Development of suckers by two‐year‐old birch (Betula pendula Roth) at different temperatures and light intensities

Two‐year‐old seedlings of Betula pendula Roth of three provenances were cut to stump heights of 0 and 10 cm. The birch stumps were exposed to different light levels (25–400 μEm^?2s^?1) and temperatures (6–24°C) for 100 days in climate chambers. Birches were also cut down to seven stump heights (0, 2, 5, 10, 15, 20 and 25 cm) and exposed to light intensity 25 and 200 μEm^?2s^?1 at 12/6°C for 100 days in climate chambers. In the third experiment 10 cm stumps of birch were exposed to different light intensities (10–400 μEm^?2s^?1) for 30 days in a greenhouse at 20°C. Starch content in root systems was analyzed before and after treatment. Ten stumps per treatment were used in the experiments except the third experiment where 15 stumps were used. The number of sprouting stumps was correlated with light intensity and temperature. None of the stumps exposed to 6 or 9°C produced suckers. At stump height 0 cm fewer sprouting stumps were produced than at 10 cm. The mean height of suckers was higher the higher the temperature both on 0 and 10 cm stumps. There were differences between provenances in height growth. The number of suckers per sprouting stump was not related to temperature or light intensity. Starch content in root systems of 10 cm high stumps was 4.0% compared with 14.7% in root systems of non‐stumped birch plants after 30 days in the greenhouse. Starch content decreased from 4.0 to 3.0% with decreasing light intensity (400–10 μEm^?2S^?1). The number of suckers and their mean height were correlated with starch content depending on light intensity.     

Temperature sensitivity of qualitative race-cultivar interactions in Melampsora medusae Thüm. and Populus species

Six mono-uredospore isolates (races) of Melampsora medusae Thiim. produced qualitatively distinct reactions, in vitro, when incubated at 15 °C on leaf disks of certain cultivars of Populus deltoides Marsh. The infection types in some race-cultivar combinations were very temperature sensitive with less distinct reactions when incubated at 20 or 25°C. The significance of differential race-cultivar-temperature interaction in the epidemiology of M. medusae is discussed.     

Sensitivity to pre- and post-inoculation temperature of the reactions of Populus spp. to Melampsora medusae thüm

Replicate clones of compatible cultivars of Populus deltoides and P. euramericana, grown for 3 months on a high (28/20°C - day/night) temperature regime and incubated, following inoculation with a mixture of urediniospores of six races of Melampsora medusae, on a high (28/20°C - light/dark) temperature regime, were more resistant (as determined by uredinial number) to leaf rust than those raised and incubated on any other combination of the high (28/20°C) and low (20/10°C) pre- and post-inoculation temperature regimes. Irrespective of the parameter employed to assess disease intensity, cultivar constitution and pre- and post-inoculation temperature are significant contributors to the level of disease induced in the cultivars by the isolate of M. medusae. The rating of cultivars for relative resistance is somewhat dependant on the parameter employed to assess disease, and for most parameters there are significant interactions of cultivar and pre- and post-inoculation temperature in determining the disease level induced. The coefficients of determination between the parameters of disease level are low, hence the results of the experiment are of limited value for extrapolation to field conditions. The possibility, in future investigations, of employing a disease parameter with more epidemiological significance is discussed.     

温度对大叶桃花心木(Swietenia macrophylla King)幼苗叶片的光合影响

本文研究了大叶桃花心木（Swietenia macrophylla King）一年生幼苗在经过夜温处理后的光响应曲线和在饱和光强下的CO2反应曲线.结果表明:在大气CO2浓度下,叶片的最佳光合作用温度在25-31℃之间,而在饱和CO2浓度下为31-35℃.在25℃以下光合速率开始降低,主要是由于羧化效率的降低,而当温度超过31℃时,光合速率下降,是因为羧化效率的降低和呼吸速率的增加.CO2浓度对光合的促进作用在低温下受到抑制,这意味着未来在CO2浓度增高的情况下,高浓度的CO2对热带常绿植物光合的促进在冬天低温情况下表现不十分明显.图4参23.     

The effect of photosynthetic photon flux density on development of frost hardiness in top and roots of Larix leptolepis seedlings

Seedlings of Larix leptolepis were grown in a growth chamber under short day conditions (8 h day) at 4 different photosynthetic photon flux densities (PPFD's). After a period of 8 weeks frost hardiness of the shoot tips and roots, dry matter content, dry weight (dw), content of glucose and starch were determined. The frost hardiness in the shoot tips increased from ‐15°C at a PPFD of 55μmol m^‐2s^‐1 to about ‐35°C at 440 μmol m^‐2s^‐1. No effect of PPFD was found on frost hardiness of the roots. A high PPFD results in a high dry matter content. The effect on dry matter content was most pronounced for the shoot tips and less pronounced for the roots. The total dry weight increased for both root and top with increasing PPFD. The height of the plants increased when the PPFD increased up to 220 μmol m^‐2s^‐1.     

Micropropagation of Leptadenia pyrotechnica (Forsk.) Decne: A Multipurpose Plant of an Arid Environment

Leptadenia pyrotechnica (Forsk.) Decne belongs to the family Asclepiadaceae. It is commonly known as Kheemp in India. L. pyrotechnica is an important component of an arid ecosystem and source of fiber, forage, and medicines. We report here in vitro propagation protocol of L. pyrotechnica. Cotyledonary nodes of in vitro raised seedlings were used as an explant for multiplication of shoots. Shoots were multiplied on Modified Murashige and Skoog's (MMS) medium containing 1.33 μM BAP and additives (50 mg L^?1 ascorbic acid and 25 mg L^?1 each of citric acid, arginine, and adenine). Cultures were maintained at 30 ± 2°C temperature, 50–60 μmol m^?2 s^?1 SFP, 12 hr day^?1 photoperiod, and 60% relative humidity (RH). In vitro multiplied shoots were rooted in vitro on half-strength MS medium containing 2.46 μM IBA and 100 mg L^?1 activated charcoal. Shoots were rooted ex vitro using 2460 μM IBA pretreatment for 15 min. Plantlets were hardened in a greenhouse, and survived on a mixture of sand, garden soil, and organic manure in 3:1:1 ratio in polybags in natural habitats.     

A study on the shade tolerance ofMuehlewbeckia complera

Muehlewbeckia complera was introduced to China in 2002 as indoor-hanging ornamental foliage plant. The experiment of the shade tolerance for this species was carried out in different light intensities (0.14–946.00 μmol·m⁻²·s⁻¹). After 40 days in experimental areas, leaf photosynthentic characteristics indexes ofM. complera in different photosynthesis active radiation (PAR) were measured with LI-COR6400 apparatus, such as the light compensation point, light saturation point, and maximum net photosynthesis rate, at the same time, the increments of total leaf area and leaf amount were measured. The results showed that the optimum light intensity range forM. complera was from 9.26 μmol·m⁻²·s⁻¹ to 569.00 μmol·m⁻²·s⁻¹ (463–28150 lx, relative humidity (RH) for 46–60%, temperature at 16–22°C). Under this condition, leaf photosynthetic efficiency was tiptop. AlthoughM. complera belonged to the moderate sun-adaptation plant species, the plant growth was inhibited when PAR increased to the level of 569.000 μmol·m⁻²·s⁻¹ or above.M. complera could sprout new leaves in photosynthesis active radiation of 0.16–19.22 μmol·m⁻²·s⁻¹ (8–961 lx), or 10 μmol·m⁻²·s⁻¹ for above 6 h. Foundation item: This study was supported by the Research Foundation of Northeast Forestry University. Biography: YUE Hua (1962-), female, Associate professor in Northeast Forestry University, Harbin 150040, P. R. China. Responsible editor: Zhu Hong     

冷湿层积法对印度冷杉(Abies pindrow)和长叶云杉(Picea smithiana）种子萌发的影响

研究赤霉素(GA3),冷湿和温度 对五个种源的印度冷杉(Abies pindrow)和长叶云杉(Picea smithiana)种子萌发的影响.种子被浸泡在GA3 (10 mg(L-1)中24小时,然后在3(5(C温度的条件下冷藏15天.设计4个温度(10(C, 15(C, 20(C 和 25(C)条件来促进种子的萌发.结果表明,浸泡和冷湿处理明显增加种子的萌发率.在10 (C时种子的萌发率最高.总体结果表明,种子被浸泡在GA3 (10 mg(L-1)中24小时,冷湿藏15天,可以有效地促进印度冷杉和长叶云杉的种子萌发.统计数据表明,浸泡处理、温度和种源以及与温度的相互作用都对种子的萌发有明显的影响.     

Plantlets regeneration from root explants ofRobinia pseudoacacia L. by suspension culture

A rapid and efficient method for the regeneration of plantlets from root explants ofRobinia pseudoacacia L. by suspension culture was established. The roots taken from aseptically grown 15-day-old seedlings were used as explants. It was determined that photoperiodicity was necessary for root proliferation, and that the promotive effect of IAA (3-indoleacetic acid) on root proliferation was better than that of IBA (3-indolebutyric acid). The roots cultured in 1/2 MS liquid medium containing 3 μM IAA and 1% sucrose at 25°C under 16-hour photoperiod with 50 μmol m⁻²s⁻¹ PPFD (photosynthetic photon flux density) shaking at 100 times/min reciprocally showed high efficiency for root proliferation. BAP (6-benzylaminopurine) was found to be essential to induce adventitious shoots from the roots, and the roots cultured in the medium supplied with 3 μM BAP combined with 1–6 μM IAA for 3 weeks under the same conditions as in the root proliferation period were most suitable for adventitious shoot inducement.     

Effects of shade on arbuscular mycorrhizal colonization and growth of crops and tree seedlings in Central India

The study was conducted to investigate the effects of different light intensities (25, 50, 67, and 100% of full sun [open]) on arbuscular mycorrhizal (AM) colonization and growth of two intercrops (a rainy season crop, Phaseolus mungo Roxb. var. PU-35 and a winter crop, Triticum aestivum L. var. WH-147) and seedlings of two multipurpose tree species (Eucalyptus tereticornis Sm. [Clone C-7, ITC, Bhadrachalam] and Albizia procera Benth.) of Central India. The results showed that various plant growth parameters viz., shoot length, dry weight and phosphorus (P) uptake were adversely affected by low light intensity. Inoculations with AM fungi (Acaulospora scrobiculata Trappe, Glomus intraradix Schenck & Smith and an unidentified Glomus species) increased the plant growth on account of all measured parameters under tested light conditions. Mycorrhizal efficiency of different AM fungi varied in narrow range. AM inoculants were more efficient at higher light intensity in above mentioned plant species, except wheat. Data on colonization of P. mungo, T. aestivum, E. tereticornis and A. procera showed that formation of arbuscules, vesicles and sporocarp was delayed by lower light intensity. Colonization index of host roots and spore counts increased with increase in light intensity during successive months after inoculation. Data on effect of light regimes on microclimate of net house showed that lux meter reading decreased as per grades of shading nets used during both rainy and winter seasons. With increase in light intensity, ambient temperature, soil surface temperature and sub surface temperature at 15 cm depth increased, except that the ambient and soil surface temperature in control (open) were slightly lower than net house observations during January and February. Value of ambient temperature varied in narrow range, with in treatments as compared to soil surface and sub soil surface temperature at 15 cm depth. Soil surface temperature at 25% of full sunlight was less than respective control values by 2–11°C and sub soil temperature at 15 cm depth was less by 4–12°C. The values of different microclimate parameters varied in narrower range during winter season as compared to rainy season. While ranking the importance of two factors studied—light and AM fungi—for their effect on the growth and P uptake by different plant species, inoculations with AM fungi came in the first place (explained 50–82% variation) and light substantially increased the values of R ² in stepwise regression analysis (forward selection). The results suggest that AM inoculation may enhance the growth and P uptake of intercrops under tree shade and the tree canopy management is likely to increase the efficiency of AM inoculants in agroforestry systems. Use of excessive shading (25% of full sun or more) in nurseries may be avoided and PAR (photosynthetically active radiation) lamps may be used to increase growth and colonization index of tree seedlings.     

Light quality and intensity of light-emitting diodes during pre-cultivation of Picea abies (L.) Karst. and Pinus sylvestris L. seedlings – impact on growth performance,seedling quality and energy consumption

Three different LED lamps with continuous spectra were compared against commonly used fluorescent lights. The lamps were characterized by light output, energy consumption and spectral quality for plant growth. The biological effects of light quality were compared by pre-cultivating seedlings of Picea abies (L.) Karst. and Pinus sylvestris L. under each spectrum for 35 days in a growth chamber with controlled temperature, humidity and photoperiod. The seedlings were then transplanted and cultivated for one vegetation period at the nursery, then planted outdoors on a forest field trial and followed for three years. The seedlings showed similar growth performance for all spectra tested. LED lamps have several advantages to fluorescent light such as energy consumption, longer life span and adjustable light intensity. Regarding light intensity the effects on growth performance were studied for both species using the most promising LED spectra. The photosynthetically active radiation (PAR) was maintained at 50, 100, 200 and 400 μmol?m^?2?s^?1. Unlike energy consumption, seedling development did not display a linear relationship to light intensity. Instead, the results show an optimum light level between 100 and 200?μmol?m^?2?s^?1 for the shade tolerant Picea abies seedlings and a level of around 200?μmol?m^?2?s^?1 for the more shade intolerant Pinus sylvestris seedlings.     

白桦光合特性的研究

测定了3年生白桦的光合与呼吸作用对温度,湿度以及CO2浓度的响应;还测定了光补偿点,光饱和点和CO2补偿点。结果表明:在目前的空气CO2浓度下,光合和呼吸作用的最适温度分别是24℃和30℃;当相对湿度是80%时,白桦能维持较强的光合作用;呼吸作用与相对湿度无明显的相关性;光补偿点和光饱和点分别是25 molm-2s-1和1375 祄olm-2s-1;CO2补偿点是180 礚L-1;白桦在CO2浓度为2400 礚L-1时仍有吸收潜力。图4参19。     

温度对杉木林土壤呼吸的影响(英文)

Soil samples collected from the surface soil (0(10 cm) in an 88-year-old Chinese fir (Cunninghamia lanceolata) forest in Nanping, Fujian, China were incubated for 90 days at the temperatures of 15°C, 25°C and 35°C in laboratory. The soil CO2 evolution rates were measured at the incubation time of 2, 5, 10, 15, 20, 25, 30, 35, 40, 50, 60, 70, 80 and 90 days. The results showed that CO2 evolution rates of soil samples varied significantly with incubation time and temperature during the incubation period. Mean CO2 evolution rate and cumulative amount of CO2 evolution from soil were highest at 35°C, followed by those at 25°C, and 15°C. Substantial differences in CO2 evolution rate were found in Q10 values calculated for the 2nd and 90th day of incubation. The Q10 value for the average CO2 evolution rate was 2.0 at the temperature range of 15-25°C, but it decreased to 1.2 at 25- 35°C. Soil CO2 evolution rates decreased with the incubation time. The cumulative mineralized C at the end of incubation period (on the 90th day) was less than 10% of the initial C amounts prior to incubation.     

Temperature-dependent differences in biological traits between two strains of <Emphasis Type="Italic">Trichogramma cacoeciae</Emphasis> (Hymenoptera: Trichogrammatidae)

Parasitoids’ efficiency in controlling pests depends not only on their ability to parasitize their hosts but also on how much they are adapted to climatic conditions (notably temperature) of the area where they are planned to be released. In addition, the optimal conditions for production of parasitoids used for inundative releases like Trichogramma spp. may also vary largely as a function of strains. Using the parasitoid Trichogramma cacoeciae Marchal as biological model, we studied how temperature affects important parasitoid efficiency-related biological traits under laboratory conditions. Emergence, mortality rates and fecundity of two strains of T. cacoeciae, one originating from France (Alsace) and the other one from Tunisia (Degache), were compared at constant temperatures of 15, 20, 25 and 30°C. The parasitoids of the French strain showed highest fecundity at 25°C with wasps that had been reared at 20 or 25°C. The Tunisian strain showed the highest fecundity at 25°C, but only when wasps were previously reared at 25 or 30°C. For both strains, the highest mortality occurred among wasps that had laid eggs at 30°C. Emergence rates were relatively high at all temperatures, although the French strain did better at 15–25°C and the Tunisian one at 20–30°C. Because of the differences in biological traits of these two T. cacoeciae strains in relation to the temperature, a judicious choice must be made among the various strains when using this species in biological control programs.     

Temperature-dependent functional response of two aphid parasitoids, Aphidius colemani and Aphidius matricariae (Hymenoptera: Aphidiidae), on the cotton aphid

The functional response of two aphid parasitoids, Aphidius colemani Viereck and Aphidius matricariae (Haliday) (Hymenoptera: Aphidiidae), on the cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae), was examined. Five constant temperatures (10, 15, 20, 25, and 30°C) and six host densities (2, 4, 8, 16, 32, and 64) were used during a 24-h period. At each temperature, 2–64 third-instar nymphs of A. gossypii were exposed to individual wasp mating pairs. A type II functional response model for both parasitoid wasps was fit separately for each temperature. The results showed that instantaneous attack rate (a) in A. colemani increased linearly as the temperature increases from 10 to 30°C, but in A. matricariae, (a) increased almost linearly with temperature to reach a maximum at 25°C, and then decreased at 30°C, displaying an asymmetrical dome-shaped pattern. The highest instantaneous attack rate for A. colemani and A. matricariae were calculated 0.940 ± 0.144 day⁻¹ at 30°C and 0.687 ± 0.157 day⁻¹ at 25°C, respectively. Handling time (T _h) for A. colemani was inversely proportional to temperature and ranged from 0.093 ± 0.026 day at 10°C to 0.032 ± 0.004 day at 30°C, but in A. matricariae, (T _h) was between 0.078 ± 0.015 day at 10°C and 0.036 ± 0.014 day at 20°C. A. colemani achieved higher parasitism rate than A. matricariae at higher temperatures. This observation suggests that A. colemani maybe more effective for biological control of the cotton aphid during warmer periods.     

Determining thresholds of low soil temperature for ecophysiological traits of black spruce and jack pine seedlings

Many studies have estimated approximately ranges of thresholds of low soil temperature in the growth and ecophysiological traits of trees, but difficultly determined the exact values. To resolve the problem, black spruce (Picea mariana) and jack pine (Pinus banksiana) seedlings were exposed to 5, 10, 15, 20, 25, 30 and 35°C soil temperature in greenhouses. After 90 days of the treatment, net photosynthetic rate (A), stomatal conductance (gs), transpiration rate (E), water use efficiency (WUE) and specific l...     

Alkaloid variations in Catharanthus roseus seedlings treated by different temperatures in short term and long term

A study was conducted to investigate the effects of high temperature on variations of alkaloid metabolism in C. roseus seedlings in Key Laboratory of Forest Plant Ecology, Northeast Forestry University, Heilongiang, China. 60-day-old C. roseus seedlings with 3-4 pairs of leaves were incubated in chambers with temperature of 30℃ and 40℃for short-term heat shock experiment and 20℃, 25℃ and 35℃ for long-term experiment. The contents of vindoline, catharanthine, vinblastine and vincristine in C. roseus leaves and root were checked at different temperatures in short term （1-6 h） and long term （1-16 d）. Results showed that under short-term heat shock, the contents of vindoline, catharanthine and vinblastine in leaves of the seedlings were higher at 40℃ than at 30℃, but after 6 h treatment, the contents of vindoline and catharanthine under the two temperatures came to the same level. Catharanthine was exclusively distributed in C. roseus roots and its content was increased by 40% after two hours incubation at 40℃, while increased slowly at 30℃ incubation and reached the highest value at 6 h. In the Long-term experiment, concentrations of monomeric alkaloids catharanthine and vindoline were higher at 20℃ than at 25℃ and had a sharp increase under the condition of 35℃. While for dimeric alkaloid, it showed that the higher the temperature, the earlier the peak value of vinblastine content appears. Vincristine had a continuous enhancement and attained 0.027 mg.g^-1 at 16th day under 35℃ condition which was higher than those in the other conditions. It was concluded that high temperature could promote the accumulation of different alkaloids in C. roseus and the accumulation characteristic is highly related to treatment time.     

Photosynthesis in co-occurring invasive Acacia spp. and native Bornean heath forest trees at the post-establishment invasion stage

Seedlings of invasive species often exhibit superior physiological traits that facilitate their spread at early stages of invasion, although it is unclear whether these traits persist at the post-establishment stage. To determine whether mature exotic Acacia spp. possess superior traits over mature native plants, we compared foliar gas exchange and chlorophyll a fluorescence of Acacia auriculiformis and Acacia mangium coexisting with tropical heath forest tree species Buchanania arborescens and Dillenia suffruticosa in Brunei Darussalam. The CO₂ assimilation rates of Acacia spp. were significantly higher than those of heath species at current prevailing conditions of ~400 ppm ambient CO₂, 1,500 µmol m^?2 s^?1 photosynthetically active radiation and 30°C leaf temperature. The photosystem II of Acacia spp. exhibited significantly higher maximum quantum yield of primary photochemistry at comparable temperatures, and was more sensitive to an elevated temperature (42°C for 1 h). Better photosynthetic performance of Acacia spp., due to larger stomatal openings, better light harvesting efficiency, and greater plasticity in photosystem II, may enable adult Acacia trees to sustain a competitive growth advantage and suppress native tropical heath forest species. The competitive advantage maintained by Acacia spp. in post-establishment stage likely facilitates the establishment of monospecific Acacia stands in invaded heath forests.     

Micropropagation of Anogeissus rotundifolia Blatt,and Hallb.-An Endemic and Rare Tree of the Thar Desert

Abstract

Multiple shoots and plantlets were developed in vitro from cotyledonary nodal segments of in vitro raised seedlings of Anogeissus rotundifolia (syn. A. sericea var. nummularia)-a rare and endemic tree species of the Thar Desert. About 15-20 shoots differentiated from a single cotyledonary node within four weeks on Mu-rashige and Skoog's (MS) basal medium containing 0.1 mg l^?1 indole-3-acetic acid (IAA) + 2.0 mg l^?1 6-benzylaminopurine (BAP) + additives (25 mg l^?1 each of adenine sulphate, L-arginine, and citric acid, and 50 mg l^?1 of ascorbic acid) at 26 ± 2°C temperature and 36 μmol m^?2 s^?1 photon flux density with a 12 h/day photoperiod. The shoots produced in vitro were further multiplied by subculturing on fresh medium. The original cotyledonary nodal segment was repeatedly transferred (5 to 6 times) onto fresh medium containing 1.0 mg l ^?1 BAP + 0.1 mg I ^?1 IAA + additives to yield fresh crops of multiple shoots. These shoots were rooted on half-strength MS medium supplemented with 0.1 mg l^?1 indole-3-butyric acid (IBA). Plantlets were transferred to pots containing sand-dune soil and ver-miculite it the ratio of 4:1 (v/v) and hardened in a growth chamber for two weeks and finally transferred to a greenhouse. From a single cotyledonary node about 1500 plantlets could be developed within four months. The method developed is useful for mass multiplication and for the conservation of germplasm of Anogeissus rotundifolia.