Optimum Germination Research Articles

Effect of Pre-treatments on Seed Germination and Seedling Growth in Psidium guineense Swartz

This work aimed to evaluate the effect of pre-treatments with gibberellin, the initial substrate humidity, and incubation temperature on the germination of Psidium guineense Swartz seeds. The seeds were submitted to four pre-treatments with gibberellin (GA3 ) (50 and 100 mg L-1)and distilled water during 24 hours, and control. Sowing was carried out on Germitest® paper that was moistened with distilled water at humidity levels corresponding to 1.5 and 2.5 times the weight of dry paper. The seeds were then incubated at a constant temperature (25 or 30 °C) and alternate temperatures (20-30 °C). Experiments were randomized, with a factorial scheme 4 × 2 × 3 (pre-treatment × initial substrate humidity × temperature) with four replicates of 25 seeds each. Germination rate and seedling growth of P. guineense were not affected by pre-germination treatments. For an optimum germination rate and seedling growth, seeds of P. guineense should be sown at alternate temperatures of 20-30 °C or 25 °C and in substrate moisture of 1.5 or 2.5 times the dry paper mass.

A novel in vitro germination method revealed the influence of environmental variance on the pecan pollen viability

Pecan is one of the most important horticultural nut crops in the world. Germination tests are vital to the safe application of artificial pollination and cross breeding of pecan. Although many in vitro germination methods have been proposed, the realization of robust and reproducible methods to induce morphologically normal growth pollen tubes in vitro for detailed dynamic observation has often proved challenging in pecan. We employed a mixing and spreading method to realize the uniform distribution and germination on agarose medium, which resulted in the unprecedented level of germinational repeatability and observability. With this method, we investigated the influence of environmental variance on the in vitro germination of pecan pollen. The data from germination rate, burst rate, pollen tube length and germination speed indicated the pecan pollen had an optimal germination temperature at 25°C but optimal rehydration temperature at 16°C which was lower than minimum germination temperature. And this optimal rehydration temperature was harmful to pollen germination if pollen was ready to germinate after rehydration. It helped researchers understand the mechanism of probable promotion of high day/low night temperatures to pollen germination in nature. Results further revealed that pecan pollen didn’t lose their viability rapidly in first several days at ambient conditions but changed to a different rehydration and germination condition. In addition, we proposed here a new germination speed parameter GT50 to indicate the early change of pollen viability.

The Effect of Glycinebetaine Priming on Seed Germination of Six Turfgrass Species under Drought, Salinity, or Temperature Stress

Glycinebetaine (GB) seed priming enhances stress tolerance in various plants during the germination and seedling growth stage; however, information regarding turfgrass is limited. In this study, GB at 5 to 50 mm was used to prime seeds of six turfgrass species to evaluate the potential of GB priming in enhancing tolerance to drought, salinity, and sub-optimal temperature during germination. Stress tolerance was determined as relative final germination percentage (FGP) and daily germination percentage (DGP), expressed as percentage of germination under stress conditions compared with the control treatment (i.e., unprimed seeds germinated under non-stress condition) for each species. Daily germination percentage was more sensitive to stress than FGP. Perennial ryegrass (Lolium perenne L.) showed high tolerance to drought, salinity, and chilling temperatures (5 and 10 °C below optimal germination temperature) followed by tall fescue (Festuca arundinacea Schreb.) and creeping bentgrass (Agrostis palustris L.), whereas kentucky bluegrass (Poa pratensis L.), bermudagrass [Cynodon dactylon var. dactylon (L.) Pers.], and zoysiagrass (Zoysia japonica Steud.) were stress-sensitive. Kentucky bluegrass and bermudagrass showed higher germination at 10 mm GB under temperature stress and drought and temperature stresses, respectively; however, other grasses showed limited responses to seed priming. Our results showed that the efficacy of GB priming is plant-, GB concentration-, and stressor-dependent.

Optimal temperature and light conditions for germination of Elymus glabriflorus

As of date, information regarding seed physiology and germination requirements of southeastern wildrye ( Elymus glabriflorus (Vasey ex L.H. Dewey) Scribn. & C.R. Ball [Poaceae]) is limited. Five seed accessions were collected across a variety of habitats at different latitudes and were placed under a range of temperature and light regimes to determine optimal conditions for germination. Temperature treatments for germination included alternating day/night regimes from 10 to 25 °C in 5° increments. Light testing consisted of 4 treatments: constant light, constant dark, short day (8 h), and long day (16 h). Results from the temperature experiment indicated no correlation between latitude and temperature for optimal germination. The collection from the southernmost site, Laurel, Mississippi, and the northernmost site, Upton, Kentucky, had an optimal germination temperature of 20 °C. The short-day (8-h) treatment had the greatest initial germination (41% for 2010 and 61% for 2013). These results indicate that temperature requirements for germination of E. glabriflorus seed range from 15 to 20 °C and that shortening day length (

Predicting the impact of increasing temperatures on seed germination among populations of Western AustralianBanksia(Proteaceae)

AbstractTemperature is a significant factor influencing seed germination and for many species temperature-mediated germination cues are vital for plant persistence. Rising temperatures forecast as a result of anthropogenic climate change may have a substantial influence on the population and range dynamics of plant species. Here, we report on the thermal constraints on seed germination in natural populations of four congenericBanksiaspecies collected from a longitudinal climate gradient in Western Australia. We investigated whether germination niche: (1) varied between species; (2) varied among populations of each species; and (3) varied in a consistent manner reflecting the climatic gradients of seed origin. We hypothesized that species would differ and that populations from warmer sites would have a broader temperature window for germination than populations from cooler sites. Species differed in the breadth of their germination niche, but temperatures that stimulated the most rapid and complete germination were similar across all species. A sharp reduction in germination percentage occurred above the optimum temperature, which coincided with significant delays in germination relative to the optimum. The temperatures causing these declines varied among populations. Across the species, there was a significant correlation between optimum germination temperature and mean annual temperature at seed source; however, there was no relationship at the population level for individual species. These data provide insight into the vulnerability ofBanksiaspecies to climate change, with those populations that require lower temperatures for germination, or have narrower optimal ranges for germination, likely to be most vulnerable to a warming climate.

The effect of temperature on germination of chlamydospores of Phytophthora ramorum

Mycelium-free chlamydospores of 12 isolates of P. ramorum representing three clonal lineages were produced with a method involving incubation in nonsterile sand at 20 C in darkness for 30 d. Chlamydospores were incubated on selective agar medium at 5, 10, 15, 20, 25 and 30 C and germination assessed after 1, 2, 4, 6 and 8 d incubation. The optimal temperature for germination based on 8 d incubation was 20 C for all three clonal lineages tested (NA1, NA2, EU1). Mean germination rates were 2, 21, 44, 67, 32 and 0 percent at 5, 10, 15, 20, 25 and 30 C respectively for all isolates combined. The highest mean germination rate was scored by isolates of the EU1 clonal lineage at 20 C (85%) after 8 d incubation However, substantial variation was observed among isolates within each clonal lineage. Overall temperatures and days of incubation on which germination was assessed isolates of the NA1 clonal lineage had the lowest mean germination, even though one isolate had the highest germination of any isolate in any lineage. The results indicate that 20 C is the optimal germination temperature for P. ramorum chlamydospores and that a great disparity in germination percentage can exist within isolates, even within a single clonal lineage.

Determination of cardinal germination temperatures of two ecotypes of Thymus daenensis subsp. daenensis

Thymus daenensis is an important endemic medicinal plant of Iran. In the present study, the germination behaviour of two ecotypes of T. daenensis subsp. daenensis, Elam and Isfahan, was studied at various temperatures (3 to 40°C) to (1) calculate cardinal temperatures and (2) determine whether germination behaviour varied between ecotypes. To determine the cardinal temperatures, the relationship between germination rate and temperature was considered. Temperature had a significant effect on both final germination percentage and germination rate in both ecotypes. The optimum germination rate occurred within the temperature range 11.2 to 24.3°C for the Elam ecotype and 23 to 34.6°C for the Isfahan ecotype. The calculated base temperatures (Tb) for the Elam and Isfahan ecotypes were between 0.3 and 1.3°C and 1.3 and 4.4°C, respectively. The ceiling temperature (Tc) for the Elam and Isfahan ecotypes was 40.9 and 42.3°C, respectively. The Elam ecotype appears to be adapted for germination at lower temperatures to avoid summer drought and maximise the benefit of water availability in winter. Conversely, the Isfahan ecotype was adapted to germinate at higher temperatures.

Effect of Germination Temperature on the Functional Properties of Grain Amaranthus

Grain amaranthus in its ordinary state may be modified by germination to perform extraordinary role as emulsifier for our fast- growing food industry with a concomitant increase in food production to satisfy the ever-increasing population of the world with its associated food insecurity. Hence, this study aimed at determining the optimum germination temperature for the maximum improvement of the functional properties of grain amaranthus with the view of using this as an emulsifier in food processing. The dry grains were germinated at 30oC, 32oC, 34oC, 36oC, 38oC, 40oC and designated as T30, T32, T34, T36, T38, T40 respectively and T00 for the negative control. The water and oil absorption capacities (WAC and OAC) were determined by centrifuging the samples in water and then groundnut oil . The emulsifying capacity (EC) and emulsion stability (ES) were determined by homogenizing the samples in groundnut oil and later centrifuging. Result was expressed as mean and Analysis of Variance and Least Significant Difference were was used for comparison. The WAC increased from 107.58% in T00 to 118.97% in T30 with the peak value of 124.94% in T40. The OAC increased from 31.07% in the negative control to 33.13% in T30 with the peak value of 35.96% in T38. The emulsifying capacity was 2.0 1% in T00 and increased to 24.63% in T30. This property increased with increase in germination temperature to the maximum value of 31.17% in T40. The emulsion stability ranged between 1.20% in T00 to 2.31% in T36. Foam capacity in the negative control was zero and in T30 was 3.99% while the peak value was 8.45% in T32. The Hydrophile:Lipophile Balance (HLB) ranged between 3.28 in T38 to 4.16 in T40 which was higher than that of standard emulsifier, lecithin, with the value of 4.0. This shows that germinated grain amaranth may exhibit the same or even better emulsifying properties than lecithin which is a universal emulsifier even though it may not exert appreciable foaming properties where this is required.

Conservation physiology of plants.

Conservation physiology of plants.

Seasonal changes in germination and dormancy of buried seeds of endemic Brazilian Eriocaulaceae

AbstractSeeds can synchronize their germination and dormancy cycles to regular seasonal environmental changes. The present work sought to evaluate thein-situlongevity of the buried seeds of two species ofSyngonanthusand two species ofComanthera(Eriocaulaceae) in the region of natural occurrence (Serra do Cipó Range, south-eastern Brazil), and to relate their germination responses to seasonal climatic changes. Samples were exhumed bimonthly and germination was tested under a 12-h photoperiod (30 μmol m− 2s− 1) at optimal germination temperature. The seeds ofComantherashowed high deterioration after the first year of burial, especiallyC. elegans, which reflects their incapacity to form viable soil seed banks. The buried seeds ofC. bisulcata, S. anthemidiflorusandS. verticillatusacquired secondary dormancy during the rainy season (spring/summer, higher temperatures) which was alleviated during the subsequent dry season (autumn/winter, lower temperatures). It is concluded thatC. bisulcata, S. anthemidiflorus, andS. verticillatusform seed banks of the persistent type and demonstrate consecutive cycles of germination/dormancy, accompanying annual seasonal changes for at least 2 years.

Germination Eco-physiology of Angelica glauca Edgew Seeds

Aims: Angelica glauca Edgew is a heavily exploited critically endangered medicinal cum aromatic herb of Himalayan region. Poor and erratic seed germination is one of the constraints in its in-situ as well as ex-situ conservation and large scale cultivation. Moreover, our understanding of the eco-physiological aspects of the seed germination in this species is very limited. The present study aimed to understand the effect of different temperature regimes, photoperiodic conditions and sowing depths on seed germination in A. glauca using laboratory and nursery conditions. Study Design: Complete Randomized Design was executed. Place and Duration of Study: G.B. Pant Institute of Himalayan Environment and Development, Mohal-Kullu (HP), India between April 2006 and July 2008. Methodology: Germinability of the seeds were evaluated under different temperature regimes viz.(5, 15, 25 and 30C) and photoperiods (light-24 hrs, dark-24 hrs and alternate Original Research Article European Journal of Medicinal Plants, 4(4): 404-412, 2014 405 photoperiods-16 hrs dark and 8 hrs light) in laboratory; and at sowing depths (0.5, 1.0, 1.5 and 2.0 cm) in controlled nursery conditions. Results: In photoperiodic conditions, encouraging results were obtained under alternate light regimes which favored maximum (77.78%; p<0.05) mean germination along with minimum MGT (42.08 days) and Germination Potential Index (114.6) under laboratory condition. All these parameters performed significantly better at 25C as compared to other temperature regimes tested. In nursery condition, seed sown at 1.0cm depth gave comparatively higher (p<0.05) seedling emergence. Poor seedling emergence at higher sowing depth clearly indicated the requirement of light for germination in A. glauca seeds. Conclusion: Study concludes that alternate photoperiods (16 hrs dark and 8 hrs light), temperature (25C) and soil depths not more than 1.0cm are effective treatments to achieve optimum germination in A. glauca. These technicalities could be easily adopted by the poor and unskilled farmers for economic cultivation of this species.

Bet hedging in desert winter annual plants: optimal germination strategies in a variable environment

In bet hedging, organisms sacrifice short-term success to reduce the long-term variance in success. Delayed germination is the classic example of bet hedging, in which a fraction of seeds remain dormant as a hedge against the risk of complete reproductive failure. Here, we investigate the adaptive nature of delayed germination as a bet hedging strategy using long-term demographic data on Sonoran Desert winter annual plants. Using stochastic population models, we estimate fitness as a function of delayed germination and identify evolutionarily stable strategies for 12 abundant species in the community. Results indicate that delayed germination meets the criteria as a bet hedging strategy for all species. Density-dependent models, but not density-independent ones, predicted optimal germination strategies that correspond remarkably well with observed patterns. By incorporating naturally occurring variation in seed and seedling dynamics, our results present a rigorous test of bet hedging theory within the relevant environmental context.

English

In order to investigate the effect of temperature and salinity on the germination of the wild leaf vegetable Corchorus olitorus L., seeds of two varieties of C. olitorus from ΄Bou Salem΄ and ΄Menzel Bouzelfa΄ responses were determined in complete darkness over a wide range of temperatures and salinities. The final germination percentage (FGP) and mean time to germination (MTG) were measured. Germination was inhibited by either an increase or decrease in temperature. For the two varieties, optimal germination was at 30&deg;C. Highest germination percentages were obtained under no-saline conditions. The final germination percentage and germination rate (estimated by MTG) significantly decreased with increasing salt. This study has shown a high degree of variation of these characters mainly related to geographical origin. It was observed also that ΄Menzel Bouzelfa΄ variety was less affected by the imposed salt stress than ΄Bou Salem΄ variety. &nbsp; Key words: Corchorus olitorus, germination responses, salinity, temperature.

The effect of salinity on the germination of dimorphic seeds ofAtriplex micrantha, an annual inhabiting Junggar Desert

The fruits of Atriplex micrantha C. A. Mey. have dimorphism. It has two types of fruits that are different in shape, size, color of seeds and size of bracts attached fruits. The effects of different salts stresses on the seed germination of A. micrantha were studied. The results show the germination percentage and rate decreased as salinity increased and optimal germination was obtained in distilled water. Germination of brown seed was not affected by NaCl at concentrations below 0.2mol/L, and was decreased by NaCl at higher concentrations, and fell to 0 at 2.0mol/L. The black seed could not germinate at 0.4mol/L. The salinity tolerance of brown seed is better. Seeds which were incubated in NaCl solution for 20d recovered after being transferred to distilled water and the germination percentage of recovery from high salinity concentrations was higher than low concentrations. In high salinity (4mol/L NaCl), the percentage of recovery of black seed can achieve 84%, while brown seed only 46%.

Seed Germination and Seedling Development of Anadenanthera Colubrina in Response to Weight and Temperature Conditions

The aim of the study was investigated the effects of seed weight and temperature on the germination behavior, and development of seedlings of Anadenanthera colubrina. Germination was carried out using the five constant temperature regimes (20, 25, 30, 35 and 40oC) under photoperiod (12h) and two classes of seeds: heavy (≥ 0.095g) and light (<0.095g). The experimental design was totally random, with four replications of 25 seeds. The temperature was significant for germination percentage, germination velocity index and mean germination time. There was no effect of seed weight, and there was no interaction between temperature and seed weight for three response variables. Optimum germination for A. colubrina seeds was recorded in four of the five temperatures studied (20, 25, 30 and 35oC) for both heavy and light seeds. At each temperature, the average root length was similar and, the seedling dry weight was greater for the heavy seed class. There was no effect of temperature on the seed mass to the production of normal seedlings, except at 40oC. Variation in seed weight, in A. colubrina, can be a part of their strategy for increasing the probability of success of seed germination and subsequent survival of the species a regeneration niche.

外来杂草小花山桃草种子休眠萌发特性研究

PDF HTML阅读 XML下载 导出引用 引用提醒 外来杂草小花山桃草种子休眠萌发特性 DOI: 10.5846/stxb201303150425 作者: 作者单位: 河南科技大学林学院,浙江农林大学林业与生物技术学院,河南科技大学林学院,浙江农林大学林业与生物技术学院,河南科技大学林学院 作者简介: 通讯作者: 中图分类号: 基金项目: 河南科技大学博士基金资助(09001076); 河南科技大学科学研究基金项目(2007ZY025) Seed dormancy and germination characteristics of Gaura parviflora, an exotic weed species in China Author: Affiliation: Forestry College,Henan University of Science＆Technology,School of Forestry and Biotechnology, Zhejiang A,Forestry College,Henan University of Science＆Technology,School of Forestry and Biotechnology, Zhejiang A,Forestry College,Henan University of Science＆Technology Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:种子萌发和出苗是植物一生中对环境胁迫最为敏感的阶段,外来植物在这一时期对环境条件的适应能力是决定其入侵能力大小的关键因素之一.通过室内外试验研究了小花山桃草种子休眠特性以及贮藏时间、果皮、温度、pH 值、水势、盐分和埋土深度对其种子萌发、幼苗生长和出苗的影响.结果表明:小花山桃草蒴果中4 粒种子的大小差异显著(P < 0.01),但它们的活力和萌发率差别不大,4 粒种子活力均高达96%以上.休眠解除后,萌发率均高达98%以上;坚硬果皮的机械阻碍是引起种子休眠的主要原因;在室温储藏条件下,种子萌发率随贮藏时间的增加先增加后降低.贮藏1个月,萌发率提高到54%(贮藏前为0).贮藏3-6 个月时,萌发率达最大值(98.5%-99%).贮藏1a后,萌发率和萌发速度显著下降,但萌发率仍高达90%以上;在室外,有10.5%的蒴果前两粒种子(果实柱头端)同时萌发出苗.室外埋藏1a后,蒴果中未萌发的3 粒种子的发芽率分别为45.5%、90.5%和88.5%;小花山桃草种子萌发的温度范围为5-35 ℃,15-25 ℃最适于种子萌发,25 ℃最有利于幼苗生长;小花山桃草能忍受一定的盐胁迫和干旱胁迫,盐浓度和水势为0.15 mol/L和-0.5 MPa时,种子萌发率分别为33.5%和9%.种子萌发和幼苗生长最适宜的土壤含水量为50%;小花山桃草对pH 值具有较广泛的适应性,在pH 值为5-9范围内均可萌发;小花山桃草种子在土壤表面的出苗率为43%,埋土深度2 cm时,出苗率最高(89.5%),埋土深度大于10 cm时,不再出苗.小花山桃草种子休眠萌发特征以及出苗特点是其快速入侵的基础.研究结果为预测小花山桃草潜在分布范围以及提出科学合理的综合治理措施提供了理论依据. Abstract:Seed germination and early seedling growth are the stages in a plant's life cycle during which it is most sensitive to environmental stresses. The adaptability of an alien plant at this stage to unfavorable environmental conditions is one of the key factors determining its invasiveness. In this study, experiments were conducted to evaluate the effects of dormancy features, storage time, pericarp, temperature, pH, osmotic stress, salt stress and seed burial depth on seed germination, seedling growth and seedling emergence in Gaura parviflora. Although the four seeds of each capsule were found to differ significantly with respect to weight (P < 0.01), their vigor and germination rates were similar to one another. Seed vigor was greater than 96%, and germination was higher than 98% after release from dormancy. The pericarp of G. parviflora affected seed germination via physical obstruction, and was the major cause of seed dormancy. After storage at room temperature, G. parviflora seed germination initially increased; at longer storage times, however, it decreased. Prior to storage, no germination occurred. After one month of storage, germination rates as high as 54% were observed, with maximum germination (98.5%-99%) taking place after 3-6 months of storage. Germination rate and germination speed decreased significantly after one year of storage, although the germination rate was still greater than 90%. The first two seeds of G. parviflora capsules germinated (10.5%) and emerged at the same time under outdoor conditions. After one year of burial in the soil, germination rates of the remaining second, third and fourth ungerminated seeds averaged 45.5%, 90.5% and 88.5%, respectively. Gaura parviflora seeds germinated at temperatures ranging from 5 ℃ to 35 ℃, with optimum germination occurring at 15-25 ℃, and optimum seedling growth taking place at 25 ℃. Gaura parviflora seeds were fairly tolerant of high salt stress and low water potential, with germination rates of 33.5% and 9% observed at a salinity level of 0.15 mol/L and an osmotic potential of -0.5 MPa, respectively. The optimum soil moisture content for seed germination and seedling growth was 50%. Gaura parviflora seeds were able to germinate over a broad range of pH values, ranging from pH 5 to 9. When seeds were placed on the soil surface, the seedling emergence rate was 43%. Maximum seedling emergence (89.5%) occurred at a burial depth of 2 cm. No seedlings emerged when a burial depth of 10 cm was used. Seed dormancy, seed germination and seedling emergence are the critical factors responsible for the rapid invasion characteristics of this species. Our results should be helpful for predicting potential distribution areas of G. parviflora and for developing effective management strategies for this species. 参考文献 相似文献 引证文献

Reproductive biology of seven taxa of &lt;i&gt;Magnolia&lt;/i&gt; L. in the south of Russian Far East

This paper presents the phenology of seven taxa of the genus Magnolia L., pollen biology on germination and storage conditions, seed productivity, germinating ability of seeds and its dependence on stratification and germination conditions. It has been found that M. kobus DC, M. kobus var. boreales Sarg., M. obovata Thurb., M. officinalis Rehd. et Wils., M. salicifolia (Sieb. et Zucc.) Maxim., M. sieboldii K. Koch. and M. tripetala L. in cultivated condition produce pollen at a low viability rate (9.4 - 31.7%). Real seed productivity of the taxa being studied is less than their potential productivity. However, M. obovata, M. officinalis and M. tripetala are characterized by high seed germinating ability, up to 94%. Optimal germination conditions for seeds of M. tripetala, M. officinalis and M. obovata require protected ground (greenhouse) and stratification at 4ºC during 30 days. The high germinating ability of M. sieboldii seeds in the open ground is explained by stratification duration and temperature required for this species. Sarcotesta effects on higher seed germinating ability have been observed in M. obovata only.DOI: http://dx.doi.org/10.3329/bjpt.v20i2.17390Bangladesh J. Plant Taxon. 20(2): 163-170, 2013

Ecology of Typha domigensis Pers

In a shallow pond at Biratnagar, Nepal, importance value index of T. domingensis ranged between 134 (September) and 179 (May), and net primary productivity of the plant along with associated species was 1001.23 g/m2/yr. Maximum concentrations of nitrogen (2.76%) and potassium (2.87%) occurred in leaves, and phosphorus (0.95%) in roots of the plant in January, and three month old air-dried seeds of the plant had optimum germination (84%) under red light on moist filter papers. The pond water had minimum values of pH (6.12), turbidity (51.2 NTU), conductivity (5.39 ds/m), total dissolved solids (75.5 mg/l, nitrate and nitrite (0.01 mg/l) and potassium (5.6 mg/l) in September; total nitrogen (1.01 mg/l) in May; and ammonia (0.26 mg/l) and total phosphorus (0.72 mg/l) in January. The sediment (mud) of the pond was silty-sandy loam with annual averages of pH 6.6, nitrogen 0.23%, phosphorus 0.006%, potassium 0.04%, organic carbon 4.05% and C/N ratio 17.6:1.&#x0D;

Human Threat On Phenological Cycle Of Selected Dry Deciduous Tree Species In North Gujarat Region (Ngr), Gujarat, India

Phenological observations were taken for 13 woody species for two years (Jan 2006 - Dec 2007) in dry deciduous forest of North Gujarat. The phenological behavior of most of the woody species was almost similar in two different years. Leaf initiation started in the month of March with peak April – May before pre-monsoon showers and leaf - fall began in October with a peak in November and December. Flowering in most of the woody species was observed in the month of February continued till May, fruit appearance for these species from March, with a peak of August. In July and August 69% of woody species appeared in fruit ripening stage. While monsoon begins same duration, that allow to the optimal germination of tree species. An observing human impact on selected species facing seasonal threats, more number of species faced cutting during leaf fall period or before on setting of flowers. International Journal of Environment, Volume-2, Issue-1, Sep-Nov 2013, Pages 60-69 DOI: http://dx.doi.org/10.3126/ije.v2i1.9208

Seed germination of calendula in response to temperature

Calendula (Calendula officinalis L.) seeds contain high concentrations of calendic acid (C18:3) which can be used as tung and linseed oil substitutes. Calendula is adapted to temperate climate, but field studies in western Minnesota indicated that stand establishment was susceptible to high soil temperatures immediately after planting in spring. Consequently, understanding the temperature conditions that govern germination of calendula is necessary to incorporate the crop into crop rotations of the Upper Midwest, U.S. Temperature gradient bar and heat-shock experiments were used to characterize calendula (cv. ‘Carola’) sensitivity before and during germination. Seed germinated between 2 and 32°C with the optimum germination temperature at 16–17°C. Heat shock temperatures (35–40°C) of less than 50h duration reduced germination (at 16°C) below 50%. At 45°C, 100% seed lethality was induced within 24h of heat treatment. Accordingly, calendula seed should be sown in the field only if forecasted soil conditions are expected to be below 30°C during seed germination.