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  • Author or Editor: Jun Li x
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Low mobility and solubility reduce the availability of traditional phosphorus (P) fertilizer in red acidic soil. Hydroxyapatite (HAP), especially nano-hydroxyapatite (n-HAP), may be more efficient than P fertilizer because of its nanoparticle characteristics. Camellia oleifera (C. oleifera) is an edible oil tree whose productivity is greatly affected by P fertilizer. During this study, we investigated the migration of different particle sizes of HAP (20 nm, 200 nm, and 80 μm) and their effects on the seedling growth of C. oleifera cultivar Huashuo (HS) cuttings. A column experiment showed that the efflux ratio was negatively correlated with particle size in red acidic soil. The leaching results revealed that the contents of total P and available P in the 20-nm treatment were significantly higher than those in the 200-nm and 80-μm treatments in the deep soil (10–15 cm or 15–20 cm), whereas the application of 20-nm n-HAP caused 13.43% wastage of available P. During the container experiments, 200-nm and 20-nm HAP significantly promoted the growth of the seedlings in terms of seedling height, stem diameter, and biomass. The available P contents in the rhizosphere and nonrhizosphere soils were negatively correlated with the HAP particle sizes. In conclusion, the migration of HAP is inversely correlated with particle size, and HAP improves the P bioavailability in red acidic soil. In summary, 200-nm HAP was the best P fertilizer for the seedlings of HS among the three particle sizes. This study offers preliminary results indicating that 200-nm HAP might be a better P fertilizer compared with other two HAP particle sizes for use in future C. oleifera orchards.

Open Access

Half or whole root systems of micropropagated `Gala' apple (Malus ×domestica Borkh.) plants were subjected to drought stress by regulating the osmotic potential of the nutrient solution using polyethylene glycol (20% w/v) to investigate the effect of root drying on NO3- content and metabolism in roots and leaves and on leaf photosynthesis. No significant difference in predawn leaf water potential was found between half root stress (HRS) and control (CK), while predawn leaf water potential from both was significantly higher than for the whole root stress (WRS) treatment. However, diurnal leaf water potential of HRS was lower than CK and higher than WRS during most of the daytime. Neither HRS nor WRS influenced foliar NO3- concentration, but both significantly reduced NO3- concentration in drought-stressed roots as early as 4 hours after stress treatment started. This reduced NO3- concentration was maintained in HRS and WRS roots to the end of the experiment. However, there were no significant differences in NO3- concerntation between CK roots and unstressed roots of HRS. Similar to the effect on root NO3- concentration, both HRS and WRS reduced nitrate reductase activity in drought-stressed roots. Moreover, leaf net photosynthesis, stomatal conductance and transpiration rate of HRS plants were reduced significantly throughout the experiment when compared with CK plants, but the values were higher than those of WRS plants in the first 7 days of stress treatment though not at later times. Net photosynthesis, stomatal conductance and transpiration rate were correlated to root NO3- concentration. This correlation may simply reflect the fact that water stress affected both NO3- concentration in roots and leaf gas exchange in the same direction.

Free access

Cold stress is one of the most important environmental factors affecting crop growth and agricultural production. Induced changes of gene expression and metabolism are critical for plants responding and acclimating to cold stress. Banana (Musa sp.) is one of the most important food crops in the tropical and subtropical countries of the world. Banana, which originated from tropical regions, is sensitive to cold, which can result in serious losses in commercial banana production. To investigate the response of the banana to cold stress conditions, changes in protein expression were analyzed using a comparative proteomics approach. ‘Brazil’ banana (Musa acuminata AAA group) is a common banana cultivar in southern China. ‘Brazil’ banana plantlets were exposed to 5 °C for 24 hours and then total crude protein was extracted from treatment and control leaves by phenol extraction, separated with two-dimensional gel electrophoresis, and subsequently identified by mass spectrometry (MS). Out of the more than 400 protein spots reproducibly detected, only 41 protein spots exhibited a change in intensity by at least 2-fold, with 26 proteins increasing and 15 proteins decreasing expression. Of these, 28 differentially expressed proteins were identified by MS. The identified proteins, including well-known and novel cold-responsive proteins, are involved in several cellular processes, including antioxidation and antipathogen, photosynthesis, chaperones, protein synthesis, signal transduction, energy metabolism, and other cellular functions. Proteins related to antioxidation, pathogen resistance, molecular chaperones, and energy metabolism were up-regulated, and proteins related to ethylene synthesis, protein synthesis, and epigenetic modification were down-regulated in response to cold temperature treatment. The banana plantlets incubated at cold temperatures demonstrated major changes in increased reactive oxygen species (ROS) scavenging, defense against diseases, and energy supply. Increased antioxidation capability in banana was also discovered in plantain, which has greater cold tolerance than banana in response to cold stress conditions. Therefore, we hypothesized that an increased antioxidation ability could be a common characteristic of banana and plantain in response to cold stress conditions. These findings may provide a better understanding of the physiological processes of banana in response to cold stress conditions.

Free access

Rhododendron delavayi Franch. is an important ornamental plant and often plays a role in natural hybridization with other sympatric species in Rhododendron subgenus Hymenanthes. Fifteen microsatellite loci were developed and characterized in this species. The average allele number of these microsatellites was four per locus, ranging from three to six. The ranges of expected (HE ) and observed (HO ) heterozygosities were 0.0365 to 0.7091 and 0.0263 to 0.9512, respectively. Cross-species amplification in R. agastum and R. decorum showed that a subset of these markers holds promise for congeneric species study. These sets of markers are potentially useful to investigate the genetic structure and gene flow of R. delavayi and other congeneric species.

Free access

Sea buckthorn (Hippophae rhamnoides) is an ecologically and economically valuable species that has been widely cultivated as a new berry crop rich in nutritional and medicinal compounds. RNA Sequencing (RNA-Seq) simple sequence repeat (SSR) markers were developed to evaluate the genetic relationships among 91 plants of 31 cultivars from two subspecies, mongolica and sinensis, as well as intraspecific hybrids between them. A total of 7540 RNA-Seq SSRs were identified as potential molecular markers, in which AG/CT (27.57%) was the most abundant unit type. AT/AT (9.93%), and AAG/CTT (11.95%) are the other main repeat motifs. A total of 110 primer pairs were randomly selected for validation of amplification. Seventeen SSR loci, located in genes encoding metabolic processes and cellulose synthases, were identified to be polymorphic among different sea buckthorn cultivars. These SSR loci generated 48 alleles, ranging from 2 to 5 per locus. Cluster analysis based on the proportion of shared alleles and unweighted pair group method with arithmetic average (UPGMA) algorithm divided all the genotypes into two main groups, with all of the ssp. sinensis cultivars (native to China) and hybrids in one group and ssp. mongolica cultivars (introduced from Russia) in the other group, which was in good agreement with their taxonomic classification. The RNA-Seq SSRs developed in this study have a potential use in the conservation of sea buckthorn germplasm and marker-assisted breeding (MAB).

Free access

Advancements in electronic devices have led to increases in mental stress in modern adults, and removing this stress is crucial for mental health. The purpose of this study is to examine the psychophysiological benefits of contact with indoor plants. The effects of transplanting plants (horticultural activity) and work on a mobile phone (control activity) were assessed by blood pressure measurement, electroencephalography (EEG), the semantic differential method (SDM), and the State-Trait Anxiety Inventory (STAI). The SDM data showed that the subjects felt more relaxed, comfortable and natural, and experienced lower anxiety after the transplantation of plants than the control group. Participant’s total alpha and beta wave mean values increased over time during the transplantation task but decreased at the end of the control task. The mean meditation score was significantly higher after transplanting plants. Our study results indicate that contact with plants may minimize mental stress.

Free access

Light, as the energy and signal sources for plant growth and development, is one of the most important environment factors in recently developed plant factories with artificial light (PFALs). To find the optimal combination of light wavelengths for lettuce (Lactuca sativa cv. ‘Tiberius’) plant growth in a PFAL, four treatments, each using red (R; 662 nm) and blue light (B; 447 nm) with a ratio of 4:1 and photon flux density (PFD) of 150 μmol·m−2·s−1, and mixing, respectively, with 50 μmol·m−2·s−1 of green light (G; 525 nm; RBG), yellow light (Y; 592 nm; RBY), orange light (O; 605 nm; RBO) and far-red light (FR; 742 nm; RBFR), were set up during this experiment. A combination of R and B with a ratio of 4:1 and PFD of 200 μmol·m−2·s−1 was set as the control (RB). The responses of lettuce growth, morphology, anatomical structure of the lettuce leaf, photosynthetic performance, lettuce nutritional quality, and energy use efficiency were investigated. The results showed that RBG, RBO, and RBFR increased the shoot fresh weight of lettuce by 20.5%, 19.6%, and 40.4%, and they increased the shoot dry weight of lettuce by 24.2%, 13.4%, and 45.2%, respectively, compared with those under RB. The Pn under RBY was significantly lower than that under RB, although no significant differences in chlorophyll or carotenoid content were found between RBY and RB. RBG increased the lettuce leaf area, the thickness of the leaf palisade tissue, Pn, and light use efficiency compared with those under RB. Plants grown under RBO showed better photosynthetic capacity, such as higher Pn, ΦPSII, and other photosynthetic parameters. RBFR caused an increase in lettuce leaf area and energy use efficiency, but a decrease in leaf thickness and Pn of the single leaf. Moreover, tipburn injury was observed under RBFR. Therefore, these results demonstrate that RBG and RBO can be considered optimal combinations of light wavelengths for lettuce growth in a PFAL in this experiment, although plant growth can also be improved by using RBFR.

Open Access

Although atmospheric evaporative demand mediates water flow and constrains water-use efficiency (WUE) to a large extent, the potential to reduce irrigation demand and improve water productivity by regulating the atmospheric water driving force is highly uncertain. To bridge this gap, water transport in combination with plant productivity was examined in cucumber (Cucumis sativus L.) grown at contrasting evaporative demand gradients. Reducing the excessive vapor pressure deficit (VPD) decreased the water flow rate, which reduced irrigation consumption significantly by 16.4%. Reducing excessive evaporative demand moderated plant water stress, as leaf dehydration, hydraulic limitation, and excessive negative water potential were prevented by maintaining water balance in the low-VPD treatment. The moderation of plant water stress by reducing evaporative demand sustained stomatal function for photosynthesis and plant growth, which increased substantially fruit yield and shoot biomass by 20.1% and 18.4%, respectively. From a physiological perspective, a reduction in irrigation demand and an improvement in plant productivity were achieved concomitantly by reducing the excessive VPD. Consequently, WUE based on the criteria of plant biomass and fruit yield was increased significantly by 43.1% and 40.5%, respectively.

Free access

The marginal soil temperature on the south side of a greenhouse remains at low temperatures in winter for long periods, which affects crop growth and land-use efficiency, it is of great significance to grasp the influencing factors of soil temperature change to improve the marginal soil temperature on the south side of the greenhouse. This study was conducted in at typical greenhouse in the cold and arid area of northern China and used the Grey Relational Analysis (GRA) method, the relational degree between the marginal soil temperature on the south side of the greenhouse and environmental factors under different lining structures was analyzed, and established the soil temperature transfer function. The results show that soil temperature had the greatest correlation with the soil humidity and air humidity inside and outside the greenhouse, and the second greatest correlation was the relation with the air temperature inside and outside the greenhouse and the outdoor soil temperature; the lining structure could effectively reduce the relation between soil temperature and humidity inside and outside the greenhouse. Polystyrene extruded board (PEB) had a greater degree of relational reduction than other lining materials in the test. Through verification analysis, the mean absolute error of soil temperature of 5 cm was less than 0.85 °C, the average absolute error of soil temperature at 15 cm was less than 0.57 °C, and the average absolute error of soil temperature at 25 and 55 cm was less than 0.2 °C. In conclusion, the constructed soil temperature transfer function could be used to predict the variation trend of soil temperature, and the PEB material lining structure had good thermal insulation.

Open Access