Ryuichi Suwa

PRESSURE SHOCKWAVES TO ENHANCE OIL EXTRACTION FROM JATROPHA CURCAS L

ABSTRACT Kinetic data regarding the intensity of maceration and subsequent pretreatment with pressure shockwaves (50 MPa to 60 MPa) are described in detail and evaluated statistically. Mass balances as well as the study on liquid environment are reported, allowing further process optimization according to financial aspects. It was verified on a laboratory scale by Soxhlet apparatus that oil extraction over 94% may be reached. Achieving such a high level of disintegration opens wide options for application of hydrolysis in order to break apart the remaining lignocellulose cell walls and access the last oil remaining in the vacuoles.

The use of underwater high-voltage discharges to improve the efficiency of Jatropha curcas L. biodiesel production.

Underwater high‐voltage discharges (3.5 kV) resulting in 4.9 kJ shock waves (50–60 MPa) were studied at the laboratory scale as a Jatropha curcas L. seed disintegration method. Grinding and macerating in an excess of methanol (3.5:1) was advantageous because methanol acts both as a liquid carrier for the pressure shock waves and as a solvent that increases the efficiency of oil extraction while remaining usable for esterification. The influence of the number of shock waves and the intensity of methanol maceration on the heat values of the pressed cake are stated in detail. Soxhlet extraction demonstrated that a greater than 94% oil extraction was achieved. The increased disintegration of vacuoles rich in oil was documented by surface area analysis, mineralization kinetics analysis, and electron microscopy. The working volumes were small, and the proportion of energy inadequate compared to the yields released; however, much can be improved by upgrading the process.

Effects of duration and combination of drought and flood conditions on leaf photosynthesis, growth and sugar content in sugarcane

Abstract Global climate change will result in extreme environments, such as droughts and floods. We investigated the individual and combined effects of droughts and floods of varying duration on sugarcane (Saccharum spp.) growth using a pot experiment under glasshouse conditions with the following six treatments: drought for 15 d, prolonged drought for 30 d, flood for 15 d, prolonged flood for 30 d, short flood followed by prolonged drought, and prolonged flood followed by prolonged drought. Plants that were subjected to drought conditions, including drought after a flood, had reduced CO2 assimilation (through stomatal closure) and leaf areas, whereas flood conditions showed no effect. During flooding, some roots died, and adventitious roots with well-developed aerenchyma appeared from the submerged nodes. At the time of harvest, there were no significant differences in stem fresh weight, sucrose content, or sugar yield between the treatments. However, ion content analysis revealed that flood conditions caused an accumulation of sodium in the bottom of stems and adventitious roots. Therefore, under flood conditions, plants may develop adventitious roots, which may offset the negative effects of root death, helping them to maintain their growth and yield.

Eclipse Effects on CO2 Profile within and above Sorghum Canopy

Abstract We analyzed the effects of a partial solar eclipse (22 July 2009) on microclimate including vertical gradients of CO2 concentrations ([CO2]), so called [CO2] profile, in a mature sorghum canopy. Together with CO2 measurement, major photosynthetic drivers of microclimate, light intensity, temperature and atmospheric H2O concentration ([H2O]) were also measured simultaneously at the same place and height. [CO2] at 6.0, 3.2, 2.1, 1.4, 0.7, 0 m above the ground (canopy height was 3.2 m) increased by 5.8, 4.8, 9.0, 7.8, 6.4, 7.6μmol mol-1, respectively, from 1 hour before the eclipse maximum to the eclipse maximum, during which theincident solar radiation above the canopy dropped by 1473 μmol photons m-2 s-1. However, it declined by 3.4, 10.6, 10.8, 6.0, 5.4, and 5.8μmol mol-1, respectively, from the eclipse to 1 hour later,during which the incident radiation increased by 1350μmol photons m-2 s-1. The [CO2] profile during the eclipse was uniform except for higher [CO2] near the ground. Comparative analysis of theeffect of light intensity on the microclimate during the eclipse-induced light decreasing phase (ELDP) and eclipse-induced light increasing phase (ELIP) revealed that [CO2], [H2O], temperature and relative humidity (RH) are significantly correlated with the light intensity above the canopy in a nearly linear fashion. Furthermore it indicated that detected less light-reacted canopy photosynthesis at a higher layer within the canopy during ELIP might be due to slower response of stomatal opening (than closing) to the light intensity above the canopy.

Effects of vertical gradient of leaf nitrogen content on canopy photosynthesis in tall and dwarf cultivars of sorghum.

Abstract The vertical profile of leaf nitrogen (N) content per unit leaf area (NLA) is important for increasing crop productivity via optimizing N use for canopy photosynthesis. To investigate the effects of plant height on the optimality, we analyzed the NLA profiles with respect to light gradient twice during vegetative growth in canopies of tall and dwarf cultivars of sorghum. The gradients of the NLA profiles relative to the light gradients were similar in the two cultivars although the vertical light gradient was steeper in the dwarf cultivar with doubled leaf area density (LAD). This suggests that light attenuation is more influential on the NLA profile than is plant height or LAD. The advantage of the observed NLA profile for the canopy CO2 uptake as compared to the uniform NLA profile was similar in the cultivars except when the N allocation rate to the canopy decreased relative to the leaf area expansion in the dwarf cultivar. These results suggested that the optimality of the advantage of the NLA gradient may not be directly influenced by the plant height, but by the balance between N allocation and leaf area expansion. The balance may be altered by the difference in the biomass allocation in the shoot between the tall and dwarf sorghum. These factors are to be taken into consideration in breeding programs that target stature in order to potentially increase production in sorghum. Key words:

Effects of Different Kinds of Potassium and Chloride Salts on Sugarcane Quality and Photosynthesis

Appropriate fertilizer management practices are important to improve sugarcane quality. We have ever reported that KCl and K2SO4 had different effects on sugarcane quality and that only excessive KCl application decreased sucrose concentration in juice, indicating that Cl− is the key factor for the quality improvement. In this study, to see the individual effects of Cl− independent of K+, we established treatments using different kinds of K+ and Cl− salts (50xa0mMxa0KCl, 25xa0mM K2SO4, mixture of 12.5xa0mM MgCl2 and 12.5xa0mM CaCl2, and 50xa0mM NaCl). The treatments did not greatly affect quantitative parameters. Plants treated with KCl and K2SO4 had significantly higher juice K+ concentrations. On the other hand, Cl− concentration was remarkably high only in the KCl treatment and the other Cl− salt treatments hardly enhanced Cl− accumulation, suggesting that Cl− needs K+ to be efficiently absorbed. Juice sucrose concentration was lowest in the KCl treatment, and the other treatments had no adverse effects. We observed neither declines of stomatal conductance nor Fv/Fm; however, the KCl treatment showed a slightly lower CO2 assimilation rate, which may have accounted for the sucrose reduction. From this study, we could not evaluate the single effects of Cl− but revealed that Cl− could have a negative impact on sugarcane quality only when K+ is supplied above sufficiency levels, so that we need to reduce K+ as well as Cl− concentrations to improve sugarcane quality.

Changes in photosynthesis, growth, and sugar content of commercial sugarcane cultivars and Erianthus under flood conditions

Abstract Sugarcane (Saccharum spp.) is an economical crop in the tropical and subtropical countries. However, because of global climate change, flooding has become problematic, particularly during the rainy season, in Thailand. We investigated the effects of floods on three commercial sugarcane cultivars, namely NiF8, U-thong 6 (UT6), and U-thong 9 (UT9), as well as Erianthus spp. Growth was assessed using a pot experiment in a glasshouse with two treatments: (1) control and (2) 60 d of flooding followed by 30 d of normal conditions. In comparison with control, during prolonged flooding, Erianthus showed greatly decreased CO2 assimilation, whereas NiF8, UT6, and UT9 showed slightly declined CO2 assimilation. Growth in plants subjected to 60 d of flooding was less influenced by floods while sucrose content was not affected except in UT6. During flooding, some roots died, resulting in plants compensating adventitious roots to offset the negative effects of root death and to assist them in maintaining their growth, which appeared from the submerged nodes, with different characteristics for each cultivar. However, 30 d after draining, roots remained damaged, while adventitious roots died, resulting in lesser growth as compared with the control, but it did not significantly affect sucrose content and sugar yield. This study suggests that sugarcane plants need to produce the adventitious roots to compensate their roots’ death during flooding and require time to recover their root system after flooding for obtaining the optimum yield and quality at harvest.