Day Of Anthesis Research Articles

Floral phenology and standardization of hand pollination of Clove (Syzygium aromaticum (L.) Merr. & Perry)

Clove (Syzygium aromaticum (L.) Merr. & Perry) has a rich history and is highly valued for its culinary and medicinal uses. However, its limited genetic diversity and tendency for self-pollination pose challenges for optimizing its cultivation in India. Hybridization becomes imperative to broaden its genetic spectrum. This study, hence, focuses on refining techniques related to floral biology, pollen management and artificial hand pollination in clove. The study revealed that anthesis in clove occurs from 2:30 PM to 6:30 PM, with peak flower opening between 3:30 PM and 5:30 PM. Each flower possesses an impressive array of stamens ranging from 167 to 343 and anther dehiscence begins 36 h before anthesis and continues until the day of anthesis. Pollen grain dimensions show a polar diameter ranging from 17.06-18.22 ?m and an equatorial diameter ranging from 19.40-20.70 ?m. Stigma receptivity extends from the second to the sixth day of flowering, peaking on the fifth day. Emasculation is recommended 36 h before flower opening. Maximum pollen viability and fertility are observed 12 h before flower opening. Thus, pollen collection for pollination is standardized at this time. Drying pollen at 50 °C and storing it at 7 °C in a refrigerator maintain maximum viability after 60 days while drying pollen at 45 °C and storing it in a desiccator ensure maximum fertility. Artificial hand pollination results in a fruit set of 28.87 %. Artificial hand pollination results in a promising fruit set of 28.87 %, underscoring its efficacy in enhancing clove cultivation.

Impact of climate change on rice growth and yield in China: Analysis based on climate year type

Climate change threatens China’s rice production, making it crucial to assess the impact of climate change and climate year type (CYT) on rice production across regions to safeguard food security. The impact of climate change under nine CYTs with different combinations of temperature and precipitation on two rice cropping systems, including single rice and double rice (early and late rice) was evaluated. The results indicate that: (1) the Northeast region was expected to undergo the greatest warming of 2.03–2.48 °C, and future climate conditions would be dominated by Warm-Humid, Warm-Normal, and Warm-Dry CYTs across all regions. (2) Climate change would significantly shorten anthesis days after sowing and maturity days after sowing of single rice by 6–12 days and 9–24 days, with little change observed for late rice (< 1 day). Late rice yield suffered more from climate change compared to single and early rice yield, declining by 8.8 %–16.13 %. (3) Different CYTs exhibited varying impacts on rice yields. Yields were projected to decrease by approximately 4.765 % to 18.645 % in Warm-Humid, Warm-Normal, and Warm-Dry CYTs. Conversely, the Northeast region was anticipated to experience an increase in yield. (4) Relationships between rice yield and meteorological factors varied by region, variety, and CYT. Among the nine CYTs, high killing degree days, mean daily temperature, mean solar radiation and warm spell duration index were the main factors influencing changes in rice yield, explaining nearly 80 % of yield change. Our results would help to develop adaptation strategies in different regions and rice cropping systems.

In vitro studies on the pollen viability and germination of Impatiens cordata Wight. an endemic species of the Southern-Western Ghats

Impatiens cordata is an endemic balsam in the southern Western Ghats. The present work aimed to study pollen morphology, fertility, viability, cytology, and in vitro pollen germination studies of I. cordata. The study also focused on finding a relationship between pollen viability and germination. The results revealed that the I. cordata pollen grains are elliptical and quadrangular. The pollen grains are bicellular, mainly tetracolpate, with some tricolpate occurrences, and have reticulate exine ornamentation. Brew baker’s medium supplemented with 5% sucrose had the most remarkable ability to germinate in vitro. The stain and the number of days significantly affect germination. The peak of pollen viability was observed on the day of anthesis. The results of the Alexander stain were more strongly correlated with in vitro germination and suggested that for pollen viability studies, the Alexander stain is considered the best stain compared to others.

Correlation and Clustering for Yield and Its Attributing Traits in Maize (Zea mays L.) Hybrids

Present investigation was conducted in 144 maize hybrids of CIMMYT, Hyderabad along with 6 checks at ICRISAT, Hyderabad. The genotypes were evaluated for six quantitative traits: plant height, ear height, anthesis days, silking days, ear per plant and grain yield. Correlation among the traits came to a conclusion that anthesis days and silking are positively correlated with grain yield genotypically and plant height, ear height and ear per plant are positively correlated with grain yield phenotypically. Hence selection on five traits plays a vital role in increasing the grain yield. Clustering of genotypes based on the six traits divide the germplasm into two clusters. Each cluster has 85 and 65 genotypes respectively. Clustering the genotypes based the quantitative traits helps in understanding the relatedness between the genotypes.

Association and Diversity Studies for Yield and Its Attributing Traits in Maize (Zea mays L.) Hybrids

Present investigation was conducted in 144 maize hybrids of CIMMYT, Hyderabad along with 6 checks at ICRISAT, Hyderabad. The genotypes were evaluated for six quantitative traits that are plant height, ear height, anthesis days, silking days and grain yield. Correlation among the traits came to a conclusion that plant height and ear height are positively correlated with grain yield. Path analysis revealed there is highest direct association of plant height on grain yield and ear height had a highest indirect positive association with grain yield. Hence selection plant height and ear height days plays a vital role in increasing yield. Clustering of genotypes based on the six traits divide the germplasm into two clusters. 85 and 65 genotypes were found in each clusters. Clustering the genotypes based the quantitative traits revealed close relatedness between the genotypes. Knowledge on association and diversity identified in our study help in plant breeding process.

Involvement of CgHSFB1 in the regulation of self-incompatibility in 'Shatian' pummelo.

As self-incompatibility is a major issue in pummelo breeding and production, its mechanism in citrus was analyzed to improve breeding efficiency and reduce production costs. Rutaceae belongs to S-RNase type of gametophytic self-incompatibility. While the function of S-RNase/SLF and the mechanism of self-incompatibility have been studied extensively, the transcriptional regulation of S-RNase has been less studied. We performed transcriptome sequencing with the styles of 'Shatian' pummelo on the day of anthesis and 1-5days before anthesis, and found that the transcript level of S-RNase gradually decreased with flower development. By analyzing differentially expressed genes and correlation with the expression trend of S-RNase, we identified a candidate gene, CgHSFB1, and utilized biochemical experiments such as yeast one-hybrid assay, electrophoretic mobility shift assay and dual-luciferase assay, as well as transient transformation of citrus calli and Citrus microcarpa and demonstrated that CgHSFB1 could directly bind to the S1-RNase promoter and repress the expression of S1-RNase, which is involved in the pummelo self-incompatibility response. In contrast, CgHSFB1 did not bind to the promoter of S2-RNase, and there was specificity in the regulation of S-RNase.

Floral biology and reproductive potential of Annona hybrid Arka Sahan

Annona hybrid Arka Sahan has become a commercially important fruit in recent times and it needs an assisted pollination to get good size. Studies on floral biology of Annona hybrid Arka Sahan revealed that major bloom occurs during March-April. Most of the flowers start opening during the afternoon and continued till 7.00 pm, while, pollen dehiscence mainly occurred in early morning in the following day. The maximum stigma receptivity was recorded on the day of anthesis. Completely pendulous petal was more common in Arka Sahan flowers resulting = improper pollination. The minimum number of beetles and bees were observed between 7.00 to 8.00 am. Pollen germination and viability were lower at anthesis (5.8% and 44%, respectively) and declined as the day progressed. The pendulous nature of petals eventually brings some un-pollinated stigmas potentially resulting in delayed selfing leading to misshaped fruits.

Floral biology and reproductive potential of Annona hybrid Arka Sahan

Annona hybrid Arka Sahan has become a commercially important fruit in recent times and it needs an assisted pollination to get good size. Studies on floral biology of Annona hybrid Arka Sahan revealed that major bloom occurs during March-April. Most of the flowers start opening during the afternoon and continued till 7.00 pm, while, pollen dehiscence mainly occurred in early morning in the following day. The maximum stigma receptivity was recorded on the day of anthesis. Completely pendulous petal was more common in Arka Sahan flowers resulting = improper pollination. The minimum number of beetles and bees were observed between 7.00 to 8.00 am. Pollen germination and viability were lower at anthesis (5.8% and 44%, respectively) and declined as the day progressed. The pendulous nature of petals eventually brings some un-pollinated stigmas potentially resulting in delayed selfing leading to misshaped fruits.

Unraveling Genetic Variability, Correlation and Path Analysis for Yield and Its Components in Barley (Hordeum vulgare L.)

The current study aimed to assess the genetic variability of yield and yield-related traits while examining the direct and indirect effects of trait interactions. Conducted at a research farm in Chaudhary Charan Singh University, Meerut, Uttar Pradesh, India, the experiment involved fourteen parents and their BC1F1 crosses, analyzed using a randomized block design (RBD). Significant differences were observed among the varieties for most traits, indicating a broad range of mean values and diversity. Both phenotypic and genotypic coefficients of variance (PCV and GCV) were generally low, with biological yield showing the highest values (26.57 for GCV and 40.48 for PCV). PCV values were slightly higher than GCV values. Traits such as seed per spike, biological yield, flag leaf breadth, days of heading, and days of maturity exhibited relatively high heritability. Notably, grain yield showed high heritability and genetic progress, making it a favourable selection indicator. Several traits, including days of anthesis, days of maturity, and spike length, demonstrated significant positive correlations with yield while also showing significant negative correlations with grain filling period and biological yield. Conversely, these traits showed highly non-significant positive correlations with harvest index, plant height, thousand seeds weight, and chlorophyll content and highly non-significant negative correlations with tiller number and seeds per spike.

Effect of Preharvest Treatment Using Jasmonic Acid and Methyl Jasmonate on the Physicochemical Properties and Antioxidant Activities of Red-fleshed Dragon Fruit (Hylocereus polyrhizus L.)

This study investigated the effect of exogenous plant growth regulators (PGR), namely jasmonic acid (JA) and methyl jasmonate (MeJA), on the physicochemical properties of flesh and peels of red-fleshed dragon fruit (Hylocereus polyrhizus). The fruit was sprayed with 100 and 1,000 ppm of JA and MeJA at 15 and 22 days of anthesis and harvested after 35 days. Then, the flesh and peels were analyzed for total soluble solids (TSS), total betacyanins, betanin, total phenolics (TP), total flavonoids (TF), and color characteristics. The fruit peels contained significantly higher (p&lt;0.05) TP and antioxidant activities compared to flesh. No significant difference was detected between the variables in the peels, except for significantly higher (p&lt;0.05) of total betacyanins (~295.6 and ~299.9 mg/100 g) and TP (~614.1 and 566.1 mg GAE/100 g) were recorded in control and 100 ppm MeJA, respectively. In the flesh, 1,000 ppm MeJA-treated fruit possessed the highest total betacyanins (~139.2 mg/100 g), betanin (~356.0 mg/g), TP (~244.9 mg GAE/100 g), TF (~329.0 mg CE/100 g), Trolox equivalent antioxidant capacity (TEAC) (63.2 µmol TE/g) and reducing power (~21.5 µmol TE/g). Overall, 1,000 ppm MeJA was more effective in enhancing the accumulation of bioactive compounds and antioxidant activities in the flesh of red-fleshed dragon fruit compared to other PGR treatments.

Analyses of the sexual reproductive traits for conservation and sustainable utilization of Dactylorhiza hatagirea – A critically endangered medicinal orchid of North-western Himalaya

To undertake scientifically appropriate management and conservation practices, understanding the reproductive biology of endemic and threatened species is critical. Dactylorhiza hatagirea is an important medicinal plant whose reproductive strategies and adaptive evolution mechanisms are still not fully clear. The present study was conducted in the North-western Himalaya of India to understand the reproductive biology, breeding system and pollination ecology of D. hatagirea; an endemic and critically endangered orchid. It is a perennial herb that grows along the altitudinal gradients of 2100–3107 m.a.s.l. and overcomes harsh winters through underground perrenating tubers. The flowering commences from May to July and the flowers are completely zygomorphic with male and female reproductive organs fused to constitute gynostemium. Analysis of variance (ANOVA) show significant statistical difference (p < 0.05) between the floral traits for most of the characters. Each flower bears two dark green colored pollinaria with an average of 212.14 ± 14.4 pollinia. Pollen occur as tetrads and polyads in massulae and their viability was greater than 95 ± 4.2 %. Stigma receptivity was confirmed on the day of anthesis and reaches its peak on 5–6th day. Cruden outcrossing index (5), asynchronous anthesis, conspicuous inflorescences, nectaries, presence of rostellum and herkogamy points towards outcrossing nature while pollen ovule ratio (1.27 ± 0.4) and the greater value of self-incompatibility (0.9) reflect that plants are potent cross-breeders. Pollination treatments significantly impacted seed set in D. hatagirea (one-way ANOVA; F = 23.14; p = 0.001) with an average seed set of 92.75 % ± 0.95 for manual xenogamy (p < 0.01), 89.5 % ± 2.38 for geitonogamy (p < 0.01) and 17 % ± 2.2 for bagged inflorescences (p<0.05). Pollination syndrome is exclusively entomophilly. Insignificant difference was reported in the timining for the insect visitation to flowers (calculated value = 3.4; critical value = 5.1; p < 0.01), however different environmental factors created a significant impact on the frequency of insect visitation (calculated value = 9.7; critical value = 4.3; p < 0.01). Apis cerana, Apis mellifera and Bombus asiaticus show highest pollination indices (p < 0.01) and were characterized as dominant pollinators. This study provides a detailed explanation and substantial understanding regarding operative reproductive mechanism of this threatened medicinal plant and can be used by conservation biologists to develop holistic and effective conservation strategies and address the unique challenges that this threatened species face in the wild.

Determination of Optimal Plant Density of Adapted Maize Varieties in the Low and Mid-altitude Ecologies of Tanzania

Purpose: The objective of this study is to validate the commonly recommended plant density in the target zone to maximize maize production and productivity. The commonly recommended plant density is 44,444 plants/ha for decades. However, there is no recent study done to validate this practice if it optimizes productivity under current climate and soil fertility variability. A blanket recommendation has been used for decades without validation for optimum productivity that farmer can realize. &#x0D; Methodology: The factorial experiment was used with the total of 18 treatment combinations in a Randomized Complete Block Design (RCBD) with three replications according to Gomez, A and Gomez, K (1983). The open pollinated varieties (OPV) commonly grown by small scale farmers were planted in three different plant densities of 44,444, 53,333 and 66,666 plants per hector with inter and intra row spacings of 0.75mx0.3m, 0.75mx0.25m and 0.75mx0.2m respectively. Field management was done as usual following the recommended agronomic practices.&#x0D; Findings: Analysis of variance (ANOVA) was done using GENSTAT (9th edition) statistical programme software and presented in a tabular form. The results indicated no significant difference in all parameters analysed except for 50% anthesis days (AD) and 50% Silking days (SD) both at 0.1% levels. The overall site mean for grain yield was found to be 6.43t/ha, 7.31t/ha and 6.11t/ha for the plant density of 44,444plants/ha, 53,333plants/ha and 66,666plants/ha respectively. Therefore, based on these findings the optimum plant density was found to be 53,333/ha unlike the commonly used plant density of 44,444 plants/ha.&#x0D; Unique Contribution to Theory, Practice and Policy: This study contributes to existing experience and practice commonly recommended by extension officers in many parts of the country without performing a site-specific study to determine the optimum spacing for particular environment. This, study also open up an avenue for further research to validate various research technologies. Plant population, in addition to plant height, maturity class, and row spacings, affects the geometry of plant spacing and leaf distribution. All these factors may affect light and CO2 penetration in the canopy, as well as water use rate (Tharp, B and Kells, J, 2001)

Floral biology studies in wild melon [Cucumis melo L. ssp. agrestis (Naudin) Pangalo var. agrestis Naudin

Studies on floral morphology, phenology and biology of wild melon revealed that the ratio of staminate and pistillate flowers was 3.40:1. The longevity of the male flowers were between 5 and 6 days, whereas, female flowers between 6 and 7 days. Anthesis was observed from 4.00 am to 10.00 am, while, the anther dehiscence started from 5.00 am which was continued to 7.00 am. The peak anthesis was observed from 8.00 am to 9.00 am and anther dehiscence from 6.00 am to 6.30 am. Freshly opened flowers showed pollen viability up to 98.35%, decreased upon closure and crashed to 17.48% in 3 days. Pollen germination was occurred after 15 minutes of incubation and continued up to 24 h of incubation. The stigma receptivity lasts from one to two days of anthesis. Major pollinator of wild melons observed was honey bee, mostly visited between 9:00 am to 6:00 pm.

Calibration and Validation of Cropgro (DSSAT 4.7) Model for Chickpea (Cicer arietinum L.) Crop in Raipur

In agriculture aspect crop simulation models play key role in developing the decision making research, technology management and policy options. It acts as useful tool to predict the growth development and production of a crop under varying soil, crop input and climatic condition. The DSSAT CROPGRO model was calibrated and validated through field experiment on chickpea crop during rabi seasons i.e. 2020-21 and 2021-22 at instructional farm Indira Gandhi Krishi Vishwavidyalaya, Raipur Chhattisgarh. The experiment was laid out in randomized block design (factorial) considering 9 treatments of two factors 3 dates of sowing (D1=Nov. 10, D2=Nov. 25, D3=Dec. 10) and 3 cultivars (V1=Vaibhav, V2=JG-14 and V3=JG-16). The results reported highest deviation percentage at anthesis days was (4.8 to 10 %) and physiological maturity was (1.7 to 5.5%) for JG-16 cultivar, whereas in seed yield the highest deviation percent was (6.2 to 9%) for Vaibhav cultivar. Similarly after validation the highest deviation percentage at anthesis days was (0 to 10.7%) for JG-16, at physiological maturity (1.8 to 3.6%) for Vaibhav and in seed yield (2.4 to 9.5%) for JG-16.

Embryological observations on seed abortion in Hibiscus syriacus L. and physiological studies on nutrients, enzyme activity and endogenous hormones

Under natural conditions, most Hibiscus syriacus L. individuals form very few mature seeds or the mature seeds that do form are of poor quality. As a result, seed yield is poor and seeds have low natural germinability. These phenomena strongly hinder utilization of the excellent germplasm resources of H. syriacus. The study has shown that pollen activity and stigma receptivity were high on the day of anthesis, and the pistils and stamens were fertile. Pollen release and stigma receptivity were synchronous. But in styles following self and cross-pollination, pollen tube abnormalities (distortion and twisting of the pollen tubes) and callose deposition were observed. Cross-pollinated pollen tubes elongated faster and fewer pollen tube abnormalities were observed compared with self-pollinated pollen tubes. And during embryo development, abnormalities during the heart-shaped embryo stage led to embryo abortion. Imbalance in antioxidant enzyme activities and low contents of auxin and cytokinin during early stages of embryo development may affect embryo development. Therefore, a low frequency of outcrossing and mid-development embryo abortion may be important developmental causes of H. syriacus seed abortion. Nutrient deficiencies, imbalance in antioxidant enzyme activities, and a high content of abscisic acid at advanced stages of seed development may be physiological causes of seed abortion.

Identification of the Initial Anthesis of Soybean Varieties Based on UAV Multispectral Time-Series Images

Accurate and high-throughput identification of the initial anthesis of soybean varieties is important for the breeding and screening of high-quality soybean cultivars in field trials. The objectives of this study were to identify the initial day of anthesis (IADAS) of soybean varieties based on remote sensing multispectral time-series images acquired by unmanned aerial vehicles (UAVs), and analyze the differences in the initial anthesis of the same soybean varieties between two different climatic regions, Shijiazhuang (SJZ) and Xuzhou (XZ). First, the temporal dynamics of several key crop growth indicators and spectral indices were analyzed to find an effective indicator that favors the identification of IADAS, including leaf area index (LAI), above-ground biomass (AGB), canopy height (CH), normalized-difference vegetation index (NDVI), red edge chlorophyll index (CIred edge), green normalized-difference vegetation index (GNDVI), enhanced vegetation index (EVI), two-band enhanced vegetation index (EVI2) and normalized-difference red-edge index (NDRE). Next, this study compared several functions, like the symmetric gauss function (SGF), asymmetric gauss function (AGF), double logistic function (DLF), and fourier function (FF), for time-series curve fitting, and then estimated the IADAS of soybean varieties with the first-order derivative maximal feature (FDmax) of the CIred edge phenology curves. The relative thresholds of the CIred edge curves were also used to estimate IADAS, in two ways: a single threshold for all of the soybean varieties, and three different relative thresholds for early, middle, and late anthesis varieties, respectively. Finally, this study presented the variations in the IADAS of the same soybean varieties between two different climatic regions and discussed the probable causal factors. The results showed that CIred edge was more suitable for soybean IADAS identification compared with the other investigated indicators because it had no saturation during the whole crop lifespan. Compared with DLF, AGF and FF, SGF provided a better fitting of the CIred edge time-series curves without overfitting problems, although the coefficient of determination (R2) and root mean square error (RMSE) were not the best. The FDmax of the SGF-fitted CIred edge curve (SGF_CIred edge) provided good estimates of the IADAS, with an RMSE and mean average error (MAE) of 3.79 days and 3.00 days, respectively. The SGF-fitted_CIred edge curve can be used to group the soybean varieties into early, middle and late groups. Additionally, the accuracy of the IADAS was improved (RMSE = 3.69 days and MAE = 3.09 days) by using three different relative thresholds (i.e., RT50, RT55, RT60) for the three flowering groups compared to when using a single threshold (RT50). In addition, it was found that the IADAS of the same soybean varieties varied greatly when planted in two different climatic regions due to the genotype–environment interactions. Overall, this study demonstrated that the IADAS of soybean varieties can be identified efficiently and accurately based on UAV remote sensing multispectral time-series data.

Discovering useful genetic variation in the seed parent gene pool for sorghum improvement.

Multi-parent populations contain valuable genetic material for dissecting complex, quantitative traits and provide a unique opportunity to capture multi-allelic variation compared to the biparental populations. A multi-parent advanced generation inter-cross (MAGIC) B-line (MBL) population composed of 708 F6 recombinant inbred lines (RILs), was recently developed from four diverse founders. These selected founders strategically represented the four most prevalent botanical races (kafir, guinea, durra, and caudatum) to capture a significant source of genetic variation to study the quantitative traits in grain sorghum [Sorghum bicolor (L.) Moench]. MBL was phenotyped at two field locations for seven yield-influencing traits: panicle type (PT), days to anthesis (DTA), plant height (PH), grain yield (GY), 1000-grain weight (TGW), tiller number per meter (TN) and yield per panicle (YPP). High phenotypic variation was observed for all the quantitative traits, with broad-sense heritabilities ranging from 0.34 (TN) to 0.84 (PH). The entire population was genotyped using Diversity Arrays Technology (DArTseq), and 8,800 single nucleotide polymorphisms (SNPs) were generated. A set of polymorphic, quality-filtered markers (3,751 SNPs) and phenotypic data were used for genome-wide association studies (GWAS). We identified 52 marker-trait associations (MTAs) for the seven traits using BLUPs generated from replicated plots in two locations. We also identified desirable allelic combinations based on the plant height loci (Dw1, Dw2, and Dw3), which influences yield related traits. Additionally, two novel MTAs were identified each on Chr1 and Chr7 for yield traits independent of dwarfing genes. We further performed a multi-variate adaptive shrinkage analysis and 15 MTAs with pleiotropic effect were identified. The five best performing MBL progenies were selected carrying desirable allelic combinations. Since the MBL population was designed to capture significant diversity for maintainer line (B-line) accessions, these progenies can serve as valuable resources to develop superior sorghum hybrids after validation of their general combining abilities via crossing with elite pollinators. Further, newly identified desirable allelic combinations can be used to enrich the maintainer germplasm lines through marker-assisted backcross breeding.

The adaptation top crosses of anthocyanins corn in lowland zone of Palu Indonesia

Anthocyanins corn held to increase of human health, the color of seeds was orange to black. The experiment was to studied characters of some families as top crosses anthocyanins corn under interaction genotypes (G), and season (S) in valley of Palu in Indonesia. The experiment was conducted by randomized complete block design with three replications in experimental farm of Sidondo under two season rainy and dry condition. There are ten top crosses populations as anthocyanins corn as candidate included check to evaluated on 2017. The objective of experiment was to study of characters and to find of which is genotypes was stable and high yield to promoting as candidate for F1 top crosses varieties. Interaction data between genotype (G) and season (S) were analyzed manually. The result show that there are significant interaction GxS and founded the genotypes would be promising as new F1 candidate was PMU(S1) Synt. F. C1-2-3xtester: PPH(S1) C2. The potential would be founded 6.0 - 7.0 t/ha, characters of candidate was scored one of plant aspect, position of ear height is middle of plant height, and there are 45 days for anthesis. The released top crosses of anthocyanin corn would be develop under poor farmers for aims to increase income, health and anticipated of mall nutrition.

Multi-locus genome-wide association study of fusarium head blight in relation to days to anthesis and plant height in a spring wheat association panel.

Fusarium head blight (FHB) is a highly destructive fungal disease of wheat to which host resistance is quantitatively inherited and largely influenced by the environment. Resistance to FHB has been associated with taller height and later maturity; however, a further understanding of these relationships is needed. An association mapping panel (AMP) of 192 predominantly Canadian spring wheat was genotyped with the wheat 90K single-nucleotide polymorphism (SNP) array. The AMP was assessed for FHB incidence (INC), severity (SEV) and index (IND), days to anthesis (DTA), and plant height (PLHT) between 2015 and 2017 at three Canadian FHB-inoculated nurseries. Seven multi-environment trial (MET) datasets were deployed in a genome-wide association study (GWAS) using a single-locus mixed linear model (MLM) and a multi-locus random SNP-effect mixed linear model (mrMLM). MLM detected four quantitative trait nucleotides (QTNs) for INC on chromosomes 2D and 3D and for SEV and IND on chromosome 3B. Further, mrMLM identified 291 QTNs: 50 (INC), 72 (SEV), 90 (IND), 41 (DTA), and 38 (PLHT). At two or more environments, 17 QTNs for FHB, DTA, and PLHT were detected. Of these 17, 12 QTNs were pleiotropic for FHB traits, DTA, and PLHT on chromosomes 1A, 1D, 2D, 3B, 5A, 6B, 7A, and 7B; two QTNs for DTA were detected on chromosomes 1B and 7A; and three PLHT QTNs were located on chromosomes 4B and 6B. The 1B DTA QTN and the three pleiotropic QTNs on chromosomes 1A, 3B, and 6B are potentially identical to corresponding quantitative trait loci (QTLs) in durum wheat. Further, the 3B pleiotropic QTN for FHB INC, SEV, and IND co-locates with TraesCS3B02G024900 within the Fhb1 region on chromosome 3B and is ~3 Mb from a cloned Fhb1 candidate gene TaHRC. While the PLHT QTN on chromosome 6B is putatively novel, the 1B DTA QTN co-locates with a disease resistance protein located ~10 Mb from a Flowering Locus T1-like gene TaFT3-B1, and the 7A DTA QTN is ~5 Mb away from a maturity QTL QMat.dms-7A.3 of another study. GWAS and QTN candidate genes enabled the characterization of FHB resistance in relation to DTA and PLHT. This approach should eventually generate additional and reliable trait-specific markers for breeding selection, in addition to providing useful information for FHB trait discovery.

Study on pollen viability and stigma receptivity throughout the flowering period in the selected taxa of the Gesneriaceae family

ABSTRACT Plants in the Gesneriaceae family are appreciated for their decorative leaves and flowers, ease of cultivation, and shade tolerance. Sexual hybridisation has long been carried out for producing novel hybrids. However, scientific knowledge is lacking on the correct timing of pollination in this family. This study was conducted to elucidate the optimal timing for pollination by screening pollen viability and stigma receptivity throughout the flowering period in eight gesneriad taxa. Pollen viability was evaluated by the in vitro germination test and stigma receptivity was based on stigma morphology and pistil length. The flowering duration varied from 10 days in Alsobia to 18 days in Streptocarpus. While the pollens of Episcia, Kohleria, Saintpaulia, Sinningia, and Smithiantha had totally lost viability 2–5 days before the flowers withered, a slightly contrasting situation was observed in the cases of Alsobia, Deinostigma, and Streptocarpus, where a small portion of pollen grains remained viable towards the end of the flowering period. The highest pollen germination rate was recorded from 1 day in Alsobia, Episcia, and Kohleria, to 9 days in Deinostigma. The reduction in pollen germination was rapid in Alsobia, Saintpaulia, and Smithiantha, and moderate in the remaining taxa. The greatest pollen tube growth occurred at 1–3 days after flower opening and decreased rapidly in all the taxa tested. The longest pistil of 2.03–3.50 cm was observed at 3–8 days of anthesis depending on the plant tested. The findings in this study suggest that higher pollination success may be achieved using pollen grains of newly opened flowers and stigmas of mature flowers in this family.