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1.
Climatic response of budburst in the mountain birch at two areas in northern Fennoscandia and possible responses to global change 总被引:3,自引:0,他引:3
The relationship between the climate and budburst of the mountain birch was evaluated for two areas in subarctic (ca 69°N) Fennoscandia; at Abisko, Swedish Lapland, and at Kevo, Finnish Lapland. Thermal time (TT, degree‐day sums) to budburst was calculated for experimental conditions in the laboratory and for in situ observations of budburst. Two types of models predicting leaf emergence in situ were used: 1) TT to budburst for different threshold temperatures based on daily mean (TTMean) or daily maximum (TTMax) temperatures and 2) ecophysiological budburst models. The obtained models were used to estimate effects of a changed climate. Laboratory experiments of TT to budburst indicated no differences in the thermal requirements at the two areas. Temperature requirements of budburst declined successively during the progression of spring, from ca 250 degree‐days (>+2°C) in January to ca 100 in May. No significant trend in the date of budburst was found over the last 70 (Abisko) or 20 (Kevo) yr. There were some differences in the type of model that best explained the date of budburst in situ at the two areas. For Kevo the best prediction (minimum root mean square error, RMSE) of budburst was obtained by a simple thermal time model (TTMean>5.5°C) from 1 January (RMSE=2.1). For budburst at Abisko, models based on daily maximum temperature fitted better than those based on daily means. For Abisko, models based on thermal time accumulation only showed systematic errors in the predicted budburst that were correlated with budburst previous year (BBPY). Including this apparent memory effect in the model decreased the error by 2.4 d. The best prediction for Abisko was thus obtained using TTMAX>6.5 (RMSE=3.1) from 1 January. Using these models to predict the effect of a changed air temperature climate indicate 3–8 d earlier budburst for a one‐degree increase in temperature, the effect being smaller for Kevo than for Abisko. For both areas a change in May temperature has a larger effect on the date of budburst than changes in any other month. 相似文献
2.
单氰胺对葡萄休眠过程中冬芽水分和碳水化合物的影响 总被引:3,自引:0,他引:3
以酿酒葡萄品种'赤霞珠'和'霞多丽'为材料,对其冬芽休眠进程和休眠过程中冬芽水分和碳水化合物含量的变化进行分析.结果表明,(1)在陕西杨陵地区气候条件下,'霞多丽'、'赤霞珠'分别在12月20日和1月9日达到深度休眠,随后开始休眠解除阶段.(2)在芽休眠过程中,两个品种冬芽的总水分含量、自由水含量和淀粉含量均随休眠的加深而降低,随休眠的解除而增加,而冬芽的束缚水含量、束缚水/自由水比值、可溶性糖含量均在休眠加深阶段持续上升,在休眠解除阶段逐渐降低.(3)单氰胺处理后,两品种冬芽中自由水含量显著增加,束缚水的比例同时显著降低,且'赤霞珠'的变化幅度大于'霞多丽',但其总水分、可溶性糖和淀粉等含量在休眠过程中无显著变化.(4)葡萄冬芽中的水分含量及存在状态、可溶性糖含量和淀粉含量的变化与其休眠进程密切相关;单氰胺处理能够增加冬芽自由水含量,降低其束缚水含量,从而有效打破葡萄休眠. 相似文献
3.
David R. Smart Laszlo Kocsis M. Andrew Walker Christine Stockert 《Journal of Plant Growth Regulation》2003,21(4):296-314
Viticulture has historically depended upon clonal propagation of winegrape, tablegrape, and rootstock cultivars. Dependence on clonal propagation is perpetuated by consumer preference, legal regulations, a reproductive biology that is incompatible with sustaining genetic lines, and the fact that grapevine breeding is a slow process. Adventitious root formation is a key component to successful clonal propagation. In spite of this fact, grapevine has not been a centerpiece for adventitious root research. Dormant woody canes represent complex assemblages of tissues and organs. Factors that further contribute to such complexity include levels of endogenous plant growth regulators, the extent and duration of dormancy, carbohydrate storage, transport, the presence or absence of dormant buds or emergent shoots, and preconditioning treatments. For the above reasons, the mechanisms driving adventitious root formation by grapevine and other woody cuttings are poorly understood. We present results indicating that the dormant bud on cane cuttings from a non-recalcitrant to root Vitis vinifera cultivar, cv. Cabernet Sauvignon, slows or inhibits adventitious root emergence. In contrast to Cabernet Sauvignon, removal of the dormant bud from cane cuttings of a recalcitrant to root hybrid rootstock (V. berlandieri × V. riparia cv. 420A) and an intermediate to root hybrid rootstock (V. riparia × V. rupestris cv. 101-14) had no influence on adventitious root emergence. Reciprocal transplanting of nodes containing dormant buds among all three cultivars did not affect rooting behavior. Our results indicate that the commonly held belief that bud removal diminishes adventitious root emergence is not true. 相似文献
4.
Tor Myking 《Trees - Structure and Function》1997,12(2):107-112
Effects of fluctuating and constant temperatures on budburst time, and respiration in winter buds were studied in Betula pubescens Ehrh. Dormant seedlings were chilled at 0°C for 4 months and then allowed to sprout in long days (LD, 24 h) at constant temperatures
of 6, 9, 12, 15, 18 and 21°C, and at diurnally fluctuating temperatures (12/12 h, LD 24 h) with means of 9, 12, 15 and 18°C.
No difference in thermal time requirements for budburst was found between plants receiving constant and fluctuating temperatures.
The base temperature for thermal time accumulation was estimated to 1°C. Respiration in post-dormant (dormancy fully released)
excised winter buds from an adult tree increased exponentially with temperature and was 20 times as high at 30°C than at 0°C.
However, respiration in buds without scales was 30% higher at 0°C, and it was 2.7 times higher at 24°C than in intact buds.
Thus, the tight bud scales probably constrain respiration and growth and are likely to delay budburst in spring. Arrhenius
plots of the respiration data were biphasic with breaks at 13–15°C. However, this phase transition is unlikely to be associated
with chilling sensitivity since the present species is hardy and adapted to a boreal climate.
Received: 10 January 1997 / Accepted: 23 June 1997 相似文献
5.
Several physiological processes controlling tree phenology remain poorly understood and in particular bud dormancy. Many studies have emphasised the action of chilling temperatures in breaking dormancy. However, the effect of the preceding summer temperatures has rarely been investigated although there is some evidence that they may be involved in the settlement and intensity of dormancy as well as cold acclimation. In this paper, thermal time to budburst in relation to the duration of chilling outdoors, preceding summer temperatures and forcing temperatures was studied by outdoors experiments in seedlings of Platanus acerifolia , Vitis vinifera , Quercus pubescens and Castanea sativa . Results showed that temperatures of the preceding summer had no significant effect on the timing of budburst, P. acerifolia and Q. pubescens showed a very weak response to the duration of chilling, and the phenological characteristics of each species were found to be adapted to the climate conditions of its own geographical area. The phenological model used in this study explained 82–100% of the variance of the data without taking into account summer temperatures. Thus, although summer temperatures may be well involved in the intensity of dormancy and cold hardiness, they do not significantly affect budburst and therefore may not need to be considered in phenological models for predicting budburst. 相似文献
6.
Fu YH Campioli M Demarée G Deckmyn A Hamdi R Janssens IA Deckmyn G 《International journal of biometeorology》2012,56(1):153-164
Numerous phenology models developed to predict the budburst date of trees have been merged into one Unified model (Chuine,
2000, J. Theor. Biol. 207, 337–347). In this study, we tested a simplified version of the Unified model (Unichill model) on
six woody species. Budburst and temperature data were available for five sites across Belgium from 1957 to 1995. We calibrated
the Unichill model using a Bayesian calibration procedure, which reduced the uncertainty of the parameter coefficients and
quantified the prediction uncertainty. The model performance differed among species. For two species (chestnut and black locust),
the model showed good performance when tested against independent data not used for calibration. For the four other species
(beech, oak, birch, ash), the model performed poorly. Model performance improved substantially for most species when using
site-specific parameter coefficients instead of across-site parameter coefficients. This suggested that budburst is influenced
by local environment and/or genetic differences among populations. Chestnut, black locust and birch were found to be temperature-driven
species, and we therefore analyzed the sensitivity of budburst date to forcing temperature in those three species. Model results
showed that budburst advanced with increasing temperature for 1–3 days °C−1, which agreed with the observed trends. In synthesis, our results suggest that the Unichill model can be successfully applied
to chestnut and black locust (with both across-site and site-specific calibration) and to birch (with site-specific calibration).
For other species, temperature is not the only determinant of budburst and additional influencing factors will need to be
included in the model. 相似文献
7.
Viticulture has historically depended upon clonal propagation of winegrape, tablegrape, and rootstock cultivars. Dependence on clonal propagation is perpetuated by consumer preference, legal regulations, a reproductive biology that is incompatible with sustaining genetic lines, and the fact that grapevine breeding is a slow process. Adventitious root formation is a key component to successful clonal propagation. In spite of this fact, grapevine has not been a centerpiece for adventitious root research. Dormant woody canes represent complex assemblages of tissues and organs. Factors that further contribute to such complexity include levels of endogenous plant growth regulators, the extent and duration of dormancy, carbohydrate storage, transport, the presence or absence of dormant buds or emergent shoots, and preconditioning treatments. For the above reasons, the mechanisms driving adventitious root formation by grapevine and other woody cuttings are poorly understood. We present results indicating that the dormant bud on cane cuttings from a non-recalcitrant to root Vitis vinifera cultivar, cv. Cabernet Sauvignon, slows or inhibits adventitious root emergence. In contrast to Cabernet Sauvignon, removal of the dormant bud from cane cuttings of a recalcitrant to root hybrid rootstock (V. berlandieri × V. riparia cv. 420A) and an intermediate to root hybrid rootstock (V. riparia × V. rupestris cv. 101-14) had no influence on adventitious root emergence. Reciprocal transplanting of nodes containing dormant buds among all three cultivars did not affect rooting behavior. Our results indicate that the commonly held belief that bud removal diminishes adventitious root emergence is not true. 相似文献
8.
Daylength and thermal time responses of budburst during dormancy release in some northern deciduous trees 总被引:5,自引:0,他引:5
O. M. Heide 《Physiologia plantarum》1993,88(4):531-540
Dormancy release and thermal time to budburst as affected by duration of chilling outdoors, followed by different flushing temperatures and daylengths in a phytotron, were studied in cuttings of several northern tree species. In Betula pubescens, B. pendula and Prunus padus vegetative buds were released from dormancy already in December, in Populus tremula in January, whereas in Alnus incana and A. glutinosa dormancy was not released until February. Thermal time (day degrees >0°C) to budburst decreased non-linearily with increasing duration of chilling (i. e. duration outdoors), and the slope of this relationship differed among species. The estimated effective base temperature for accumulation of thermal time varied from + 1°C in P. tremula to −4°C in P. padus . The use of 0°C as base temperature is recommended. Long days reduced the thermal time to budburst at all flushing temperatures (9, 15 and 21°C) in all the above species and in Corylus avellana , whereas Sorbus aucuparia and Rubus idaeus showed no daylength response. Since the chilling requirement of all species was far exceeded even in a winter with January-March temperatures 6.5°C above normal, it is concluded that under Scandinavian conditions, the main effect of climatic warming would be earlier budburst and, associated with that, a longer growing season and increased risk of spring frost injury. 相似文献
9.
Budburst models have mainly been developed to capture the processes of individual trees, and vary in their complexity and plant physiological realism. We evaluated how well eleven models capture the variation in budburst of birch and Norway spruce in Germany, Austria, the United Kingdom and Finland. The comparison was based on the models performance in relation to their underlying physiological assumptions with four different calibration schemes. The models were not able to accurately simulate the timing of budburst. In general the models overestimated the temperature effect, thereby the timing of budburst was simulated too early in the United Kingdom and too late in Finland. Among the better performing models were three models based on the growing degree day concept, with or without day length or chilling, and an empirical model based on spring temperatures. These models were also the models least influenced by the calibration data. For birch the best calibration scheme was based on multiple sites in either Germany or Europe, and for Norway spruce the best scheme included multiple sites in Germany or cold years of all sites. Most model and calibration combinations indicated greater bias with higher spring temperatures, mostly simulating earlier than observed budburst. 相似文献
10.
Tor Myking 《Trees - Structure and Function》1998,12(4):224-229
Respiration in vegetative buds of mature Betula pendula, Alnus glutinosa and Prunus padus trees was measured monthly at 15°C from mid-October 1996 to natural outdoor budburst in April 1997. In B. pendula the effect of bud water content on respiration was also estimated (December–April) by artificial imbibition of buds for 24
h prior to measurement of respiration. For estimation of corresponding bud dormancy status, batches of twigs were forced at
identical monthly intervals at 15°C in long days (24 h), and budburst recorded. In all species dormancy was deepest when the
leaves were shed in October, and dormancy was first alleviated in P. padus followed by B. pendula and A. glutinosa. However, bud respiration capacity was not related to dormancy release as it decreased in all species from October to November
and displayed no notable increase until February in P. padus, March in B. pendula and April in A. glutinosa, after completion of dormancy release. Rather, increase in respiration coincided with growth resumption prior to budburst.
Artificial imbibition of B. pendula buds increased the water content by approximately 10% (FW) and induced a doubling of the respiration rate (December–February).
Moreover, the seasonal variation in bud water content (October–April) explained 94% of the variation in respiration in B. pendula and P. padus, and 84% in A. glutinosa. These observations suggest an important role of water content for respiration. During a cold period from mid-December to
mid-January with mean temperature of –9.7°C dormancy release was arrested in P. padus, and to some degree in A. glutinosa, whereas dormancy release progressed normally in B. pendula. This indicates species differences in lower critical temperatures for dormancy release.
Received: 30 June 1997 / Acceped: 1 October 1997 相似文献
11.
Simulating phenological characteristics of two dominant grass species in a semi-arid steppe ecosystem 总被引:3,自引:0,他引:3
Wenping Yuan Guangsheng Zhou Yuhui Wang Xi Han Yingshun Wang 《Ecological Research》2007,22(5):784-791
Vegetation phenology has a strong effect on terrestrial carbon cycles, local weather, and global radiation partitioning between
sensible and latent heat fluxes. Based on phenological data that were collected from a typical steppe ecosystem at Xilingol
Grazing and Meteorological Station from 1985 to 2003, we studied the phenological characteristics of Leymus chinensis and Stipa krylovii. We found that the dates for budburst of L. chinensis and S. krylovii were delayed with increasing temperature during winter and spring seasons; these results differed from existing research
in which earlier spring events were attributed to the changes in increasing air temperature in winter and spring. The results
also suggested that water availability was an important controlling factor for phenology in addition to temperature in grassland
plants. The classical cumulative temperature model simulated the phenology well in wet years, but not in the beginning of
growing season in all years from 1985 to 2003. The disparity between the simulation and the observation appeared to be related
to soil water. Based on our research findings, a water-heat-based phenological model was developed for simulating the beginning
of growing season for these two grass species. The simulated results of the new model showed a significant correlation with
the observation of beginning date of the growing season, and both mean values of the absolute error were less than 6 days. 相似文献
12.
Sara Mira M. Elena González-Benito Ana M. Ibars Elena Estrelles 《Biodiversity and Conservation》2011,20(2):345-358
The influence of seed testa color, temperature and seed water content on dormancy release and seed viability loss in the endangered,
endemic species Silene diclinis (Lag.) M. Laínz was evaluated. Dormant heterogeneous seeds (black, red and grey colored) were exposed to three different
temperatures (5, 20, and 35°C) and two relative humidities (33 and 60%) in order to assay their dormancy release. Longevity
behavior was studied for the three colored seeds, storing samples at nine different combinations of temperature (5, 20 and
35°C) and relative humidities (33, 60 and 90%). According to our findings, seed heteromorphism was not related to neither
break of dormancy nor seed storage behavior. Silene diclinis seeds present dormancy after collection, and need an after-ripening period to germinate. Temperature and relative humidity
are positively correlated with dormancy release and seed ageing. Therefore, both factors must be carefully controlled during
seed manipulation in the laboratory for long term seed conservation purposes. When seeds are stored immediately after collection
(dormant), if the temperature of storage is above the base temperature for dormancy release found in this work (between 2.7
and 1.6°C), seeds may eventually overcome dormancy. On the other hand if seeds are stored after an after-ripening period,
storage at low temperature does not induce secondary dormancy. 相似文献
13.
Marjorie Bison Nigel G. Yoccoz Bradley Carlson Geoffrey Klein Idaline Laigle Colin Van Reeth Daphn Asse Anne Delestrade 《Ecology and evolution》2020,10(18):10219-10229
Temperatures in mountain areas are increasing at a higher rate than the Northern Hemisphere land average, but how fauna may respond, in particular in terms of phenology, remains poorly understood. The aim of this study was to assess how elevation could modify the relationships between climate variability (air temperature and snow melt‐out date), the timing of plant phenology and egg‐laying date of the coal tit (Periparus ater). We collected 9 years (2011–2019) of data on egg‐laying date, spring air temperature, snow melt‐out date, and larch budburst date at two elevations (~1,300 m and ~1,900 m asl) on a slope located in the Mont‐Blanc Massif in the French Alps. We found that at low elevation, larch budburst date had a direct influence on egg‐laying date, while at high‐altitude snow melt‐out date was the limiting factor. At both elevations, air temperature had a similar effect on egg‐laying date, but was a poorer predictor than larch budburst or snowmelt date. Our results shed light on proximate drivers of breeding phenology responses to interannual climate variability in mountain areas and suggest that factors directly influencing species phenology vary at different elevations. Predicting the future responses of species in a climate change context will require testing the transferability of models and accounting for nonstationary relationships between environmental predictors and the timing of phenological events. 相似文献
14.
Markus Brändel 《Wetlands Ecology and Management》2006,14(1):11-28
In the temperate region temperature is the main factor influencing the germination period of plant species. The purpose of
this study was to examine effects of constant and fluctuating temperatures on dormancy and germination under laboratory and
field conditions in the three wetland species Lycopus europaeus, Mentha aquatica and Stachys palustris. The results should give indications if the temperature-dependent regulation of dormancy and germination is phylogenetically
constrained. Tests for germination requirements showed a minimum temperature for germination of 9 °C in Mentha and 12 °C in Lycopus and Stachys, and a maximum temperature of 33 °C for Lycopus and 36 °C for Mentha and Stachys. Fluctuating temperatures promoted germination in all three species but the amplitude required for high germination (>50%)
differed: it was 8 °C in Mentha, 10 °C in Stachys and 14 °C in Lycopus (mean temperature 22 °C). The effect of temperatures on the level of dormancy was examined in the laboratory by imbibing
seeds at temperatures between 3 °C and 18 °C for periods between 2 and 28 weeks, as well as by a 30-month burial period, followed
by germination tests at various temperatures, in light and darkness. In the laboratory only low temperatures
(≤12 °C) relieved primary dormancy in seeds of Lycopus, while in Mentha and Stachys also higher temperatures lead to an increase of germination. Dormancy was only induced in Lycopus seeds after prolonged imbibition at 12 °C in the laboratory. Buried seeds of all species exhibited annual dormancy cycles
with lower germination in summer and higher germination from autumn to spring. Exhumed seeds, however, showed considerable
differences in periods of germination success. Dormancy was relieved when ambient temperatures were below 12 °C. Ambient temperatures
that caused an induction of dormancy varied depending on species and test condition, but even low temperatures (8 °C) were
effective. At high test temperatures (25 °C) in light, exhumed seeds of all three species showed high germination throughout
the year. The three species showed various differences in the effects of temperatures on dormancy and germination. Similarities
in dormancy and germination found among the species are in common with other spring-germinating species occurring in wetlands,
so it seems that the temperature dependent regulation of dormancy and germination are related to habitat and not to phylogenetic
relatedness. 相似文献
15.
Budburst phenology is a key driver of ecosystem structure and functioning, and it is sensitive to global change. Both cold winter temperatures (chilling) and spring warming (forcing) are important for budburst. Future climate warming is expected to have a contrasting effect on chilling and forcing, and subsequently to have a non-linear effect on budburst timing. To clarify the different effects of warming during chilling and forcing phases of budburst phenology in deciduous trees, (i) we conducted a temperature manipulation experiment, with separate winter and spring warming treatments on well irrigated and fertilized saplings of beech, birch and oak, and (ii) we analyzed the observations with five temperature-based budburst models (Thermal Time model, Parallel model, Sequential model, Alternating model, and Unified model). The results show that both winter warming and spring warming significantly advanced budburst date, with the combination of winter plus spring warming accelerating budburst most. As expected, all three species were more sensitive to spring warming than to winter warming. Although the different chilling requirement, the warming sensitivity was not significantly different among the studied species. Model evaluation showed that both one- and two- phase models (without and with chilling, respectively) are able to accurately predict budburst. For beech, the Sequential model reproduced budburst dates best. For oak and birch, both Sequential model and the Thermal Time model yielded good fit with the data but the latter was slightly better in case of high parameter uncertainty. However, for late-flushing species, the Sequential model is likely be the most appropriate to predict budburst data in a future warmer climate. 相似文献
16.
Background and Aims
Grapevine (Vitis spp.) cold hardiness varies dynamically throughout the dormant season, primarily in response to changes in temperature. The development and possible uses of a discrete-dynamic model of bud cold hardiness for three Vitis genotypes are described.Methods
Iterative methods were used to optimize and evaluate model parameters by minimizing the root mean square error between observed and predicted bud hardiness, using up to 22 years of low-temperature exotherm data. Three grape cultivars were studied: Cabernet Sauvignon, Chardonnay (both V. vinifera) and Concord (V. labruscana). The model uses time steps of 1 d along with the measured daily mean air temperature to calculate the change in bud hardiness, which is then added to the hardiness from the previous day. Cultivar-dependent thermal time thresholds determine whether buds acclimate (gain hardiness) or deacclimate (lose hardiness).Key Results
The parameterized model predicted bud hardiness for Cabernet Sauvignon and Chardonnay with an r2 = 0·89 and for Concord with an r2 = 0·82. Thermal time thresholds and (de-)acclimation rates changed between the early and late dormant season and were cultivar dependent but independent of each other. The timing of these changes was also unique for each cultivar. Concord achieved the greatest mid-winter hardiness but had the highest deacclimation rate, which resulted in rapid loss of hardiness in spring. Cabernet Sauvignon was least hardy, yet maintained its hardiness latest as a result of late transition to eco-dormancy, a high threshold temperature required to induce deacclimation and a low deacclimation rate.Conclusions
A robust model of grapevine bud cold hardiness was developed that will aid in the anticipation of and response to potential injury from fluctuations in winter temperature and from extreme cold events. The model parameters that produce the best fit also permit insight into dynamic differences in hardiness among genotypes. 相似文献17.
Grapevine N fertilization may affect and be affected by arbuscular mycorrhizal (AM) fungal colonization and change berry composition.
We studied the effects of different N fertilizers on AM fungal grapevine root colonization and sporulation, and on grapevine growth, nutrition, and berry composition, by conducting
a 3.5-year pot study supplying grapevine plants with either urea, calcium nitrate, ammonium sulfate, or ammonium nitrate.
We measured the percentage of AM fungal root colonization, AM fungal sporulation, grapevine shoot dry weight and number of
leaves, nutrient composition (macro- and micronutrients), and grapevine berry soluble solids (total sugars or °Brix) and total acidity. Urea suppressed AM fungal root colonization and sporulation. Mycorrhizal grapevine plants had higher shoot
dry weight and number of leaves than non-mycorrhizal and with a higher growth response with calcium nitrate as the N source.
For the macronutrients P and K, and for the micronutrient B, leaf concentration was higher in mycorrhizal plants. Non-mycorrhizal
plants had higher concentration of microelements Zn, Mn, Fe, and Cu than mycorrhizal. There were no differences in soluble
solids (°Brix) in grapevine berries among mycorrhizal and non-mycorrhizal plants. However, non-mycorrhizal grapevine berries
had higher acid content with ammonium nitrate, although they did not have better N nutrition and vegetative growth. 相似文献
18.
Zulima González-Parrado Carmen Reyes Fuertes-Rodríguez Ana M. Vega-Maray Rosa M. Valencia-Barrera F. Javier Rodríguez-Rajo Delia Fernández-González 《Aerobiologia》2006,22(1):47-53
Winter-flowering trees such as the alder (Alnus glutinosa (L.) Gaertner) can survive periods of adverse climatic conditions, entering a period of dormancy in the early fall. The end
of dormancy and the start of the pollen season require a period of low temperatures followed by another of warm temperatures.
These requirements were studied from 1995 to 2002, in order to develop a model to predict the onset of the alder pollen season
in Ponferrada (Spain). Chilling accumulation took place from late October to late December or early January. The best result
was obtained with a threshold temperature of 6.5 °C and an average of 848 chilling hours (CH). Heat requirements were calculated
at maximum temperature, an average 143 growth degree days (GDD) were needed, with a threshold temperature of 0 °C. In order
to validate models, predicted values were compared with real values for 2002–2003, 2003–2004 and 2004–2005, years not used
in developing the models. Predictions for the pollen-season start-date differed only slightly from observed dates: in 2002–2003
predicted and observed dates were the same, in 2003–2004 there was a difference of 7 days and in 2004–2005 a difference of
3 days. 相似文献
19.
Microtubers of 13 cultivars, largely grown in Italy and other European countries, were induced. They were stored in the dark at 3°C for different periods (28, 56, 84 and 105 days), prior to being transferred to 20°C for between 4 and 17 weeks. Following removal to room temperature, sprouting was recorded and dormancy duration quantified. Dormancy decreased from 28.1 to 19.9, 11.1 and 7.8 days with reduced time of storage. Cvs Arsy, Nicola and Jaerla took consistently more time for dormancy release. The dormancy duration was linearly and inversely correlated with the length of storage. After sprouting, tubers were held at 20°C for various intervals and a range of physiological ages (0, 368, 720 and 1008 degree days) were accumulated. The field comparison of microtubers evidenced a plant growth response and tuber yield/plant affected by the cultivar and physiological age. In early cultivars (Jaerla), a better performance was shown by younger tubers; the opposite trend was noted in Alpha (a later cultivar) with an increase in stems/plant, tubers/plant and tuber yield/plant for tubers with greater physiological age. Like conventional seed tubers, microtubers showed differences in optimum physiological age associated with cultivar earliness. This study has provided some indications on how to enhance emergence and haulm development of plants from microtubers. 相似文献
20.
Inflorescence apices are suitable explants for the rapid in vitro propagation of Musa spp. However, the diploid and triploid banana cultivars showed different in vitro responses with respect to the hormone combinations
in Murashige and Skoog medium. The diploid cultivar (Sannachenkadali, AA) induced a maximum number of multiple shoots in 8.9 μM
6-benzyl adenine (BA) whereas the triploid cultivar (Red banana, AAA) exhibited maximum multiplication in 22.2 μM 6-benzyl
adenine. MS medium supplemented with 11.4 μM indole acetic acid and 17.8 μM BA was also suitable for shoot proliferation in
triploid cultivar but not in the diploid cultivar. The regenerated shoots were rooted in Murashige and Skoog basal medium
within 10–15 days. The rooted plantlets were transferred to vermiculite and maintained at a temperature of 25 ± 2°C for 10 days
and then at room temperature (30–32°C) for 2 weeks before transferring to potted soil compost mixture. The plantlets showed
100% survival. 相似文献