Simulating the influence of vernalization, photoperiod and optimum temperature on wheat developmental rates

Background and Aims

Accurately representing development is essential for applying crop simulations to investigate the effects of climate, genotypes or crop management. Development in wheat (Triticum aestivum, T. durum) is primarily driven by temperature, but affected by vernalization and photoperiod, and is often simulated by reducing thermal-time accumulation using vernalization or photoperiod factors or limiting accumulation when a lower optimum temperature (T_optl) is exceeded. In this study T_optl and methods for representing effects of vernalization and photoperiod on anthesis were examined using a range of planting dates and genotypes.

Methods

An examination was made of T_optl values of 15, 20, 25 and 50 °C, and either the most limiting or the multiplicative value of the vernalization and photoperiod development rate factors for simulating anthesis. Field data were from replicated trials at Ludhiana, Punjab, India with July through to December planting dates and seven cultivars varying in vernalization response.

Key Results

Simulations of anthesis were similar for T_optl values of 20, 25 and 50 °C, but a T_optl of 15 °C resulted in a consistent bias towards predicting anthesis late for early planting dates. Results for T_optl above 15 °C may have occurred because mean temperatures rarely exceeded 20 °C before anthesis for many planting dates. For cultivars having a strong vernalization response, anthesis was more accurately simulated when vernalization and photoperiod factors were multiplied rather than using the most limiting of the two factors.

Conclusions

Setting T_optl to a high value (30 °C) and multiplying the vernalization and photoperiod factors resulted in accurately simulating anthesis for a wide range of planting dates and genotypes. However, for environments where average temperatures exceed 20 °C for much of the pre-anthesis period, a lower T_optl (23 °C) might be appropriate. These results highlight the value of testing a model over a wide range of environments.Key words: Wheat, Triticum aestivum, T. durum, air temperature, thermal time, shoot apex, phenology, growth stages, anthesis, flowering     

The influence of local spring temperature variance on temperature sensitivity of spring phenology

The impact of climate warming on the advancement of plant spring phenology has been heavily investigated over the last decade and there exists great variability among plants in their phenological sensitivity to temperature. However, few studies have explicitly linked phenological sensitivity to local climate variance. Here, we set out to test the hypothesis that the strength of phenological sensitivity declines with increased local spring temperature variance, by synthesizing results across ground observations. We assemble ground‐based long‐term (20–50 years) spring phenology database (PEP725 database) and the corresponding climate dataset. We find a prevalent decline in the strength of phenological sensitivity with increasing local spring temperature variance at the species level from ground observations. It suggests that plants might be less likely to track climatic warming at locations with larger local spring temperature variance. This might be related to the possibility that the frost risk could be higher in a larger local spring temperature variance and plants adapt to avoid this risk by relying more on other cues (e.g., high chill requirements, photoperiod) for spring phenology, thus suppressing phenological responses to spring warming. This study illuminates that local spring temperature variance is an understudied source in the study of phenological sensitivity and highlight the necessity of incorporating this factor to improve the predictability of plant responses to anthropogenic climate change in future studies.     

Species diversity, abundance, and phenology of aphid natural enemies on spring wheats resistant and susceptible to Russian wheat aphid

The species composition, relativeabundance, and seasonal dynamics of selectednatural enemies of cereal aphids were monitoredin spring wheat fields in Moscow, Idaho in 1997and 1998. Trials also examined the potentialimpact of resistance to Russian wheat aphid(RWA), Diuraphis noxia (Mordvilko)(Homoptera: Aphididae) in wheat, on aphidbiological control agents. Natural enemypopulations were monitored on two springwheats: D. noxia susceptible variety`Centennial' and resistant genotype `IDO488'. Field plots were artificially infested withadult D. noxia, and sampled for cerealaphids and parasitoids weekly. Coccinellidpredators were monitored once in 1997 and twicein 1998. The coccinellids Hippodamiaconvergens Guerin, Coccinellaseptempunctata L., C. transversoguttataBrown and C. trifasciata Mulsant weredetected. No significant differences in adultor immature coccinellid densities were observedbetween the D. noxia resistant andsusceptible genotypes. During both years, themost abundant primary hymenopteran parasitoidswere Diaeretiella rapae (M'Intosh), Aphidius ervi Haliday, A. avenaphis(Fitch), and Lysiphlebus testaceipes(Cresson), Aphelinus varipes (Foerster),Aphidius colemani Viereck, Aphidiuspicipes (Nees), Aphidius sp., Monoctonus washingtonensis Pike & Stary, Praon gallicum Stary, Praon occidentaleBaker, and Praon sp. were also detected. Numbers of both D. noxia and D.rapae were significantly greater on Centennialthan on IDO488 in both years. When all speciesof cereal aphids and parasitoids areconsidered, the total percentage parasitism wasnot significantly different between thegenotypes. There was no interaction betweenD. noxia resistance and the populationdensity of the predators or parasitoidsmonitored. These results suggest that the D. noxia resistant line had no adverse impacton natural enemies under the conditions ofthese field experiments.     

Responses of alloplasmic (cytoplasm=Triticum timopheevii) and euplasmic wheats (Triticum aestivum) to photoperiod and vernalization

Summary Heritability estimated from sire family variance components, ignoring dams, pools conventional paternal and maternal half sib estimates, in a way which is biased upward, and sub-optimal for minimizing the sampling variance. Standard error of a sire family estimate will be smaller than that of the equivalent paternal half sib estimate, but not as small as that of an estimate obtained by optimal pooling of paternal and maternal half sib estimates. If only additive genetic variance components are significant, the bias may be removed by use of a computed average genetic relationship for sire families, in place of a nominal R = 0.25. Average genetic relationship may be computed from mean and variance of dam family size within sire families. If dominance, epistatic, or maternal components are significant, this simple correction is not appropriate. In situations likely to be encountered in large domestic species such as sheep and cattle (dam family size small and uniform) bias will be negligible. The method could be useful where cost of dam identification is a limiting factor.     

Effects of growth temperature and winter duration on leaf phenology of Erythronium japonicum,a forest spring geophyte

The effects of growth temperature and winter duration on the leaf phenology of Erythronium japonicum were examined in two experiments. Bulbs wintered in the field were cultivated at 10 and 20° C and the bulbs were cultivated at 15° C after chilling treatment at 3° C for 60 and 120 days and without chilling in winter. The plants cultivated at 20° C showed significantly earlier leaf emergence, a more rapid rate of leaf extension and shorter leaf longevity than those cultivated at 10° C. The decrease in the leaf longevity at 20° C resulted from the decreases in the durations of all of the developmental, mature, and senescent phases. The bulbs without chilling treatment did not sprout leaves and those with chilling treatment sprouted leaves. The increase in the length of chilling treatment from 60 to 120 days affected leaf phenology in same manner as the increase in the growth temperature from 10 to 20° C.     

温度对叶用莴苣春化的影响

为了探讨温度对叶用莴苣春化的影响,进而明确其春化类型,本试验选用两个易抽薹叶用莴苣品种GB-30和GB-31为试材,分别进行20 d的4、20和25 ℃处理,然后均进行高温胁迫促进抽薹,采用石蜡切片观察茎尖花芽分化进程,并结合后期抽薹开花情况来判断是否进行春化,并确定其春化类型.结果表明:两个品种在前期经过3种温度处理后,在高温胁迫第8天时均有不同程度的抽薹.两个品种不同温度处理下花芽均进行了分化,前期4 ℃处理并没有使其花芽分化明显提前,后期的高温胁迫可以明显促进花芽分化进程.两品种间在不同温度处理下完成各发育阶段所需天数存在差异,两品种各处理从催芽到开花以及从高温到开花的有效积温也存在差异.前期未经低温处理的叶用莴苣也进入花芽分化、抽薹、现蕾及开花阶段,表明叶用莴苣为非低温春化型植物,后期高温处理能明显促进其抽薹开花,而且从催芽开始只有有效积温达到约2500 ℃·d才能开花.     

Effects of temperature on aphid phenology

Daily samples between 1964 and 1991 from suction traps throughout Great Britain were used to study the migration phenologies of five aphid species: Brachycaudus helichrysi, Elatobium abietinum, Metopolophium dirhodum, Myzus persicae and Sitobion avenae, and their relationship with temperature. Regression relationships have been established between characteristics of aphid phenology and temperature, latitude and longitude for each species. There were differences between species in the period for which temperature was most strongly associated with aphid phenology. The study indicates that temperature, especially winter temperature, is the dominant factor affecting aphid phenology, for all five species. A 1 °C increase in average winter temperature advanced the migration phenology by 4–19 days depending on species. Effects of temperature on the aphid phenology are similar between holocyclic and anholocyclic species, unlike the effects of temperature on date of first flight record which have been previously shown to be important only in anholocyclic species.     

温度和光周期协同作用对蒙古栎幼苗春季物候的影响

植物物候对气候变化非常敏感,但关于物候对不同气候因子协同作用的响应机制仍不清楚。为此,以蒙古栎为研究对象,针对蒙古栎物候的主要影响因子温度和光周期,利用大型人工气候室,模拟研究了温度与光周期协同作用（对照、增温1.5℃、增温2.0℃,不同光周期（10 h、14 h、18 h）及其协同作用（对照处理、增温1.5℃×18 h、增温1.5℃×10 h、增温2.0℃×18 h、增温2.0℃×10 h））对蒙古栎春季物候的影响与机制。结果表明：（1）相同水分条件下,不同升温程度对蒙古栎幼苗春季物候的影响不同。温升1.5℃促进蒙古栎幼苗春季物候（芽膨大期、芽开放期、展叶始期和展叶盛期）提前;而温升2.0℃则对不同春季物候的影响不同,表现为促进芽休眠解除和芽开放,但抑制叶片展开。（2）相同水分条件下,不同光周期对蒙古栎幼苗不同春季物候的影响存在差异。长光周期对蒙古栎幼苗展叶盛期影响最大,短光周期对芽膨大期影响最大,但均表现为抑制作用。（3）相同水分条件下,温度升高与光周期增加协同作用有助于促进蒙古栎幼苗春季物候提前,但温度升高与光周期缩短协同作用则对春季物候有抑制作用。（4）蒙古栎幼苗春季物候变化与前期气候胁迫程度存在显著正相关,表明前期气候因子也是物候变化的重要影响因子。研究结果丰富了蒙古栎物候响应多气候因子协同作用的认知,有助于促进物候模型的完善。     

Interaction of vernalization, photoperiod and high temperature in flowering of Arabidopsis thaliana (L.) HEYNH.

Flowering of Arabidopsis thaliana (L.) HEYNH., var. "Stockholm",plants, raised from vernalized seeds, may be modified by thephotoperiodic conditions or a short (1 week) exposure to hightemperature (32°C) following vernalization, depending onthe duration of the cold treatment. When vernalization is partial(1 to 4 weeks at 4°C), both short days (8hr light) and hightemperature have a devernalizing effect, but when the cold requirementhas been fully satisfied, after 5 to 6 weeks at 4°C, devernalizationis no longer possible. There is no interaction between photoperiodand high temperature. Fully vernalized plant flower in bothlong and short days, although flowering is delayed in shortdays. This delay is not a photoperiodic effect, however, butmay be ascribed to the decreased radiant energy available inan 8-hr photoperiod. Thus, fully vernalized Arabidopsis plantsare day-neutral. (Received November 5, 1969; )     

Effects of temperature and photoperiod on the seasonal timing of Western honey bee colonies and an early spring flowering plant

Temperature and photoperiod are important Zeitgebers for plants and pollinators to synchronize growth and reproduction with suitable environmental conditions and their mutualistic interaction partners. Global warming can disturb this temporal synchronization since interacting species may respond differently to new combinations of photoperiod and temperature under future climates, but experimental studies on the potential phenological responses of plants and pollinators are lacking. We simulated current and future combinations of temperature and photoperiod to assess effects on the overwintering and spring phenology of an early flowering plant species (Crocus sieberi) and the Western honey bee (Apis mellifera). We could show that increased mean temperatures in winter and early spring advanced the flowering phenology of C. sieberi and intensified brood rearing activity of A. mellifera but did not advance their brood rearing activity. Flowering phenology of C. sieberi also relied on photoperiod, while brood rearing activity of A. mellifera did not. The results confirm that increases in temperature can induce changes in phenological responses and suggest that photoperiod can also play a critical role in these responses, with currently unknown consequences for real‐world ecosystems in a warming climate.     

Molecular characterization of vernalization loci VRN1 in wild and cultivated wheats

Background  

Variability of the VRN1 promoter region of the unique collection of spring polyploid and wild diploid wheat species together with diploid goatgrasses (donor of B and D genomes of polyploid wheats) were investigated. Accessions of wild diploid (T. boeoticum, T. urartu) and tetraploid (T. araraticum, T. timopheevii) species were studied for the first time.     

Effects of photoperiod and temperature on the development of Bonagota cranaodes

Abstract.  The Brazilian apple leafroller, Bonagota cranaodes (Meyrick) (Lepidoptera: Tortricidae) is reared in the laboratory under a long-day (LD 14 : 10 h) and a short-day (LD 7 : 17 h) photoperiod at 22 °C, and under two different temperatures (10–13 °C and 21–22 °C). The development time from larval to adult eclosion do not differ between the two photoperiods, but did between the two temperature regimes. However, the larvae do not enter diapause, even under short day conditions and low temperatures. The number of adults obtained does not differ with temperature and light conditions. Field captures with pheromone traps show that Brazilian apple leafroller occurs in apple orchards throughout the year and the population densities are lower in winter. Accordingly, control measures should be taken during the off-season.     

升温、光周期和氮添加变化对兴安落叶松幼苗叶黄期的影响

物候是气候变化敏感指标,是陆地生态系统模型的关键参数。目前关于气候变化对物候影响的研究较多,但关于多环境因子交互作用对秋季物候影响的研究尚不充分,制约着物候变化机制的认知与模型发展。以兴安落叶松幼苗叶黄期为研究对象,采用控制实验研究叶黄期对升温、光周期和氮添加变化及其交互作用的响应。结果表明：（1）升温对兴安落叶松幼苗叶黄期的影响较显著,升温使叶黄始期和叶黄普期显著提前,完全变色期不显著推迟;（2）光周期变化对叶黄期的影响极显著,光周期延长使叶黄始期和叶黄普期显著提前,完全变色期显著推迟;（3）叶黄期与氮添加量相关性不显著;（4）升温、光周期和氮添加变化双因子交互作用对叶黄始期和叶黄普期的影响均极显著且均存在极值,但对完全变色期的影响均不显著：升温与光周期延长交互作用使叶黄始期和叶黄普期提前,且在升温1.5℃、光周期14h时最显著;光周期延长与氮添加交互作用使叶黄始期和叶黄普期提前,且在施低氮（5g N m^-2 a^-1）、光周期10h时最显著;升温与氮添加交互作用使叶黄始期和叶黄普期提前,且在施高氮（20g N m^-2 a^-1）、升温1.5℃时最显著;（5）升温、光周期和氮添加变化交互作用对叶黄始期和叶黄普期影响极显著,对完全变色期的影响不显著。这表明,升温、光周期延长和氮添加将延长兴安落叶松幼苗叶黄期,从而增加兴安落叶松幼苗的固碳时间。研究结果可为物候模型发展以及森林生态系统碳估算提供依据。     

光照和温度对大绒鼠产热特征的影响

为了解横断山地区大绒鼠对光照和温度两个因子的适应性特征,将大绒鼠分为4组,分别于5±1℃,6L:18D:5±1℃,18L:6D;30±1℃,6L:18D和30±1℃,18L:6D 4个条件下驯化28 d.分别测定了对照组(0 d)和驯化28 d后,每一个体的体重、体温和产热能力;并测定驯化28 d后4组大绒鼠个体的肝脏和褐色脂肪组织的产热活性变化.结果显示,在低温诱导下大绒鼠体重下降,体温降低,静止代谢率升高,非颤抖性产热能力增加,肝脏和褐色脂肪组织的产热活性也出现相应提升;在高温下出现与低温时相反的现象;但光照周期对大绒鼠的体重、体温、产热能力及肝脏和褐色脂肪组织的产热活性均没有显著影响.推测由于横断山的低纬度、高海拔特征可能导致大绒鼠在季节适应过程中对温度的敏感程度高于光照.     

Effects of photoperiod and temperature on testicular function in amphibians

Most amphibians present an annual testicular cycle characterized by a quiescent period (late autumn-winter) and a spermatogenic period (spring and summer). At the end of the period of spermatogenesis undifferentiated interstitial cells transform into steroid-secreting Leydig cells which regress in spring at the beginning of the new spermatogenetic cycle. The testicular cycle is controlled by the pituitary gonadotropin levels which are high in autumn and winter, low in spring and increase temporarily in the middle of summer. Photoperiod and temperature seem to be the most important external factors involved in the regulation of this cycle in many amphibian species since the colder the geographic area, the longer the quiescent period and the shorter the spermatogenic period. This suggests the occurrence of a potentially continuous cycle in these species, in contrast with that which occurs in other species having an endogenous rhythm of testicular function which is much less sensitive to environmental factors. Although the specific response to temperature can vary widely between species, the most frequent observation in amphibians with a potentially continuous cycle is that exposure to mild temperatures (15-20 degrees C, according to the spring temperatures of the different geographic areas) stimulates spermatogenesis even during the period of testicular quiescence. If this mild temperature is combined with a long photoperiod, complete spermatogenesis is attained. Experiments performed during the period of germ-cell proliferation (development from spermatogonia to round spermatids) indicated that low temperatures (below 11 degrees C) as well as short photoperiods (less than 8 h of light) hinder germ-cell proliferation. Moderately high temperatures (about 30 degrees C) do not impair this proliferation. In the newt Triturus marmoratus, it has been shown that an excessively long photoperiod (over 16 h) has the same effect as a short photoperiod. In this species eyes are not required for the testicular photoperiodic response. Photoperiod appears to have no effect on spermiogenesis (differentiation of round spermatids into spermatozoa), because once round spermatids are formed, spermiogenesis will occur even in total darkness. Mild temperatures seem to be necessary for spermiogenesis as well as for androgen biosynthesis because neither process will take place at extreme temperatures. Results on the effect of photoperiod in steroidogenesis differ between species.     

Effects of temperature, photoperiod, and light intensity on the calling rhythm in Arctiid moths

Mean times of onset for calling in Haploa clymene (Brown), Spilosoma virginica (Fabricius), Pareuchaetes insulata (Walker), Cycnia tenera (Hübner), and Euchaetes egle (Drury) advance to earlier times in the photoperiod at lower temperatures. Temperature has no apparent effect on the calling period in Pyrrharctia isabella (J. E. Smith), Spilosoma congrua Walker, and Apantesis nais (Drury). The relationship between the temperatures experienced by each of these species as adults and the response of their calling rhythms to temperature is discussed. Lights-on can elicit calling behaviour in C. tenera, although it is not an absolute requirement because calling eventually begins when lights-on is delayed 4 h and calling also begins prior to lights-on at lower temperatures. Calling periods lengthen in C. tenera and S. congrua when the scotophase is prolonged and in S. congrua after the onset of a lower photophase light intensity (40 lux), suggesting that a higher photophase light intensity (450 lux) inhibits calling and thus causes its termination.

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Résumé Aux faibles températures le moment moyen de déclenchement de l'appel apparaît plus tôt au cours de la photopériode chez Haploa clymene Brown, Spilosoma virginica Fab., Pareuchaetes insulata Walk., Cycnia tenera Hübn. et Euchaetes egle Drury. La température n'a apparemment pas d'effet sur le moment où l'appel débute chez Pyrrharctica isabella J.E. Smith, S. congrua Walk. et Apantesis nais Drury.L'analyse porte sur les relations entre les températures subies par les adultes de ces espèces et leurs réactions d'appel aux différentes températures. L'apparition de la lumière peut induire le comportement d'appel chez C. tenera, bien que ce ne soit pas indispensable puisqu'il peut éventuellement commencer à des températures plus basses avant l'illumination quand celle-ci est retardée de 4 heures. Les périodes d'appel sont prolongées avec la scotophase chez C. tenera et S. congrua, et même après l'apparition d'une photophase à faible intensité lumineuse (40 lux), l'appel de S. congrua se poursuit, ce qui suggère que les photophases à intensité lumineuse plus élevée (450 lux) inhibent l'appel et ainsi en provoquent la fin.

     

温度和光周期对亚洲玉米螟羽化节律的影响

实验在不同的温度和光周期条件下研究了亚洲玉米螟Ostrinia furnacalis(Guenée)的羽化节律。结果表明:在8¹6 h的暗期中亚洲玉米螟羽化高峰均集中在暗期,羽化活动随光暗交替表现出节律性。这种节律性受到暗长的影响,暗期越短羽化高峰越提前,反之亦然;其次温度也影响羽化节律,在22℃中各光周期的羽化高峰均比25℃出现的更晚。此外亚洲玉米螟在持续的光期中羽化不表现出内源性节律,而在持续暗期中却表现出内源性节律,且该内源性节律在22℃和25℃下基本相同约为24 h。     

Effects of temperature and photoperiod on flowering in Hyptis brevipes

Few tropical species have been tested for their flowering response under controlled conditions. Hyptis brevipes Poit, is an annual herb, commonly found in wet margins of streams and ponds, being considered a weed for some perennial plantations in Brazil. Under experimental glasshouse conditions, this species proved to be an obligate short-day plant. Flowering was delayed when photoperiods longer than 8 h were given, the critical photoperiod being between 12 and 13 h. When both temperature and photoperiod were controlled, at 20°C a longer protoperiod (by almost 1 h) is still inductive compared to 25 and 30°C. The number of short-day cycles required for full induction is relatively high and dependent upon temperature; at 20°C or above, 10 cycles are adequate, but at 15°C, more short-day cycles are needed. The number of inflorescences formed as well as the floral index vary according to daylength × temperature × inductive cycle number, allowing flowering to be assessed quantitatively. Long days are inhibitory to flowering, either suppressing it completely (when symmetrically intercalated among 24 inductive cycles) or preventing the floral index from increasing.     

Effects of photoperiod and temperature on sexual recrudescence in the male weakfish,Cynoscion regalis

Synopsis Male weakfish,Cynoscion regalis, were collected in the south-west portion of Delaware Bay from April through August of 1992. Histological examination of testes collected from these specimens was used as a baseline for comparison with laboratory data. Weakfish testes were found to be of the unrestricted, continuous spermatogenic type and spermatogenesis was apparently prenuptial. The effects of photoperiod and temperature on gonadal maturation were studied in the laboratory using fish collected in June and July 1991. These fish were exposed to two months of simulated winter conditions prior to assignment to one of four experimental photoperiod/temperature regimes. The treatments included combinations of long day (LD,15 h light) or short day (SD, 9 h light) and high (HT, 20° C) or low (LT, 13° C) water temperatures. The four treatment groups were LD/HT, LD/LT, SD/HT, SD/LT. The LD/HT group was the only one to mature fully, expressing increased plasma androgen levels, increased gonadosomatic index (GSI) and advanced spermatogenesis, as well as hypertrophy of the sonic muscles, a seasonally expressed secondary sexual characteristic of male weakfish. High temperatures promoted the later stages of spermatogenesis, which were apparently inhibited by low temperatures. The presence of an endogenous annual cycle is suggested by the partial maturation of the testes and sonic muscles in all treatment groups, regardless of photoperiod/temperature regime.