Phylloxera infestation and the uptake and distribution of 13C and 15N tracers in grape vines

In order to study the reason phylloxera (Daktulosphaira vitifolia Fitch) feeding on roots leads to decreased plant productivity, the uptake and distribution of 13C photosynthates and 15N in the grape vine 'Wuhe 8612' in response to phylloxera infestation were investigated. Phylloxera and grapevines cocultivated in pots were treated with 13CO2 and 15N-urea. The plant weight, nitrogen concentration and accumulation, 15N utilization efficiency, Nitrogen derived from fertilizer (Ndff%), and carbon isotope ratio (δ13C) of different organs were measured. Phylloxera infestation significantly reduced grape weight, shoot length, and N concentration and accumulation in different organs, whereas it increased the ratio between N content of the of roots and above-ground organs. Phylloxera infestation reduced leaf and root nitrogen 15N utilization efficiency, by 24 % and 14 %, respectively compared to controls. Labeled leaves of infested plants took up rather more 13C and 15N and exported a substantial amount of these nutrients to roots. Labeled roots took up rather more 15N and exported a small amount of these nutrients to upper leaves. This study found that phylloxera infestation reduced 13C and 15N uptake in leaves and roots, but increased N and photosynthates, which were mostly distributed to the roots, but also to the upper leaves. These factors together led to weak grape vine growth.

Comparison of cold hardiness in the leaves of various grape cultivars based on photochemical reflectance index

We compared cold hardiness in the leaves of 12 grape cultivars, including two wild species, two Vitis vinifera × V. labrusca, three HPDs (interspecific crosses) and five V. vinifera L. cultivars using PRI-T curves and analysis of variance (ANOVA). The photochemical reflectance index (PRI) of most grape leaves decreased linearly when frozen progressively in darkness, but these patterns varied. The PRI of diploid cultivars and blanc cultivars at the standard temperature (PRI 4°C) remained relatively steady during exposure to successively lower temperatures (0, -2, -4 and -6°C) compared with polyploid and noir cultivars, representing a boundary dividing grape cultivars into frost tolerant and vulnerable. According to this principle, which was tested by ANOVA, the cold hardiness of the four species was ranked (from high to low) as V. vinifera L. > HPD = wild species > V. vinifera × V. labrusca. The cold hardiness of the 12 cultivars was divided into three classes: Resistant: PRI increased markedly compared with the control, RPRI((PRI-PRIcontrol)/PRIcontrol) > 0 (p < 0.05), indicating high freezing tolerance and wide temperature adaption; Tolerant: PRI changed little compared with the control (p < 0.05), RPRI trended to 0, indicating relative stability when exposed to a short period of freezing temperatures; Vulnerable: PRI decreased dramatically compared with the control, RPRI < 0 (p < 0.05), indicating that photosynthesis was inhibited or damaged due to freezing. We also observed seasonal differences in the cold hardiness of the cultivars; grape leaves were more vulnerable to cold in fall than in spring. This study provides a practical method for estimating cold hardiness in grape

Preliminary study of regulation technology of wind field distribution on QTT site based on test of equivalent wind field

The effect of wind gust on the large reflector antenna is one of the main factors that can affect the antenna performance and therefore, this effect must be minimized to meet the strict performance requirement in the world largest steerable telescope, which is QiTai Telescope (QTT). In this paper, the characteristics of the topography as well as the wind distribution around QTT site have been analyzed and consequently, a technology for improving the wind distribution in an active way has been proposed. Additionally, an equivalent wind distribution test rig for the proposed technology has been built in the lab and the corresponding experiment has been carried out. The experimental data indicated that the proposed technology was a promising tool for regulating the wind distribution for the large reflector antenna and it was found that the proposed technology can significantly reduce the wind speed as well as the wind impact range after the wind regulation has been given in the test. The results in this paper has provided a solid foundation for the regulation of the wind distribution of the QTT site

Effects of Long-Term High Temperatures in the Root Zone on the Physiological Characteristics of Grapevine Leaves and Roots: Implications for Viticulture Practices

Ridging cultivation and root restriction cultivation are beneficial due to their improvement of the soil permeability in the root zone of grapevine, and they are widely used in southern China, Japan, and other countries. However, with the intensification of global warming, when using ridging or root restriction cultivation, the soil temperature in the root zone can often reach 30 °C or even more than 35 °C during the summer, which is not conducive to the growth of grapevines. The aim of this study was to explore the effects of high root zone temperatures on the photosynthetic fluorescence characteristics of grapevine leaves, root respiration, and degree of lignification of roots and shoots, as well as to provide a theoretical foundation for the management of grapevine production and cultivation. One-year-old potted ‘Kyoho’ was used as the study material. Three root temperature treatments were implemented for 15 days (9:00–16:00): 25 °C (CK), 30 °C (T1), and 35 °C (T2). The results showed that the malondialdehyde and H2O2 levels in leaves increased, while the chlorophyll content decreased. The oxygen-evolving complex was inactivated, and PSII donor and acceptor sides were blocked, thus reducing the photosynthetic gas exchange capacity at high root zone temperatures. The grapevine root activity and root/shoot ratio decreased. Simultaneously, the lignin content in the roots and shoots increased. In addition, there was a significant increase in the expression of key genes (PAL, C4H, 4CL, F5H, COMT, CCR, and CAD) in the root lignin synthesis pathway. Heightened root zone temperatures increased cyanide-resistant respiration in roots and heat release in the PPP pathway to alleviate stress damage. Therefore, it is recommended to use grass, mulching, and other cultivation management methods to maintain root zone temperatures below 30 °C in order to ensure the normal growth of grapevines and promote a high and stable yield

A New GM(1,1) Model Based on Cubic Monotonicity-Preserving Interpolation Spline

In the classical GM(1,1) model, an accumulated generating operation is made on the original non-negative sequence to obtain a monotone increasing 1-AGO sequence, and the forecasting model is established based on the 1-AGO sequence. A great number of scholars have improved the accuracy of grey model prediction through better developed background value and the equation for the time response. In this work, we reconstruct the background value based on a new developed monotonicity-preserving piecewise cubic interpolations spline, and thereby establish a new GM(1,1) model. Numerical examples show that the new GM(1,1) model has better prediction quality of data than the original GM(1,1) model and improves the precision of prediction in practice

‘Miguang’ Grape Response to Pergola and Single-Curtain Training Systems

Background and Aims: Grapevine shoot growth and light utilization are typically adjusted through the use of canopy management strategies that are adapted to the local climate. In this study, we analyze the effects of a pergola (PER) and single-curtain training system (SCT) on the microclimate, light interception, photosynthetic capacity, and assimilate distribution of ‘Miguang’ grape in a rainy region of China. Methods and Results: We measured light interception, spectral absorptance, leaf area, chlorophyll content, photosynthetic rate, soluble sugar and starch content per cane, assimilate distribution berry weight, soluble solids, and titratable acid content. SCT produced a higher photosynthetic photon flux density in the cluster region, a canopy light absorptance in the 450–800 nm wavelength range, higher chlorophyll content, and larger leaf area of the middle node leaves. It produced lower basal and top leaves leaf areas. At berry expansion (E-L-31) and veraison (E-L-35), the net photosynthetic capacity of the leaves from the base to the middle nodes was higher with SCT than with the PER, and the net photosynthetic capacity of leaves near the top was reduced with SCT. At the harvest period, the net photosynthetic rate of the middle and top node leaves and the shoot photosynthetic rate were higher with SCT than with the PER. The distribution of assimilates to the fruit was higher with SCT. In addition, SCT produced a higher shoot soluble sugar and lower internode length from the fourth to sixth nodes, and it produced a higher shoot starch content and internode diameter in the fourth internode. Conclusions: SCT significantly improved photosynthetic photon flux density in the cluster, promoted assimilate distribution to fruit, decreased vegetative growth, increased chlorophyll content, increased the leaf size of the middle node on the primary shoot, and increased shoot soluble sugar from the fourth to sixth nodes. Significance of this Study: The results of this study can provide a relevant theoretical basis and technical support for grape canopy management

Integrated mRNA and miRNA transcriptome analysis of grape in responses to salt stress

Salt stress is an important factor which may negatively affect plant growth and development. High concentrations of Na+ ions can destroy the ion balance in plant somatic cells, as well as destroying cell membranes and forming a large number of reactive oxygen species (ROS) and other damage mechanisms. However, plants have evolved numerous defense mechanisms in response to the damages caused by salt stress conditions. Grape (Vitis vinifera L.), a type of economic crop, is widely planted throughout the world. It has been found that salt stress is an important factor affecting the quality and growth of grape crops. In this study, a high-throughput sequencing method was used to identify the differentially expressed miRNAs and mRNAs in grapes as responses to salt stress. A total of 7,856 differentially expressed genes under the salt stress conditions were successfully identified, of which 3,504 genes were observed to have up-regulated expressions and 4,352 genes had down-regulated expressions. In addition, this study also identified 3,027 miRNAs from the sequencing data using bowtie and mireap software. Among those, 174 were found to be highly conserved, and the remaining miRNAs were less conserved. In order to analyze the expression levels of those miRNAs under salt stress conditions, a TPM algorithm and DESeq software were utilized to screen the differentially expressed miRNAs among different treatments. Subsequently, a total of thirty-nine differentially expressed miRNAs were identified, of which fourteen were observed to be up-regulated miRNAs and twenty-five were down-regulated under the salt stress conditions. A regulatory network was built in order to examine the responses of grape plants to salt stress, with the goal of laying a solid foundation for revealing the molecular mechanism of grape in responses to salt stress

Effect of Seawater Irrigation on the Sugars, Organic Acids, and Volatiles in ‘Reliance’ Grape

Ongoing climate change in recent decades exacerbated the decline in agricultural water use, and seawater irrigation could feasibly alleviate the shortage of water resources, which restricts viticulture in some countries. However, studies on the effects of seawater irrigation on grape volatiles are limited. Herein, ‘Reliance’ grapevines were irrigated with diluted seawater (10% concentrations) in the field since the pea-size berry stage (S1), stage EL 32 (S2), and the pre-veraison period (S3) every seven days. Results showed irrigation with seawater significantly increased the sugar content and decreased the organic acids when compared with the control berries. Seawater irrigation did not induce secondary soil salinization, and it enhanced the volatiles in the fatty acid and isoprene pathways without affecting the amino acid pathway aroma. More terpenes were found in seawater-treated berries, including citronellol, β-myrcene, α-terpineol, and trans-rose oxide. Gene profiling by RT-qPCR analysis revealed that VvLOXA could be the primary gene in C6 volatile biosynthesis altered by the seawater. Moreover, seawater irrigation during the pea-size period had the best effect on fruit quality. This work adds to our understanding of the effect of seawater irrigation on grape aroma quality and provides a sufficient basis for the utilization of seawater in vineyards