Showing papers in "Environment control in biology in 2002"
Journal Article•
30 citations
TL;DR: It is hoped that by defining the primary chilling-induced lesions that cause the metabolic dysfunctions in warm climate plants that it will be possible to devise strategies to minimize the sensitivity of these crops.
Abstract: Many important agronomic species grown in temperate climates have been imported from warmer tropical and subtropical habitats. Unlike native temperate climate species, most plants from warm climate evolutionary origins have very little capacity to acclimate to cool much less freezing temperatures. Because the cool temperature sensitivity of these crops plays a central role in determining the growing range as well as annual variations in their economic success, there is intense interest in discovering the mechanistic bases for low temperature sensitivity. It is hoped that by defining the primary chilling-induced lesions that cause the metabolic dysfunctions in warm climate plants that it will be possible to devise strategies to minimize the sensitivity. However, the relevant physiological bases of chilling sensitivity depends critically on the seasonal climatic conditions of the target growing region, whether the low temperature episodes occur at night or in the light, as well as on the species of warm climate plant under consideration. These issues are considered in the context of what is currently understood about the underlying mechanisms of chilling sensitivity.
22 citations
TL;DR: It is concluded that salinity was essentially a form of water stress, and that the resultant improvement of fruit quality and prevention of fruit cracking would be caused by the inhibition of water influx into the fruit.
Abstract: Effects of salinity stress at various fruit development stages from flowering to harvest on yield and fruit quality were investigated in single-truss tomato plants grown in hydroponics. Salinity stress was imposed by applying the concentrated drainage (EC 5.0 dS m-1) instead of the standard solution (EC 1.2 dS m-1) . Rates of water uptake and leaf photosynthesis were significantly inhibited by salinity at various growth stages. The earlier the salinity stress was applied, the lower the fruit weight and the higher the soluble solids content. Fruit fresh weight was severely decreased by salinity, whereas, fruit dry weight was less affected. When salinity was applied too early, there was a high rate of occurrence of blossom-end rot. Salinity stress beginning several days before harvest markedly prevented fruit cracking. From these results, we concluded that salinity was essentially a form of water stress, and that the resultant improvement of fruit quality and prevention of fruit cracking would be caused by the inhibition of water influx into the fruit. In single-truss tomato system, growers can easily produce various tomato fruit with different sizes and soluble solids contents by varying the time of application of the concentrated nutrient solution.
14 citations
TL;DR: In this paper, a comparison of the mass spectra of synthetic (PEG, PMMA, PS, PDMS) and bio-polymers (neutral cyclic and acyclic, sulfated and basic mono-and polysaccharides) using nor-harmane and gentisic acid (GA) as UV-MALDI-TOF-MS matrices in positive and negative ion modes in linear, reflectron and post-source decay (PSD) modes was made.
Abstract: 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 of synthetic (PEG, PMMA, PS, PDMS) and bio-polymers (neutral cyclic and acyclic, sulfated and basic mono- and polysaccharides) by using nor-harmane and gentisic acid (GA) as UV (337 nm) -MALDI-TOF-MS matrices in positive and negative ion modes in linear, reflectron and post-source decay (PSD) modes. The majority of the examples discussed shows nor-harmane working better as matrix than GA. This peculiarity is quite noticeable in negative ion mode. Because the initiation of the UV-MALDI process is a photochemical reaction (matrix+hν (337 nm) → matrix), the acid-base character of nor-harmane in the ground and the lower electronic excited singlet state, together with other photophysical properties are discussed in brief. Excellent results obtained with commercial synthetic polymers and commercial 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.
13 citations
TL;DR: Overall, there is support that, to some extent, plants behave like “hydraulic machines” and that water flow within plants may be described by just a few physical principles.
Abstract: A sufficient balance in the supply and loss of water is an important prerequisite for the occurrence, growth and productivity of plants. For a higher plant, the water balance is given by the difference between water uptake across the root and water losses by transpiration in the shoot. Much is known about the mechanisms used by plants to minimize water losses across stomata. For technical reasons, much less is known about the input side of the balance, i.e. about the regulation of water uptake from the soil. Results are summarized on water uptake in great detail (cell, tissue, organ, and whole plant levels) . Experimental findings result in models of the water transport across roots which incorporate molecular mechanisms, i.e. the gating of water channels (aquaporins) by different external and internal factors. The recent criticism of the cohesion theory of the ascent of sap in plants is discussed. Recent results support the theory. They show that the evidence gainst the theory was based on artifacts. Overall, there is support that, to some extent, plants behave like“hydraulic machines”and that water flow within plants may be described by just a few physical principles.
12 citations
TL;DR: In this article, the effects of NaCI addition to the nutrient solution on the activities of acid and neutral invertases (AI and NI) (EC 3.2.1.13) of cucumber (Cucumis sativus L. cv. No. 5) fruits were studied.
Abstract: Effects of NaCI addition to the nutrient solution on the activities of acid and neutral invertases (AI and NI) (EC 3.2.1.26) and sucrose synthase (SS) (EC 2.4.1.13) of cucumber (Cucumis sativus L. cv. Asomidori No. 5) fruits were studied. In spring of 1992, cucumber plants were grown with solution culture in a greenhouse. The aeration rate of the solution was kept low. Sixty millimolar NaCI was added to the solution when 10th leaf was expanding. In control fruits, AT activity was fairly constant until 7 d after anthesis. On the day of anthesis, AT activity at 60 mM NaCl tended to be higher than control. At 60 mM NaCI, AT activity tended to be higher in the proximal half than in the distal half of a fruit. In control fruits, SS activity declined as fruits grew. SS activity tended to be lower in fruit at 60 mM NaCI. The developmental changes in the activities of AT and SS tended to be different between pollinated and parthenocarpic fruit. The activity of NI was much lower than those of AT and SS.
11 citations
TL;DR: The system described features generalized functions for process control, configurable to meet greenhouse control requirements and is equipped with an on-line process optimization tool, which was built based on a modified search algorithm with accelerated learning.
Abstract: Greenhouses are complex systems with many variants and many different user requirements. Modern technologies are cost effective and very powerful to meeting diverse user control and management requirements. Optimization tools are making analytical and expert methods practically applicable. The system described features generalized functions for process control, configurable to meet greenhouse control requirements. Intelligence is shared among low level control loops in the controller and high level decisions made at the central process computer. An open Knowledge Based System, in the form of tasks and subtasks, provides an elegant way of rapid program development. Fuzzy decisions and fuzzy controllers at the supervisory level can provide adaptive reference (set-point) generators, which are key elements for near-optimal greenhouse control. The system is also equipped with an on-line process optimization tool, which was built based on a modified search algorithm with accelerated learning. Each process when entered under the optimizing monitor, is performance driven, conducts real experiments on the site and uses a modified descent method to maximize performance. An adaptive system guides the selection of control parameter values on-line, in a process searching for the global minimum of the cost function. This paper presents the general features of the system, how it can be set-up to achieve specific goals and presents results of tests conducted for low, medium and high level control and supervision.
9 citations
TL;DR: In this article, continuous measurements of solar radiation (Rs), net radiation (Rn), and photosynthetically active radiation (PAR) were conducted in Kohn Kaen, Northeast Thailand characterized as dry-and-wet tropics over 4 years (RsandRn) and a year (PAR).
Abstract: Continuous measurements of solar radiation (Rs), net radiation (Rn) and photosynthetically active radiation (PAR) were conducted in Kohn Kaen, Northeast Thailand characterized as dry-and-wet tropics over 4 years (RsandRn) and a year (PAR) . Monthly mean solar radiation was more than 15 MJ m-2over a year with its minimum occurring in dry season. Monthly mean net radiation in the dry season was a half of that in the rainy season. On daily basis, PAR/Rs-ratio changed from 1.81μmol MJ-1in January to 2.08μmol MJ-1in July. Equations for converting instantaneous and daily solar radiation to PAR were empirically derived with daily mean water vapor pressure as a parameter.
9 citations
TL;DR: Results indicated that under low N supply, the growth rates of the local varieties were higher than those of the improved varieties due to their higher NAR and NUR.
Abstract: Appropriate and effective nitrogen (N) use is an important factor to realize the sustainable rice production and to avoid environmental pollution. In this study, the low N conditions were induced by two different treatments; the restricted supply of N fertilizer by soil culture and the sudden depression of N by water culture. The growth responses of eight varieties of indica rice to low N supply were analyzed using fundamental growth parameters and specific nitrogen utilization rate (NUR) . The relative growth rate (RGR) was generally higher in the local varieties than improved varieties in both experiments. The net assimilation rate (NAR) showed a close correlation with RGR, whereas the specific leaf area and leaf weight ratio did not. A highly positive correlation was found between RGR and NUR. Among the local varieties, Pokkali showed the highest RGR, NAR and NUR in both experiments. These results indicated that under low N supply, the growth rates of the local varieties were higher than those of the improved varieties due to their higher NAR and NUR.
9 citations
8 citations
TL;DR: Findings suggest phosphorylation process may not be the major regulatory mechanism in pineapple PEPC, and in vivo sensitivity to inhibition by L-malate of phosphoenolpyruvate carboxylase is investigated for two CAM plants Kalanchoe pinnata and pineapple.
Abstract: The in vivo sensitivity to inhibition by L-malate of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) in rapidly prepared crude extracts (within 2 min) was investigated for two CAM plants Kalanchoe pinnata and pineapple (Ananas comosus (L.) Merr. cv. Smooth-cayenne N67-10) . The phosphorylation process may not occur in pineapple PEPC. Variations were also observed in apparent kinetic properties and molecular mass as well as subunit composition of PEPC from these plants. Two different subunits (major polypeptide 112 kDa and minor polypeptide 119 kDa) were separated from day and night forms of PEPC from K. pinnata but only one identical subunit (107 kDa) from pineapple. The integrity of both forms of in vivo PEPC from these plants was demonstrated by Western blot analyses using anti-N-terminus antibody. K. pinnata lost malate sensitivity about 87% whereas pineapple PEPC lost only 21% sensitivity at night in the presence of 2 mM L-malate. The apparent Ki (L-malate) was 6.4-fold higher in phase I (5.8 mM) than that in phase III (0.9 mM) from K. pinnata but it was only 1.0 and 0.5 mM for day and night PEPC respectively from pineapple. These findings suggest phosphorylation process may not be the major regulatory mechanism in pineapple PEPC.
TL;DR: A rapid translocation of photosynthate from bundle sheath cells to the phloem in grasses with C4-MS type (NADP-ME) may contribute to maintain their high performances in photosynthesis and WUE through shorter IVD.
Abstract: The gas exchange rates of C3- and C4-grass leaves at low and high vapor pressure difference (VPD) conditions were measured and demonstrated the effects of anatomical and morphological features of the leaves, i.e. stomatal frequency and size and interveinal distance (IVD), on gas exchange characteristics. When the photosynthesis type was ignored, there was a positive correlation between stomatal frequency and stomatal conductance. However, there was less significant correlation between stomatal frequency and transpiration rate when plotted species within the same photosynthetic pathway. There was a negative correlation between stomatal frequency and net photosynthetic rate, suggesting that CO2 diffusion process from ambient to intercellular space was not much affected by the stomatal morphology, instead that a consequence of biochemical differences in photosynthetic characteristics of the mesophyll was more important. An increase in IVD significantly decreased net photosynthetic rate and water use efficiency (WUE) . In addition to the regulation of CO2 concentrating mechanism in Kranz cells of the C4 subtypes, a rapid translocation of photosynthate from bundle sheath cells to the phloem in grasses with C4-MS type (NADP-ME) may contribute to maintain their high performances in photosynthesis and WUE through shorter IVD.
TL;DR: In this article, the authors give an overview about the biological control of net carbon fluxes, ranging from gross primary productivity, GPP (photosynthesis), and net primary productivity (plant growth), to net ecosystem productivity, NEP (CO2 assimilation minus heterotrophic respiration), including non-respiratory losses, such as harvest and fire.
Abstract: The Kyoto protocol and the agreement reached at Bonn requires an assessment of the net carbon balance at different scales, ranging from projects and nations to continents. In the following we give an overview about the biological control of net carbon fluxes. Depending on the processes under consideration, these range from gross primary productivity, GPP (photosynthesis), and net primary productivity, NPP (plant growth), to net ecosystem productivity, NEP (CO2 assimilation minus heterotrophic respiration), and net biome productivity, NBP, including non-respiratory losses, such as by harvest and fire. We give an overview about the quantification of these processes based on Europe and Siberia. The Kyoto commitment is focused on the woody component of NPP, which is in the order of 1 to 2 t C ha-1 year-1. But, if all respiratory and non-respiratory losses are considered, the NBP decreases to less than 0.5 t C ha-1 year-1. Given the uncertainty of the assessments, and the difference between NPP and NBP it appears questionable to include biological sinks into the carbon accounting of fossil fuel emissions.
TL;DR: In this article, a non-destructive evaluation method of water stress by measuring stem diameter (SD) was investigated by using a laser sensor at internode between the 2nd and the 3rd leaves of tomato plant during the growing period.
Abstract: In order to develop an irrigation control system for applying optimum water stress to produce high-Brix tomato fruits with restricted root-zone hydroponics, a non-destructive evaluation method of water stress by measuring stem diameter (SD) was investigated. SD was continuously measured by using a laser sensor at internode between the 2nd and the 3rd leaves of tomato plant during the growing period. Relative stem diameter (RSD) was used as an index of a water stress, which is calculated from a percentage of SD toward maximum stem diameter (MSD) . When RSD is 100%, there is no water stress. And if the RSD is smaller than 100%, an intensity of water stress is bigger. RSD indicated a diurnal change which decreased to less than 100% after the sunrise and recovered to 100% from the evening to midnight. With a substrate drying, the relationship between RSD and leaf photosynthetic rate (Pr) was expressed as linear regression lines with high coefficient of correlation. The positive correlation between RSD in one plant grown in cultivation bed and relative water content (RWC) of leaves in other plants was investigated, except for the harvesting time of the double-truss cultivation. These results indicate that RSD is useful for an evaluation of water stress as an index for irrigation control in tomato cultivation, while a time constraint should be concerned in evaluating water stress by RSD measured at same stem position.
TL;DR: In this article, the spectral ratio of B/photosynthetic photon flux (PPF) and R/PPF on clear days changed reversibly during the morning and in the evening; variability was less during the daytime.
Abstract: Photon flux (PF) in the spectral regions of 300-400 nm (UV), 400-500 nm (B), 500-600 nm (G), 600-700 nm (R) and 700-800 nm (Fr) were observed almost daily with a spectroradiometer (LI-1800) at noon in from Jan. 2000 to Mar. 2001 at Gifu (lat. 35°25' N and long. 136°46' E) . The spectral ratio of B/photosynthetic photon flux (PPF) and R/PPF on clear days changed reversibly during the morning and in the evening; variability was less during the daytime. Whereas G/PPF was almost constant during the whole studies period irrespective of fine or cloudy weather. The B/PPF ratio increased rapidly from 24.6% on the winter solstice to 27.1% on the vernal equinox. After reaching a peak of 27.3% on the first day of autumn, it decreased gradually from the autumnal equinox to the winter solstice. The seasonal changes in R/PPF showed opposite tendencies for B/PPF. This cycle of spectral photon flux probably assists plants in making a distinction between spring and autumn season. We found that the PPF as well as UV, B, G, R and Fr values were nealy equal in vernal equinox and autumnal equinox. The R/PPF ratio for the fine days was high and B/PPF was low in comparison with the cloudy days.
TL;DR: The results indicate that 1/2 strength is sufficient for high yield of bush snap bean and water and nutrient uptake increased with increasing nutrient levels.
Abstract: This study was conducted to determine the influence of nutrient solution levels on the growth, yield, mineral contents and some physiological characters of bush snap bean, and to determine their effects on water and nutrient uptake. The treatments used were 1/4, 1/2, 1, 11/2 and 2 times of the standard Enshi-shoho solution concentration. Increasing nutrient strength reduced vine length, but increased plant fresh and dry weights, leaf chlorophyll, photosynthetic rate, transpiration rate and stomatal conductance at flowering and early pod development stages. Water and nutrient uptake increased with increasing nutrient levels. N, P and K contents in the leaf blades and young pods increased while Ca and Mg decreased with increasing nutrient strength. Leaf blades had higher total-N, Ca and Mg contents, while pods did higher P and K. Percent pod set was slightly improved in 1/2 to 2-strength treatments. Pod yield was comparable among 1/2, 1, 11/2 and 2-strength treatments. The results indicate that 1/2 strength is sufficient for high yield of bush snap bean.
TL;DR: In this article, an experimental study has been conducted to investigate the effectiveness of this irrigation control system on characteristics of growth, yield and fruit quality of tomato plants, and the results suggested that amount of irrigation in L-SP was controlled with evapotranspiration rate under high intensity water stress.
Abstract: Irrigation control system using relative stem diameter (RSD) as the index of water stress was developed to stabilize a tomato production of high-Brix fruits by restricted root-zone hydroponics. This experiment has been conducted to investigate the effectiveness of this irrigation control system on characteristics of growth, yield and fruit quality of tomato plants. In this control system, irrigation starts when RSD is lower than the set point (SP) in the irrigation time period. Irrigation timing has been controlled with high SP (H-SP) and low SP (L-SP) in double-truss tomato cultivation by the hydroponics. As a result, RSD, amount of irrigation, plant height, leaf area, total fruit number and weight in L-SP were smaller than those in H-SP. However, Brix and acid content of tomato fruit in L-SP were higher than those in H-SP. Although a significant positive relationship was observed between evapotranspiration rate and amount of irrigation during growing period, the correlation coefficient in L-SP was higher than that in H-SP. These results suggested that amount of irrigation in L-SP was controlled with evapotranspiration rate under high intensity water stress and that application of optimum water stress by this irrigation control system was effective for the tomato production of high-Brix fruit.
TL;DR: Results show that propagation method using both SNC and SPB as propagules in the system reduces the electricity cost and shortens the multiplication period.
Abstract: Multiplication ratios (average number of harvestable propagules per stock plant) and electric energy consumption per harvestable propagule (single nodal cutting with an unfolded leaf, SNC) as affected by two propagation methods, propagation method using SNC only as propagules and propagation method using both SNC and stock plant base with an unfolded leaf (SPB) as propagules were investigated for sweetpotato (Ipomoea batatas (L.) Lam.) vegetative propagation in a closed transplant production system. Total number of harvestable propagules and electric energy consumption per harvestable propagule n multiplication cycles after the start of propagation (P (n) and Ep (n), respectively) were simulated for the two propagation methods, based on the results of the experiment : multiplication ratios were 1.8 and 3.7 for SNC and SPB, respectively, when a multiplication cycle was 12 d. P (10) were 89 to 197 times greater in the propagation method using both SNC and SPB than in the propagation method using SNC only. E (n) five or more multiplication cycles after the start of propagation in the propagation method using both SNC and SPB were reduced by 40% compared with those in the propagation method using SNC only. Results show that propagation method using both SNC and SPB as propagules in the system reduces the electricity cost and shortens the multiplication period.
TL;DR: It is suggested that there were large differences in adventitious shoot formation ability among these four cultivars of Sagagiku group, and that TDZ and CPPU were effective for shoot formation in some cultivar of chrysanthemum.
Abstract: Four cultivars of Sagagiku group in chrysanthemum were treated with different types of cytokinin to form adventitious shoots from leaf explants. The maximum adventitious shoot formation rate, 82.2%, was observed in the medium with 2.5×10-5 M of thidiazuron (TDZ), an urea-type Cytokinin, in ‘Ogura-nishiki, ’ followed by ‘Sagano-aki’ (56.7%) in the medium with 2.5×10-6 M of N- (2-chloro-4-pyridyl) -N'-phenylurea (CPPU), an urea-type cytokinin, ‘Sagano-yuki’ (12.2%) in the medium with 2.5×10-6 M of 6-benzylamino purine (BA), a purine-type cytokinin, and ‘Sagano-haru’ (1.3%) in the medium with 5.0×10-6 M of TDZ. Vigorous roots and significantly higher root formation rates were observed in the medium without 3-indolebutyric acid. In ‘Sagano-haru, ’ however, no roots were differentiated and died during root induction culture. These results suggested that there were large differences in adventitious shoot formation ability among these four cultivars of Sagagiku group, and that TDZ and CPPU were effective for shoot formation in some cultivars of chrysanthemum.
TL;DR: In this paper, the effects of shading at different growth stages (stage-I: vegetative to beginning of tuber initiation, stage-II: tuber initiation to initial tuber bulking and stage-III: bulking to maturity) on nitrate reductase (NR) activity, plant growth and yield of field grown potatoes (Solanum tuberosum L.; cv. May Queen and Dejima) under two levels of spacing were studied.
Abstract: The effects of shade (C: unshaded control, S1: 48% shading and S2: 76% shading) at different growth stages (stage-I: vegetative to beginning of tuber initiation, stage-II : tuber initiation to initial tuber bulking and stage-III : tuber bulking to maturity) on nitrate reductase (NR) activity, plant growth and yield of field grown potatoes (Solanum tuberosum L.; cv. May Queen and Dejima) under two levels of spacing were studied. Main stem length was increased by higher intensity of shading and denser plant spacing at all stages of growth. Denser plant spacing also increased the leaf area index (LAI). Shading at early stage delayed tuber initiation. Increasing shading intensity consistently decreased dry matter production and marketable tuber weight and decreased the tuber yield. The yield reduction was greatest (41%) in S2 plants at stage-II and smallest (15%) in S1 plants at stage-III. On an average (cultivar, spacing and growth stages) 19 and 30% yield reduction was observed for the reduction of 48 and 76% solar radiation, respectively. The NR activity in leaves decreased by shading. On an average, 16 and 25% reduction in NR activity was observed for the reduction of 48 and 76% solar energy, respectively. The reduction coefficient of yield or NR activity for light was 0.40 and 0.33 respectively for both levels of shade applied. From this study it could be concluded that shading at stage-II is very critical for tuber yield and is directly related to the reduction of NR activity and yield.
TL;DR: Variations in both light intensity and night temperature showed great effects on the Cymbidiumplants, and low night temperature promoted the development of leads, while low light intensity retarded lead development.
Abstract: The mericlonedCymbidiumLovely Angel‘The Two Virgins’is known among commercial growers as a difficult cultivar in which to induce leads. At Yatsugatake Experimental Farm, Yamanashi Agricultural Experimental Station (Takane, Kitakoma, 955 m elevation), we studied the effects of autumn and winter light and temperature management on the number of leads in this cultivar. Variations in both light intensity and night temperature showed great effects on theCymbidiumplants. Low night temperature promoted the development of leads, while low light intensity retarded lead development. The number of leads was not correlated with obvious growth characteristics such as the number of leaves or leaf length.
TL;DR: Bush snap bean cv.
Abstract: Bush snap bean cv. Torukatto was used to investigate the effects of root zone temperatures (RZTs) and N-K levels on the growth, abscissions of flowers and pods, pod production and mineral contents. The effects of RZTs were more pronounced than N-K supply on the vegetative as well as reproductive performance in this cultivar. RZTs at 20, 25 and 30°C enhanced plant growth while 35°C RZT reduced it producing plants with less vegetative growth of vine, greener leaves and smaller leaf area. Moreover, photosynthetic activity tended to increase with an increase in RZT up to 30°C in combination with either of the N-K levels. Higher number of pods was obtained from plants grown with 20, 25 and 30°C RZT. Increased total-N, Ca and Mg contents were observed in leaf blades while P was higher in the pods and K was similar in both organs. The results suggest that maintaining the root zone temperature within the range of 20 to 30°C may act more effective for growth performance regardless of N-K supply in the nutrient solution. High RZT of 35°C has an adverse effect on root growth that can lead to the death of root tissues.
TL;DR: The partitioning rate of total leaf N to the Rubisco-N was influenced most severely by low N supply among the N fractions examined.
Abstract: Nitrogen (N) fractions such as chloroplast, total soluble protein and ribulose-1, 5-bisphosphate carboxylase (Rubisco) in rice leaves were determined for 8 cultivars of indica rice at two N supply levels. The conversion rates from absorbed N to chloroplast-N ranged from 78 to 84%, and the rates depended not on the exogenous N levels but on the cultivars. The amounts of total soluble protein and Rubisco increased linearly with increasing leaf N content, and their correlation coefficients were significantly high. The proportion of total soluble protein-N to total leaf N was different among cultivars, and their values varied from 59 to 75% in the control plot and from 43 to 61% in the low N plot. The Rubisco-N accounted for about 24 to 45% of total leaf N in the control plot and varied from only 5.8 to 27% in the low N plot depending on cultivars. The partitioning rate of total leaf N to the Rubisco-N was influenced most severely by low N supply among the N fractions examined.
TL;DR: An overview of research on large-scale transplant production by somatic embryo culture and its control of environment is given, mainly for bioenvironmental and bioprocess engineers.
Abstract: Somatic embryogenesis has been recognized as the theoretically most effective method for micropropagation of transplants and the material of artificial seeds. The main advantages of somatic embryogenesis over axillary or adventitious shoot propagation are that the procedures of cutting plantlets into segments and transferring segments onto new media in the proliferation phase are not necessary. The main problems restricting the commercial application of somatic embryogenesis for plant micropropagation are poor productivity and quality of embryos produced in liquid culture. Induction of somatic embryogenesis in liquid culture using bioreactor systems offers opportunities for bioprocess automation and environmental control, and consequently is expected to reduce manual labor and costs. This review gives an overview of research on large-scale transplant production by somatic embryo culture and its control of environment, mainly for bioenvironmental and bioprocess engineers.
TL;DR: The thermal image system recognizing the position of the fruit with the preparation of the manipulator is necessary for the development of the robot automating for the harvesting of the tomato.
Abstract: Image system recognizing the position of the fruit with the preparation of the manipulator is necessary for the development of the robot automating for the harvesting of the tomato. When there is only one fruit, it is easy work, because the red color may be searched. Actually, there are many mature and immature fruits together on the branch. The quality deteriorates, when immature fruit is injured. It is important to harvest only the matured fruit without injuring another fruit. It is necessary to harvest from the fruit in the front, when there is a fruit in multiple conditions. The thermal image was utilized in order to recognize the mature and immature fruit. And, it was developed and was utilized by the new wire size reduction method in order to separate multiple fruits. As the result, it succeeded in the separation of the fruit.
TL;DR: In this paper, different volumes of nutrient solutions with a 2.4 dS⋅m-1 electric conductivity were supplied to control the leaching fraction (LF) at 0, 15 and 30% of the applied solutions.
Abstract: Cucumbers were grown in bag cultures with bark and peat medium to establish an appropriate administrative method of nutrient solution. Different volumes of nutrient solutions with a 2.4 dS⋅m-1electric conductivity (EC) were supplied to control the leaching fraction (LF) at 0, 15 and 30% of the applied solutions. The renewal frequencies in reservoir were set at zero or twice. The yield, leaf area, chlorophyll and N content of the leaves were greater in the 15 and 30% LFs than those in the 0%, with no difference between the 15% and 30% LFs. Solution renewal did not affect these parameters, EC and nutrient composition in the reservoir. The poor growth in the 0% LF could be ascribed to osmotic stress because the EC of the nutrient solution in the medium significantly increased. However, there were few differences in the nutrient accumulation inside the medium in all treatments. More than 20 to 40% of the nutrients, except for NH4-N, applied to the plants was discarded by the renewal. These results suggest that if EC 2.4 dS⋅m-1 was adopted for this growing system, more than a 15% LF should flow out to avoid an increased EC in the medium. The renewal of the nutrient solution in reservoirs is not beneficial for the increasing yield.
TL;DR: In this paper, the applicability of a simple evapolimeter devised to control irrigation based on evaporation rate (Ep) was investigated, which was composed of a combshaped water tank, which is assembled with polyvinyl chloride pipes (φ20 mm), and an evaporating disk made of φ200 mm non-woven fabric sheet.
Abstract: An accurate irrigation control system needs to be developed in order to improve the stability of high Brix tomato production under the moderate water stress by restricted root-zone hydroponics. In this paper, applicability of a simple evapolimeter devised to control irrigation based on evaporation rate (Ep) was investigated. The evaporimeter is composed of a combshaped water tank, which is assembled with polyvinyl chloride pipes (φ20 mm), and an evaporating disk made of φ200 mm non-woven fabric sheet. In this evaporimeter, Ep is evaluated as the difference of water levels in the water tank measured by an ultra sonic level sensor with the precision of 0.1 mm. The irrigation control system attached with this evaporimeter starts irrigation when the cumulative evaporation (ΣEp) exceeds the irrigation point (IP) of ΣEp during the irrigation period in the day and thus the higher IPs result in longer intervals of irrigation per ΣEp. Transpiration rate of tomato plants at the 6th leaf stage was more closely correlated with Ep than with photosynthetic photon flux density. A high positive correlation between the amount of irrigation and cumulative evapotranspiration was evident on a daily basis, except the early stages of cultivation. In tomato production with this irrigation control system, more than 9% Brix fruits were successfully harvested when the IP was adjusted to an appropriate level to optimize the water stress of plants.
TL;DR: In intermittent lighting with a 1-h light/23-h dark cycle, the succulent elongation and the reduction of photosynthetic rate were suppressed to some extent at a PPFD from 0.5 to 10 μmol m-2 s-1.
Abstract: We investigated the effect of dim light on the growth and photosynthetic ability of cabbage plug-transplants stored for 14 d at l0°C. Transplants stored in darkness were elongated succulently by etiolation, and their leaf chlorophyll content and photosynthetic rate decreased. Both intermittent and continuous lighting at a photosynthetic photon flux density (PPFD) of 10 μmol m-2 s-1 suppressed the succulent elongation. Longer photoperiod resulted in greater shoot elongation accompanied by dry matter deposition. The leaf chlorophyll content and photosynthetic rate in all lighting conditions remained higher than those in darkness. The photosynthetic rate in intermittent lighting was higher than that in continuous lighting. In intermittent lighting with a 1-h light/23-h dark cycle, the succulent elongation and the reduction of photosynthetic rate were suppressed to some extent at a PPFD from 0.5 to 10 μmol m-2 s-1. These results suggest that intermittent dim light could be used for preserving the quality of cabbage plug-transplants during low-temperature storage.
TL;DR: In the two cultivars (Cymb. Rose Wine‘Fruity Drop’ and Great Katty’) that were grown under shaded conditions for the period, their fresh weight was lower than the control's, especially the root's, which was more than 50% lower at 3 months after the low-light treatment.
Abstract: This experiment was carried out to determine the effect of low light intensity from May 15 to August 31 (3.5 months) on the growth of mericlonedCymbidiumorchid. In the two cultivars (Cymb. Rose Wine‘Fruity Drop’ andCymb. Great Katty‘Little Louransan’) that were grown under shaded conditions for the period, their fresh weight was lower than the control's, especially the root's, which was more than 50% lower at 3 months after the low-light treatment. The number of leaves and leaf length were also smaller even 1 year after treatment. In regard to leads, shadedCymb. Rose Wine‘Fruity Drop’ showed much reduced development of new lead, and the ratio of plants that developed no lead was also higher in comparison with the control. ForCymb. Great Katty‘Little Louransan, ’ the ratio of plants that developed new leads was not different between the treatment, but their growth was poorer in shaded plant.