Inflorescence Appearance Research Articles

OPTIMIZATION OF CONDITIONS FOR OBTAINING URTICA DIOICA L. EXTRACT AND THE STUDY OF ITS ANTIOXIDANT PROPERTIES

The purpose of the presented study was to select optimal conditions and develop a technology for obtaining nettle extract, which in the future can be used in food technologies. Nettles were harvested in May before the appearance of inflorescences. The place where the plant is collected is a forest near the village of Lvovka in the Shigonsky district of the Samara region. Mathematical optimization of the conditions for obtaining water-alcohol extract of nettle dioecious was carried out. Nettle extraction was carried out in the traditional way, with ultrasound treatment and ultrahigh frequency currents. To obtain an extract with the highest yield of extractives, it is recommended to use 75% ethyl alcohol as an extractant at a hydromodule of 1 : 10, a temperature in the range from 45 to 55 °C, and an extraction time of 2 hours. In addition, it is possible to use ultrasonic radiation or microwave processing to obtain the extract, which also contribute to an increase in the yield of dry substances. Nettle extract, prepared with the help of ultrahigh frequency currents, showed the greatest antioxidant activity. This extract contains 1309.9 mg of gallic acid and 322.9 mg of catechin per 100 g of feedstock, and its antioxidant activity is 2.5 mg/ml. At the same time, with the help of a microwave field, the extract can be obtained in a minimum time.

Physiological Performance of Oil Palm Inflorescences (Elaeis guineensis Jacq) After Drought Stress on 3 Different Soil Types in Central Kalimantan

Oil palm is a plantation crop that requires an amount of rainfall ranging from 1,750–2,500 mm/year as a condition for good growth. Long dry conditions will have an impact on decreasing productivity. Water deficit can cause growth stagnation and if it occurs continuously can cause irreversible physiological changes in plants, resulting in death. This study aims to study the relationship between water deficit events and the flowering physiology of oil palm plants in 3 soil types in Central Kalimantan. This study is explorative in nature with a quantitative descriptive research method using 3 types of soil: mineral, peat, sand; and 2 plant ages: Young (=7 years) and Prime (> 7 years) and each observation plot consisted of 10 trees selected systematically 5 x 5. The results showed that the occurrence of water deficit had different effects on several phases of FFB formation in phase of sex differentiation & leaf initiated on mineral soil, phase of sex differentiation & female inflorescence on peat and phase of sex differentiation, female inflorescence & inflorescence abortion on sandy soil in the Young plant category. The Prime category occurs in the ripeness, anthesis & inflorescence abortion phases on mineral soils, the anthesis & inflorescence abortion phases on peat and the inflorescence abortion & female inflorescence phases on sandy soils. Apart from the stages of FFB formation, the incidence of water deficit also affects the position of the appearance of bud inflorescences, female & male inflorescences anthesis, male inflorescences receptive & male inflorescences post anthesis, black fruit and red fruit in each soil type and plant category.

Effect of the Climatic Conditions in Central Europe on the Growth and Yield of Cornelian Cherry Cultivars

Fruit of Cornelian cherry can be used fresh or processed, and cultivation practices are developing in this direction. Due to the rarity of its cultivation, Cornelian cherry is harvested from natural sites of occurrence. However, the fruit from natural sites is of lower quality than the cultivars, as their seedlings differ in terms of fruit ripening. The objective of this experiment was the evaluation of approximately a dozen cultivars in terms of growth and fruit yield under the conditions of Central Europe. The effect of climatic conditions on the onset date of particular phenological stages was also assessed. All the analysed cultivars are suitable commodity crops, but they should be accurately selected depending on the direction of production. The first phenological stage of Cornelian cherry is the appearance of inflorescences before the development of leaves. The start of particular phenophases depends on the temperature and precipitation. Cornelian cherries cultivated under ecological conditions show satisfactory fruit size and generally a small percentage of stone. Most cultivars have an elongated fruit shape, and the shape factor decreases with their growth and ripening. The fruit grows along a double sigmoid, and its first intensive growth occurs following the extinction of intensive shoot growth.

Non-Invasive and Confirmatory Differentiation of Hermaphrodite from Both Male and Female Cannabis Plants Using a Hand-Held Raman Spectrometer

Cannabis (Cannabis sativa L.) is a dioecious plant that produces both male and female inflorescences. In nature, male and female plants can be found with nearly equal frequency, which determines species out-crossing. In cannabis farming, only female plants are preferred due to their high yield of cannabinoids. In addition to unfavorable male plants, commercial production of cannabis faces the appearance of hermaphroditic inflorescences, species displaying both pistillate flowers and anthers. Such plants can out-cross female plants, simultaneously producing undesired seeds. The problem of hermaphroditic cannabis triggered a search for analytical tools that can be used for their rapid detection and identification. In this study, we investigate the potential of Raman spectroscopy (RS), an emerging sensing technique that can be used to probe plant biochemistry. Our results show that the biochemistry of male, female and hermaphroditic cannabis plants is drastically different which allows for their confirmatory identification using a hand-held Raman spectrometer. Furthermore, the coupling of machine learning approaches enables the identification of hermaphrodites with 98.7% accuracy, whereas both male and female plants can be identified with 100% accuracy. Considering the label-free, non-invasive and non-destructive nature of RS, the developed optical sensing approach can transform cannabis farming in the U.S. and overseas.

Inflorescence appearance timing and production rate traits in wild Zoysiagrass (Zoysia spp)

Zoysiagrass (Zoysia spp.) has excellent turf quality and can be applied to various uses for personal space to public sports areas or commercial landscapes. However, it has disadvantages such as slow growth rate, cold hardiness, low seed yield, and hard to establish from seeds, which cannot be improved with agricultural practices. Therefore, breeding a new cultivar as a hybrid could be an efficient strategy to improve the Zoysiagrass cultivar. In fact, hybrid zoysiagrass shows mixed traits of both parents in morphology and heterosis in growth. However, inflorescence appearance and its rate are known to make a hybrid. Thus, the variety of inflorescence appearance timing and production rate were investigated among 549 genetic resources. As a result, only 5.38% of the variety among survived zoysiagrass after transplanting showed more than 30% inflorescence appearance within the given period. During that, some varieties showed a reduction of total inflorescence. Hence, we report the diversity of inflorescence appearance timing and production rate that could be useful for breeders and researchers breeding new Zoysiagrass cultivars.

Camelina sativa (L. Crantz) Fresh Forage Productive Performance and Quality at Different Vegetative Stages: Effects of Dietary Supplementation in Ionica Goats on Milk Quality

The research meant to study the productive performances of Camelina sativa and the effects of feeding Camelina fresh forage harvested during five phenological stages (I: main stem elongation; II: maximum stem elongation: III: inflorescence appearance; IV: flowering; V: fruit set visible) on the yield, chemical composition and fatty acid profile of milk from autochthonous Ionica goats. Goats were randomly assigned to two groups (n = 15) that received a traditional forage mixture (Control) or Camelina forage harvested at different stages (CAM). The field experiment was conducted in two years; no significant differences between years were recorded for any of the Camelina production traits. The total biomass increased (p < 0.05) from phase I (1.4 t/ha) to phase V (5.2 t/ha). The distribution of stem, leaves and pod also changed during growth, showing a significant increase of stem from 40.8 to 45.6% and of pod from 0 to 19.4%, whereas leaves decreased from 59.2 to 35.1%. The milk yield and chemical composition were unaffected by the diet, while supplementation with Camelina forage increased milk CLA content (on average 1.14 vs. 0.78%). A markedly higher concentration of PUFAs was found in milk from goats fed Camelina harvested during the last three phenological stages. The index of thrombogenicity of milk from the CAM fed goats was significantly lower compared to the control group. In conclusion, Camelina sativa is a multi-purpose crop that may be successfully cultivated in Southern Italy regions and used as fresh forage for goat feeding. Milk obtained from Camelina fed goats showed satisfactory chemical and fatty acid composition, with potential benefits for human health.

Contribution to monitoring the influence of air temperature on some phenological stages of the date palm (cultivar ‘Deglet Nour’) in Biskra

Algeria, one of the potential date producers in the world, is exposed to the different impacts of global warming. This climatic phenomenon probably has repercussions on date palm cultivation. The main purpose of this contribution is to monitor the phenological stages of the date palm and calculate the thermal requirements for this plant, also the study of impacts temperature on date growth. The results obtained are compared with older data recorded in the same region. We recorded the temperatures of the air measured inside two palm groves in the wilaya (state) of Biskra, namely Zaouiet Ben Ouaar and Mangae Bougtaf. At the same time, weekly observations were made to follow the phenological stages of Deglet Nour during two agricultural seasons (2015–2017), at the level of these two palm groves; in order to highlight the relationship between air temperature and the growth of the cultivar date studied. The first results show that Deglet Nour, in Biskra, ripens after around 250 days from the date of appearance of female inflorescences, with thermal requirements that exceed 4000 °C. Air temperature is one of the limiting factors of date palm growth. It has a direct influence on the development of dates and on the quality and yield of this product. Phoenix dactylifera L. can withstand extreme temperatures, going from freezing to over 50 °C.

Урожайность семян и качество масла Guizotia abyssinica в условиях центральной степи Крыма

Guizotia abyssinica or niger is an oilseed crop that belongs to the family of Asteraceae, which is cultivated in Ethiopia and India. This crop is environmentally modifiable and does not greatly depend on soil and climatic conditions. The aforementioned peculiarities, as well as the achievements of Russian breeders, inspired scientists to study Guizotia abyssinica in various regions of the country. The aim of the research was to assess the possibility of cultivating Guizotia abyssinica for seeds in the central steppe of the Crimea. Field trials were conducted in 2019–2020 on the experimental fields of the Department of Introductions and Technologies in Agriculture and Livestock Farming of the FSBSI “Research Institute of Agriculture of Crimea” (village of Klepinino, Krasnogvardeysky district). Guizotia abyssinica variety ‘Medeya’ (originator – FSBSI “Federal Research Center of Fibre Crops”) served as plant material for this research. The experimental design included the following options: planting dates (factor A) - second decade of March, third decade of March, first decade of April; seeding rates (factor B) – 1.0; 1.5; 2.0; 2.5; 3.0 million seeds per hectare. In the course of the research, we found that the niger crop growing season length varies from 135 to 161 days under conditions of the central steppe of the Crimea. Nevertheless, this figure can be considered arbitrary since frequent summer showers in the Crimea lead to the appearance of new inflorescences and lengthen the growing season. It should be noted that one of the disadvantages of this crop is shattering. The highest seed yield (4.0 centners per hectare) was obtained in 2019, which was more favorable in moisture supply (sowing date – mid March/late March; seed rate – 2.0–2.5 million seeds/ha). In 2020, Guizotia abyssinica seed yield was even lower and varied from 0.5 to 0.8 cwt/ha depending on the variant of the experiment. The niger seeds oil content, depending on the sowing date, was 34.8–36.2 % in 2019 and 35.9–38.0 % in 2020. It has been established that sowing at a later date causes a decrease in oil content. We identified 11 fatty acids in the niger oil with linoleic (С 18:2) – 61.0–70.3 %; oleic (С18:1) – 13.8–19.9 %; palmitic (С16:0) – 7.3–8.8 %; stearic (С18:0) – 6,3–8,2 % acids being the dominant ones. Thus, for two years of research in the Central Steppe of the Crimea, Guizotia abyssinica has established itself as an unproductive crop that forms valuable oilseeds with an oil content of up to 38.0 %.

Fenologia, exigências térmicas e composição mineral de folhas de variedades de oliveira no Rio Grande do Sul

Com o objetivo de caracterizar a fenologia, exigências térmicas e composição mineral de folhas de variedades de oliveira, foram realizadas observações e coletadas amostras de 2015 a 2018, em um olival em Encruzilhada do Sul. As observações foram feitas em 10 variedades: Cipressino, Coratina, Manzanilla, Arbosana, Koroneiki, Picual, Arbequina, Alfafara, Lecino e Frantoio. Para as determinações fenológicas foram observadas as datas da poda (P), início do cacho (IC), aparecimento de inflorescência (AI) e início da frutificação (IF). Para a composição mineral, foram amostradas e analisadas folhas das variedades, no inverno, primavera, verão e outono. Houve diferenças da fenologia entre variedades e entre safras. Na safra de 2015/2016 o ciclo foi mais curto que em 2016/2017. Em 2015/2016 a Arbosana e Alfafara foram mais tardias, enquanto em 2016/2017 não houve diferença entre variedades. As variedades apresentaram diferenças com relação ao teor na folha de todos os nutrientes analisados. A diferença mais evidente foi do teor de fósforo, sendo que as variedades Arbequina e Arbosana apresentaram maior teor. Os nutrientes apresentaram diferenças nos teores nas folhas nas diferentes épocas de amostragem, com exceção de cálcio e boro.

Macronutrient dynamics in leaves and bunches of black pepper

Abstract: The objective of this work was to determine the macronutrient dynamics in leaves and bunches of black pepper (Piper nigrum) throughout the plant reproductive cycles. The experiment was carried out in a commercial field of 'Bragantina' black pepper. Leaves and bunches were sampled every 21 days for one year, during two crop cycles. The bunches were sampled from the twenty eighth day after the appearance of inflorescences until the complete fruit maturation. Samples of leaves and bunches were dried, and the contents of N, P, K, Ca, Mg, and S were determined. N, K, and Ca were the most common macronutrients found in the bunches and leaves of black pepper. The accumulation of dry matter in the bunches was similar for both cycles and it was adjusted to the linear and quadratic models. The accumulation and content of macronutrients followed the dry matter behavior trend. Macronutrient contents in leaves oscillate during the year, and K and Mg vary more than N, P, Ca, and S. The macronutrient contents in black pepper leaves and bunches depends on the plant vegetative stage, and this variation should be considered in the planning of the fertilization management.

The anti-ethylene growth regulator silver thiosulfate (STS) increases flower production and longevity in cassava (Manihot esculenta Crantz)

Cassava, which produces edible starchy roots, is an important staple food for hundreds of millions of people in the tropics. Breeding of cassava is hampered by its poor flower production, flower abortion, and lack of reproductive prolificacy. The current work determined that ethylene signalling affects floral development in cassava and that the anti-ethylene plant growth regulator silver thiosulfate (STS) mitigates the effects of ethylene on flower development. STS did not affect the timing of flower initiation, but improved early inflorescence and flower development as well as flower longevity such that flower numbers were increased. STS did not affect shoot and storage root growth. Studies of silver accumulation and treatment localization support the hypothesis that the beneficial effects of STS are confined to tissues of the shoot apex. The most effective timing of application was before inflorescence appearance extending to post-flower appearance. Based on this work a recommended protocol for STS use was developed. This work has the potential to improve methods for enhancing cassava flower development in breeding nurseries and thereby synchronize flowering of desired parents and enable the production of abundant progeny of desired crosses.

Phenology and thermal requirements of the atemoya tree (Annona cherimola Mill. X Annona squamosa L.)

ABSTRACT The present study had as the main objective the documentation and characterization of the different phenological stages, as well as the definition of the thermal requirements, of the atemoya tree for two agronomic seasons. From shoot development to senescence and beginning of the rest period eight main stages were described (shoot development, leaf development, shoot/bud growth, inflorescence appearance, flowering, fruit development, fruit maturity and senescence and the beginning of the rest period). The number of days and the thermal requirements for completing each phenological stage were different between the two agronomic seasons of the atemoya. The first and second agronomic season presented a period of 217 and 206 days, with thermal requirements of 2469 and 2302 degree days, respectively.

Genetic Analysis of Yield and Related Characters of Lablab Bean

An experiment was conducted with a view to determine the nature and extent of gene action of yield and yield related characters of lablab bean. Five parents and their 10 F1s synthesized from 5 x 5 half diallel cross were evaluated in a Randomized Complete Block Design with three replications. The analysis of variance showed that the difference among the genotypes (parents and F1s) were highly significant for all the characters which revealed the presence of wide variability among the genotypes under this study. Hayman’s ANOVA (modified by Jones) suggested that the presence of additive and dominance gene actions for all the characters. The ‘Vr-Wr’ graph indicated partial dominance for the characters viz. days to first inflorescence appearance, days to first flowering, days to pod maturity, days to seed maturity, number of nodes per inflorescence, edible pod length, edible pod breadth, edible pod weight and pod yield per plant. Over dominance was observed for number of inflorescences per plant, number of pods per inflorescence and hundred seed weight. Complete dominance was observed only for number of pods per plant in lablab bean. As the development of hybrid variety is not possible in lablab bean, diallel selective mating system may be adopted for improvement of yield traits by using knowledge of gene actions. The hybrids with predominant additive gene action for yield related traits may be advanced to obtain transgressive segregants and pure lines for higher pod yield per plant.

Foliar application of 5-aminolevulinic acid to promote bioactive potential and nutritional value of purslane, a vegetable for future

Decent taste and the salt and drought tolerance of purslane (Portulaca oleracea L.) make it a potential vegetable crop for the future. This study investigates the effects of foliar application of 5-aminolevulinic acid (5-ALA), a new plant growth regulator, on the growth, mineral composition, and bioactive compounds of purslane. Three different levels of 5-ALA (0, 25 and 50 mg L-1) were sprayed at 1) two leaved stage and 2) upon the onset of inflorescence appearance on purslane seedlings. Results showed that 5-ALA application enhanced biomass accumulation in the plant shoot and increased shoot length. Concentration of nitrogen, potassium, magnesium, zinc and iron increased in the shoots of 5-ALA treated plants, while the calcium concentration remained unaffected. Phenolic compounds of the plant were catechin, chlorogenic acid, and ellagic acid, with catechin being the main compound. Further on, Trans-ferulic acid, hesperedin and eugenol were detected in the extract of 5-ALA-treated plants. Application of 5-ALA also increased fatty acids in the plant leaves. Total phenolics, ascorbic acid contents and antioxidative activity of shoot were increased in the 5-ALA-treated plants. Moreover, pH of root exudates of the plants was decreased in 5-ALA treated plants. The results revealed that exogenous 5-ALA has growth regulatory effects and can enhance the growth, and improve nutritional quality and pharmaceutical properties of P. oleracea. In this regard, the best results were obtained by application of 50 mg 5-ALA L-1.

The effect of high temperature and water stress on the development of bract browning in Protea ‘Pink Ice’

Protea 'Pink Ice' is a Cape Flora cut flower product that is widely planted in the Western Cape, South Africa, predominantly in the warmer and drier regions. Harvests coincide with mid-summer to early autumn, a period generally characterized by hot, dry conditions and high irradiance levels. 'Pink Ice' and other Protea cultivars harvested in this window are particularly prone to develop a preharvest disorder of the involucral bracts, described as 'Bract Browning' by Smith et al. (2015) or commonly referred to by the industry as 'dirty nail syndrome'. Bract browning can significantly reduce the market value and export potential of Protea ornamental stems by affecting the inflorescence appearance. The aim of this study was to obtain a better understanding of the effect of water and high temperature stress on the development of bract browning in Protea inflorescences. Flowering, two-year-old 'Pink Ice' potted plants were subjected to three irrigation and two temperature treatments in a factorial, randomized complete block design. An 'ambient' and a 'warmed/elevated' temperature (ambient temperature +1.6 degrees C) treatments were combined with three irrigation schedules consisting of an estimated optimal (x) irrigation application supplied throughout the season, and irrigation treatments which provided either half (1/2x) or double (2x) the amount of water provided at optimal irrigation. Results indicated no interaction between heat and water stress as main effects; however, both factors significant influenced the development of bract browning. Elevated temperatures only increased bract browning in Zone 1 (top third) of the inflorescence, with significantly less marketable flowers associated with the warmed treatment. Reduced irrigation impacted significantly on all zones of the inflorescence. With an expected rise in temperature and a possible increase in heat wave incidences as predicted with climate change, it is critical to develop effective strategies to prevent or ameliorate the development of bract browning in order to continue to deliver premium quality products to a highly competitive international market.

Effects of application timing of saline irrigation water on broccoli production and quality

Irrigation with moderately saline water is a necessity in many semi-arid areas of the Mediterranean Basin, and requires adequate irrigation management strategies. Broccoli (Brassica oleracea var. italica), a crop moderately sensitive to salinity stress, was used to evaluate the effects of the application of saline (S) and non-saline (NS) irrigation water during two growth phases in terms of plant growth, water status, floret yield, glucosinolate profile, and quality. Use of S-water (4 dS m−1) from transplanting to appearance of the inflorescence, alternated with NS-water (2 dS m−1) from inflorescence appearance to harvest and vice versa were compared with continuous use of S- or NS-water. Irrigation with S-water during the first growth-phase decreased leaf water and osmotic potential, net CO2 assimilation rate, and favoured Na+ and Cl− accumulation at toxic levels causing ion imbalances and reducing broccoli plant growth. Application of S-water exclusively after inflorescence appearance caused a 22.2% decrease of the head dry biomass compared to NS-NS plants. Regardless of application timing, irrigation with S-water decreased broccoli yield and head mean fresh weight compared to NS-NS plants by 20% and 24%, respectively. Use of S-water in one or both growth stages improved broccoli dry matter and soluble solid content, while had no impact on total glucosinolate concentration. However, application of S-water during the first growth-phase resulted in an increase of indolic glucosinolates (glucobrassicin and neoglucobrassicin) and potential effects on broccoli nutritional properties and flavour.

Effects of salt stress imposed during two growth phases on cauliflower production and quality.

Cultivation of cauliflower is diffused in Mediterranean areas where water salinity results in the need to identify alternative irrigation sources or management strategies. Using saline water during two growth phases (from transplanting to visible appearance of inflorescence or from appearance of inflorescence to head harvest), the present study aimed to identify the growth period that is more suitable for irrigation with low quality water in relation to cauliflower production and quality. Salinity affected cauliflower growth mainly when imposed in the first growth phase. The growth reduction depended mainly on ion-specific effects, although slight nutrient imbalances as a result of Na+ and Cl- antagonisms were observed. The use of non-saline water in the first or second growth period reduced both the osmotic and toxic effects of salinity. When salinity was applied during inflorescence growth, yield was reduced because of a restriction of water accumulation in the head. The results of the present study demonstrate the possibility of producing marketable cauliflower heads under conditions of salinity by timing the application of the best quality water during the first growth phase to improve fruit quality and during the second phase to reduce the negative effects of salinity on yield. © 2016 Society of Chemical Industry.

The role of structural and temporal factors in the architectural development of the mango tree: evidences from simulation

The mango tree architecture can be defined as an arborescence of vegetative growth units and inflorescences in terminal position. The vegetative and reproductive development of the mango tree is affected by endogenous structural and temporal factors and their interplays. This could explain for example the well-known phenological asynchronisms within and between trees. However, the relative importance of these factors in the architectural development has not yet been assessed. For this purpose, we designed a model of mango tree architectural development. In this model, the appearance of growth units and inflorescences was decomposed into elementary events describing the occurrence, the intensity and the timing of vegetative and reproductive development. The corresponding probabilities were estimated using generalized linear models (GLMs) and were affected by different structural and temporal factors, such as the apical or lateral position, or the vegetative or reproductive fate, of the previous growth unit. GLMs were estimated on the basis of mango tree architectures, cultivar Cogshall, measured during two production cycles in Reunion Island. A model of architectural development was then designed using the L-systems formalism and consisted in successive applications of development rules in order to assemble in parallel new units in different topological positions and with different fates. As a result, a simulation of the model gave an integrative view of the dynamics of the population of growth units and inflorescences of the tree. We could assess in this way more precisely the impact of the structural and temporal factors on the vegetative and reproductive development of the mango tree by comparing simulated with actual tree architectures. Additionally, a 3D representation could be estimated to visualise the generated structures. As a perspective, this model of architectural development is a cornerstone for an integrative crop model of the mango tree including carbon-and water-related ecophysiological processes for mango fruit development (see poster of Gretchi et al. in this symposium). (Texte integral)

INVOLUCRAL BRACT BROWNING IN PROTEAS - THE WHAT, HOW AND WHAT NOW?

Involucral bract browning in Protea is characterised by brown blemishes that develop pre-harvest on the tips and/or margins of the involucral bracts, resembling a nail, hence the common term of dirty nail syndrome. These blemishes can occur on all sides of the inflorescence, or can be concentrated on the most sun-exposed side. Bract browning can seriously reduce the market value and export potential of this niche cut flower product, as it has a strong impact on the inflorescence appearance. Despite the visual and financial impact these blemishes can have on pack out rates at the producer level, bract browning in Protea has not been characterised yet, with no classification system for bract browning within South African export regulations, which currently only account for general blemishes. The aim of the study was to characterize bract browning in Protea 'Pink Ice' by using the South African export blemish quality standards as well as an adaptation of the classification system developed for Telopea species using three zones, on a 0-6 illustrative rating scale. Acceptability was determined for local market standards by benchmarking with a packing facility. Characterization of bract browning is required to assist the industry to assess the severity of involucral bract browning and to develop new strategies to prevent and/or ameliorate the development of bract browning in order to deliver premium quality products to a highly competitive international market.

Diapause incidence and duration in the pest mango blossom gall midge, Procontarinia mangiferae (Felt), on Reunion Island.

The mango blossom gall midge, Procontarinia mangiferae, is a multivoltine species that induces galls in inflorescences and leaves of the mango tree, Mangifera indica. In subtropical Reunion Island, populations of P. mangiferae are observed all-year round, but the pattern and the role of dormancy in their life cycle have never been documented. We performed field and laboratory experiments using more than 15,000 larvae. We demonstrated that a larval diapause may affect a part of the midge population, regardless of the season. The total duration of the diapause varied from 6 weeks to more than 1 year. One year of field monitoring showed that the highest incidence of diapause was observed in larvae collected during the summer from mango leaves, where it affected approximately one-third of the individuals. This facultative diapause allows the permanent presence of P. mangiferae in the orchards. By recording diapause duration during 22 weeks under controlled conditions, we showed that high temperatures (26 °C) increased diapause duration and extended the range of the dates of diapause emergence, whereas cool temperatures (20 °C) shortened diapause duration and shortened the range of the dates of emergence from diapause. A temperature decrease from 26 to 20 °C triggered the emergence of diapausing individuals. These mechanisms ensure the synchronization of the emergence of diapausing individuals with the appearance of mango inflorescences, which is also induced by cool winter temperatures.