Mingfeng Li’s research while affiliated with Huazhong Agricultural University and other places

Background and aims The purpose of this study was to examine the developmental defects of cell walls and vessels at the ring sites of cotton petioles and thereby understand the effects of petiole rings on nutrient transport in cotton. Methods Boric acid was applied as basal fertilizer in boron-deficient cotton field to verify the relationship between boron concentration and ring formation on cotton petioles. Petiole samples were taken from boron-deficient cotton plants to analyze the differences in cell wall properties and anatomical structure between the ring and non-ring sites. Results Under boron deficiency stress, chloroplasts were deformed and slightly disintegrated at the ring sites of the petioles. The cell walls within the rings were irregularly thickened by 44.1%, while their mechanical strength was markedly reduced by 38.9% compared to those of the non-ring sites. There were also changes in the hydrogen bonding within carbohydrates and proteins and the structure of pectins along with cellulose accumulation in the cell walls at the ring sites. A large number of tiny vessels were formed in the petiole rings, resulting in the squeezing and rupture of vessels. Boron, magnesium, and manganese concentrations in various parts of the petioles varied substantially in the order of lower part > middle part > upper part. Conclusions Boron application reduces the probability of ring formation on the petioles of cotton. The cell walls and vessels are destructed at the ring sites of the petioles, which impairs their mechanical support and mineral nutrient transport functions in boron-deficient cotton.

Potato starch serves as an excellent raw material or food additive in the food industry. With the advancement of the potato staple food strategy in China, improving the potato starch yield and quality has attracted more and more attention. Potassium is an essential nutrient for potato due to its direct effects on the yield and quality of potato tubers. Here, the effects of three different potassium levels on potato starch physicochemical properties were evaluated by field experiments. With increasing potassium application rates, the amylose content, phosphorus content and particle size decreased, thereby resulting in low gelatinization temperature, breakdown and setback viscosity, and high swelling power, relative crystallinity and transparency. Our study indicated that enhanced potassium application improved the resistance to heating and shear stress and decreased the retrogradation of starch, and the application of 270 kg/ha potassium fertilizer could obtain highest tuber and starch production with desirable starch physicochemical properties. The integrated results also provide some novel insights into the management of the fertilizing conditions to obtain native starches with special properties.

Background: Foliar spray of selenium (Se) has increasingly been applied to improve Se concentrations in grain crops, but little information is available about the properties of Se-enriched fruits. In this study, selenium distribution in blueberry and Se effect on blueberry quality were investigated by foliar spraying selenite or selenate (200 g ha-1) on two blueberry cultivars (Bluecrop and Northland) during the young fruit or coloring stage. Results: Selenium concentration in blueberry was mainly affected by cultivar and spray stage relative to Se source. Northland was 1.3 to 1.5 times higher than Bluecrop in Se enrichment. The Se treatment at the young fruit stage induced a 1.5-2.3-fold increase over that at the coloring stage in the Se concentration of blueberry. Additionally, selenium was mainly stored in pomace, with an accumulative distribution ratio of 89.3 to 94.9%. The proportion of organic Se reached up to 77.0% in blueberry. Furthermore, the foliar application of Se significantly increased the anthocyanin concentration and the intact fruit rate of blueberry. Conclusion: Se-enriched blueberry can be used as a 'functional food'. As Se was mainly accumulated in the pomace, consuming blueberries as fresh fruit, dried fruit and jam can improve the efficiency of Se supplement.

The main symptom of boron (B) deficiency in cotton is the formation of brown rings on leaf petioles. The objective of the present study was to determine the changes in the anatomical structure and chemical composition of petioles and photosynthesis of leaves in cotton under B deficiency. Compared to the control, B deficiency treatment resulted in large increases in the number of petioles with brown rings per plant (160.0%) and the number of rings on the petiole per functional leaf (711.1%) in cotton seedlings. The relative absorbance intensity in the fingerprint region of polysaccharide structure was decreased in petiole rings under B deficiency, while lignin contents were increased. Cotton plants mitigated the impairment of transport function in cotton petioles by increasing the areas of vascular bundles, phloem, xylem, and phloem fiber. Moreover, the stomatal conductance, photosynthetic rate, and transpiration rate in leaves were significantly decreased under B deficiency, thus impeding photosynthesis in cotton plants. Therefore, B deficiency reduces transport function in petioles and photosynthesis in leaves, and leads to the formation of noticeable brown rings on petioles of cotton seedlings.

Foliar spray of selenium (Se) has increasingly been applied to improve Se concentrations in crops. There is a lack of systematic and in-depth study comparing the effects of foliar spray with different Se sources at different growth stages. In this study, selenite or selenate (75 g Se ha⁻¹) was sprayed to the foliage of rice plants at the late tillering or full heading stage. Se concentrations in different parts of rice plants were determined to assess the effects of foliar spray with different Se sources at different growth stages on Se distribution in the plant, Se metabolism in the grains, and Se recovery efficiency in the brown rice. At the same spraying stages, total Se, organic Se, and protein Se concentrations in brown rice obtained with selenate were ∼2-fold those obtained with selenite. With the same Se sources, total Se, organic Se, and protein Se concentrations in brown rice treated at full heading were 2-fold higher than those treated at late tillering. The delay of spraying stage decreased the distribution ratio of Se in straw and roots, while it increased the distribution ratio of Se in grain; this trend was more evident with selenate. The proportions of organic Se and protein Se in brown rice showed no differences between selenite and selenate treatments at the same stages. The delay of spraying stage decreased the proportions of organic Se and protein Se in brown rice (still up to 80% and 44%, respectively), whereas the recovery efficiency of Se was improved in brown rice by more than 1-fold. In conclusion, appropriately delaying the spraying stage and selecting selenate as the Se source can be more efficient for producing Se-enriched rice.

Intake of food containing high levels of selenium (Se) poses a safety risk to human health. Sulfur (S) fertilizer exerts different regulatory effects on Se uptake in crops. In this study, field experiments were conducted in 2012–2013 and 2013–2014 to clarify the effects of different S species [60 kg ha⁻¹ S applied as elemental sulfur or magnesium sulfate] on the Se uptake and quality of seeds in rapeseed (Brassica napus L.) treated with Se [60 g ha⁻¹ Se applied as sodium selenite or sodium selenate]. The results showed that the application of sulfur or sulfate significantly reduced the Se concentrations of seeds in plants treated with selenite or selenate. The two S fertilizers caused consistent reductions in seed Se concentrations, approximately 25% for the selenite treatment and 40% for the selenate treatment. The seed Se concentrations of selenate-treated plants were approximately 3.0–5.0 times those of selenite-treated plants. More than 99% of the Se accumulated in seeds of selenite- or selenate-treated plants was concentrated in rapeseed meal, with less than 1% of the Se being found in rapeseed oil. The application of selenite or selenate significantly reduced the erucic acid content and increased the oleic acid content of seeds. Applying S fertilizer on the basis of Se fertilizer further reduced the erucic acid content while increasing the oleic acid content of seeds. This study indicated that Se was accumulated mainly in the rapeseed meal of seeds in B. napus treated with selenite or selenate. Application of sulfur or sulfate in combination with Se fertilizer could significantly reduce the Se concentration while improving the quality of seeds in B. napus.