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• The establishment of micropropagation protocol for Cameron Highlands White Strawberry. • High multiplication rate in full-strength MS medium + 8 µM TDZ. • No damage to the cellular arrangement was observed on the treated in vitro plants in any of the light treatments using scanning electron microscopy (SEM). • Maximum acclimatization efficiency in hydroponic solution (100% survival rate). White strawberry is botanically a member of the Fragaria genus, which is a part of the Rosaceae family, which is primarily found in Japan, where it is a well-known premium fruit. Experiments were conducted to develop a micropropagation method for Cameron Highlands white strawberries (Fragaria x Ananassa). Freshly extracted achenes were surface sterilised with 30 and 40% Clorox®. Achenes germination was studied in vitro under various light spectra [cool white LED (17.0 μ mol/s), red LED (29.30 μ mol/s), blue LED (15.70 μ mol/s), red + blue LEDs (44.80 μ mol/s)] to study how light and different LED spectra affected shoot, root, and leaf growths of seedlings in the culture. Because both treatments have a 0% contamination rate and the same germination rate which is 78.77%, the 30% Clorox® treatment was chosen as the best surface sterilisation protocol for white strawberry achene germination. Scanning electron microscopy (SEM) studies of seedlings germinated under various light treatments demonstrated that no damage to the cellular arrangement was observed in any of the light treatments. However, the stomata of seedlings treated with blue LED were found to be damaged and exhibit uneven structures. Shoot multiplication in the culture was determined by testing various concentrations of 6- benzylaminopurine (BAP) and thidiazuron (TDZ) using shoot tips (0.5 to 0.8 cm) from the 5-leaf stage of the in vitro plants. The highest mean number (6.50 ± 1.05) of shoots differentiated on MS medium with 8 µM TDZ. The regenerated plantlets were rooted on MS medium with indole-3-butyric acid (IBA) and 1-Naphthaleneacetic acid (NAA) at 0 (control), 1, 2, 3, and 5 µM. Rooting (50%) was the highest success with 1 µM IBA. All the rooted plantlets were successfully acclimatized using hydroponics and field transfer. [ABSTRACT FROM AUTHOR]

Young leaves of Artemisia princeps Pamp. (Japanese mugwort), already used as a foodstuff in Japan, can be positioned as a functional health food because of remarkably higher contents of chlorogenic acid and total polyphenol compared to common vegetables. To procure young leaves in demand on a yearround basis by hydroponic production in fully artificial lighttype plant factories, we investigated whether 24h photoperiod, known to enhance some beneficial constituents, could improve the growth and chemical constituents of Japanese mugwort plants grown hydroponically in a plant factory condition. As we previously demonstrated that lowering the nutrient solution concentration increased chlorogenic acid and total polyphenol contents of the leaves without reducing the growth, plants were cultivated with a lower concentration of nutrient solution. The results indicated that it is possible to grow Japanese mugwort hydroponically under 24h photoperiod in a plant factory condition with a nutrient solution concentration as low as 25% of the standard. In addition, under 24h photoperiod, plant growth was greatly accelerated and chlorogenic acid as well as total polyphenol were increased, suggesting that 24h photoperiod is highly beneficial for Japanese mugwort production in a fully artificial lighttype plant factory. [ABSTRACT FROM AUTHOR]

The occurrence of extreme warm events and early snowmelt is predicted to increase in high‐latitude ecosystems, even during periods of time when there is no coincident reduction in total precipitation. However, because extreme events like these occur unpredictably, little is known about how advancing snowmelt by a single extreme warm event, without a reduction in precipitation amount, influences overstory trees and understory vegetation simultaneously in an ecosystem. We conducted a warming experiment (four 20 × 20 m plots) in temperate forests of Japan to determine the effects of earlier snowmelt on both understory dwarf bamboo plants and overstory birch trees. Our experimental treatment advanced snowmelt by about 10 days and increased soil temperatures that were associated with increased rates of soil nitrogen (N) mineralization and nitrification. Furthermore, these changes led to lower C:N ratios of leaves together with the greater growth of understory bamboo vegetation, with no changes in leaf C:N or growth rates of overstory birch trees. Together, our results demonstrate that advancing snowmelt by an extreme warm event in temperate forests is likely to affect N cycling and will benefit understory vegetation without a commensurate change in overstory vegetation, likely due to the increase in available soil N. These results also demonstrate that with the projected increase in the frequency of extreme warm events and advanced snowmelt, understory vegetation is likely to benefit more than overstory trees in Japanese temperate forests with heavy snow. [ABSTRACT FROM AUTHOR]

The self-sufficiency ratio and national average yield of wheat are low in Japan. Reducing the yield gap and receiving the government subsidy for grain quality are vital strategies for profitability. Elucidating optimum nitrogen application scheme is awaited to attain both higher yield and appropriate grain protein content (GPC) for wheat cultivation in Japan. Such decision support can be realized by integrating field experimental knowledge to crop growth models, although they have scarcely been utilized for wheat production in Japan. Therefore, the purposes of this study were to apply a widely used crop growth model (APSIM) to wheat growth on an Andosol in the Kanto region in Japan by calibration and validation. Selected model parameters of APSIM-wheat for phenology, leaf growth, and grain formation were readjusted based on the phenology and growth data of soft and hard wheat cultivars. Then the model was validated by using similar variables obtained in an independent experiment. For the simulation of the optimum sowing for winter wheat in the Kanto area (November), the root mean square error for grain yield was 23 and 48 g m−2 for Ayahikari and Yumeshiho varieties, respectively, and that for GPC was 1.9 and 1.4%. Thus, the overall model performance was acceptable for optimum sowing. However, grain yield and dry matter production were significantly overestimated when the data of late sowing groups were included. Therefore, further model improvement was suggested to add an algorithm to reduce the number of emerged plants under cold temperature in late sowing conditions. [ABSTRACT FROM AUTHOR]

Riparian habitats are associated with diverse hydrological conditions that may enhance population differentiation in species inhabiting areas close to water. Cardamine scutata Thunb. is a widespread riparian herb that is typically characterized by compound leaves. On the Nohbi Plain in central Honshu, Japan, it has, however, been reported that plants of C. scutata occurring in tidal wetlands along the lower reaches of large rivers have simpler leaves than those inhabiting areas further upstream. In this study, we quantitatively describe environmental conditions, leaf shape and other phenotypic traits of populations in tidal and non‐tidal habitats. Measurements of the electrical conductivity of interstitial water and fluctuations in water levels indicated that tidal populations of C. scutata occurred in typical tidal freshwater wetlands. We found that tidal and non‐tidal populations are characterized by distinct leaf shapes, simple and compound, respectively, under both field and common growth conditions. These observations indicate that differences in leaf shape reflect a genetic differentiation between populations of the same species inhabiting distinct habitats. In addition to leaf shape, we found several phenotypic differences relating to growth form, with plants in tidal populations having elongated hollowed stems and elongated inflorescences. We conclude that tidal populations of C. scutata are a discrete ecotype inhabiting freshwater tidal wetlands, presumably derived either through adaptation or genetic drift. [ABSTRACT FROM AUTHOR]

Air temperature is one of the most critical climatic factors controlling rice growth, development, and production in current and future climatic scenarii predicting increasingly frequent situations of extreme and/or fluctuating temperatures. With its large spectrum of geographical origins and cropping areas, one can credit tropical japonica rice subspecies of a probable genetic diversity of its response to air temperature, which is of major interest for the breeding of better adapted rice varieties. A panel of 195 rice accessions (175 japonica plus 20 reference cultivars) was studied in controlled environment to estimate cardinal (base, optimum, and maximum) temperatures based on the monitoring of the elongation rate (LERmax) of the sixth leaf on the main stem in response to six fixed thermal treatments ranging from 16 to 35 °C. A dedicated statistical framework was elaborated for estimating LERmax, cardinal temperature and related uncertainties. Developed statistical framework enhanced the precision of cardinal temperatures estimated compared to previously reported methods, especially for base temperature. Maximum temperature was trickier to estimate and will require further studies. A significant genotypic variability for base and optimal temperature was pointed out, suggesting tropical japonica subspecies represents a relevant genetic pool to breed for rice genotypes adapted to various thermal situations. These results also suggested that using genotype-dependent cardinal temperature values should enhance the way crop growth models account for genotype × environment interactions hence their predictive value in current and future climatic conditions. [ABSTRACT FROM AUTHOR]

Two varieties of Aucuba japonica differ in ways that can be considered adaptive to differing geo-climatic conditions in their respective distribution ranges. Irrespective of growth stage, the mean leaf size of A. japonica var. japonica was significantly larger than A. japonica var. borealis. Smaller leaf size and ultimately smaller stature of A. japonica var. borealis are an advantage under the higher snow load and lower temperatures in the forests along the East Sea where the variety grows. Snow load also acted as an important driving force for structural modifications of A. japonica var. borealis from cellular level in leaves to the organization of branch extension growth. Global warming by changing snowfall patterns in Japan may lead to range shifts in the two varieties of A. japonica. [ABSTRACT FROM AUTHOR]

A new model for determining leaf growth in vegetative shoots of the seagrass Zostera marina (eelgrass) is described. This model requires the weights of individual mature and immature whole leaves and leaf plastochrone interval (P L) as parameters, differing from the conventional leaf marking technique (CLM) that requires cutting and separation between new and old tissue of leaves. The techniques required for the model are the same as for the plastochrone method, but the parameters differ between both methods in use of the weight of individual immature leaves. In a mesocosm study, eelgrass growth was examined, and parameters for the new model and plastochrone method (the weights of individual mature and immature leaves and P L) were measured. Leaf growth rate was measured using the CLM and determined by the new method and the plastochrone method. The results were then compared between the CLM, the new model, and the plastochrone method. The results obtained with the new model were similar to those obtained with the CLM. However, the results of the plastochrone method differed from those of the CLM, while the weight of immature leaves varied seasonally. The new model was also used to determine leaf growth in a natural eelgrass bed in Mikawa Bay, Japan, and revealed the growth rates in all shoots and those of different ages. This method would be advantageous as an accurate means of direct measurement in fieldwork, and should therefore be a useful tool for monitoring seagrass growth. [Copyright &y& Elsevier]

The crown foliage dynamics of Kandelia obovata (S., L.) Yong were investigated, including leaf recruitment, survival and leaf growth. Newly flushed leaves occurred successively throughout the year, with a maximum in July and a minimum in January. The highest leaf death was in August, whereas it was the lowest in January. The relative mortality rate of leaves seemed to depend on the season when new leaves flushed. The growth pattern of leaves varied among seasons. The maximum leaf area was significantly larger in winter than in autumn, but showed no significant difference between the winter and the other seasons. The half-expansion period and the intrinsic rate of increase were respectively longer and lower in winter than in the other seasons. Therefore, leaves flushed in summer grew faster in their initial stage and attained their maximum leaf area sooner than those flushed in winter. This most likely results from the difference in temperature between summer and winter. The crown leaf area was almost stable throughout the year, as if homeostatic control is likely to function. Stipule litterfall decreased significantly with increasing flower and propagule litterfalls, indicating that a high production of flowers and propagules results in low leaf recruitment. This may be because flower production and propagule growth impose a severe burden on K. obovata. [ABSTRACT FROM AUTHOR]

Tree height ( H) of Kandelia obovata trees decreased sharply from 5 m at the forest interior behind the terrestrial forest to 1.5 m at the forest edge near the river bank according to an increase in the yearly waterlogged period along a belt transect. The decreasing tree stature was attributed to a decrease in the asymptote of H in the D 0.1 (stem diameter at H/10)- H relationship toward the edge. The K. obovata trees were well classified into interior and edge types using a discriminant function based on the habitat-specific D 0.1– H relationships. Allometric equations, as a function of D H, differed significantly between the interior and edge types in the estimation of the phytomasses of stems and leaves, and the leaf area per tree. On the other hand, common allometric equations were successfully established in the estimation of respective phytomasses of aboveground parts and branches. Biomass and leaf area index decreased toward the forest edge. The biomass allocation to stems decreased toward the edge, whereas those to branches and leaves increased. A dramatic change in stem diameter increment resulted in differences in the D 0.1– H relationship along the tree height gradient. Relative growth rate of biomass and light-saturated net photosynthesis, which paralleled net assimilation rate from the interior to the edge, showed their maximum peaks in the middle of the belt transect. This indicates that there exists an optimal environmental condition for growth of K. obovata trees. Leaf nitrogen content tended to increase to the edge with increasing waterlogged period. [ABSTRACT FROM AUTHOR]

Abstract: The seasonal changes in throughfall (TF) and stemflow (SF) chemistry and the canopy interactions of K+ and N compounds were studied in a Japanese cedar forest near the Sea of Japan. The fluxes of most ions, including non-sea-salt SO4 2−, from TF, SF, and rainfall showed distinct seasonal trends, increasing from autumn to winter, owing to the seasonal west wind, while the fluxes of NH4 + and K+ ions from TF+SF might have a large effect of canopy interactions. The contact angle (CA) of water droplets on leaves decreased with leaf aging, suggesting that surface wettability increases with leaf age. The K+ concentration in TF was negatively correlated with the CA of 1-year-old leaves, while the NH4 + concentration was positively correlated with the CA. The net fluxes of NH4 + and NO3 − from TF were positively correlated with the CA. The increase in wettability may accelerate leaching of K+ or uptake of NH4 +. [Copyright &y& Elsevier]