A Fundamental Study on the Control of Glasshouse Plant Environment (2)

The increase in carbon dioxide in the atmosphere is one of the main causes of global warming. Remote sensing technology has become an important means of monitoring the distribution of carbon dioxide gas. By remotely monitoring the temporal and spatial distributions of atmospheric carbon dioxide, people can further deepen their understanding of the global carbon process. The GOSAT (Greenhouse Gases Observing SATellite) CO2 L4B concentration data from 2010 to 2015 were validated using local station atmospheric data. The spatial and temporal distributions of the carbon dioxide concentration and its variation characteristics were analyzed. Based on the total primary productivity data and human emissions of carbon dioxide data, the influencing factors of spatial variations in carbon dioxide were analyzed. The results show that: (1) The correlation coefficient between GOSATL4B data and ground-measured data is above 0.95, which indicates that the remotely acquired data have high precision and stability. (2) The spatial distribution characteristics of carbon dioxide at different atmospheric pressure heights are quite different. The variation in the long-term series mean of carbon dioxide concentration levels at 17 vertical heights was studied. The fluctuations in concentration changes at different height levels vary, and the closer to the surface, the greater the fluctuation is. The near-surface carbon dioxide concentration (975 hPa) has the largest fluctuation. When the atmospheric pressure is low (for example, 150 or 100 hPa), the high carbon dioxide concentration region is banded and concentrated near the equator. The trends in carbon dioxide concentration over land and sea surfaces are similar, and the common pattern is that the concentration of carbon dioxide has been increasing. (3) The near-surface carbon dioxide concentration (975 hPa) has clearly different spatial characteristics. There are four high-value centers across the globe: East Asia, western Europe, the US East Coast, and Central Africa. The concentration of carbon dioxide in the Northern Hemisphere near the ground is higher than that in the Southern Hemisphere. The fluctuation in the Southern Hemisphere is relatively small, and the trend is opposite that in the Northern Hemisphere. (4) The concentration of carbon dioxide showed a significant growth trend during the study period. By studying the change characteristics of the monthly global average at the 975 hPa level (approximately 300 m above sea level) from January 2010 to October 2015, it can be seen that the global CO2 concentration has been above 400 ppm for most of the year, and it is increasing each year. (5) Compared with the Southern Hemisphere, the cyclical changes in carbon dioxide concentration in the Northern Hemisphere are obvious and large, while the trend in the Southern Hemisphere is relatively stable, and the change is small. There are opposite trends in the cyclical changes in the carbon dioxide concentration in the Northern and Southern Hemispheres. When the carbon concentration in the Northern Hemisphere resides over the annual high-value area, the Southern Hemisphere has a low-value area of carbon dioxide concentration every year. In addition, the change in carbon dioxide concentration during the year is obvious with seasonal changes. This should be related to changes in vegetation phenology and different seasons in the Northern and Southern Hemispheres. (6) Four countries in East Asia (Korea, Mongolia, Japan and China) from 2010 to 2014 were selected to analyze the relationship between GPP (gross primary production) and near-surface carbon dioxide concentration. These two factors have a significant inverse correlation. When carbon dioxide is at a minimum, the GPP is at its peak, and when carbon dioxide reaches its peak, the GPP reaches a minimum. The above relationship fully indicates that terrestrial ecosystems play an important role as carbon sink contributors in the carbon cycle. (7) The relationship between atmospheric carbon dioxide and carbon dioxide data from human activities from the Global Atmospheric Research Emissions Database was analyzed. The former is significantly and positively correlated with carbon dioxide emissions caused by human activities, indicating that human activities are an important factor in the increase in carbon dioxide.

ASSIMILATION AND RESPIRATION OF EXCISED LEAVES AT HIGH CONCENTRATIONS OF CARBON DIOXIDE

Background. Soybean is one of the main oil and protein crops in the world, which occupies the largest cultivated area among legumes. However, adverse growing conditions, particularly salinity, can cause significant yield losses. It is known that salt stress affects morphological indices and physiological processes in soybean plants. Given the fact that the main factors contributing to the soybean-rhizobial symbiosis productivity are nitrogen fixation and CO2 assimilation, it is important to find ways to optimize these processes, in particular under salinity conditions. Materials and Methods. The research was conducted on symbiotic systems created with the participation of soybean plants (Glycine max (L.) Merr.) of the Samorodok variety and nodule bacteria Bradyrhizobium japonicum RS08 strain, cultivated with the addition of Ge and Mo nanocarboxylates. Results. It was revealed that salinity inhibited the activity of the symbiotic and photosynthetic apparatuses in soybean. With that, the degree of the symbiotic apparatus activity suppression under salinity conditions decreased over time. The addition of Ge nanocarboxylate to the inoculation suspension had a positive effect on the net CO2 assimilation rate in plant leaves under salinity at the bean-filling stage, and Mo – at all studied development stages. The transpiration rate closely correlated with the net assimilation rate, although the degree of its suppression by salinity was much less than that of photosynthesis. Positive correlations were found between nitrogen-fixing activity and the calculated net CO2 assimilation rate by the whole plant. A close positive correlation was found between the net assimilation rate at the bean filling stage and the grain productivity of soybean plants. At the same time, under inoculation with a suspension of rhizobia with the addition of Mo nanocarboxylate, the weight of the grain from the plant was the largest both among the control plants (without salinity) and among the salinity treatments. Conclusions. The obtained results indicate that, according to all investigated physiological parameters, inoculation of soybean seeds with Bradyrhizobium japonicum RS08 strain with the addition of Mo nanocarboxylate was the most effective in maintaining the activity of the symbiotic and photosynthetic apparatuses and, ultimately, grain productivity of plants both under normal conditions and under salinity.

Critical temperature for sub-lethal cold injury of strawberry leaves

Carbon assimilation at low carbon dioxide levels was measured on three Oryza specics (O. sativa L. cv. Toyonishiki, O. officinalis Wall, and O. meyriana Baill.), Brassica napus L. cv. Michinokunatane and Triticum aestivum L. cv. Konosu No.25. Measurements were made at two different oxygen concentrations; 140% and 21% (atmospheric pressure). An improvement in measurement device was made for ensuring an accuracy of the meter readings. That is, a recorder with a modulator was used to enlarge the differences in the carbon dioxide concentration; two- and five-fold for carbon dioxide levels above and below carbon dioxidc compensation point (gamma), respectively. It seems that HEATH and ORCHARD (1968) and HOLMGREN and JARVIS (1967) Changed the carbon dioxide concentration at large intervals, resulting in 3 to 5 measurements below gamma. Such a few measurements would obscure the statistics of the carbon dioxide exchangc rate at low carbon dioxide levels. The changes of carbon dioxide concentration in this experiment, however, were made at intervals of about 2 or 4 ppm from 0 ppm to gamma, resulting in 7 to 14 mean values below it. As the characteristics of carbon dioxide absorption at low carbon dioxide levels, GABRIELSEN (1948) proposed the 'threshold hyPothesis' in which gamma was regarded as a threshold value below which no assimilaton occurred, while HEATH and 0RCHARD (1968) postulated the existence of a 'third process', in addition to ordinary (dark) respiration and assimilation, which could be expected to have a different balance between respiration and assimilation. They denied the adoptation of the threshold hypothesis. From the prescnt experiment in which the carbon dioxide exchange rates were traced by Changing the Carbon dioxide concentrations at very small intervals, hwever, it appeared that the rate of carbon dioxide uptake at low carbon dioxide levels and atmospheric oxygen pressure tended to decrease toward 1/2 gamma carbon dioxide level, and the carbon dioxide uptake seems to cease and only the carbon dioxide release secms to occur below it. In case of measurements at 14% oxygen concentration the situation was similar to those at 2l% oxygen concentration, but a considerable decrease of the value of gamma. Thus, the process of carbon dioxide uptake at low carbon dioxide levels seems to imply the threshold hypothesis and 1/2 gamma seems to be an approximation of the threshold value. The assimilation rate is estimated as the ratio of carbon dioxide concentration differences between ambient air and assimilation center to the sum of diffusion resistances.As an estimate of carbon dioxide levels in the assimilation center in this formula, GAASTRA (1959) proposed zero, while BIERHUIZEN and SLAYTER (1964) adopted the Practise of using gamma to estimate it. From the results mentioned above, we could propose to use 1/2 gamma as its primary approximation because the photosynthetic center would be exposed to this carbon dioxide level but not absorb it.

Abstract. Gas exchange measurements were performed to test the hypothesis that failure of stomata to open in senescing leaves of Nicotiana glauca is caused by elevated concentrations of carbon dioxide in the intercellular spaces of leaf mesophyll tissue (ci). Senescing leaves selected for experiments were completely chlorotic and lacked positive rates of photosynthesis. When stomata in detached epidermis from senescing leaves were illuminated in CO2‐free air, they opened to similar apertures as those in detached epidermis from nonsenescing leaves. To compare the effects of changes in ci on stomatal responses of the two leaf types, leaf ‘flags’ of either nonsenescing or senescing leaves were illuminated at a photosynthetic photon flux density of 500 μmol m−2 s−1 in a gas exchange cuvette. Leaf temperatures were maintained at 23.5 ± 0.5°C, and vapour pressure differences between leaves and the air were maintained between 0.70 and 0.75kPa. Ci was adjusted by changing external concentrations of carbon dioxide in air circulating through the cuvette. Conductances and photosynthetic rates of nonsenescing leaves changed in response to changes in ci, but neither the conductances nor the photosynthetic rates of senescing leaves were affected significantly by changes in q. We conclude that guard cells of senescing leaves of Nicotiana glauca do not lose the capacity to respond to changes in carbon dioxide concentration and that increases in ci resulting from declining rates of mesophyll photosynthesis are not the sole cause of maintenance of stomatal closure during leaf senescence. The data suggest that factors external to guard cells may prevent them from responding to changes in carbon dioxide concentrations in intact senescing leaves.

Leaf gas exchange, temperature, and incident radiation were measured in situ for 20 mature trees of 12 deciduous species spanning a range of heights from 7.9 to 30.1 m and growing in the southern Appalachian Mountains. Air temperature, water vapor pressure, total radiation, photosynthetically active radiation, and carbon dioxide concentration were also measured. Estimated mean, light-saturated net assimilation rates ( micro mol m(-2) s(-1)) were: Quercus coccinea Muenchh. (10.3), Q. prinus L. (9.9), Q. rubra L. (8.9), Betula lenta L. (8.1), Liriodendron tulipifera L. (7.9), Q. alba L. (7.6), Carya glabra Mill. (7.2), Acer rubrum L. (5.6), Nyssa sylvatica Marsh. (3.9), Cornus florida L. (3.5), and Acer pensylvanicum L. (1.7). There were significant differences in both net assimilation rates and quantum yield efficiencies between species, with the understory species C. florida and A. pensylvanicum exhibiting lower net assimilation rates at saturation and higher estimated quantum yield efficiencies than the other species. Average temperature and light decreased from the canopy top to bottom, whereas ambient CO(2) concentration increased, and vapor pressure and vapor pressure deficits were inconsistent. We observed curvilinear effects of temperature and vapor pressure deficit on net assimilation response to light, and these effects varied by species. Errors in predicted net assimilation ranged from 1 to 3 micro mol m(-2) s(-1) under the environmental conditions prevailing during the study.

Effect of oxygen and carbon dioxide concentration upon the development of hematogenous metastases and transplants

Scientific evidence about the seriousness of the climate threat to agriculture is now unambiguous, but the ex- act magnitude is uncertain because of complex interactions and feedback processes in the ecosystem and the economy. Climate-related factors that would affect agricultural productivity in coming decades are: changes in temperature, precipitation, carbon dioxide (CO ), fertilization, short-term weather variability and surface water 2 run-off. Simulation of future climate in India under A2 scenario by IITM, Pune and Hadley Centre, UK, indicate that during the last quarter of present century the country will experience an increase in mean annual tempera- ture by 3-5C. Summer monsoon rainfall will increase by 20%, and extreme rainfall events would rise sharply in western and south-central parts. However, the arid western Rajasthan and the adjoining Punjab and Haryana will possibly experience notable decline in summer monsoon, and slight increase in winter rainfall, with pro- nounced variability in rainfall and fewer rainy days. Consequently, there will be higher incidence of droughts and floods in arid western India, affecting both rainy ( kharif) and winter ( rabi) season crops. Since a number of high- value crops are grown during the rabi, the negative impact on farmers economy would possibly be higher. Change in CO concentration too can show uncertainty in crop yields, but studies on the interrelationship be- 2 tween changes in rainfall, temperature and CO concentration and their effect on yield changes are quite few. 2 Adaptation and mitigation strategies to address the impact of climate change on agriculture are needed ur- gently through new research and proper interpretation of the accumulated research results from the decades of dryland research under different agro-climatic settings. Use of alternative crops or cultivars adapted to the likely changes, alteration in the planting date, and management of plant spacing and input supply might help in re- ducing the adverse impact. Use of resource-conservation technologies and a shift from sole cropping to diversi- fied farming system is highly warranted. Horticulture and agro-forestry need to be given more encouragement. Enabling policies on crop insurance, subsidies and pricing related to water and energy uses need to be strengthened at the earliest. Policies that would encourage farmers to enrich organic matter in the soil need emphasis. Also, it is necessary to develop a robust early warning system of spatio-temporal changes in weather as well as other environmental parameters. Contingency crop planning will require greater attention. Long-term strategic approaches to efficiently conserve and utilize rain water on the one hand and in-season tac- tical approaches to mitigate the adverse effects of weather aberrations on the other are also needed. Consider- ation of depletion rate of soil water is more important when the crops are grown primarily on stored soil water. Under such situations, wide rows and low plant populations are highly desirable. Water-conservation practices will become economically feasible when nutrient deficiencies are also corrected. Late onset of monsoon rains often leads to delayed planting and specific crop contingency plans have been developed for different agro-cli- matic zones to address the issue.

During each of the four years 1957-60 the growth of the carrot crops in a long-term manurial experiment was studied. Significant increases in the yield of roots were produced by the application of farmyard manure and of potassic fertilizer but not by the application of nitrogenous or phosphatic fertilizers. The mean annual yields, and the responses to the applications of FYM and K, varied considerably from year to year.The applications of FYM resulted in increases of 15-20% in the net assimilation rates and relative growth rates of the plants but these increases persisted for only 4-7 weeks when growth of the leaves on all plots was exponential. Subsequently net assimilation and relative growth rates of the plants on the FYM plots were slightly less than those on the no-FYM plots. It appeared that the initial differences in net assimilation rates were the main cause of the increased leafiness of the plants on the FYM plots, and hence of the increases in yields of roots.Year-to-year differences in the total weight of leaves produced were related mainly to differences in the amount of rainfall during their growth. Yearly variation in root yields, however, was related both to the amount and to the distribution of the rainfall during growth.The relative importance of variations in net assimilation rate and in leaf weight ratio are discussed.

Summary1. Stomata have been found to respond to small changes in carbon dioxide concentration within the leaf, and movements due to illumination, temperature, leaf‐water content, or metabolic inhibitors can be explained, at least in part, by their affecting the internal carbon dioxide concentration. This is confirmed by the fact that effects of such factors can be reversed experimentally by flushing the leaf with air of an appropriate carbon dioxide content. We conclude that changes in carbon dioxide concentration set in motion reactions affecting guard cell turgor relations (see 8 below).2. The photosynthetic production of carbohydrates, or of intermediates in their synthesis such as glycollic acid, does not seem to have any major effect on guard cell turgor, which can readily change in the absence of photosynthesis in darkness in response to different carbon dioxide concentrations. Factors which affect photo‐synthetic production ordinarily affect the internal carbon dioxide concentration and it is the latter which is more directly involved in changing guard cell turgor relations.3. In addition to the effects of environmental factors on carbon dioxide concentration, light (blue), temperature and leaf water content may also affect guard cells independently of carbon dioxide. Whether such effects are due to hydrolysis of starch or another polysaccharide, or to changes in permeability or quite another mechanism, is not known.4. As well as being effected by the environment, stomatal movements are under the control of endogenous rhythms in light and darkness. Rhythms can produce opening in darkness and partial closure in light, and hence can modify or overrule the response to external factors. However, the phase of the rhythm does come under the control of the environment through a low‐intensity light reaction sensitive to red and far‐red wavelengths. This light reaction is quite distinct from those directly concerned in the production of stomatal opening.5. Stomatal behaviour in cacti and other succulents is at first sight practically the opposite of that in other plants, in that they open at night and close during the day. We suggest that this type of behaviour may, however, be a relatively simple development from the normal pattern.6. Stimuli affecting the stomata can be transmitted within a leaf, or from one part of a plant to another. The mechanism of the transmission is not known, but it could be brought about by a chemical substance which is translocated.7. There is evidence that the processes of stomatal opening and closing are different in nature, and that one is not simply a reversal of the other. It is probable that an active (oxygen‐requiring) mechanism in involved in stomatal opening. Stomata come under the control of so many factors, both external and internal, that several processes are likely to contribute to the turgor changes which bring about their movements.8. The mechanism of carbon dioxide control over stomata is not known.

In many countries cacao (Theobroma cacao L.) is invariably grown as an understory crop in agroforestry types of cropping systems and subjected to low levels photosynthetic photon flux density (PPFD) due to presence of large number of upper story shade trees with poorly managed canopy structure. In recent years carbon dioxide concentration in the atmosphere is steadily increasing and it is unclear what impact this will have on performance of cacao grown under shade of upper story shade trees. A climatically controlled greenhouse experiment was undertaken to evaluate the effects of ambient and elevated carbon dioxide (400 and 700 μmol·mol-1) and three levels of PPFD (100, 200, and 400 μmol·m-2·s-1) on growth, and macro- and micronutrient use efficiency of three genetically contrasting cacao genotypes (CCN 51, VB 1117 and NO 81). Intraspecific variations were observed in cacao genotypes for growth parameters at ambient to elevated carbon dioxide and low to adequate levels of PPFD. With the exceptions of total root length and leaf area, irrespective of carbon dioxide and PPFD levels, all three genotypes showed significant differences in all the growth parameters. For all the cacao genotypes, increasing PPFD from 100 to 400 μmol·m-2·s-1 and carbon dioxide from 400 to 700 μmol·mol-1 increased overall growth parameters such as leaf, shoot and root biomass accumulation, stem height, leaf area, relative growth rate and net assimilation rate. Irrespective of carbon dioxide and PPFD, invariably genotypes differed significantly in macro-micronutrient uptake parameters such as concentration, uptake, influx, transport and use efficiency. With few exceptions, raising PPFD from 100 to 400 μmol·m-2·s-1 and carbon dioxide from 400 to 700 μmol·mol-1 increased nutrient use efficiency for all the cacao genotypes. Elevated carbon dioxide and adequate PPFD are beneficial in improving cacao growth and mineral nutrient uptake and use efficiency.

Seven C3 crop and three C3 weed species were grown from seed at 360 and at 700 cm3 m–3 carbon dioxide concentrations in a controlled environment chamber to compare dry mass, relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR) and photosynthetic acclimation at ambient and elevated carbon dioxide. The dry mass at the final harvest at elevated carbon dioxide relative to that at ambient carbon dioxide was highly correlated with the RGR at the lower carbon dioxide concentration. This relationship could be quite common, because it does not require that species differ in the response of RGR or photosynthesis to elevated carbon dioxide, and holds even when species differ moderately in these responses. RGR was also measured for a limited period at the end of the experiment to determine relationships with leaf gas exchange measured at this time. Relative increases in RGR at elevated carbon dioxide at this time were more highly correlated with the relative increase in NAR at elevated carbon dioxide than with the response of LAR. The amount of acclimation of photosynthesis was a good predictor of the relative increase in NAR at elevated carbon dioxide, and the long‐term increase in photosynthesis in the growth environment. No differences between crops and weeds or between cool and warm climate species were found in the responses of growth or photosynthetic acclimation to elevated carbon dioxide.

ABSTRACTA cheap CO2 enrichment system was designed to perform continuous gas exchange measurements of branches of mature European beech trees (Fagus sylvatica L.). Branches were grown at ambient (350 cm3 m‐3) and elevated CO2 (700cm3 m‐3) during the whole 1992 leafy period. Leaks resulting from airtightness defaults in the system appeared to be low enough to measure accurately net CO2 assimilation and transpiration rates during the day. However, the CO2 exchange rates during the night (respiration) were too low to allow accurate measurements. Elevated CO2 had a great effect on the net assimilation rate of branches via its influence on both the C3 photosynthetic pathway and the shade‐tolerance of beech trees (85% increase). The A/Ca curves showed no acclimation effect to high CO2, both control and enriched branches increasing their net assimilation in the same way. The decrease of net assimilation rates in mature leaves was similar for both control and enriched branches. The pattern of daily transpiration rates remained the same for both control and enriched branches, hence we can assume that there was no visible CO2 effect on stomata.

Prediction of the net assimilation and relative growth rates in four years’ experiments with young sunflower plants