutrophic lakes Dianchi, Erhai, and Xingyunhu. Notably, mean MC concentrations in Lake Dianchi during summer and Erhai during winter exceeded the World Health Organization's provisional guideline of 1 μg/L for drinking water. Seasonal analyses revealed distinct regulatory mechanisms: MC concentrations in summer were positively correlated with total phosphorus, total nitrogen, turbidity, and chlorophyll a, reflecting the influence of eutrophication on cyanobacterial growth. While solar radiation intensity (SRI) exhibited a dual role: moderate SRI in winter was associated with higher MC levels, whereas higher SRI in summer suppressed MC production, likely due to photoinhibition or MC degradation. Strikingly, water temperature showed no significant correlation with MC concentrations, suggesting that high solar radiation in the Yunnan Plateau may override temperature-dependent effects on cyanobacterial growth. These findings highlight the importance of nutrient management and the regulatory role of solar radiation in regulating MC production in high-altitude lakes. The study underscores the need for region-specific strategies to mitigate cyanobacterial risks, particularly in drinking water source lakes, by integrating nutrient control and the unique light regime of plateau ecosystems.
The complexity of the sugarcane genome, the narrow genetic base of subtropical germplasm, and the extended breeding and selection cycle pose significant challenges to conventional breeding methods. In vitro mutagenesis offers an alternative approach to generating genetic variability by harnessing both somaclonal variation and induced mutations. An in vitro mutagenesis protocol, using the chemical mutagen ethyl methanesulfonate (EMS) in an elite Argentine sugarcane cultivar, was developed. The resulting genetic variability was assessed in the field in plant and first ratoon crops. Six-week-old embryogenic calli were treated with 8, 16, 32, and 48 mM EMS. Plants were regenerated from treated calli and acclimatized in a greenhouse. The lethal dose LD50 for regeneration capacity was 31.68 mM EMS, whereas LD25 was 17.71 mM EMS. Based on these results, the plants from the 16 and 32 mM EMS treatments were phenotypically assessed in the field. These assessments showed that EMS treatments exhibited phenotypic variability due to genetic changes. Traits such as the number of stalks, stalk length, stalk weight, internode length, and Brix showed an increase in the population mean in the EMS treatments compared with the wild type. Some traits maintained changes from one year to the next, whereas others reverted to the wild-type genotype values in the second year. Mutagenic treatments generated greater and more stable genetic variation than somaclonal variation, supporting their use as effective tools for sugarcane improvement. Based on agronomic traits, 23 mutant plants were selected and advanced to subsequent generations.
Relevance . The transition of viticulture to the cultivation of grape plantations in a grafted culture has only partially solved the problem of phylloxera. Taking into account the shortcomings of the instilled culture, the problem remains urgent. In view of this, we consider it necessary to preserve and expand the indigenous grape culture. The fundamental solution to the problem should be the creation and introduction of pest-resistant genotypes based on modern advances in genetics and breeding, suitable for growing in a root crop. Currently, there are quite a lot of high-quality domestic varieties tolerant to root phylloxera and suitable for cultivation in the arsenal of domestic viticulture. native culture. Economically justified and scientifically justified ways to solve the phylloxera problem may be the introduction of pest-tolerant varieties of domestic breeding and the use of technological regulations for the use of physiologically active compounds that enhance physiological immunity and resistance of grapes to phylloxera.
The perennial grass stand, sown in 1975 in drained lowland peat soil and used without reseeding for haymaking till today, has been annually minerally fertilised and so allows obtaining high-yielding fodders with a productivity of 5.0–5.5 thousand feed units/ha. The available agrophytocenosis support the valuable botanical composition of perennial grasses, the powerful root system of which maintains the organic soil layer.
