Full Light Conditions Research Articles

Wheat and barley can increase grain yield in shade through acclimation of physiological and morphological traits in Mediterranean conditions

Major cereal yields are expected to decline significantly in coming years due to the effects of climate change temperature rise. Agroforestry systems have been recognized as a useful land management strategy that could mitigate these effects through the shelter provided by trees, but it is unclear how shade affects cereal production. Most cereal species and cultivars have been selected for full light conditions, making it necessary to determine those able to acclimate to low irradiance environments and the traits that drive this acclimation. A greenhouse experiment was conducted in central Spain to assess the photosynthetic response, leaf morphology and grain yield of nine cultivars of winter wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) at three levels of photosynthetic active radiation (100%, 90% and 50%). Cultivars were selected according to three different precocity categories and were widely used in the studied area. The main objective was to assess whether the species and cultivars could acclimate to partial shade through physiological and morphological acclimations and thus increase their grain yield for cultivation in agroforestry systems. Both species increased grain yield by 19% in shade conditions. However, they used different acclimation strategies. Barley mostly performed a physiological acclimation, while wheat had a major morphological adjustment under shaded environment. Barley had lower dark respiration (42%), lower light compensation point (73%) and higher maximum quantum yield (48%) than wheat in full light conditions, revealing that it was a more shade-tolerant species than wheat. In addition, to acclimate to low irradiance conditions, barley showed a 21% reduction of the carotenoids/chlorophyll ratio in the lowest irradiance level compared to 100% light availability and adjusted the chlorophyll a/b ratio, photosystem II quantum efficiency, electron transport rate and non-photochemical quenching to shade conditions. On the other hand, wheat showed a 48% increase in single leaf area in the 50% irradiance level than in full light to maximize light capture. Our results showed that current commercialized wheat and barley cultivars had sufficient plasticity for adaptation to shade, supporting tree presence as a tool to reduce the negative effects of climate change.

Growth characteristics of one-year-old seedlings of three autochthonous oak species in suboptimal growing conditions

The paper presents the growth characteristics of one-year-old seedlings of three autochthonous oak species (Fagaceae family): Turkey oak (Quercus cerris L.), Hungarian oak (Quercus frainetto Ten.) and downy oak (Quercus pubescens Willd.) in suboptimal growing conditions. The analyzed oak species are widely distributed in Serbia. One of the most important benefits of oak species is wood production (Hungarian and Turkey oak), and they have a promising role for the use in the future regarding the climate change as all species can be encountered on dry sites. Acorns were collected in the autumn of 2017 in natural stands and a sample of 400 acorns per each oak species was immediately sown in a nursery seedbed in the form of a random block system with four replicates. At the end of 2018, the available sample of seedlings was analyzed morphometrically. The seedlings were classified according to the number of shoot growth flushes into one-flush-growth and multi-flush growth seedlings. Turkey Oak had the highest number of seedlings which also recorded higher values in total height, root collar diameter and number of leaves. These results were obtained on alkaline soil with the presence of weeds and rodents and the absence of irrigating. The presence of multi-flush growth was recorded in all three oak species. Differences between analyzed three oak species exist in these suboptimal conditions. However, in full light conditions, a similar growth pattern was recorded, indicating to the similar adaptability of the species.

Growth characteristics of one-year-old Hungarian oak seedlings (Quercus frainetto Ten.) in full light conditions

U radu su prikazane značajke rasta jednogodišnjih biljaka sladuna u uvjetima potpunog svjetla u poljskom pokusu 2016. godine. U odnosu na višegodišnji prosjek (1981.–2010. godine) srednja temperatura zraka u vegetacijskom razdoblju 2016. godine bila je veća za 1.3<sup>°</sup>C, a količina oborina za 30.1 mm. Broj ožiljaka terminalnih pupova na jednogodišnjim biljkama sladuna (Slika 1), definira broj faza rasta u visinu na temelju kojega su izdvojeni tipovi rasta biljaka: biljke s jednofaznim, dvofaznim i trofaznim rastom. U analiziranom uzorku, 39,8% biljaka pripada jednofaznom tipu rasta, 58,2% dvofaznom, a svega 2,0% trofaznom tipu rasta (Slika 2). S obzirom na mali broj biljaka s trofaznim rastom u visinu, sve biljke su podijeljene u dvije skupine: biljke sa jednofaznim i biljke sa višestrukim rastom u visinu (Tablica 2). Postoje statistički značajne razlike u varijancama uzoraka kod svih značajki rasta između biljaka s jednofaznim i višestrukim rastom na razini p < 0,05, a na razini p < 0,01 između srednjih vrijednosti svih analiziranih elemenata rasta između biljaka s jednofaznim i višestrukim rastom. Primjetno je da raspodjela svih elemenata rasta varira između dvije definirane skupine biljaka. S obzirom na visinu primarnog rasta (H<sub>1</sub>), biljke s jednofaznim rastom su po apsolutnoj varijabilnosti nešto manje varijabilne, a po relativnoj duplo manje varijabilne od biljaka s višestrukim rastom, s blago pozitivnom asimetrijom. Što se tiče ukupne visine, biljke sa višestrukim rastom su znatno varijabilnije kako glede apsolutne varijabilnosti, tako i relativne varijabilnosti i s više izraženom desnom asimetrijom u odnosu na biljke s jednofaznim rastom. Kod biljaka s višestrukim rastom, apsolutna varijabilnost broja listova je dvostruko veća, a ukupne površine listova trostruko veća s izraženom desnom asimetrijom u usporedbi s biljkama s jednofaznim rastom. Postoje značajne razlike između raspodjela biljaka s jednofaznim i višestrukim rastom u visinu. Biljke s jednofaznim rastom imaju manju ukupnu visinu, manji promjer korjenovog vrata, manji broj i ukupnu površinu listova, ali se odlikuju većom srednjom visinom primarnog rasta u odnosu na biljke sa višestrukim rastom, što ukazuje na različite značajke rasta u početnoj fazi i tijekom vegetacijskog razdoblja između ovih tipova biljaka.

Photosynthetic Characterization and Response to Drought and Temperature in Wild Asparagus (Asparagus acutifolius L.)

The wild asparagus species Asparagus acutifolius L. is widespread in Mediterranean and subtropical environments, where its spears are consumed regularly. The species is known to have ecophysiologic plasticity, however there is no literature on this subject. This work aimed at assessing the photosynthetic characteristics of this wild species of asparagus, grown under full light (FL) and partial (i.e., about 40%) light (PL) conditions, and evaluating its ecophysiologic response to drought and temperature stress. The photosynthetic response to light of spears and of new cladodes (NC; current year) and old cladodes (OC; previous year) was measured using an infrared gas analyzer coupled with a climatized cuvette chamber. Cladodes net photosynthesis at high irradiance was also measured at varying air temperatures and decreasing soil water availability. Results indicate that developing spears were photosynthetically active with no difference between FL and PL treatments. Photosynthetic rates did not differ between NCs and OCs and were greater for FL cladodes, except at low irradiance. Well-watered plants were photosynthetically active from 0 to 45 °C, with a maximum photosynthetic rate of up to 9 µmol·m–2·s–1 at 30 °C and a decrease of about 60% at 45 °C. The species also demonstrated high tolerance to drought, with positive net photosynthesis even at predawn leaf water potential values of –2.4 MPa. Showing great ecophysiologic plasticity, this wild asparagus could be an interesting species in areas were conventional crop species are not profitable economically, or as an intercrop in agroforestry systems.

The interaction between shade and drought affects essential oil quantity and quality of Vitex agnus-castus L. leaves and seeds

Chaste tree (Vitex agnus-castus L.) is an industrial plant whose quality and yield may be affected by shade and drought. Therefore, leaf and seed dry weights, and the essential oil (EO) content and composition of leaves and seeds were determined under three shading levels (full light, 50% shading, and 80% shading) and three irrigation regimes (50, 70, and 90% available water depletion). Gas chromatography–mass spectrometry analysis showed the presence of 26 compounds (α-pinene (16.4–60.7%), β-terpinyl acetate (15.5–40.2%), caryophyllene (2.7–9.0%), and camphene (0.09–6.2%)) in the leaves, as well as 28 compounds (α-pinene (29.2–46.3%), isozonarol (33.9%), caryophyllene (1.6–26.8), β-iraldeine (0.55–22.1%), isopulegyl acetate (10.7–15.6%), and terpinolen (0.51–6.3%)) in the seeds. The highest leaf and seed dry weights, leaf essential oil content and yield, and seed essential oil yield were achieved under full light and non-stressed conditions. The highest α-pinene and caryophyllene contents were recorded in the full light condition under 70% water depletion and the highest β-terpinyl acetate was observed under 50% shading with 70% water depletion in the leaves. However, seeds had the highest β-terpinyl acetate and caryophyllene contents under 80% shading with the 50% water depletion condition. Isopulegyl acetate and bioformen were found in the seeds, but they were not obtained in the leaves. Based on the leaf and seed yield, as well as leaf essential oil content and yield, full light and 50% water depletion could be the best treatment in both leaves and seeds. However, based on the essential oil composition, 50% shading could be applied under 70% water depletion for the leaves, and 50% shading under 90% water depletion could be appropriate for the seeds.

Adaptation on low light intensity of lesser yam (Dioscorea esculenta) under artificial shading

Abstract. Lestari P, Utami NW, Wawo AH. 2019. Adaptation on low light intensity of lesser yam (Dioscorea esculenta) under artificial shading. Pros Sem Nas Masy Biodiv Indon 5: 374-382. Tubers can be used as an alternative food to reduce dependence on rice. Current status of lesser yam is considered rare. However, it can still be found in people's yards in some areas of Java island, especially the older generation. The high content of inulin in the lesser yam tuber makes it feasible to be one candidate potential functional food source. The planting of lesser yam in the agroforestry component has important meaning to increase the productivity of the alleyway between forest crop and ex situ lesser yam conservation. The introduction of low-input lowland cultivation can be a factor to attract the farmer to cultivate lesser yam. The experiments were prepared based on the RCBD nested design. The research is intended as a baseline data to determine the adaptation of lesser yam to low light intensity stress. The data can be applied to determine the age of main timber plant commodities that can still be interspersed with lesser yam. The study was conducted with nesting plots. The level of shade as the main plot consists of 0% shade, 25% shade, 55% and 75% shades. Organic fertilizer as a subplot consists of no fertilizer and with fertilizer. Each treatment having 3 replications consisting of 3 plant observations. Organic fertilizer gave since 2 weeks after planting with a dose of 25cc / lt every week until the plant is 3 months old. Observations were made in plant growth, yield, and physiological phases. Almost all observation variables showed shade treatment more affecting growth and production of crops than fertilizer treatment. This good growth shows that the canopy of the plant grows optimally in full light conditions. Under different shade conditions, total yields did not differ between shade levels up to 50%, but tuber production was more uniform in shade 25% and 50%. Further research is needed on the interaction of lesser yam in various timber commodities as a major component of agroforestry.

Influence of gap position and competition control on the leaf physiology of planted Picea glauca and natural regeneration of Populus tremuloides

Maintaining white spruce (Picea glauca (Moench) Voss) in mixture with trembling aspen (Populus tremuloides Michx.) and other broadleaf competitors following timber harvest in boreal and sub-boreal mixed-wood stands is challenging. Under-planting spruce within harvest gaps is one potential strategy, but it’s unclear which gap environments favor spruce in relation to aspen. Here we test the effect of gap position and woody release treatment on leaf area development and growth physiology of spruce and aspen. Five positions were measured from the southern understory through the gap center to the northern understory in replicated strip cuts. The woody release treatment cut all stems around spruce including aspen in subplots within each experimental gap; other subplots were left un-cut for comparison. We measured leaf area per wet weight, leaf photosynthesis, stomatal conductance, and transpiration in low- and full-light conditions. We also assessed photosynthetic plasticity in relation to light. Overall, aspen maintained higher leaf area per unit wet weight than spruce, but spruce leaf area was more sensitive to changes in gap position. Aspen also maintained higher photosynthesis and transpiration rates than spruce under both light conditions, and woody release treatment. The magnitude of difference in gas exchange rates between the two species, however, depended significantly on woody release treatment and gap position for photosynthesis, and on gap position for transpiration. Photosynthetic plasticity was not significantly different across species, gap position, or woody release treatment. Our results indicate that in order to ensure the competitive advantage of spruce in mixed-wood boreal stands, forest managers should concentrate spruce planting and competition control efforts in the centers of canopy openings.

Light environment affects the levels of resistance hormones in Syngonium podophyllum leaves and its attack by herbivores and fungi

Background: Little is known on factors determining infection of tropical plants by fungal pathogens, although multiple studies on model species show that light conditions affect the two major hormones that control resistance in plants to enemies. This is the first study using a natural population of a wild tropical plant to relate light conditions to resistance hormones and, the beneficial and detrimental interactions with insects and fungi.
 Hypothesis: Light conditions affect the endogenous levels of resistance hormones and thereby cause quantitative shifts among herbivores and nectrotrophic, biotrophic and endophytic fungi.
 Studied species: The tropical vine Syngonium podophyllum . 
 Study site: Los Tuxtlas tropical rain forest, Mexico.
 Methods: We used GC-MS to quantify the concentration of the two resistance hormones in intact leaves and natural levels of herbivory and fungal disease in S . podophyllum plants growing naturally in the full sun or in the shade.
 Results: The proportion of leaves damaged by herbivores or infected by hemibiotrophic or necrotrophic pathogens was higher in shade than under full-light conditions. Damage caused by biotrophic pathogens was frequently observed in sun but not in shade. Levels of both hormones in phenotypically healthy leaves were higher in sun than in shade.
 Conclusions: (i) light has an effect on concentrations of plant resistance hormones in nature; (ii) these differences have consequences for fungi and animals that naturally interact with the plant, and (iii) the described effect can represent a physiological mechanism via which an abiotic factor affects the members of the guilds at higher trophic levels.

Struggle to survive: aphid\u2014plant relationships under low-light stress. A case of Acyrthosiphon pisum (Harris) and Pisum sativum L.

Light is primary source of energy and also plays signaling and regulatory roles in developmental processes and defense responses of plants. The aim of the study was to determine the performance, settling preferences, probing, and feeding behavior of Acyrthosiphon pisum on Pisum sativum grown in complete darkness (NL), with light at minimum level required for photoperiodic reaction (LL) and under full-light (FL) conditions. The effect of A. pisum infestation on metabolic status and defense responses of peas under FL, LL, and NL conditions was also determined. The population growth rate was limited on LL and NL pea plants as compared to FL plants. The reproductive period of aphids on LL and NL plants was eight times shorter than on plants growing in FL. In contrast to aphids on FL plants, the majority of A. pisum rejected LL and NL plants during settling. Aphid probing activities were not impeded on LL and NL plants but the probes were significantly shorter than on FL plants and consisted mainly of non-phloem activities. The analysis of tolerance of P. sativum to A. pisum showed that on FL plants, the number of aphids was nearly five times higher than on plants growing in low light (LL) at the end of the 2-week experiment but the tolerance index of FL plants was higher than that of LL plants. The contents of chlorophyll a, chlorophyll b, carotenoids, saccharides, and phenolics and the activity of β-d-glucosidase were notably lower in LL and NL plants than in FL plants. The increase in light intensity from complete darkness to the minimum level required for photoperiodic reaction did not stimulate evident changes in the measured plant biochemical parameters. These trends occurred in aphid-free (AF) and aphid-infested (AI) plants. However, under FL conditions, β-d-glucosidase activity and the content of saccharides were lower in AI plants than in AF plants. No differences in the measured plant biochemical parameters between AI and AF plants occurred under LL and NL conditions. The low β-d-glucosidase activity and low content of phenolics in the light-deprived plants that have reduced ability to photosynthesize show that under the biotic stress of aphid infestation plants invest in supporting basic metabolism rather than in defense against herbivores.

Exploiting mycorrhizas in broad daylight: Partial mycoheterotrophy is a common nutritional strategy in meadow orchids

Abstract Partial mycoheterotrophy (PMH) is a nutritional mode in which plants utilize organic matter, i.e. carbon, both from photosynthesis and a fungal source. The latter reverses the direction of plant‐to‐fungus carbon flow as usually assumed in mycorrhizal mutualisms. Based on significant enrichment in the heavy isotope 13C, a growing number of PMH orchid species have been identified. These PMH orchids are mostly associated with fungi simultaneously forming ectomycorrhizas with forest trees. In contrast, the much more common orchids that associate with rhizoctonia fungi, which are decomposers, have stable isotope profiles most often characterized by high 15N enrichment and high nitrogen concentrations but either an insignificant 13C enrichment or depletion relative to autotrophic plants. Using hydrogen stable isotope abundances recent investigations showed PMH in rhizoctonia‐associated orchids growing under light‐limited conditions. Hydrogen isotope abundances can be used as substitute for carbon isotope abundances in cases where autotrophic and heterotrophic carbon sources are insufficiently distinctive to indicate PMH. To determine whether rhizoctonia‐associated orchids growing in habitats with high irradiance feature PMH as a nutritional mode, we sampled 13 orchid species growing in montane meadows, four forest orchid species and 34 autotrophic reference species. We analysed δ2H, δ13C, δ15N and δ18O and determined nitrogen concentrations. Orchid mycorrhizal fungi were identified by DNA sequencing. As expected, we found high enrichments in 2H, 13C, 15N and nitrogen concentrations in the ectomycorrhiza‐associated forest orchids, and the rhizoctonia‐associated Neottia cordata from a forest site was identified as PMH. Most orchids inhabiting sunny meadows lacked 13C enrichment or were even significantly depleted in 13C relative to autotrophic references. However, we infer PMH for the majority of these meadow orchids due to both significant 2H and 15N enrichment and high nitrogen concentrations. Pseudorchis albida was the sole autotrophic orchid in this study as it exhibited neither enrichment in any isotope nor a distinctive leaf nitrogen concentration. Synthesis. Our findings demonstrate that partial mycoheterotrophy is a trophic continuum between the extreme endpoints of autotrophy and full mycoheterotrophy, ranging from marginal to pronounced. In rhizoctonia‐associated orchids, partial mycoheterotrophy plays a far greater role than previously assumed, even in full light conditions.

Height growth characteristics of one-year-old northern red oak seedlings (Quercus rubra L.) in full light conditions

In this nursery experiment, 100 one-year-old northern red oak seedlings were measured at the end of the 2016 growing season. Measured growth elements were: total height, root collar diameter and total leaf area. All seedlings were classified according to the presence of polycyclism into four types: one-flush growth, two-flush growth, three-flush growth, and four-flush growth type. The number of new flushes (shoots) is a good indicator of total height, root collar diameter and total leaf area.

Impact of spatio-temporal shade dynamics on wheat growth and yield, perspectives for temperate agroforestry

A stumbling block to the adoption of silvoarable agroforestry systems is the lack of quantitative knowledge on the performance of different crops when competing for resources with trees. In North-Western Europe, light is likely to be the principal limiting resource for understorey crops, and most agronomic studies show a systematic reduction of final yield as shade increases. However the intensity of the crop response depends on both the environmental conditions and the shade characteristics. This study addressed the issue by monitoring winter wheat (Triticum aestivum L.) growth, productivity and quality under artificial shade provided by military camouflage shade-netting, and using the Hi-sAFe model to relate the artificial shade conditions to those applying in agroforestry systems. The field experiment was carried out over two consecutive years (2013–14 and 2014–15) on the experimental farm of Gembloux Agro-Bio Tech, Belgium. The shade structures recreated two shade conditions: periodic shade (PS) and continuous shade (CS), with the former using overlapping military camouflage netting to provide discontinuous light through the day, and the latter using conventional shade cloth. The experiment simulated shading from a canopy of late-flushing hybrid walnut leaves above winter wheat. Shading was imposed 16 (2013–14) and 10 (2014–15) days before flowering and retained until harvest. The crop experienced full light conditions until the maximum leaf area index stage (LAImax) had been reached. In both years, LAI followed the same dynamics between the different treatments, but in 2013–2014 an attack of the take-all disease (Gaeumannomyces graminis var. tritici) reduced yields overall and prevented significant treatment effects. In season 2014–15 the decrease in global radiation reaching the crop during a period of 66 days (CS: – 61% and PS: – 43%) significantly affected final yield (CS: – 45% and PS: – 25%), mainly through a reduction of the average grain weight and the number of grain per m2. Grain protein content increased by up to 45% under the CS treatment in 2015. Nevertheless, at the plot scale, protein yield (t/ha) did not compensate for the final grain yield decrease. The Hi-sAFe model was used to simulate an agroforestry plot with two lines of walnut trees running either north-south or east-west. The levels of artificial shade levels applied in this experiment were compared to those predicted beneath trees growing with similar climatic conditions in Belgium. The levels used in the CS treatment are only likely to occur real agroforestry conditions on 10% of the cropped area until the trees are 30 years old and only with east-west tree row orientation.

Light conditions affect the performance of Yponomeuta evonymellus on its native host Prunus padus and the alien Prunus serotina.

The bird cherry ermine moth, Yponomeuta evonymellus L., is considered an obligatory monophagous insect pest that feeds only on native European Prunus padus L. In recent years, however, increased larval feeding on alien P. serotina Ehrh. has been observed. In both species, general defoliation is extensive for shade grown trees, whereas it is high in P. padus, but very low in P. serotina, when trees are grown in full light conditions. The aim of the present study was to identify how the plant host species and light conditions affect the performance of Y. evonymellus. The influence of host species and light condition on their growth and development, characterized by the parameters of pupation, adult eclosion, body mass, potential fecundity, and wing size, was measured in a 2 × 2 experimental design (two light treatments, two hosts). In comparison with high light (HL) conditions, a greater percentage of pupation and a longer period and less dynamic adult emerge was observed under low light (LL) conditions. The effect of host species on these parameters was not significant. In contrast, mass, fecundity and all of the studied wing parameters were higher in larvae that grazed on P. padus than on P. serotina. Similarly the same parameters were also higher on shrubs in HL as compared with those grown under LL conditions. In general, light conditions, rather than plant species, were more often and to a greater extent, responsible for differences in the observed parameters of insect development and potential fecundity.

A Study on the Characteristics of Water Consumption by Transpiration of Four Garden Plants in Linzhi City, Tibet

Characteristics of water consumption by transpiration of the four garden plants in the nursery of Agricultural and Animal Husbandry College of Tibet University has been studied using the 2-year-old potted seedlings. The experiment shows that: All of the four plants had a higher water consumption by transpiration in the full light condition than in the full shade condition. The four plants had a basically same process of water consumption in the two conditions: All of them had a lower value in the morning and evening, and a peak during noon 13:00-15:00. In the full light and shade conditions, the water consumption rate of the four plants represented the same sequencing: Sorbaria sorbifolia> Rosa chinensis Jacq.> Syringa oblata Lindl> Ligustrum quihoui Carr.. In the full light condition, all four plants had the maximal water consumption rate in August and minimal water consumption rate in December. Among them, the water consumption rate of Sorbaria sorbifolia in December accounted for 79.26% that of August, and the water consumption rate of Ligustrum quihoui Carr. in December accounted for 84.22% that of August.

Structural and functional diversity and quantitative parameters of two-year shoot systems of pregenerative individuals of <em>Quercus robur</em> L. (Fagaceae) in different light conditions in the central part of European Russia

Based on topological characteristics and functional role in crown, diversity of the two-year shoot systems in pregenerative individuals of Q. robur L. growing in communities with different light level in southern part of Moscow region and reserve “Kaluzhskiye Zaseki” in Kaluga region have been typified. In full light conditions uniform branching, mesotonic and acrotonic two-year shoot systems with a great number of lateral twigs mainly contribute to the crown structure. In shadow conditions crown is formed basically from non-branching systems and two-year shoot systems with a small number of casually located lateral twigs. The number of nodes of the elementary shoots of different two-year system types is more constant than their internodes’ length. Branching types of two-year shoot systems have longer internodes than nonbranching ones do. In branching types of two-year shoot systems internodes become longer with the improvement of light conditions. Refs 26. Figs 3. Tables 3.

Cultivation Technique of Seedling Used for Raw Material of Fetal Tea

Fetal tea is a new type of tea made from seedling before its big euphylla come into leaf. So the yield and quality of seedling used for raw material of fetal tea directly affect the fetal tea yield and quality; the main purpose of this paper is to explore the effect of full light, half light and dark conditions on the growth of seedling used for raw material of fetal tea, and to provide a reference basis for the production of seedling with high quality. The tea tree seeds were cultivated with water under full light, half light and dark conditions, respectively; Then quadrats were set to observed regularly germination state of seed, growth of baconic and germ, meanwhile growth of root, stem, leaf, euphylla of “germ seedling”; By comparing the difference between different illumination conditions, the appropriate light conditions were selected as follows. The number and speed of seed crack were 27.0% and 63.4% higher under full light than under dark conditions and half light, respectively; Meanwhile the number of seed crack was 28.6% higher under dark conditions than under half light. As a result, the full light was the best for cultivating seedling used for fetal tea, dark condition was middle, and half light was worst. The baconic elongation of seed were 87.7% and 93.7% higher under full light than half light and dark condition, respectively, while 3.1% higher under half light than dark condition; therefore, full light was the best condition to promote baconic growth, half light was second, dark condition was the worst. The growth length of germ were 76.0% and 92.0% lower under half light and under dark condition than under full light, respectively, while 66.6% lower under dark condition than under half light, hence, full light was the best condition to promote germ growth, half light was second, and dark condition is the worst. Based on above results, it was concluded that cultivating tea seed with water under full light can obtain higher output of seedling used for raw material of fetal tea.

Comparing germination success and seedling traits between exotic and native pioneers: Cecropia pachystachya versus Macaranga gigantea

Cecropia is a pioneer genus from the Neotropics, whilst Macaranga is an ecological analog with a center of distribution in Southeast Asia. In the past few decades, introduced populations of Cecropia spp. have spread rapidly in Singapore, Malaysia, and Indonesia. In Singapore, Cecropia pachystachya now occupies habitats that would have been expected to be occupied by Macaranga gigantea. We conducted germination experiments under 0, 20, 50, and 70 % shading and measured the survival rates and functional traits of the seedlings of these two species from material collected in Singapore. Seeds of C. pachystachya germinated in 3–12 days, whereas seeds of M. gigantea germinated from day 13 onwards. Germination success for C. pachystachya was between 90.3 % under full-light conditions and 55.8 % under 50 % shading, while for M. gigantea only 69.1 % of seed germinated under full-light conditions and germination completely failed when seeds were shaded by 20 % or more. The seedlings of C. pachystachya also had higher survival rates, faster shoot and root biomass accumulation, larger leaves, and lower total water content than those of M. gigantea. Thus overall, C. pachystachya possesses traits that may provide a competitive edge over the native M. gigantea and will be advantageous for its spread given the increasing proliferation of disturbed landscapes in tropical Southeast Asia.

The role of mucilage in the germination of Leptocereus scopulophilus (Cactaceae) seeds from Pan de Matanzas, Cuba

Studies of seed mucilage in a number of species suggest that it has multiple ecological roles dependent on species and their environmental context. We evaluate whether mucilage facilitates seed germination for Leptocereus scopulophilus Areces, as well as whether light conditions influence the effect of the mucilage. Three combined treatments of light conditions: (1) shade (10% of sunlight), (2) semi-shade (30% of sunlight), and (3) full light exposure (100% of sunlight), and two seed types (with mucilage and washed) were used. Germinability was affected by light conditions but no effect of mucilage was found; higher germination occurred in shade than in semi-shade conditions. There was no germination in full light conditions. Germination rate (T50) was not affected by light conditions or by the mucilage, or the interaction of both factors. Minimal time to germination (Tmin) was affected by mucilage; seeds with mucilage germinated 2 days later than washed seeds. Thus, facilitation for imbibition of water does not occur in L. scopulophilus seeds. Perhaps the presence of mucilage in seeds of this species serves other purposes such as seed adhesion to soil or to deter predators.

EFFECTS OF SHADE ON STRAWBERRIES IN HYDROPONIC CULTIVATION

In order to make full use of space in hydroponic strawberry production, different kinds of frames are being used that result in shading of plants. The purpose of this study was to investigate the behavior of ‘Akihimei’ strawberry (Fragaria ×ananassa Duch.) at different positions of the double-decked frame in the greenhouse under different light conditions, especially when lower levels were in the shade. The results showed that on the southern exposed upper level the light was strongest (100%), while on the northern lower level the light was the weakest (57%). The net photosynthetic rate was linear with light intensity (y=0.0092x+1.7738, r=0.72**). Compared with plants grown on upper tier that received 100% light, the shaded strawberry plants had smaller leaves, though they also expanded in 12 days and became mature in 30 days. The leaf area of plants on the southern upper level was twice as that on the northern lower level. Early flowering and green fruit stage of the strawberries under shade were two days and five days longer, respectively, than those in full light. Strawberries under shade had about 38% early yield, 50% total yield, 57% early fruit number, 71% total fruit number, and about 30% smaller fruits compared to plants in full light. These indexes were significantly correlated with light intensity. Therefore, light intensity was a key factor in improving strawberry production. As for fruit qualities, such as firmness, SSC, ASA, TA, there were no significant differences between fruits grown under shaded conditions or in full light conditions. Furthermore, plants grown under shading conditions produced 50% fewer stolons than those under full light. We can conclude that reducing shade by developing suitable frame designs, might increase the value of protected horticulture.

Plasticity in Pinus pinaster populations of diverse origins: Comparative seedling responses to light and Nitrogen availability

The effects of light and N availability, and population on seedling morphology and biomass allocation were assessed in eleven months seedlings from ten Pinus pinaster populations. We conducted a garden experiment using a light gradient (full sunlight, HL= 337.1 μmol m2 s-1; medium light, ML= 120.6 μmol m2 s-1 and low light, LL= 30 μmol m2 s-1) and two contrasting soil fertility regimes: low-N and high-N availability. Light availability was an important factor controlling phenotypic plasticity. However, differences between productivity environments were observed, especially in full sunlight and medium light conditions, which suggest that soil fertility may be very important at early successional stages at open and medium shaded microsites, but would exert low influence in deep shade conditions. Population-specific responses were observed for many traits, which suggest a genetic control of morphological plasticity. All populations produced more total dry weight with HL and high-N. When light and/or N richness varied, growth depended upon which resource was more limiting. Results indicated ontogenetic drift but when seedlings were compared at the same size, results fitted with optimal partitioning theory. Allocation to needles was higher in HL and ML/high-N conditions, while allocation to root was higher in low-N seedlings in HL and ML conditions. With shade (ML and LL) all populations allocated more dry weight to stem, regardless N availability. A significant increment in stem height was observed with shade increase.