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Pea shoots is a popular vegetable in certain regions of the world due to their unique taste and abundance of health-promoting phytochemicals. The perishable nature and susceptibility to root rot of pea shoots necessitate a new soilless production system located close to the market. This study compared the growth of pea shoots using various cultivation methods in an LED plant factory. The results showed that early topping (4 days after transplanting, ET) promoted early harvest compared to later topping (20 days after transplanting, LT) and increased the number of harvested shoots by extending the harvest time to 2.8 times, ultimately resulting in a substantial yield improvement. Moreover, the yield of ET with a lower planting density (72 plants m−2, ET-LD) was 8.7% higher than ET with a higher planting density (126 plants m−2, ET-HD). Particularly, the average shoot fresh weight (AFW) under ET-LD exceeded that of ET-HD by 48.9%. It is advisable to consider adopting ET-LD for the cultivation of pea shoots in LED plant factories. Based on ET-LD, the yield, nutritional quality, and light use efficiency of pea shoots were further explored at different stages under three levels of light intensity (50, 100, and 150 μmol m−2·s−1). Contrasted against a light intensity of 50 μmol m−2·s−1, AFW, number of harvested shoots, and total fresh yield under a light intensity of 150 μmol m−2·s−1, increased by 60.2%, 62.8%, and 165.1%, respectively. Meanwhile, AFW, photosynthetic capacity, soluble sugar and vitamin C levels in leaves, as well as light use efficiency and photon yield, initially increased and then decreased with the extension of the planting period. Among these, soluble sugar, light use efficiency, and photon yield started to decrease after reaching the maximum value at 60–70 days after transplanting. In conclusion, a light intensity of 150 μmol m−2·s−1 with a photoperiod of 16 h d−1 using LEDs, combined with early topping within a planting period of 60–70 days, proves to be suitable for the hydroponic production of pea shoots in LED plant factories. [ABSTRACT FROM AUTHOR]

Porcine respiratory disease complex (PRDC), a respiratory disease caused by a variety of factors, is one of the most common problems in the intensive pig farms. To investigate the mixed infection incidence of wild‐type pseudorabies virus (WT PRV) and respiratory bacteria, a total of 1,293 clinical samples were collected from pigs with typical respiratory signs from 14 different provinces of China from September 2016 to February 2018. The WT PRV was detected by ELISA targeting gE antibody while the bacteria were detected by bacterial isolation and serotyping by PCR. The results revealed that the detection rate of A. pleuropneumoniae and B. bronchiseptica infection associated with WT PRV infection were 6.30% and 15.99%, respectively, which were significantly higher than those without WT PRV infection (3.41% and 4.41%) at the farm level (p <.05). There were no significant differences in the detection rate of H. parasuis, S. suis or P. multocida between WT PRV positive and negative farms (p >.05). However, the detection rate of attenuated H. parasuis and S. suis strains were 68.19% and 64.75%, respectively, in WT PRV infected farms, which were significantly higher than those (41.56% and 52.25%) in WT PRV free farms (p <.05). The prevalent serotypes of H. parasuis‐5/12 and S. suis‐2 were also investigated by multiplex PCR. These results indicated that the presence of WT PRV increased the chance of bacterial infection and the number of pathogenic strains in the respiratory system of pigs. Therefore, the eradication of pseudorabies is an effective approach to prevent and control the bacterial respiratory diseases in the intensive pig farms in China. [ABSTRACT FROM AUTHOR]

Many Dendrobium species are both ornamental and medicinal plants in China. Several wild species have been exploited to near extinction, and facility cultivation has become an important way to meet the great market demand. Most Dendrobium species have evolved into crassulacean acid metabolism (CAM) pathways in adapting to harsh epiphytic environment, leading to low daily net CO2 absorption. Photosynthetic pathways of many facultative CAM plants are regulated by various environmental factors. Light/dark cycle plays an important role in regulating the photosynthetic pathway of several CAM species. The aims of this study were to investigate whether the photosynthetic pathway of Dendrobium species could be regulated between C3 and CAM by changing light/dark cycles and the daily net CO2 absorption could be enhanced by shortening light/dark cycle. In this study, net CO2 exchange rates of D. officinale and D. primulinum were monitored continuously during two different light/dark cycles conversion compared to Kalanchoe daigremontiana as an obligate CAM plant. The net CO2 exchange pattern and stomatal behavior of D. officinale and D. primulinum were switched from CAM to C3-like by changing the light/dark cycle from 12/12 h to 4/4 h. However, this switching was not completely reversible. Compared to the original 12/12 h light/dark cycle, the dark, light, and daily net CO2 exchange amount of D. officinale were significantly increased after the light/dark cycle was changed from 4/4 h to 12/12 h, but those in D. primulinum was opposite and those in K. daigremontiana was not affected. Daily net CO2 exchange amount of D. officinale increased by 47% after the light/dark cycle was changed from 12/12 h to 4/4 h, due to the sharp increase of light net CO2 exchange amount. However, the large decrease of dark net CO2 exchange amount could not be offset by increased light net CO2 exchange amount, leading to reduced daily net CO2 exchange amount of D. primulinum. In conclusion, the 4/4 h light/dark cycle can induce the photosynthetic pathway of D. officinale and D. primulinum to C3-like, and improve the daily CO2 absorption of D. officinale. [ABSTRACT FROM AUTHOR]

In this study, spectral transmittances were measured in the wavelength range from 300 nm to 1100 nm of tomato leaves with different chlorophyll contents and compositions, and the correlations between the spectral transmittances and the contents of chlorophyll a, chlorophyll b and total chlorophyll were analyzed. With the characteristic wavelengths of 560 nm, 650 nm, 720 nm and the reference wavelength of 940 nm, nine sets of characteristic spectral parameters were obtained. According to the results of correlation analysis and regression model exploration, characteristic spectral parameters of T940/T560, T940/T650 and log (T940/T560) among the nine sets of parameters were highly correlated to the estimated contents of chlorophyll a, chlorophyll b and total chlorophyll of tomato leaves. The relative errors of total chlorophyll and chlorophyll a/b ratio were (5.1±3.7)% and (4.9±4.3)%, respectively. Therefore, the above three characteristic spectral parameters could be applied in the rapid non-destructive estimation of the contents of chlorophyll a, chlorophyll b and total chlorophyll as well as chlorophyll a/b ratio of tomato leaves. [ABSTRACT FROM AUTHOR]

Conventional light sources have been successfully used to cultivate a wide variety of horticultural crops. However, they are of limited use due to uncontrollability of spectra and energy inefficiency. Light-emitting diodes (LEDs) emerged with tremendous potential in controlled environment agriculture due to their energy efficiency, longevity, and spectral specificity, but the effects of different types of LEDs on plant growth and development must be examined. In this study, cucumber (Cucumis sativus L. cv. Zhongnong 26) seedlings were grown under four different lighting treatments that each delivered a photosynthetic photon flux density of 200 μmol/m2·s at plant canopy including triphosphate fluorescent lamps (TF), high-frequency fluorescent lamps (HF), white LEDs (WL), and red and blue LEDs (RBL). Cucumber seedlings were grown in a growth chamber at (25.0±1.5)°C with 12-hour light and 12-hour dark for 30 days after sowing, and data were subsequently collected. Seedlings grown under the WL were 45%, 12%, and 40% taller than those grown under the TF, HF and RBL, respectively. The leaf area was 23% smaller under the TF than under the HF. The shoot dry weight was 16%-22% lower under the TF than under the other lighting treatments. The transplants grown under the RBL had the lowest root dry weight and root to shoot ratio. The seedling quality index was similar among all the lighting treatments. The LEDs treatment yielded more total dry weight with unit electric power compared to the fluorescent lamps. The chlorophyll content was 13%-15% higher in plants grown under the HF and WL than that under the TF and RBL. Plants grown under the WL and RBL had greater photosynthetic rate, transpiration rate, and stomatal conductance than those grown under the TF and HF. It was concluded that high quality cucumber seedlings can be efficiently produced under the broad-spectrum WL that emit a reasonable amount of blue, green and red light, and the lack of green light and/or high ratio of red to blue light under the RBL may cause undesired plant attributes. [ABSTRACT FROM AUTHOR]

Many Dendrobium species are both ornamental and medicinal plants in China. Several wild species have been exploited to near extinction, and facility cultivation has become an important way to meet the great market demand. Most Dendrobium species have evolved into crassulacean acid metabolism (CAM) pathways in adapting to harsh epiphytic environment, leading to low daily net CO 2 absorption. Photosynthetic pathways of many facultative CAM plants are regulated by various environmental factors. Light/dark cycle plays an important role in regulating the photosynthetic pathway of several CAM species. The aims of this study were to investigate whether the photosynthetic pathway of Dendrobium species could be regulated between C3 and CAM by changing light/dark cycles and the daily net CO 2 absorption could be enhanced by shortening light/dark cycle. In this study, net CO 2 exchange rates of D. officinale and D. primulinum were monitored continuously during two different light/dark cycles conversion compared to Kalanchoe daigremontiana as an obligate CAM plant. The net CO 2 exchange pattern and stomatal behavior of D. officinale and D. primulinum were switched from CAM to C3-like by changing the light/dark cycle from 12/12 h to 4/4 h. However, this switching was not completely reversible. Compared to the original 12/12 h light/dark cycle, the dark, light, and daily net CO 2 exchange amount of D. officinale were significantly increased after the light/dark cycle was changed from 4/4 h to 12/12 h, but those in D. primulinum was opposite and those in K. daigremontiana was not affected. Daily net CO 2 exchange amount of D. officinale increased by 47% after the light/dark cycle was changed from 12/12 h to 4/4 h, due to the sharp increase of light net CO 2 exchange amount. However, the large decrease of dark net CO 2 exchange amount could not be offset by increased light net CO 2 exchange amount, leading to reduced daily net CO 2 exchange amount of D. primulinum . In conclusion, the 4/4 h light/dark cycle can induce the photosynthetic pathway of D. officinale and D. primulinum to C3-like, and improve the daily CO 2 absorption of D. officinale .