Onset Of Anthesis Research Articles

Developing Early Morning Flowering Version of Rice Variety CO 51 to Mitigate the Heat-Induced Yield Loss

By 2050, the rice production needs to be increased by at least 50% in order to meet the growing food demands of the global population. Among various yield limiting factors, high temperature is fast becoming a major threat to sustain rice yields due to its increased frequency of occurrence and severity of stress events. The development of heat-resilient rice cultivars has been slow due to the lack of relevant donors for heat tolerance traits and limited information regarding the genetic basis of these component traits. The early morning flowering (EMF) trait, contributing to heat escape by promoting flowering/anthesis during cooler hours in the morning is demonstrated to offer protection against high-temperature-induced failure of pollination and fertilization. In this study, evaluation of CO 51, IR64 and IR64-qEMF3 (NIL of IR64 harboring QTL promoting EMF revealed that qEMF3 promoted early morning flowering in IR64-qEMF3 (1½ to 2 h earlier than IR64) and thereby reduced the sterility by about 8.15%. Attempts through marker-assisted backcross breeding led to development of advanced backcross progenies (NILs) of CO 51, harboring qEMF3. Evaluation of 88 BC3F2 progenies identified 19 progenies harboring qEMF3 under homozygous conditions. Evaluation of NILs of CO 51 harboring qEMF3 during summer 2019 revealed that the NILs exhibited early (7.30 a.m.) onset of anthesis by 1½ h and completed its peak anthesis well around cooler hours (9.30 a.m.) of the day and thereby recorded reduced spikelet sterility (7.8–9.0%) than their recurrent parent CO 51 (19.2%). The current study clearly demonstrated the efficacy of early morning flowering in the mitigation of yield losses under high-temperature conditions in a farmer preferred rice variety.

High-energy-level metabolism and transport occur at the transition from closed to open flowers.

During the maturation phase of flower development, the onset of anthesis visibly marks the transition from buds to open flowers, during which petals stretch out, nectar secretion commences, and pollination occurs. Analysis of the metabolic changes occurring during this developmental transition has primarily focused on specific classes of metabolites, such as pigments and scent emission, and far less on the whole network of primary and secondary metabolites. To investigate the metabolic changes occurring at anthesis, we performed multi-platform metabolomics alongside RNA sequencing in individual florets harvested from the main inflorescence of Arabidopsis (Arabidopsis thaliana) ecotype Col-0. To trace metabolic fluxes at the level of the whole inflorescence and individual florets, we further integrated these studies with radiolabeled experiments. These extensive analyses revealed high-energy-level metabolism and transport of carbohydrates and amino acids, supporting intense metabolic rearrangements occurring at the time of this floral transition. These comprehensive data are discussed in the context of our current understanding of the metabolic shifts underlying flower opening. We envision that this analysis will facilitate the introgression of floral metabolic traits promoting pollination in crop species for which a comprehensive knowledge of flower metabolism is still limited.

Adaptability Mechanisms of Japonica Rice Based on the Comparative Temperature Conditions of Harbin and Qiqihar, Heilongjiang Province of Northeast China

Japonica rice has been considerably impacted from climate change, mainly regarding temperature variations. Adjusting the crop management practices based on the assessment of adaptability mechanisms to take full advantage of climate resources during the growing season is an important technique for japonica rice adaptation to climate changed conditions. Research based on the adaptability mechanisms of japonica rice to temperature and other environmental variables has theoretical and practical significance to constitute a theoretical foundation for sustainable japonica rice production system. A contrived study was arranged with method of replacing time with space having four different japonica cultivars namely Longdao-18, Longdao-21, Longjing-21, and Suijing-18, and carried out in Harbin and Qiqihar during the years 2017–2019 to confer with the adaptability mechanisms in terms of growth, yield and quality. The formation of the grain-filling material for superior and inferior grains was mainly in the middle phase which shared nearly 60% of whole grain-filling process. Maximum yield was noticed in Longdao-18 at Harbin and Qiqihar which was 9500 and 13,250 kg/ha, respectively. The yield contributing components fertile tillers, number of grains per panicle, and 1000-grain weight were higher at Qiqihar; therefore, there was more potential to get higher yield. The data for grain-filling components demonstrated that the filling intensity and duration at Qiqihar was contributive to increase the grain yield, whereas the limiting agents to limit yield at Harbin were the dry weights of inferior grains. The varietal differences in duration and time of day of anthesis were small. Across all cultivars and both study sites, nearly 85% of the variation of the maximum time of anthesis could be justified with mean atmospheric temperature especially mean minimum temperature. Mean onset of anthesis was earliest in Longdao-21 at Harbin, whereas it was latest in Longdao-18 at Qiqihar. The maximum time to end anthesis and the longest duration of anthesis were taken by Longdao-18, i.e., 9.0 hasr and 4.2 h, respectively. Chalkiness and brown rice percentages were elevated at Qiqihar showing Harbin produced good quality rice. This study investigated the adaptability mechanisms of japonica rice under varying temperature conditions to distinguish the stress tolerance features for future sustainability and profitability in NEC. It was concluded that there is an adaptive value for anthesis especially regarding Tmin and, moreover, earlier transplantation may produce tall plants. The results demonstrated that high temperature at the onset of anthesis at the start of the day enhanced the escape from high temperature later during the day. Early transplantation is recommended in NEC because earlier anthesis during humid days rendered for potential escape from high ambient temperature later during that day. Temperature influenced japonica rice significantly and coherently, whereas the influence of growing season precipitation was not significant. Daily mean sunshine influenced the japonica rice significantly, but the impact was less spatially coherent. The results foregrounded the response of the japonica rice to external driving factors focusing climate, but ignored socioeconomic suggesting emphasis on both driving factors to target future research and render important insights into how japonica rice can adapt in mid-high-latitude regions.

PHENOLOGY AND GROWING DEGREE DAYS OF FESTIVAL STRAWBERRY GROWN ON RED VOLCANIC ROCK AT TWO PLANT DENSITIES

Due to their correlation with temperature, growing degree days (GDD) allow to analyze the effect of climate change on plant phenology, while being also useful for scheduling activities in a cultivation system. Fruit cropping systems in general lack enough information in this regard. This research aimed to determine GDD during the phenology of Festival strawberry (Fragaria × ananassa Duch.) grown on two substrates at two plant densities under a macro-tunnel. Previously chilled (4 o C/720 h), one-leaf plants were grown from August 2016 to March 2017 either in hydroponics on red volcanic rock or in soil with fertigation at 10 or 15 plants m-2. A Steiner nutrient solution reduced to 50% of its original concentration was used. GDD were counted daily after planting using the single sine curve method with a base temperature of 3 o C. A high correlation coefficient (r > 0.964) was found between GDD and days after planting (DAP) for the phenological stages studied. The phyllochron was not affected by treatments, and 597 GDD were required as an average for the onset of leafing and a high correlation between air temperature and the emission of leaves number 2 to 10 (r = 0.9754; P ≤ 0.0001). The substrate did not affect the chronology of the reproductive phenological stages. The onset of anthesis was delayed by 17 days in plants grown at 15 plants m-2 (2039.4 GDD) compared to those grown at 10 plants m-2 (1829.7 GDD), but there was no effect of plant density for the sequent phenological stages. It is concluded that GDD have a high predictive value in Festival strawberry for DAP of the phenological stages studied; likewise, the phyllochron and reproductive phenology were not affected by substrate cultivation; however, planting at high densities could delay the onset of anthesis.

Bud pollination and other techniques are ineffective in breaking late-acting self-incompatibility in Ceiba chodatii (Malvaceae - Bombacoideae)

There are two homomorphic self-incompatibility (SI) mechanisms among flowering plants - gametophytic self-incompatibility (GSI) and sporophytic self-incompatibility (SSI). Whilst SI has the advantage of promoting outbreeding in natural populations, it can also be a problem for horticulturists and agronomists. Thus, a number of techniques have been successfully employed to break both GSI and SSI, including bud pollination, saline pre-treatment of the stigmas and simply selfing ageing flowers. We applied these three techniques to determine whether they would be effective at breaking SI in Ceiba chodatii, a species with late-acting self-incompatibility (LSI). We self- or cross-pollinated buds ranging from 1-4 days prior to anthesis and checked ageing by selfing or crossing flowers at 1-4 days after the onset of anthesis, with those at four days showing petal wilt. None of the selfed buds or ageing flowers set fruit, unlike the majority of crossed flowers. Likewise, all flowers to which 1 % saline was applied to the stigmas prior to selfing failed to set fruit. We conclude that unlike GSI and SSI, which have pre-zygotic control of self-pollen function, LSI is likely to be immune to these techniques since the focus of rejection occurs after self pollen tubes have reached the ovary.

Variability of cannabinoid contents depending on breeding methods

Purpose and objectives. To reveal new possibilities for the expression of cannabis genotypes to obtain starting material with increased contents of non-psychotropic cannabinoids, without tetrahydrocannabinol and stabilized biological traits.
 Material and methods. In our study, we took Ukrainian hemp cultivars, the populations of which were distinguished by high stability of cannabinoid contents in comparison with foreign cultivars, as a basis. The study was carried out using breeding, biochemical and statistical methods: physical mutagenesis, inbreeding, individual selection, thin-layer and gas-liquid chromatography to evaluate plants for cannabinoids (HP 6890 Series Hewlett Packard chromatograph using an internal standard).
 Results and discussion. It was found that gamma rays at a dose of 200 Gy disrupted the genotypic relationships between cannabinoids, with accumulation of their minimum or maximum amounts. Lowering the irradiation dose to 150 Gy does not destabilize the population in terms of the cannabinoid contents.
 Inbreeding can be also used in breeding for both to create inbred lines that are homozygous for the ‘no cannabinoids’ trait and to identify lines with increased contents of cannabidiol, cannabigerol or cannabichromen.
 A lot of early-bred and modern cultivars (French, Polish, Hungarian, German) show a high population variability of the cannabinoid contents, proving that no systemic breeding was conducted to stabilize these traits in the populations of these cultivars. High homogeneity of populations in terms of the formation and accumulation of cannabinoids is only intrinsic to monoecious hemp cultivars bred by the Institute of Bast Crops of NAAS.
 The homozygosity of a population primarily depends on the control of targeted cross-pollination between cannabinoid-free plants using an express testing plants for these compounds prior to anthesis onset and subsequent analysis of the selected elite plants by thin-layer chromatography.
 Given the relevance of creating hemp varieties with therapeutic properties, breeding methods have been developed to shift the balance of ‘no cannabinoid at all’ towards a genetically determined increase in one of the cannabinoids (cannabidiol, cannabigerol, cannabichromene) combined with eliminated psychotropic activity (the THC content does not exceed 0.08%).
 Studies of cannabinoid accumulation revealed differences in their formation during the growing period. Based on the fact that the maximum accumulation of cannabinoids occurs during the seed ripening onset, and, in particular, their synthesis is the most intensive in perianths and small leaves, it is possible to evaluate the prospects for creating hemp cultivars with a branched diamond-shaped inflorescence, which will provide, in addition to a high content of one or another cannabinoid, an increased yield of plant biomass.
 Conclusions. Physical mutagenesis, inbreeding and selection are promising breeding methods for reducing psychotropic tetrahydrocannabinol, stabilizing cannabis cultivars in terms of the absence of cannabinoids, increasing the contents of cannabidiol, cannabigerol and cannabichromene gaining advantage from valuable collection accessions

Erratum

Previous article FreeErratumOriginal articlePrecise Sternotribic Pollination by Settling Moths in Adenophora maximowicziana (Campanulaceae)Full TextPDF Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinked InRedditEmailQR Code SectionsMoreIn the article “Precise Sternotribic Pollination by Settling Moths in Adenophora maximowicziana (Campanulaceae)” by Daichi Funamoto (International Journal of Plant Sciences 180:200–208), the author identified errors in the article that warrant correction.On page 202, the sentence “The pistillate flowers were emasculated” should read “The staminate phase flowers were emasculated.”In figure 2, the Y-axis label is missing. It should be “Number of pollen grains.” The corrected version is provided here.Fig. 2. Number of pollen grains of Adenophora maximowicziana attached to 14 sites of the bodies of 13 noctuid moths. The data represent the mean ± SE.View Large ImageDownload PowerPointOn page 203, the sentence “Staminate phase flowers changed to pistillate phase flowers during the night, from 1800 to 2330 h” should read “Staminate phase flowers changed to pistillate phase flowers during the night, from 1800 to 2230 h.” This error is the result of data-processing mistakes that also yielded slightly incorrect data points in figure 3 but that do not affect the main conclusion of the article. A corrected version of figure 3 is also provided.Fig. 3. Number of Adenophora maximowicziana flowers at onset of anthesis (solid line with circles) and change of sexual phase (dashed line with triangles) of flowers. Shaded area indicates the approximate time of the nocturnal period.View Large ImageDownload PowerPointFinally, in table 3, the headers of both columns erroneously include “[mm].” Instead, they should be “(mean ± SE).”Both the author and the publisher deeply regret these errors. Previous article DetailsFiguresReferencesCited by International Journal of Plant Sciences Volume 182, Number 5June 2021 Article DOIhttps://doi.org/10.1086/713916 Views: 250 HistoryPublished online April 08, 2020 © 2021 by The University of Chicago. All rights reserved. Crossref reports no articles citing this article.Related articlesPrecise Sternotribic Pollination by Settling Moths in Adenophora maximowicziana (Campanulaceae)17 Jan 2019International Journal of Plant Sciences

Paternal leakage inheritance and a fitness cost are associated with the chloroplastic psbA gene controlled metribuzin tolerance in lentil (Lens culinaris)

Reciprocal F1, F2 and F3 populations of lentil (Lens culinaris Medik.) were developed by crossing between lines, with a chloroplastic psbA gene mutation conferring tolerance to the photosystem II inhibitor herbicide metribuzin, and sensitive parent PBA Flash, to understand the genetic control of the herbicide tolerance. Additionally, reciprocal BC1F2 populations were developed to identify any fitness penalty associated with the metribuzin tolerance. Phenotyping and genotyping results of the F1, F2, and F3 populations identified a predominantly maternal inheritance pattern, but with a level of paternal leakage. Paternal leakage occurred in approximately 20% of F1 phenotypes, when including lines showing heteroplasmy (the existence of maternal and paternal chloroplasts within an individual). Field experiments with BC1F2 and BC1F3 lines confirmed this biparental inheritance pattern. Grain yield was reduced by 20–40% in metribuzin tolerant backcrossed lines compared with sensitive lines. Net assimilation rate at the onset of anthesis and plant dry weight at mid anthesis and maturity were also reduced in the tolerant lines suggesting reduced photosynthetic efficiency associated with the metribuzin tolerance results in lower dry weight and grain yield in the tolerant lines. The mode of inheritance and associated yield penalty of the tolerance trait will complicate its introgression in lentil breeding programs. However, the high level of tolerance and unique weed control benefits of this trait suggest that this form of metribuzin tolerance in lentil, which is similar to triazine tolerant canola (Brassica napus L.), could be adopted.

Influence of Electromagnetic Stimulation of Seeds on the Photosynthetic Indicators in Medicago sativa L. Leaves at Various Stages of Development

The paper explores the impact of electromagnetic stimulation of Ulstar alfalfa seeds on fresh mass yield, the quantum efficiency of the plants’ photochemical reactions, and the content of photosynthetic pigments in leaves. Before sowing, seeds were subjected to electromagnetic stimulation in the following configurations: control (C), no stimulation; stimulation with He–Ne laser light with the wavelength of 632.8 nm, surface power density of 3 mW·cm−2 and exposition time of 1 min (L1) or 5 min (L5); stimulation with alternating magnetic field with the induction of 30 mT and exposition time of 1 min (F1) or 5 min (F5). It was established that the variability of alfalfa yields at the onset of anthesis was dependent on weather conditions as well as, above all, on the electromagnetic stimulation employed. At the same time, the values of fresh mass yield of alfalfa and photosynthetic efficiency were higher in the first year of cultivation (2014) compared to the last year (2016). In terms of photosynthetic efficiency, the best results were observed for L1 and F5, respectively: 0.801 and 0.800. The significantly highest values in terms of chlorophyll a and b and carotenoid content were observed in 2014 at the onset of budding in the combination involving alternating magnetic field stimulation (F5), and were, respectively, 30%, 28% and 73% relative to the control.

Effects of climate change and adaptation options on winter wheat yield under rainfed Mediterranean conditions in southern Portugal

Projected warming and drying trends over the Mediterranean region represent a substantial threat for wheat production. The present study assesses winter wheat yield response to potential climate change and estimates the quantitative effectiveness of using early flowering cultivars and early sowing dates as adaptation options for the major wheat production region of Portugal. A crop model (STICS) is used for this purpose, which is calibrated for yield simulations before projecting future yields. Climate projections over 2021–2050 and 2051–2080 under two emission scenarios (RCP4.5 and RCP8.5) are retrieved from bias-adjusted datasets, generated by a ten-member climate model ensemble. Projected intensification of water deficits and more frequent high-temperature events during late spring (April–June), coinciding with the sensitive grain filling stage, primarily result in continuous mean yield losses (relative to 1981–2010) by − 14% (both scenarios) during 2021–2050 and by − 17% (RCP4.5) or − 27% (RCP8.5) during 2051–2080, also accompanied by increased yield variabilities. Of evaluated adaptation options at various levels, using earlier flowering cultivars reveals higher yield gains (26–38%) than that of early sowings (6–10%), which are able to reverse the yield reductions. The adopted early flowering cultivars successfully advance the anthesis onset and grain filling period, which reduces or avoids the risks of exposure to enhanced drought and heat stresses in late spring. In contrast, winter warming during early sowing window could affect vernalization fulfillment by slowing effective chilling accumulation, thus increasing the pre-anthesis growth length with limited effects on advancing reproductive stage. Crop yield projections and explored adaptation options are essential to assess food security prospects (availability and stability) of dry Mediterranean areas, providing crucial insights for appropriate policymaking.

Diurnal versus nocturnal pollinators and the effect of anthesis onset on the reproductive success of Agarista revoluta (Ericaceae)

Differences in the effectiveness of diurnal and nocturnal visitors could imply specialization in plant–pollinator interactions. Consequently, floral traits (e.g. period of anthesis onset, colours, scent, and time of nectar production) could reflect adaptation to the most effective pollinator. Despite the period of anthesis onset being frequently reported as an important factor for plant reproductive success, no previous study experimentally evaluated this effect. Flowers of Agarista revoluta (Ericaceae) present anthesis both at day and at night and are visited by diurnal and nocturnal pollinators. We conducted an exclusion experiment in these flowers in order to evaluate the effectiveness of nocturnal versus diurnal pollinators and the effect of the period of anthesis onset on plant reproductive success. We also measured the nectar production in these two times of the day and analysed the structure of nectaries and osmophores in order to assess the relationship between these floral traits and the foraging activity of the most effective pollinator. Nocturnal moths were the most effective pollinators, as flowers visited by this group produced more fruits than those visited by diurnal pollinators. Nectar was produced by a nectary at the ovary base, and this secretion was higher at night. Although more flowers opened at night, the period of anthesis onset had no effect on plant reproductive success or on nectar production. Our results indicate that A. revoluta presents a floral adaptation to nocturnal moths, suggesting specialization to these pollinators and that there is no effect of the period of anthesis onset on plant reproductive success.

Floral biology, pollination requirements and behavior of floral visitors in two species of pitaya

The present work aimed to study floral biology, pollination requirements and the behavior of floral visitors in two species of pitaya, Hylocereus undatus and H. polyrhizus, in Northeastern Brazil. The experiment was carried out through diurnal and nocturnal observations and the use of flowers bagged or accessible to visitors. Results showed that flowers of both species are similar both in anatomical and functional traits. They are large, with nocturnal anthesis onset and attract night and daytime flower visitors. The floral visitors found were sphinx moths, ants, wasps and bees, with Apis mellifera accounting for 86.1% of visits to flowers. The H. undatus species is independent of biotic pollination to set and produce large and well-shaped fruits, but H. polyrhizus shows limited self-pollination and requires biotic pollination to set fruits and also to produce larger fruits. In this case, A. mellifera appears as the most likely pollinator. It is concluded that biotic pollination deficit is a limiting factor for the productivity of H. polyrhizus , but not to H. undatus under the conditions studied and that the role of pollinators, especially A. mellifera , in the quality of the fruits produced by both pitaya species needs to be investigated.

Effects of abiotic factors on fulfillment of the potential of pea cultivars

The aim and tasks of the study was to evaluate the effects of the abiotic factors (temperature regime and precipitation amount) on the yield and protein content in seeds of pea cultivars.Materials and methods. The experiments were carried out in the experimental field of the Plant Production Institute named after VYa Yuriev (PPI nd. a. VYa Yuriev) in 2008–2017 by the field experimentation techniques. Twenty six pea cultivars were studied; of them 19 were created in the Laboratory of Pea Breeding of the PPI nd. a. VYa Yuriev, and 7 cultivars were of different eco-geographical origin.Results and discussion. Over the study period, the hydrothermal regime during the pea vegetation considerably varied. Analyzing the temperature sum (Σt), precipitation amount (ΣP) and hydrothermal coefficient (HTC) during the vegetation period and the yield in the study years, we found that the lowest Σt was recorded in 2008 (1003.2°C) with ΣP of 119.2 mm, however, the average yield in that year was the highest throughout the study period – 4.31 t/ha. The highest Σt was noticed in 2013 (1349.2ºC) with ΣР of 97.1 mm, however, the average yield then was the lowest –1.45 t/ha. The calculated correlation coefficients showed insignificant of influence of ΣP on the yield (r = -0.10), and the relationship between the yield and Σt was singnificantly inverse (r = -0.64).Analysis of the sowing dates showed that pea was sown in April throughout the study period, and depending on the year conditions, emergence occurred 8–18 days later. In 2008–2017, the anthesis started within the first 10 days of June, except for 2014, when the anthesis started within the third 10 days of May. Pea seed formation, i.e., bean filling, starts immediately after the anthesis, therefore, the second 10 days of June were taken as the registration date for this phase.The yield variations were insignificant in 2008–2010 and in 2017 (V = 9.08%, V = 8.60%, V = 8.96% and V = 7.74%, respectively); medium in 2011, 2012, 2015, and 2016 (V = 11.86%, V = 10.70%, V = 15.19%, and V = 14.08%, respectively); and considerable in 2013 and 2014 (V = 21.23% and V = 26.41%, respectively). Unlike the yield, the variations in the protein content in seeds in the study year were insignificant (V = 4.02–8.64%).The yield over the study years ranged with in 0.92 t/ha - 4.80t/ha, and the protein content – within 15.59–26.01%. The average ecological yields amounted to 1.45–4.31 t / ha, the protein content of 17.90–24.04%. The variations between genotypes were within 1.85–2.42 t/ha with the variation coefficient of 31.03–47.72%. The protein content between genotypes varied from 19.45% to 23.41% with the variation coefficient of 7.24–10.34%.Over the study years, Σt significantly affected the yields of nine cultivars only, and ΣP significantly affected the protein content of eight cultivars. Kharkivskyi Etalonnyi, Oplot and Damir 2 were the only cultivars significantly influenced by the both factors. It was found that the yield was significantly influenced by Σt during the first 10 days of June (anthesis onset) in 11 cultivars and by ΣP during the second 10 days of June in the majority of cultivars (20 cultivars). The protein content in seeds of all the cultivars was variously affected by ΣP, Σt and HTC throughout the whole period of plant growth and development.Conclusions. Evaluation of the effects of the abiotic factors (ΣР, Σt and HTC) on the yield and other traits on average over the study period may not be sufficiently informative. Evaluation of the effects of ΣP and Σt during specific phases of vegetation on the traits may be more informative.

Response of wheat to post-anthesis water stress, and the nature of gene action as revealed by combining ability analysis

Post-anthesis water stress is a major limitation to wheat grain yield globally. Understanding the nature of gene action of yield related traits under post-anthesis water stress will help to breed stress-resilient genotypes. Four bread wheat genotypes having varying degree of drought tolerance were crossed in a full-diallel fashion and the resultant crosses along with the parental genotypes, were subjected to water stress after the onset of anthesis in order to investigate their comparative performance and nature of gene action. Parental genotypes Babax (B) and Westonia (W) performed better compared with C306 (C) and Dharwar Dry (D) with respect to relative reduction in grain yield and related traits under stressed condition. Direct cross B × D and reciprocal cross W × C were more tolerant to water stress, while cross between C306 and Dharwar Dry, either direct or reciprocal, produced more sensitive genotypes. Combining ability analysis revealed that both additive and non-additive gene action were involved in governing the inheritance of the studied traits, with predominance of non-additive gene action for most of the traits. Among the parents, Babax and Westonia were better combiners for grain yield under stress condition. B × D in stressed condition, and C × W in both stressed and stress-free conditions, were the most suitable specific crosses. Moreover, specificity of parental genotypes as female parents in cross combination was also evident from the significant reciprocal combining ability effects of certain traits. Low to medium narrow sense heritability and high broad sense heritability were observed for most of the studied traits in both well watered and water stress conditions. The results of the study suggested that specific cross combinations with high specific combining ability involving better performing parents with high general combining ability may generate hybrids as well as segregating populations suitable for further breeding programs.

Heat Unit Accumulation and Days to Anthesis Relationship in Tobacco Genotypes with an Introgressed QTL Affecting Leaf Number

Plant breeders and crop managers would benefit from an increased ability to predict the requirements for onset of anthesis in tobacco (Nicotiana tabacum L.). This study was performed to determine the relationship in the field between heat unit (HU) accumulation and the onset of anthesis in tobacco genotypes varying for the zygosity of an introgressed quantitative trait loci (QTL) designated as Many Leaves (Ml) affecting flowering team and leaf number. Three commercially important cultivars or breeding lines (Speight 168, K326, and NCTG‐61), their nearly isogenic homozygous (MlMl) and heterozygous (Mlml) counterparts, and three BC6F3 null‐segregant (mlml) lines, were evaluated at three locations and over 2 yr. Days to anthesis (DTA) and HU accumulation were determined. In each environment, the MlMl, Mlml, and mlml genotypes were found to be grouped according to the zygosity of the Ml trait, with the mlml genotypes flowering first followed by Mlml and MlMl genotypes, respectively. An exception to this trend was Speight 168 MlMl, which consistently fell within the Mlml grouping for DTA. No consistent relationships were observed between HU and DTA, which was highly variable among environments. Integrated HU (area under the HU curve) during the 28 d after transplanting (DAT) was positively associated (R2 = 0.98; P = 0.0001) with the range of DTA among all genotypes. Integrated HU was a better indicator of the pattern of HU attainment than merely the amount. Early HU exposure seemed important in determining the range in DTA amongst the genotypes examined.

Floral longevity, nectar production, pollen release, and stigma receptivity in Haskap (<i>Lonicera caerulea</i>)

Haskap (Lonicera caerulea L.) is a temperate fruiting shrub grown commercially in northern regions of Europe, Asia, and North America. Haskap is self-incompatible and requires insect pollinators in order to set fruit; however, very little is currently known about its floral biology or pollinator specializations, particularly in North American cultivars. Here, we examine floral longevity, nectar dynamics, the timing of anther dehiscence, and stigma receptivity in flowers of greenhouse-grown ‘Tundra’, a Haskap cultivar developed and grown in Saskatchewan, Canada. Anthesis lasted 83.3 ± 25.9 hours (mean ± SD) in un-pollinated flowers; pollination caused early senescence within 34.3 ± 15.2 hours after pollination. Nectar was present from the onset of anthesis, and nectar volume peaked at 9-16 hours after opening. Nectar volume was maintained throughout anthesis and was not resorbed prior to abscission of the corolla from the ovary, and nectar removed during anthesis was replenished to the original volume. The stigma showed a reaction to hydrogen peroxide while still in the bud stage, suggesting it is receptive even before the flower opens. Early stigma receptivity, nectar production, and anther dehiscence maximize opportunities to be successfully pollinated, along with high floral longevity and pollination-triggered senescence. These results suggest that Haskap flowers utilize a generalist, rather than a specialized, pollination strategy. Observations that some flowers open in the evening or were already open in the morning suggest that nocturnal pollinators such as moths may be important, in addition to known diurnal pollinators.

Improving field production of ergot alkaloids by application of gametocide on rye host plants

Ergot alkaloids are widely used in the pharmaceutical industry in drug preparations for treating migraines and Parkinson's disease, inducing uterine contraction, and other purposes. Phytopathogenic fungi of the genus Claviceps (e.g. C. purpurea) comprise a major biological source of ergot alkaloids. Worldwide industrial production of these alkaloids derives almost equally from two biotechnological procedures: submerged culture of the fungus in fermenters and field parasitic production in dormant fungal organs known as sclerotia (also termed ergot). Ergot yields from field cultivation are greatly affected by weather and also can be much reduced by pollen contamination from imperfectly male-sterile rye, as only unfertilized ovaries can be infected by C. purpurea spores. Two substances with gametocidal effect - maleic hydrazide and 2-chloroethylphosphonic acid - were tested during three consecutive seasons in small field experiments for the ability to induce or amplify the male sterility of rye as well as the impacts on germination of C. purpurea spores and general vitality of rye host plants. Maleic hydrazide was proven to be a highly effective gametocide on both a fertile rye variety and a variety with imperfectly induced cytoplasmic male sterility. It showed negligible effect on germination of C. purpurea spores. Both accurate dosaging of the active gametocidal compound and timing of the application just 2-3 weeks before onset of anthesis proved crucial to achieving high ergot yield with minimum grain impurities.

Impact of High Night‐Time and High Daytime Temperature Stress on Winter Wheat

AbstractHigh temperature is a major environmental factor that limits wheat (Triticum aestivum L.) productivity. Climate models predict greater increases in night‐time temperature than in daytime temperature. The objective of this research was to compare the effects of high daytime and high night‐time temperatures during anthesis on physiological (chlorophyll fluorescence, chlorophyll concentration, leaf level photosynthesis, and membrane damage), biochemical (reactive oxygen species (ROS) concentration and antioxidant capacity in leaves), growth and yield traits of wheat genotypes. Winter wheat genotypes (Ventnor and Karl 92) were grown at optimum temperatures (25/15 °C, maximum/minimum) until the onset of anthesis. Thereafter, plants were exposed to high night‐time (HN, 25/24 °C), high daytime (HD, 35/15 °C), high daytime and night‐time (HDN, 35/24 °C) or optimum temperatures for 7 days. Compared with optimum temperature, HN, HD and HDN increased ROS concentration and membrane damage and decreased antioxidant capacity, photochemical efficiency, leaf level photosynthesis, seed set, grain number and grain yield per spike. Impact of HN and HD was similar on all traits. Greater impact on seed set, grain number and grain yield per spike was observed at HDN compared with HN and HD. These results suggest that HN and HD during anthesis cause damage of a similar magnitude to winter wheat.

Is flower/corolla closure linked to decrease in viability of desiccation-sensitive pollen? Facts and hypotheses: a review of current literature with the support of some new experimental data

Pollen hydration status at dispersal depends on many parameters and on this basis two main groups of grains may be distinguished: those with a low water content are usually named orthodox or desiccation-resistant, while those with a higher water content at dispersal are known as recalcitrant or desiccation-sensitive due to their reduced mechanisms to keep water constant. On exposure, the latter lose water and die quickly. Although the end of flower receptivity may occur in different ways, in species possessing recalcitrant pollen it often consists in corolla closure. In addition to data available from current literature, also a new set of experiments was performed: the viability of pollen of eight entomophilous species having nectar as pollinator reward, desiccation-sensitive pollen and corolla closure at the end of receptivity, irrespective of pollination, was tested from the onset of anthesis until flower closure using a fluorochromatic reaction. Pollen viability fell sharply in all species, albeit at different rates, depending on initial water content, and may be also on types of carbohydrate reserves and inherent enzymes interconverting them. On the basis of experimental data and the literature, the authors speculate on the effects of corolla closure: it avoids dispersal of pollen with reduced viability, it avoids collection of unconsumed nectar while facilitating its reabsorption by the nectary parenchyma and its utilization for other purposes, and it avoids contamination by moulds and bacterial spores that could penetrate the plant via the nectar and nectary parenchyma.

Floral reward presentation favored the expression of male function in the pollen-only flowerMelastoma malabathricum

Animal-pollinated plant species modulate the presentation of pollinator rewards to maximize reproductive success. In plants providing pollen as the only reward for pollinators, it is usually difficult to unravel the dual roles of reward presentation and the realization of male and female functions (pollen removal and deposition). Exploiting the two types of anther in the androecia of Melastoma malabathricum L., we examined whether the removal of pollen for reward is regulated primarily to favor male function or female function. Pollen removal by carpenter bees from the feeding and pollination anthers, as well as pollen deposition on the stigmas, were quantified during anthesis of M. malabathricum. There was no significant difference in pollen removal rates from the feeding and pollination anthers of M. malabathricum between the onset of anthesis and flower wilting. The stigmatic pollen loads exceeded the ovule number after three sonication bouts, and female function was satisfied earlier than male function. The results support the hypothesis that the presentation of pollination reward in this species is regulated primarily to favor the expression of male function, rather than female function, in agreement with the pollen-donation hypothesis. A cooperative relationship between the feeding and pollination anthers was demonstrated in heterantherous flowers, which optimizes the balance in investments between pollinator rewards and lfunctional pollenr for gene transfer