Utilization of soil residual phosphorus and internal reuse of phosphorus by crops

The Impact of Various Organic Phosphorus Carriers on the Uptake and Use Efficiency in Barley

Organic phosphorus (OP) is an essential component of the soil P cycle, which contributes to barley nutrition after its mineralization into inorganic phosphorus (Pi). However, the dynamics of OP utilization in the barley rhizosphere remain unclear. In this study, phytin was screened out from six OP carriers, which could reflect the difference in OP utilization between a P-inefficient genotype Baudin and a P-efficient genotype CN4027. The phosphorus utilization efficiency (PUE), root morphological traits, and expression of genes associated with P utilization were assessed under P deficiency or phytin treatments. P deficiency resulted in a greater root surface area and thicker roots. In barley fed with phytin as a P carrier, the APase activities of CN4027 were 2-3-fold lower than those of Baudin, while the phytase activities of CN4027 were 2-3-fold higher than those of Baudin. The PUE in CN4027 was mainly enhanced by activating phytase to improve the root absorption and utilization of Pi resulting from OP mineralization, while the PUE in Baudin was mainly enhanced by activating APase to improve the shoot reuse capacity. A phosphate transporter gene HvPHT1;8 regulated P transport from the roots to the shoots, while a purple acid phosphatase (PAP) family gene HvPAPhy_b contributed to the reuse of P in barley.

Leaf nutrient resorption of two life-form tree species in urban gardens and their response to soil nutrient availability

Background

Leaf nutrient resorption is a key strategy in plant conservation that minimizes nutrient loss and enhances productivity. However, the differences of the nutrient resorption among garden tree species in urban ecosystems were not clearly understood, especially the differences of nitrogen resorption efficiency (NRE) and phosphorous resorption efficiency (PRE) between evergreen and deciduous trees.

Methods

We selected 40 most generally used garden tree specie belonged two life forms (evergreen and deciduous) and investigated the nitrogen (N) and phosphorus (P) concentrations in green and senesced leaves and soil nutrient concentrations of nine samples trees for each species. Then, the nutrient concentrations and resorption efficiency were compared, and the soil nutrients utilization strategies were further analyzed.

Results

The results showed that the N concentration was significantly higher in the green and senesced leaves of deciduous trees than in the leaves of evergreen trees. The two life-form trees were both N limited and evergreen trees were more sensitive to N limitation. The NRE and PRE in the deciduous trees were significantly higher than those in the evergreen trees. The NRE was significantly positively correlated with the PRE in the deciduous trees. As the soil N and P concentrations increased, the nutrient resorption efficiency (NuRE) of the evergreen trees increased, but that of the deciduous trees decreased. Compared with the deciduous trees, the evergreen trees were more sensitive to the feedback of soil N and P concentrations. These findings reveal the N and P nutrient resorption mechanism of evergreen and deciduous trees and fill a gap in the understanding of nutrient resorption in urban ecosystems.

Insight into phytase-producing microorganisms for phytate solubilization and soil sustainability

The increasing demand for food has increased dependence on chemical fertilizers that promote rapid growth and yield as well as produce toxicity and negatively affect nutritional value. Therefore, researchers are focusing on alternatives that are safe for consumption, non-toxic, cost-effective production process, and high yielding, and that require readily available substrates for mass production. The potential industrial applications of microbial enzymes have grown significantly and are still rising in the 21st century to fulfill the needs of a population that is expanding quickly and to deal with the depletion of natural resources. Due to the high demand for such enzymes, phytases have undergone extensive research to lower the amount of phytate in human food and animal feed. They constitute efficient enzymatic groups that can solubilize phytate and thus provide plants with an enriched environment. Phytases can be extracted from a variety of sources such as plants, animals, and microorganisms. Compared to plant and animal-based phytases, microbial phytases have been identified as competent, stable, and promising bioinoculants. Many reports suggest that microbial phytase can undergo mass production procedures with the use of readily available substrates. Phytases neither involve the use of any toxic chemicals during the extraction nor release any such chemicals; thus, they qualify as bioinoculants and support soil sustainability. In addition, phytase genes are now inserted into new plants/crops to enhance transgenic plants reducing the need for supplemental inorganic phosphates and phosphate accumulation in the environment. The current review covers the significance of phytase in the agriculture system, emphasizing its source, action mechanism, and vast applications.

A Novel High Temperature Resistant and Multifunctional Nitrification Inhibitor: Synthesis, Characterization, and Application

The industrialized nitrification inhibitors are not suitable for compound fertilizer fabrication through high tower melt granulation process due to their poor resistance to high temperature. In this paper, a novel high temperature resistant and multifunctional nitrification inhibitor (HTRMFNI) was synthesized. The HTRMFNI is a polymer product with the complex of silicic acid and 3,4-dimethylpyrazole (DMPZ) wrapped inside the polymer and the effective content of DMPZ is 0.484 wt %. The HTRMFNI presents good nitrification inhibitory performance and rapid phosphate-solubilizing ability. The decomposition temperature of HTRMFNI is ∼212 °C, satisfying the temperature requirements for the high tower melt granulation process. The fabricated compound fertilizer presents good nitrogen immobilization performance but loses the phosphate-solubilizing ability, possibly due to the damages of carboxyl functional group on the wrapping polymer by the high melting temperature. Moreover, the addition of HTRMFNI did not affect the physicochemical properties and the overall performance of the compound fertilizer.