Weeks Of Flowering Research Articles

Effects of Harvest Time on Medicinal Qualities of Hemp

Harvest time impacts the physicochemical properties of hemp. This study investigated the relationship between harvest time on growth parameters, physiological parameter, and color, in addition to Cannabidiol (CBD), Tetrahydrocannabinol (THC) and Cannabigerol (CBG) concentrations. Siskiyou cannabis was harvested at 5 different stages after flowering 50% at week five to week nine. The rational explanation for stages on growth parameters, physiological parameters, color, and total physiochemical properties was found, while total color changes ranged from brightness (L*) decreased gradually from 66.06 at 5 weeks to a minimum of 16.14 at 9 weeks of flowering. On the contrary, the redness (a*) and yellowness (b*) increased from –0.65 and 8.95 at 5 weeks to their peak values of 19.99 and 34.24 at 9 weeks, respectively. The hue also decreased from 110.03 at 5 weeks to a minimum of 80.14 at 9 weeks, with samples being significantly (p <0.05) different. Tetrahydrocannabinol (THC) was higher than 1 % at week 5, which was lower than their Cannabidiol (CBD) concentrations, reaching 14.35% at week 8. Cannabigerol (CBG) in dried samples reached 2.01% at week 7. The average dry weight of inflorescence per plant peaked at 36.75 g in week 8 and week 9 respectively. Significant differences in Crop Growth Rate (CGR) were noted across the harvesting periods, notably 17.13 and 16.70 g cm⁻² day⁻¹ at weeks 8 and 9, respectively, representing the highest dry weight accumulation per unit area. This increase in dry weight accumulation indicates higher efficiency. Finally, the Harvest Index (HI) showed notable discrepancies among the post-flowering harvesting times, with the greatest total dry weight observed at 0.357 and 0.345 at weeks 8 and 9, respectively. These findings could be of industrial relevance for improving post-harvest processes while maintaining the quality of this regulated crop.

Impact of Harvest Time and Pruning Technique on Total CBD Concentration and Yield of Medicinal Cannabis.

The definition of optimum harvest and pruning interventions are important factors varying inflorescence yield and cannabinoid composition. This study investigated the impact of (i) harvest time (HT) and (ii) pruning techniques (PT) on plant biomass accumulation, CBD and CBDA-concentrations and total CBD yield of a chemotype III medical cannabis genotype under indoor cultivation. The experiment consisted of four HTs between 5 and 11 weeks of flowering and three PTs-apical cut (T); removal of side shoots (L) and control (C), not pruned plants. Results showed that inflorescence dry weight increased continuously, while the total CBD concentration did not differ significantly over time. For the studied genotype, optimum harvest time defined by highest total CBD yield was found at 9 weeks of flowering. Total CBD-concentration of inflorescences in different fractions of the plant’s height was significantly higher in the top (9.9%) in comparison with mid (8.2%) and low (7.7%) fractions. The T plants produced significantly higher dry weight of inflorescences and leaves than L and C. Total CBD yield of inflorescences for PTs were significantly different among pruned groups, but do not differ from the control group. However, a trend for higher yields was observed (T > C > L).

Effects of short-term environmental stresses on the onset of cannabinoid production in young immature flowers of industrial hemp (Cannabis sativa L.)

BackgroundsCannabis sativa L. produces at least 120 cannabinoids. Although genetic variation is the main factor in cannabinoid production, the effects of short-term environmental stresses in the early flowering stage remains largely unknown.MethodsTo investigate the effects of short-term environmental stresses on the onset of cannabinoid production in young immature flowers, a hemp variety, Green-Thunder (5–8% CBD/mg of dry weight), was treated with mechanical damage, insect herbivory, extreme heat, or drought stress for 5–7 days during the first 2 weeks of flowering. Three hemp tissues, including flowers, leaves, and stems, were collected from hemp grown under these stress conditions at multiple time points during the first 2 weeks after transition to the short photoperiod and analyzed using high pressure liquid chromatography to quantify phytocannabinoids including cannabigerolic acid (CBGA), cannabigerol (CBG), cannabidiolic acid (CBDA), cannabidiol (CBD), Δ-tetrahydrocannabinolic acid (THCA), Δ-tetrahydrocannabinol (THC), and cannabinol (CBN).ResultsThe 5 days of mechanical wounding did not affect the production of any of the cannabinoids during the initial stage of flowering. However, after 5 days of herbivore treatment, there was a significant difference in concentration between day 1 and day 6 of CBGA (control: 308 μg/g; treatment – 24 μg/g), CBG (control: 69 μg/g; treatment: 52 μg/g), and CBD (control: 755 μg/g; treatment: 194 μg/g) between the control and treatment plants. The 7 days of heat treatment at 45–50 oC significantly reduced the production of CBGA during this observed window (control: 206 μg/g; treatment: 182 μg/g) and CBG (control: 21 μg/g; treatment: − 112 μg/g). Notably, the largest change was observed after 7 days of drought stress, when plants showed a 40% greater accumulation of CBG (control: 336 μg/g; treatment: 622 μg/g), and a significant decrease (70–80%) in CBD (control: 1182 μg/g; treatment: 297 μg/g) and THC amounts (control: 3927 μg/g; treatment: 580 μg/g).ConclusionsAlthough this observation is limited in the early flowering stage, the common field stresses are adequate to induce changes in the cannabinoid profiles, particularly drought stress being the most impactful stress for hemp flower initiation with the altering the cannabinoid production by decreasing CBD and THC accumulation while increasing CBG by 40%.

Проявление гетерозиса у F1 гибридов петунии

The article presents the results of a study of the manifestation of hypothetical and true heterosis in the hybrid petunia according to some decorative features in the conditions of the protected ground of Moscow. The presence of a heterosis effect and overdomination in the time of flowering of the first flower, the diameter of the flower and the number of flowers for the first two weeks of flowering was established. All hybrid combinations showed a small negative hypothetical and true heterosis effect on the early entry of petunia plants into the flowering phase. Keywords: PETUNIA, HETEROSIS, HYBRID, DOMINANCE, OVERDOMINATION

Assessment of Fruit Drop in Different Cultivars of Litchi

Individual panicles produce hundreds of pistillate flowers but only a small proportion of these bear fruit and reach maturity. There are some stages of fruit drop during growth and development caused by different factors. An experimental trial was conducted in National Active Germplasm Site (NAGS) at ICAR-NRC on Litchi, Muzaffarpur, to assess the fruit drop due to different factors during 2014–2015. The result revealed that four factors viz., improper pollination and fertilization, embryo abortion, seed and fruit borer, and normal fruit abscission were associated with fruit drop in litchi and fruit drop varied from 23.53–77.54% with a maximum in Shahi and lowest in Elaichi during the first week of flowering. Fruit drop increased to 92.65–97.86% during the third week of flowering because of improper pollination and fertilization, and it reached a maximum level of 98.51–99.70% at the time of ripening stage with the lowest in Deshi. Embryo abortion was one primary cause of fruit drop during the 4th week whereas infestation of seed and fruit borer was the major factor for fruit drop during the 5–7th week. Such fruit drop can be controlled by managing the infestation of borer. Abscission due to ethylene production and heat stress during the maturity of fruit was yet another cause of fruit drop. This study will help to researcher to find out the time of infestation of seed and fruit borer which causes heavy fruit drop and it can be controlled with pest management option.

Impact of Three Different Light Spectra on the Yield, Morphology and Growth Trajectory of Three Different Cannabis sativa L. Strains.

Cannabis is one of the oldest cultivated plants, but plant breeding and cultivation are restricted by country specific regulations. Plant growth, morphology and metabolism can be manipulated by changing light quality and intensity. Three morphologically different strains were grown under three different light spectra with three real light repetitions. Light dispersion was included into the statistical evaluation. The light spectra considered had an influence on the morphology of the plant, especially the height. Here, the shade avoidance induced by the lower R:FR ratio under the ceramic metal halide lamp (CHD) was of particular interest. The sugar leaves seemed to be of elementary importance in the last growth phase for yield composition. Furthermore, the last four weeks of flowering were crucial to influence the yield composition of Cannabis sativa L. through light spectra. The dry flower yield was significantly higher under both LED treatments compared to the conventional CHD light source. Our results indicate that the plant morphology can be artificially manipulated by the choice of light treatment to create shorter plants with more lateral branches which seem to be beneficial for yield development. Furthermore, the choice of cultivar has to be taken into account when interpreting results of light studies, as Cannabis sativa L. subspecies and thus bred strains highly differ in their phenotypic characteristics.

About the creation of sterile lines of sweet pepper in breeding for heterosis

Relevance. Development of valuable sterile lines of sweet pepper using nuclear-cytoplasmic male sterility is associated with the search for stable sterility maintainers in collection material.Material and methods. The purpose of the research is to optimize the identification of the desired genotypes and accelerate the development of sterile lines using artificial climate chambers. The research material was a sterile line msTol55, which under the conditions of a film greenhouse showed partial fertility at the beginning or at the end of the growing season. The place of cultivation is artificial climate chamber, a film spring greenhouse.50-day-old seedlings were planted in pots on 10.01, the period of growing plants in the chamber - until 20.04, then the adult plants were transplanted into a spring film greenhouse. According to the traditional technology, the cassette seedlings of the same line were planted in the greenhouse on 15.04. The number of tested plants is 16-20 pcs. Growing mode in the chamber: 12 hours were illuminated with DRLV lamps, while the temperature was at the level of 26-28°C, from 20.00 to 8.00 the lamps were not illuminated, the temperature was 14-15°C. The actual sterility / fertility of the flowers was determined by the level of contamination of the fruits at the beginning of their formation.Results. The maintained temperature regime for growing in an artificial climate chamber made it possible to identify sterile (30%) and partially fertile plants (70%) in the first 2 weeks of flowering. When adult plants were transplanted into a spring greenhouse, the number of sterile plants increased to 56%. When growing the line msTol55 in a spring greenhouse using the usual technology, partial setting of seeded and little seeded fruits on 60% of the plants was observed from the third decade of May to the second decade of July, then all plants set only non-seeded fruits. Based on the results obtained, it is advisable to identify the breeding material for the Rf gene in the ACC, since the proposed growing regime serves as a provocative background and allows for more effective control over the manifestation of sterility.

Eddy covariance measurements of carbon dioxide and water fluxes in US mid-south cotton production

An eddy covariance (EC) system was used over a production-scale, US mid-south cotton field in order to improve understanding of carbon and water flux dynamics in cotton production. Measurement outcomes of NEE and ET from agricultural cropping systems in the humid US mid-south may differ from measurements made in arid production regions due to variation in precipitation, relative humidity, and cloud cover. Local measurements are needed for timely irrigation water management decisions and to assess their impact on the carbon cycle. Measurements were made in a 63-ha field in Northeast Arkansas in the 2016 and 2017 growing seasons (May-October). Average daily NEE during the growing season was driven largely by gross primary production (GPP) measured at -1.80 ± 0.26 g C m−2 d-1 ranging between -13.5 and 2.4 g m−2 d-1 during 2016 and -1.97 ± 0.26 g C m−2 d-1 ranging between -11.1 and 5.9 g m−2 d-1 during 2017. Across both years the average daily GPP during the growing season was 7.65 ± 0.45 g C m−2 d-1 during 2016 and 8.33 ± 0.37 g C m−2 d-1 during 2017. GPP was lowest during emergence and post-harvest and highest from the first week of flowering (FF) stage to about 3 weeks after cutout (cessation of vegetative expansion and production of new fruiting sites). Measured ET was lowest early and late in the season, and highest from FF until cutout. Across both seasons, average ET was 3.5 ± 0.1 mm d-1, more specifically 3.3 ± 0.1 mm d-1 during 2016 and 3.6 ± 0.1 mm d-1 during 2017. Peak water use was 7.6 mm d-1 during both growing seasons. Measured ET values were similar to results from lysimeter studies conducted in humid southeastern US climates, but lower than those observed in studies in arid regions. The water use efficiency of harvest yield per evapotranspiration flux was 0.26 kg lint cotton m-3 water and 0.34 kg lint m-3 water in 2016 and 2017, respectively which 1.5–2 times those of other studies, likely due to higher yields and lower evapotranspiration measured in this study. The findings suggest that US mid-south cotton production should continue to be managed differently than other more arid US cotton production regions.

Termination of Insecticide Applications for Tarnished Plant Bug (Hemiptera: Miridae) Management in Cotton

Tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is the most important insect pest of cotton, Gossypium hirsutum L., in the states of Arkansas, Louisiana, Mississippi, Tennessee, and Missouri. Foliar insecticide sprays are an important tactic within an integrated pest management (IPM) program for this pest which occurs from early flower bud development to cut out, a stage where the plant has reached the capacity for supporting fruiting positions and equivalent to when there are five nodes above the uppermost first position white flower (NAWF 5). Currently, NAWF and heat unit accumulation monitoring is limited, resulting in a need for a more simplified insecticide termination method that has the potential for wider adoption. Experiments were conducted in 2015 and 2016 in the previously mentioned states to determine when to terminate insecticide sprays for tarnished plant bug based on week of flowering. Treatments included terminating sprays after the second through sixth weeks of flowering, a season-long control, and an untreated control. In general, insecticides reduced densities of tarnished plant bugs in the sprayed treatments. When analyzed by location, treatments that resulted in cotton yields similar to the season-long control ranged from weeks two through five of flowering. These data suggest that treatments can be terminated after the fifth week of flowering. Data from this study indicate applications terminated after the fifth week of flowering would be similar to the current recommended termination timing of NAWF 5 plus 350 heat units. Results from this experiment will be used to better define a simplified IPM strategy for tarnished plant bug in cotton.

Evaluating Optimal Spray Timing, Planting Date, and Current Thresholds for Lygus lineolaris (Hemiptera: Miridae) in Virginia and North Carolina Cotton.

Economically damaging infestations of Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae), the tarnished plant bug, have been increasing in North Carolina and Virginia cotton since 2009. We conducted experiments to compare prophylactically timed sprays based on cotton phenology and current action thresholds based on sweep net and drop cloth sampling. In the second year of the study, we included planting date as a factor, with early and late-planted cotton. We found L. lineolaris nymph densities were reduced by at least 60% in North Carolina and 74% in Virginia in threshold plots when compared with the untreated control. Protecting the crop from first square through the fourth week of bloom afforded at least 30% control across planting dates in Virginia and at least 40% control in North Carolina. Economic returns were two to three times greater in early-planted cotton than in late-planted cotton. Treating cotton at action threshold or using prophylactic sprays from first square until the sixth week of bloom in early-planted cotton yielded over $500/ha in net returns in both North Carolina and Virginia. This study supports previous research that shows controlling L. lineolaris infestations during squaring and early weeks of flowering is critical for maximizing yield potential. Our findings also suggest that prebloom and bloom thresholds based on adult and nymphal density devised in the Mid-South may need revision in North Carolina and Virginia.

Identification of quantitative trait loci (QTL) for fruit-quality traits and number of weeks of flowering in the cultivated strawberry

Fruit quality and repeat flowering are two major foci of several strawberry breeding programs. The identification of quantitative trait loci (QTL) and molecular markers linked to these traits could improve breeding efficiency. In this work, an F1 population derived from the cross ‘Delmarvel’ × ‘Selva’ was used to develop a genetic linkage map for QTL analyses of fruit-quality traits and number of weeks of flowering. Some QTL for fruit-quality traits were identified on the same homoeologous groups found in previous studies, supporting trait association in multiple genetic backgrounds and utility in multiple breeding programs. None of the QTL for soluble solids colocated with a QTL for titratable acids, and, although the total soluble solid contents were significantly and positively correlated with titratable acids, the correlation coefficient value of 0.2452 and independence of QTL indicate that selection for high soluble solids can be practiced independently of selection for low acidity. One genomic region associated with the total number of weeks of flowering was identified quantitatively on LG IV-S-1. The most significant marker, FxaACAO2I8C-145S, explained 43.3 % of the phenotypic variation. The repeat-flowering trait, scored qualitatively, mapped to the same region as the QTL. Dominance of the repeat-flowering allele was demonstrated by the determination that the repeat-flowering parent was heterozygous. This genomic region appears to be the same region identified in multiple mapping populations and testing environments. Markers linked in multiple populations and testing environments to fruit-quality traits and repeat flowering should be tested widely for use in marker-assisted breeding.

Susceptibility of Flowering Cotton to Damage and Yield Loss from Tarnished Plant Bug (Hemiptera: Miridae)

The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is a major pest of cotton in the midsouthern United States, including the states of Arkansas, Mississippi, Louisiana, western Tennessee, and southeastern Missouri. Insecticides provide the primary form of control for this pest, and numerous applications are required annually to control the tarnished plant bug. Little information exists regarding when to terminate insecticide applications targeting tarnished plant bugs in cotton. Numerous sprays are made late in the season to protect a small percentage of the overall yield. Experiments were conducted at the Mississippi State University Delta Research and Extension Center to determine the impact of tarnished plant bug infestation timings on cotton yield. Two separate planting dates were utilized to determine the weeks of flowering that tarnished plant bugs can cause significant yield losses. There was a significant planting date by treatment interaction. Overall, yields were greater in the first planting date than the second planting date. In both planting dates, the first 4 wk of flowering were the most critical for tarnished plant bug control, and this is when the greatest yield losses occurred. Also, when no insecticide applications were made after the fourth week of flowering, no significant yield loss was observed. These data demonstrate the importance of scouting and adhering to treatment thresholds during the early flowering period. These data also suggest that thresholds may be able to be modified or eliminated after the fourth week of flowering, but more research is needed to confirm this.

Identification of Facultative Apomixis in Fluted Pumpkin (Telfairia occidentalis Hook F.) through Emasculation Method

Apomixis is seed and embryo formation without fertilization. A study was carried out from August, 2012 to May, 2014 in order to investigate the possibility of occurrence of apomixis in fluted pumpkin (Telfairia occidentalis Hook. F.) using emasculation method. Five genotypes of fluted pumpkin were used. Ten plants from each genotype were planted out in a screened environment at the Original Research Article Fayeun et al.; AJEA, 10(1): 1-10, 2016; Article no.AJEA.15261 2 department of Crop, Soil and Pest Management, Federal University of Technology, Akure. The crop being dioecious, all the male plants were emasculated (by total removal from the site) as soon as they were noticed, leaving only the female plants. Seeds obtained from the fruits of isolated female plants were later subjected to viability test. After several weeks of flowering, flowers and developing ovaries abortion, they eventually set fruits. All the genotypes produced fruits (one or two) though at different times. Both apomictic and parthenocarpic fruits were produced. The seeds obtained from the apomictic fruits of all the genotypes had high seedling emergence percentage and good seedling vigour. Apomictic fruits, seeds and seedlings were similar to those of sexually produced fruits. The observed facultative apomixis could be as a result of natural selection. This study confirms that apomictic form of reproduction occurs naturally in fluted pumpkin. Facultative apomixis in the fluted pumpkin is being reported for the first time and its implication in the genetic improvement of the crop is discussed.

Identification of QTL associated with flower and runner production in octoploid strawberry (Fragaria×ananassa)

BACKGROUND: Understanding the genetics of flowering in the strawberry (Fragaria × ananassa) will aid in the development of breeding strategies. OBJECTIVE: To search for quantitative trait loci (QTL) associated with remontancy and weeks of flowering in the strawberry. METHODS: Previously collected phenotypic data from two non-remontant ‘Honeoye’ × remontant ‘Tribute’ strawberry populations and simple sequence repeats (SSR) markers were used to search for QTL associated with repeat flowering, weeks of flowering and runner production, as well as the ability to produce flowers and runners at 17, 20 and 23 ◦ C. RESULTS: As was discovered in other studies, we found a major QTL that regulated remontancy and weeks of flowering on homeologous linkage group IV of ‘Tribute’. This QTL also had a negative effect on runner production and a positive influence on flower production under high temperatures. A number of additional QTL were discovered that significantly (LOD >3.0) influenced flower and runner production. CONCLUSIONS: Remontancy/non-remontancy is controlled by a major gene/locus and several minor modifying ones.

Plant-pollinator interactions in Crambe abyssinica Hochst. (Brassicaceae) associated with environmental variables.

Despite the economic importance of Crambe abyssinica, the present study is the first report on bees that occur with this species, and could aid in developing alternative methods for controlling insect pests without seriously impacting pollinators. The present study examined the following questions: (1) Which species are potential pollinators of C. abyssinica? (2) How do environmental conditions influence pollinator visitation fluctuations? Insects were sampled on a weekly basis between 08:00 and 16:00 during five weeks of flowering. When the results of analyses of variance were significant, the data was adjusted using regression equations at a 5% level of probability; the environmental variables were examined using Pearson's correlation coefficient. Apis mellifera, Geotrigona mombuca, Exomalopsis (Exomalopsis) fulvofasciata, Plebeia sp. and Dialictus sp. were observed visiting C. abyssinica flowers. A. mellifera and G. mombuca were observed to be potential pollinators, with the former demonstrating visitation peaks during flowering weeks II and IV at 12:00 and 08:00, respectively and the latter visiting during weeks III and IV at 12:00 and 10:00, respectively. Environmental factors such as temperature, relative humidity, and wind speed have different effect on the activity of bees.

Genetic mapping of day-neutrality in cultivated strawberry

Day-neutrality is a highly desirable trait in strawberry (Fragaria L.)-breeding programs worldwide due to its importance in extending the harvest season in commercial production. Day-neutral genotypes are photoperiod insensitive and will initiate flowers under any photoperiod conditions as long as temperatures are moderate (below 30/26 °C day/night). In the current study, the inheritance of day-neutrality was investigated using an F1 population derived from the cross ‘Tribute’ × ‘Honeoye’. The day-neutral trait was scored qualitatively [day-neutral (DN) or short-day (SD)], and quantitatively (number of weeks of flowering). When qualitatively scored in five locations, the DN trait fit a 1:1 segregation ratio in the hot summers of Maryland (MD), Minnesota (MN) and Michigan (MI). Segregation was skewed toward additional DN progeny in the cooler summers of California (CA) and Oregon (OR). Regardless of evaluation location, the trait was mapped on linkage group IV-T-1 of the ‘Tribute’ map near the markers ChFaM148-184T and ChFaM011-163T. Quantitative-trait loci (QTL) for number of weeks of flowering in MD and CA and for stolon or ‘runner’ production in MN, MI and OR also were identified on linkage group IV-T-1 of the ‘Tribute’ map. These QTL were significantly associated with the qualitatively scored trait and its closely linked molecular markers. The marker ChFaM148-184T explained 63.8 % of the total phenotypic variation for the number of weeks of flowering for MD and 32.4 % of the total phenotypic variation for runner production in MN. Consequently, it was hypothesized that a single major gene or tightly linked cluster of genes in coupling control day-neutrality in this population. The results found in the current study suggest that day-neutrality can be qualitatively scored at least in the locations where the temperatures do not allow SD plants to behave as DN.

GROWTH, FLOWERING AND PHOTOSYNTETIC PIGMENTS OF PELARGONIUM × HORTORUM L.H. BAILEY ‘SURVIVOR HOT PINK’ AND ‘GRAFFITI FIRE’ GROWN IN SUBSTRATES CONTAINING SEWAGE SLUDGE COMPOST

The aim of this study was to assess usability of composts made of sewage sludge and either straw or leaves used as substrates for growing zonal pelargoniums. The study plants ‘Hot Pink’ cv. of Survivor group and ‘Fire’ cv. of Graffiti group were grown in 5 different substrates. The control substrate was high peat (100%) deacidified with chalk and dolomite up to pH 5.8–6.0 and supplemented with 2.5 g·dm-3 of Azofoska multicomponent fertilizer. The other four substrates contained two types of composts: SSRS – sewage sludge, straw (1:1, v/v) and SSL – sewage sludge, leaves (1:1, v/v), mixed with high peat at two different proportions, 1:3 (v/v) and 1:7 (v/v). Chemical composition of the substrates was investigated and they were supplemented with nitrogen and potassium as recommended for pelargoniums. Plant morphological parameters were evaluated during flowering. They included plant height and diameter, number of shoots and leaves, leaf assimilation area and leaf weight. Leaf chlorophyll and carotenoid content was also estimated. Inflorescence related parameters included inflorescence diameter and inflorescence stem length, number of flowers per inflorescence and flower diameter. All inflorescences formed over 10 weeks of flowering were counted. Plant ornamental value was assessed using a five-score bonitation scale. The investigated composts were found to be useful components of the substrates for zonal pelargonium production. Irrespective of the compost share, the tested substrates significantly affected most of the evaluated morphological traits. The substrate containing the compost made of sewage sludge and straw (SSRS) and peat (1:3, v/v) was found the most beneficial for pelargonium foliage, i.e. the number of leaves, their fresh weight and assimilation area. Leaf chlorophyll and carotenoid content in the pelargoniums grown in the substrates containing either dose of SSRS compost did not differ from the control plants. Substrate type did not affect bonitation score of ‘Survivor Hot Pink’ cultivar. The bonitation score of ‘Graffiti Fire’ cultivar was the highest for plants growing in the substrates with either SSRS or SSL compost plus peat in 1:3 ratio (v/v).

Canopy-scale wavelength and vegetative index sensitivities to cotton growth parameters and nitrogen status

Temporal and spatial variability of plant available N in the humid southeastern region of the United States often results in within-field over- and under- application of this nutrient to cotton. Although ground-based canopy reflectance has the potential to quantify crop N status in real-time and drive variable rate fertilizer N applications, currently utilized vegetation indices often fail to correlate strongly with crop N status. Therefore, the objective of this study was to examine relationships between canopy reflectance across wavelengths and calculated ratios and vegetation indices prior to and at flowering to biomass, leaf tissue N concentration, aboveground total N content and lint yield. Data was collected during the third week of flower bud formation and the first week of flowering during the 2008–2010 growing seasons at Mississippi State, MS, USA. Analysis of wavelength sensitivities indicated reflectance near 670 nm was most highly correlated to plant height, but relatively poorly correlated to lint yield, total plant N content and leaf N concentration. The strongest wavelength correlations with leaf N concentration, lint yield and plant total N content were noted near 700 nm. Subsequent analysis indicated indices utilizing reflectance in the red edge region correlated more strongly to leaf N status and total plant N content when compared to indices relying on reflectance in green or red regions. Comparisons between simple red edge indices and more complex calculations of the red edge inflection point suggested a simplified version of the Canopy Chlorophyll Content Index calculation may provide reasonable reliability for real-time detection of cotton N status.

Flowering dynamics of peach-leaved bellflower (Campanula persicifolia L.) 'alba' treated with bioregulators, grown in an unheated plastic tunnel and in field

The effect of BA, GA<sub>3</sub> and BA+GA<sub>3</sub> on flowering of peach-leaved bellflower (<i>Campanula persicifolia</i> L.) 'Alba', grown in an unheated plastic tunnel or in open field, was investigated. Bioregulators at the following applications: 0, 100, 200, 400 mg x dm<sup>-3</sup>, were applied foliarly twice. It has been found that the cultivation of peach-leaved bellflower in an unheated plastic tunnel accelerates flowering of plants by about 2 - 3 weeks, compared to open field cultivation, in the first and second year of flowering of plants. It is advisable to apply gibberellic acid at a concentration of 400 mg x dm<sup>-3</sup> in plastic tunnel cultivation of bellflower and at a concentration of 200 mg x dm<sup>-3</sup> in field cultivation, since this treatment accelerates flowering by 2 - 9 days. It is recommended that gibberellic acid should be applied at a concentration of 400 mg x dm<sup>-3</sup>, which extends the flowering period of peach-leaved bellflower grown in a plastic tunnel by 6 - 13 days. When peach-leaved bellflower is grown in an unheated plastic tunnel, full flowering is predicted to occur in the first or second week from the beginning of flowering of plants. When bellflower is grown in open field, full bloom of inflorescences is expected in the second week of flowering of plants. Irrespective of the type of substance applied in both years of cultivation, in the unheated plastic tunnel the largest amount of inflorescences was ready for cutting in the first decade of June, and in the field in the second decade of June.

Expression of Ornamental Traits in Container versus Field Plants in a Vitex L. Breeding Program

New ornamental cultivars must display horticultural superiority when grown in containers or in the field. The objectives of this study were to determine whether container or field is most appropriate for initial selection of ornamental traits in a Vitex breeding program by determining whether quantitative traits of breeding interest were expressed similarly in the two environments and by determining trait correlations in each environment. Segregating populations of Vitex and their parents were cloned and grown in containers and in the field. Ornamentally significant traits evaluated included first flower date, last flower date, flowering period, total weeks of flowering, inflorescence number, inflorescence length, flower rating, plant height, plant width, and Cercospora leaf spot resistance. Overall, field-grown plants were taller and wider than plants grown in containers. Field-grown plants also had a later first flowering date, longer flowering period, greater total weeks flowering, longer inflorescence length, larger inflorescence number, and more flowers on the inflorescence. Significant genotype × environment interactions were found for height and width measurements taken 19 and 33 weeks after planting, first flower date, total weeks in flower, inflorescence number, flower rating, and Cercospora rating. Most trait correlations were either non-significant or so low so that selection of these traits would be independent of other traits. High correlations were present in both environments between height measurements taken at 19 weeks and 33 weeks after planting. High correlation in the field and moderate correlation in containers were found between width measurements taken 19 and 33 weeks after planting. Correlation was high between flowering period and first flower date in both the field and container. Correlation between last flower date and flowering period was high in containers and moderate in the field. High correlation was present in both environments between flowering period and total weeks of flowering. Containers were determined to be best for initial selection for most traits having significant genotype × environment effects.