In an effort to gain an understanding of the processes governing matrix-assisted ultraviolet laser desorption/ionization (UV-MALDI), we made a direct comparison of the mass spectra (MS) of carbohydrates (neutral cyclic and acyclic, sulfated and acid mono- and polysaccharides) by using nor-harmane and several classical matrices (gentisic acid (GA); 2,4,6-trihydroxixyacetophenone (THAP); among others) as UV-MALDI matrices in positive and negative ion modes in linear, reflectron and post-source decay (PSD) modes. The peculiarity of nor-harmane is that behaves better as matrix than GA in negative ion mode. Because the initiation of the UV-MALDI process is a photochemical reaction (matrix+hν (337 or 355 nm) → matrix*), the acid-base character of nor-harmane in the ground and the lower electronic excited singlet state, together with other photophysical properties such as prompt heat release to the medium are discussed in brief. Excellent results obtained with cyclodextrins with nor-harmane allow us to propose these analyte-matrix systems for UV-MALDI-TOF MS calibration in positive and negative ion modes in linear, reflectron and PSD modes.
Whole plant carbon exchange rate (CER) measurements provide an integral assessment of how an entire plant responds to biotic and abiotic factors. CER determination is based on measurements of CO2 uptake and release that can be determined using various types of systems including Closed, Semi-closed, and Open systems. This review focused on important design and operational considerations of Open CER measurement systems. Primary mechanical and biological factors that may influence measurement accuracy including chamber leakage, CO2 differential between air inlet and outlet of a chamber, chamber air humidity, canopy air speed, acidity of growth media, and irrigation water to name a few. Proper design and operation of a whole canopy photosynthesis system are necessary to assure accuracy of the CER measurements that may be used to assess both short-term responses and long-term yield of a plant as a result of given stimuli.
Qing-geng-cai (Brassica chinensis L., cv. Seitei) and spinach (Spinacia oleracea L., cv. Sunlight) seedlings were grown in plug trays at 3 planting densities and 2 air current speeds either in a closed transplant production system (CTPS) or in a greenhouse in which the air current speed was not controlled. The growth parameters such as dry mass, plant height, and leaf area; uniformity of qing-geng-cai; and growth of spinach seedlings decreased with the increase in planting density in the CTPS. At higher air current speeds, the growth of the qing-geng-cai seedlings decreased. However, the growth of the spinach seedlings was not affected by the air current speed. Based on these results, the differences in the extent of mutual shading and space in the seedling populations caused by the differences in canopy height and leaf angle appear to be responsible for differences in the effect of air current speed on the growth of seedlings of each species. The growth and uniformity of qing-geng-cai and the growth of spinach seedlings were greater in the CTPS than in the greenhouse. Based on the abovementioned results, we conclude that growth in the CTPS facilitates denser seedling production and shorter production period in comparison to that in the greenhouse.
Leaf lettuce (Lactuca sativa L. cv. Greenwave) was grown in combinatory environments of electric conductivity (EC) of nutrient solution and photosynthetic photon flux (PPF) to investigate their influence on fresh weight and leaf area in plantlet and fresh weight of leaf at harvest. The experiments were conducted under the combinations of three levels of EC, of 1.0, 2.0 dS m−1 and tap water and three levels of PPF of 50, 100 and 150 μmol m−2 s−1 to examine fresh weight and leaf area of plantlet. Although PPF had no influence on fresh weight grown in tap water, fresh weight significantly increased as PPF increased in nutrient solution of EC 1.0 and 2.0 dS m−1. Leaf area cultured in tap water decreased as PPF increased, however leaf area greatly increased as PPF increased in nutrient solution of EC 1.0 and 2.0 dS m−1. Plantlet grown under two levels of nutrient solution as tap water and EC 1.0 dS m−1 and three levels of PPF 50, 100 and 150 μmol m−2 s−1 were transplanted to hydroponic system with EC 2.0 dS m−1, PPF 200 μmol m−2 s−1, photoperiod 14 h and temperature 24°C to investigate the effect of condition at germination and raising seedling stages on fresh weight at harvest. Fresh weight of leaf lettuce showed similar tendency as fresh weight of plantlet, and it was found that EC of nutrient solution and PPF at the stage of germination and raising seedling significantly influenced fresh weight at harvest.
The phase responses of the circadian rhythm for a 2-h dark pulse under continuous red light in the transgenic Arabidopsis thaliana CCA1::LUC were investigated using bioluminescence technology. By application of a 2-h dark pulse at subjective dusk, a small phase advance was induced (about 2 h phase advance). In contrast, by the application of a 2-h dark pulse at subjective dawn, a phase delay was induced (about 4 h phase delay). The phase response curve (PRC) was categorized as type-1 PRC and was described by a sinusoidal curve with a second harmonic component. The internal fluctuation of the circadian rhythm under continuous red light was also investigated. In addition, the establishment of a model for the control of the circadian rhythm is discussed.
The chemical composition of grass is useful field information for grassland management. The objective of this study was to develop a field-scale system for estimating the chemical compositions of grass in meadows by using hyperspectral imaging. A hyperspectral imaging sensor was mounted on the roof of a vehicle, and hyperspectral images of a whole meadow field were acquired as the vehicle was driven. Models for estimating seven chemical compositions of grass (crude protein, acid detergent fiber, neutral detergent fiber, calcium, phosphorus, magnesium and potassium) were developed using multiple linear regression analysis (MLR), multi-layered neural network (MLNN) and partial least squares regression analysis (PLSR), and these estimation models were compared and discussed. An EI test to confirm the practical accuracy was conducted, and as a result, EI values ranged from 15.6 to 33.9, and the EI ranks were B or C, except for the MLNN models for Ca and P. Therefore, most of the estimation models were effective in estimating of chemical compositions. In conclusion, this study showed the possibility of field-scale estimation of the chemical compositions of grass by using the hyperspectral imaging system.
Pseudomonas fluorescens strain LRB3W1, a rhizobacterium isolated from lettuce, showed both an iron-chelating, siderophore activity and phytohormone indole-3-acetic acid production. Strain LRB3W1 was inoculated into the rhizosphere soils of 11 lettuce cultivars seedlings, resulting in increased growth of both shoot and root in most lettuce cultivars. A marked increase in growth was observed under iron-limiting conditions. Under high-iron conditions, growth of plants inoculated with the bacterium was not significantly increased. These data show that an iron chelator, siderophore, produced by the bacterium plays an important role in the growth enhancement of lettuce by the bacterium under iron-limiting conditions. Population dynamics of the bacterium in the rhizosphere was not influenced by the iron concentration.
The effect of pigmentation on superoxide disumtase (SOD), catalase (CAT), ascorbate peroxidase (APX) as well as ethylene production, carbon dioxide production, malondialdehyde (MDA) content, ascorbic acid (AsA) content, surface color, hardness, and weight loss on green mature tomato fruits (Lycopersicon esculentum Mill.) stored at 16°C (relative humidity of about 95%) were investigated. During post-harvest ripening, measurements were carried out when surface color was at green, yellow, orange, and red color stages. An increase in ethylene production during transition from yellow to orange stages compared to carbon dioxide production was found. Results indicated CAT activity significantly increased from green to yellow and orange color stages, however SOD and APX activities indicated no significant difference from green to yellow and orange color stages. At the red color stage, SOD, CAT and APX activities indicated lowest levels. The MDA as index of lipid peroxidation content indicated low at the red color stage.