Yongchun Zhang

Preparation of a novel rape pollen shell microencapsulation and its use for protein adsorption and pH-controlled release

Abstract This study aims to synthesize hollow microspheres (HMS) from rape pollen via H3PO4 hydrothermal carbonization. The rape pollen hollow shell was used as the carrier and bovine serum albumin as a model protein. The properties of HMS were characterized by scanning electron microscope (SEM), solid-state nuclear magnetic resonance and elemental analysis. The SEM images clearly showed that the HMS had perfect spherical morphology and porous hollow surface. In the separated filtrate, a large number of sucroses were detected by high-performance liquid chromatography, suggesting that the hydrolysis of starch molecules occurred during the hydrothermal process. The formation of HMS was that the rape pollen inclusion was removed from rape pollen shell to preserve integral HMS by H3PO4 hydrothermal. The HMS possessed amphiphilic surfaces, which was suitable for protein adsorpion and pH-controlled release application.

Effect of water stress on dry mass accumulation and allocation in sweet potato based on stable isotope analysis

Zhang, H., Zhu, L., Zhang, C., Ning, Y. and Zhang, Y. 2015. Effect of water stress on dry mass accumulation and allocation in sweet potato based on stable isotope analysis. Can. J. Plant Sci. 95: 263-271. Pot experiments were conducted to study the effect of water stress on the dry mass accumulation, allocation, ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) activity and stable carbon isotope composition in sweet potato (Ipomoea batatas L.). Three water regimes (50, 75 and 100% field water capacity, respectively) were investigated. Water stress effects on dry mass accumulation, allocation, gas exchange, stable carbon isotope composition and Rubisco enzyme activity were detected in sweet potato at different stages (seedling, vegetative, early maturity, and late maturity). In addition, relationships between Rubisco activity and photosynthetic rate, dry stress allocation and Δ13C under different water regimes were explored. The allocation of dry mass and Δ13C in leaves, petioles, stems and roots exhibited highest level in soil with 100% moisture content at different growth stages. The photosynthetic rate, transpiration, stomatal conductance, and RuBisCo activity of sweet potato at different growth stages also increased with increasing soil water content. The regression equations between the activity of RuBisCo and photosynthetic rate in 50, 75 and 100% field capacity were y=0.675x - 1.846, y=0.798x - 1.370, and y=0.516x+3.887. A positive correlation between dry mass allocation and Δ13C was observed. Water stress could affect dry mass accumulation, allocation, gas exchange, RuBisCo activity, and Δ13C content in sweet potato organs during plant development stages.

The role of iron oxides in the preservation of soil organic matter under long-term fertilization

PurposeThe aim of this paper is to enlighten the role of highly reactive iron (Fe) minerals in soil organic carbon (SOC) preservation in soil aggregates.Materials and methodsThe effects of four long-term (37-year) fertilization regimes (NPK, chemical fertilization; NPKM, chemical fertilization + cattle manure; M, cattle manure; CK, non-fertilization control) on organic carbon (OC) stability, soil iron fractions in bulk soil, and soil aggregates were studied to characterize the capacity and mechanism of Fe minerals to preserve SOM in soil.Results and discussionLong-term fertilization significantly altered the Fe fractions in soil and soil aggregates. The two applications with manure (NPKM and M) increased the non-crystalline Fe content, while the chemical fertilizer (NPK) increased the crystalline Fe content. Besides, long-term fertilization with manure greatly increased the content of SOC and soil total nitrogen (STN). The non-crystalline Fe was positively correlated with the SOC content in both soil and soil aggregates. Meanwhile, the long-term fertilization treatments greatly changed the mass distribution and OC content of soil aggregates.ConclusionsLong-term manure fertilization promoted the formation of non-crystalline Fe fractions, which bounds to SOC to form soil macro-aggregates. Thus, the formation of SOC-Fe association in soil and soil aggregates plays a crucial role in SOC preservation.

Potassium starvation affects biomass partitioning and sink–source responses in three sweet potato genotypes with contrasting potassium-use efficiency

Rooted single leaves of sweet potato (Ipomoea batatas L.) produce and translocate photosynthates, thus representing an ideal model for characterising the source–sink relationships and responses to various environments. A hydroponics culture study was conducted with rooted single leaves of sweet potato to determine intraspecific variation in growth, biomass partitioning, and associated physiological changes in response to variable potassium (K) supply among genotypes Ji22 (low K-use efficiency), Nan88 (high K-uptake efficiency) and Xu28 (high K-use efficiency). Potassium deficiency suppressed biomass accumulation in blades, petioles and roots in all three genotypes. Root length of diameters <0.25 mm and 0.25–0.5 mm was significantly less for K-deficient than K-sufficient roots of all genotypes, but the difference was proportionally greater in the K-inefficient genotype Ji22 than the other two genotypes. Potassium deficiency also severely inhibited net photosynthesis of blades in Nan88 and Ji22, as well reducing photosynthate translocation, increasing starch, hexose and sucrose concentrations, and decreasing K concentration in blades. The genotypes varied in photosynthesis-related responses to the K deficiency. Xu28 had greater blade K concentration and net photosynthesis as well as stable maximum quantum yield of photosystem II (FV/FM, with FV = FM – F0) under K deficiency, possibly because of a better source–sink balance and more efficient translocation of photosynthates to roots and K to blade compared with genotypes Ji22 and Nan88. Impaired phloem loading during K deficiency was associated with a decline in photosynthetic rate and decreased carbohydrate supply from blades, resulting in restricted root growth.