Salinity tolerance is an important physiological index for crop breeding.  Roots are typically the first plant tissue to withstand salt stress.  In this study, we found that the tomato (Solanum lycopersicum) trehalose-6-phosphate phosphatase (SlTPP4) gene is induced by abscisic acid (ABA) and salt, and is mainly expressed in roots.  Overexpression of SlTPP4 in tomato enhanced tolerance to salt stress, resulting in better growth performance.  Under saline conditions, SlTPP4 overexpression plants demonstrated enhanced sucrose metabolism, as well as increased expression of genes related to salt tolerance.  At the same time, expression of genes related to ABA biosynthesis and signal transduction was enhanced or altered, respectively.  In-depth exploration demonstrated that SlTPP4 enhances Casparian band development in roots to restrict the intake of Na⁺.  Our study thus clarifies the mechanism of SlTPP4-mediated salt tolerance, which will be of great importance for the breeding of salt-tolerant tomato crops.

Genetic improvement has promoted wheat’s grain yield and nitrogen use efficiency (NUE) during the past decades. Therefore, the current wheat cultivars exhibit higher grain yield and NUE than previous cultivars in the Yangtze River Basin, China since the 2000s. However, the critical traits and mechanisms of the increased grain yield and NUE remain unknown. This study explores the mechanisms underlying these new cultivars’ increased grain yield and NUE by studying 21 local cultivars cultivated for three growing seasons from 2016 to 2019. Significantly positive correlations were observed between grain yield and NUE in the three years. The cultivars were grouped into high (HH), medium (MM), and low (LL) grain yield and NUE groups. The HH group exhibited significantly high grain yield and NUE. High grain yield was attributed to more effective ears by high tiller fertility and greater single-spike yield by increasing postanthesis single-stem biomass. Compared to other groups, the HH group demonstrated a longer leaf stay-green ability and a greater flag leaf photosynthetic rate after anthesis. It also showed higher N accumulation at pre-anthesis, which contributed to increasing N accumulation per stem, including stem and leaf sheath, leaf blade, and unit leaf area at preanthesis, and promoting N uptake efficiency, the main contribution of high NUE. Moreover, tiller fertility was positively related to N accumulation per stem, N accumulation per unit leaf area, leaf stay-green ability, and flag leaf photosynthetic rate, which indicates that improving tiller fertility promoted N uptake, leaf N accumulation, and photosynthetic ability, thereby achieving synchronous improvements in grain yield and NUE. Therefore, tiller fertility is proposed as an important kernel indicator that can be used in the breeding and management of cultivars to improve agricultural efficiency and sustainability.

High-performance liquid chromatography (HPLC) was employed to determine drug release rates based on emamectin benzoate concentrations in the medium.  Release kinetics equations were used to fit the drug release behavior.  The effects of particle size and release medium pH on the release rate were also investigated.  The indoor toxicity of emamectin benzoate-loaded polylactic acid microspheres on the diamondback moth larva (Plutella xylostella) was studied to explore drug sustained-release performance.  In acidic and neutral media, the drug release behavior of the microspheres was in accord with the first-order kinetics equation.  Increasing the spray dosage of emamectin benzoate-loaded polylactic acid microspheres initially resulted in an equivalent insecticidal efficacy with the conventional emamectin benzoate microemulsion.  However, the drug persistence period was four-fold longer than that observed using the conventional formulation.  The developed emamectin benzoate-loaded polylactic acid microspheres showed dramatic sustained-release performance.  A treatment threshold of greater than 35 mg mL^–1 was established for an efficient accumulated release concentration of emamectin benzoate-loaded microspheres.

Soil aggregate stability and organic carbon (OC) are regarded as effective indicators of soil structure and quality. A longterm field experiment was established in 2006 to examine the influence of tillage systems on soil aggregation and OC in a sandy loam soil in the Huang-Huai-Hai Plain of China. The study involved eight treatments: plowing every year with (TS) and without residue (T), plowing every 2 years with (2TS) and without residue (2T), plowing every 4 years with (4TS) and without residue (4T), and no plowing with (NTS) and without residue (NT). In 2013, soil samples were collected at depths of 0–5, 5–10 and 10–20 cm, and separated into three aggregate-size classes: macroaggregates (>250 μm), microaggregates (53–250 μm) and the silt+clay fraction (<53 μm) using wet sieving method. Soil parameters measured were water-stable aggregates, geometric mean diameter (GMD), mean weight diameter (MWD) and OC concentrations in different aggregate- size fractions and in bulk soil. The tillage treatments significantly (P<0.05) influenced soil aggregate stability and OC distribution. Higher MWD and GMD were observed in 2TS, 4TS and NTS as compared to T. With increasing soil depth, the amount of macroaggregates and MWD and GMD values were increased, while the proportions of microaggregates and the silt+clay fraction were declined. The OC concentrations in different aggregate fractions at all soil depths followed the order of macroaggregates>microaggregates>silt+clay fraction. In the 0–5 cm soil layer, concentrations of macroaggregateassociated OC in 2TS, 4TS and NTS were 14, 56 and 83% higher than for T, whereas T had the greatest concentration of OC associated with the silt+clay fraction in the 10–20 cm layer. Soil OC concentrations under 4TS and NTS were significantly higher (P<0.05) than that of T in the 0–10 cm layer. Residue retention promoted formation of macroaggregates, increased macroaggregate-associated OC concentrations and thus increased total soil OC stock. The macroaggregate-associated OC was positively correlated (R2=0.96) with soil OC concentration, while the silt+clay fraction-associated OC was negatively correlated (R2=0.82) with soil OC concentration. The concentration of soil OC was positively correlated with MWD (R2=0.94) and GMD (R2=0.92). We concluded that increasing tillage intensity led to a loss of carbon (C)-rich macroaggregates and an increase of C-depleted silt+clay fraction. The conservation tillage system, especially NTS and 4TS, increased soil aggregate stability and promoted OC accumulation in macroaggregates, provided the potential to improve soil C sequestration and soil structure in the Huang-Huai-Hai Plain of China.

A preliminary screening for garlic viruses in garlic plants in Hunan, China, using existing monoplex (simplex) reverse transcription- polymerase chain reaction (RT-PCR) procedures detected four viruses/virus groups. These viruses/virus groups were Onion yellow dwarf virus (OYDV), Leek yellow stripe virus (LYSV), Shallot latent virus (SLV) and allexiviruses (e.g., garlic viruses A, B, C, D, E, X). Sequence analysis of the projected allexivirus amplicons revealed the allexivirus in the infected garlic plants was Garlic virus D (GarV-D), which shared 92–97% sequence identities with various isolates from the world. A multiplex RT-PCR (mRT-PCR) was therefore developed to simultaneously detect and differentiate the four viruses/virus groups. To achieve this, four primer pairs targeting allexiviruses, OYDV, LYSV and SLV were designed. The anticipated amplicon sizes are 183 bp (allexiviruses), 265 bp (OYDV), 404 bp (LYSV) and 592 bp (SLV), respectively. All primer pairs produced virus-specific fragments in both simplex and multiplex formats, thus confirming the efficacy of the newly developed mRT-PCR for detection of these viruses. The mRT-PCR further was evaluated by applying it to garlic plant samples collected in two geographic locations in Hunan. Allexiviruses, OYDV, LYSV and SLV were detected in 50.9, 40.3, 28.3 and 58.5% of leaf samples, respectively; and mixed infections with two or more viruses accounted for 54% of the garlic samples. The results obtained by mRT-PCR were confirmed by simplex RT-PCR assays. In conclusion, this newly developed mRT-PCR provides a rapid, sensitive and reliable method for the detection and identification of major garlic viruses.

The purpose of the present study was to survey contents of trace elements of Cu, Mn, Fe, and Zn in the surface layer (0-20 cm) in the soil, pasture and serum of sheep in Huangcheng area of Qilian mountain grassland, China. Also the soil-plant- animal continuum was analyzed. Soil (n=300), pasture (n=60), and blood serum samples from sheep (n=480) were collected from Huangcheng area of Qilian mountain grassland, China. The contents of trace element in the samples were analyzed by atomic absorption spectrophotometer after digestion. The soil trace elements density distribution shows a ladder-like pattern distribution. Equations developed in the present study for prediction of Fe (R2=0.943) and Zn (R2=0.882) had significant R2 values.

O3 is not only greenhouse gas but also a primary gaseous contaminant in the atmosphere. It has long-lasting effects on crop growth, yield and quality, and brings a series of ecological and environmental problems. A free-air controlled enrichment (FACE) system was applied to study the effect of elevated ozone concentration on activities of key enzymes of starch synthesis of Yangmai 16 in 2009-2010. The main-plot treatment had two levels of O3: ambient level (A-O3) and 50% higher than ambient level (E-O3). The main results were that accumulation rate of amylose, amylopectin and starch were represented in a single peak curve, and their content and accumulation amount rose gradually. The O3 elevation decreased the accumulation rate of amylose, amylopectin and starch amylase, reduced the accumulation amount of amylopectin and starch, and decreased the content of amylopectin and starch, but increased the content of amylose. With the increase of O3 concentration, the enzyme activity of grain granule-bound starch synthase (GBSS), soluble starch synthase (SSS) and starch branching enzyme (SBE) decreased after anthesis. The activities of GBSS and SSS had highly significant correlations with amylose, amylopectin and starch accumulation rate, and the activity of SBE had significant correlations with these items. So the O3 elevation decreased the activity of key enzymes of starch synthesis, which led to the variation of starch synthesis. Key words:

Phosphorus (P) is one of the most widely occurring nutrients for development and growth of wheat. In this study; the effects of P application amount on grain yield; protein content; and phosphorus use efficiency (PUE) were studied by agronomic management of P fertilizer on spring weak-gluten wheat (Triticum aestivum L.) grown under field conditions for  yr. The experiments were performed at five levels of PO application amount; including ; ; ; ; and  kg ha-. As a result; with increase in P fertilizer; grain yield; and P agricultural efficiency (AEP) increased in a quadratic equitation; but partial factor productivity of P (PFPP) decreased in a logarithmic eq. When  kg ha- PO was applied; the grain yield reached the highest level; but the protein content in gain was lower than .%; a threshold for the protein content to evaluate weak-gluten wheat suitable for production of cake and biscuit. Yangmai  and Ningmai  could tolerate to higher P level of soils than Yangmai  that had more loss in grain yield when P fertilizer was over-applied. AEP had a concomitant relationship with grain yield and was a better descriptor for P use efficiency in the wheat. A high P use efficiency resulted in leaf area index (LAI); increased chlorophyll content and photosynthetic rate; and stable acid phophatase (APase) activity to accumulate more dry matter after anthesis; which explained that the optimum P fertilizer increased grain yield and improved grain quality of weak-gluten wheat.