Phenology and fruit set of peach trees cultivated in Dois Vizinhos, Paraná State, Brazil

Understanding the dormancy phases and dynamics of commercial cultivars in the regions where they are grown allows for the implementation of different cultural practices and aids in the understanding of the temperature requirements for collaboration with genetic improvement programs. The objective of this study was to determine the budding, flowering, and fruit set rates of peach trees cultivated in the municipality of Dois Vizinhos, Southwestern Paraná, Brazil. The present work was developed using the collection of peach trees in the fruit growing sector of the Universidade Tecnológica Federal do Paraná. Sixteen peach cultivars were evaluated: Rubimel, Leonense, Coral, Marli, Charme, Riograndense, Douradão, Chimarrita, Granada, BR-1, Bonão, and Eldorado (all planted in 2009), as well as Regalo, Kampai, Fascínio, and Zilli (planted in 2014). The experimental design was completely randomized with four replications of one plant each, in a 16 × 2 bifactorial arrangement (cultivars × year/harvest). Phenology evaluations were performed weekly by counting open (anthesis) and sprouted flower buds, and the fruit set rate was measured just before fruit thinning. Flowering (%), budding (%), and fruit set (%) rates were calculated. It was found that the year/harvest 2016 promoted the highest rates of sprouting and fruit set. The Bonão cultivar showed greater flowering intensity and regularity in the crop years evaluated (2016 and 2017). Coral and Kampai present fruit sets with greater intensities and regularities when compared to the other cultivars evaluated under the climatic condition of the municipality of Dois Vizinhos. The Riograndense cultivar showed greater irregularity in flowering and fruit production.

Deep complex morphophysiological dormancy in seeds of Viburnum plicatum var. formosanum (Adoxaceae) from subtropical mountains

Viburnum is a temperate-zone genus that also occurs in mountains of South America and Malesia, and seeds of many species have morphophysiological dormancy (MPD). Information on the level of MPD in seeds of species in various clades of Viburnum potentially would increase our understanding of the evolutionary relationships between the nine levels of MPD. Our aim was to determine the level of MPD in seeds of Viburnum plicatum var. formosanum that is endemic to mountains (1800–3000 m a.s.l.) in Taiwan and a member of the Lutescentia clade. The temperature requirements for embryo growth and root and shoot emergence and response of seeds to gibberellic acid (GA) were determined. No fresh seeds germinated during 16 weeks of incubation at 15/5, 20/10, 25/15, 30/20 or 25°C. Embryo growth and root emergence occurred during moist cold stratification at 5°C or at a temperature sequence of 15/5 to 5°C. During cold stratification, embryos length increased from 0.76 ± 0.06 to 3.40 ± 0.26 mm and the embryo length:seed length ratio from 0.20 ± 0.02 to 0.68 ± 0.07. In a temperature sequence simulating field conditions, embryos grew inside seeds at 5°C, roots emerged at 15/5°C and shoots emerged at 20/10°C. The optimum temperature for embryo growth was 5°C. Neither GA3 nor GA4 was effective in promoting root emergence. We conclude that seeds of V. plicatum var. formosanum have deep complex MPD, which is a first report for Viburnum. Dormancy release during the cool season at high elevations helps to ensure that seeds germinate at the beginning of the warm season.

Different light and temperature requirements for survival and growth in three species of Kallymeniaceae (Rhodophyta) from the Mediterranean Sea

Laboratory experiments have shown that light and temperature requirements are critical determining factors for thallus survival and growth of three Mediterranean Kallymeniaceae (Rhodophyta): Verlaquea lacerata, Croisettea requienii, and Meredithia microphylla, and explain their current bathymetric and habitat distribution. Verlaquea lacerata is annual and survived more than 1.5 years in culture, while C. requienii and M. microphylla are perennial and survived more than four and nine years in culture, respectively. The maximum survival was observed at 20–50 µmol photon m−2 s−1 and 10 and 12 °C within an 8:16 h light:dark regime for the three species, while a strong decrease in survival was observed at temperatures of 24 and 26 °C, indicating a weak tolerance to warming temperatures in the Mediterranean. The maximum value of the rate of daily marginal extension per initial surface area was similar in the three species: 0.017 day−1 for V. lacerata (10 °C/8:16 h light:dark regime/10 µmol photon m−2 s−1), 0.021 day−1 for C. requienii (18 °C/14:10 h light:dark regime/10 µmol photon m−2 s−1), and 0.017 day−1 for M. microphylla (12 °C/8:16 h light:dark regime/20 µmol photon m−2 s−1). The experiments permitted the establishment of culture conditions for the target species, and the successful culture of marginal fragments indicates the possibility of indefinitely maintaining the species in the laboratory for bioconservation purposes.

Influence of Cooling and Heating Systems on Pen Fouling, Lying Behavior, and Performance of Rearing Piglets

The rearing of piglets is a demanding phase of pig production partly because of the changing temperature requirements of the piglets during rearing. Piglets need high temperatures in the resting area, especially at the beginning, while the optimal temperature is lower toward the end of rearing. To meet the changing temperature demands of the piglets and also to optimize the pen structure, one floor cooling and two heating systems were examined in this study. In two rearing compartments, four pens with 48 piglets each were equipped with a heated cover above a heated/cooled lying area. The lying behavior and performance of 1152 piglets, in addition to the pen fouling, were recorded over six rearing periods. There was no difference between the two heating systems in the lying behavior. However, the acceptance of the lying area was very high in all pens and periods with heating. The cooling had a significant influence on the lying behavior depending on the rearing week. Significantly more piglets lay on the cooled lying area compared with the control pen during the last weeks. The fouling of the pens was not affected by the cooling or heating systems; however, the fouling in all pens was very low. The tested pen structure in combination with a heating and cooling system is a well-functioning way of integrating a solid lying area.

Effect of storage conditions and sodium hypochlorite treatment on germination of Cucumis prophetarum (Cucurbitaceae) seeds from arid Arabian deserts

Background This is the first study on seed germination of Cucumis prophetarum in the Arabian Peninsula. Light and temperature as the main environmental factors and seed storage conditions greatly affect the germination of many Cucurbitaceae species. C. prophetarum is the perennial prostrate with woody rootstocks that grow throughout the year in the arid Arabian deserts. We examined the effects of seed storage conditions and sterilization by sodium hypochlorite (NaOCL) on germination of C. prophetarum seeds. Matured, fresh and field stored seeds were collected in March of 2016 and 2017 from a population in the United Arab Emirates. Fresh and the stored seeds (field, freeze, and room temperature) were germinated at three temperature regimes (15/25, 20/30 and 25/35°C) in both continuous darkness and alternating 12 h light/12 h darkness. Results The fresh and freeze stored seeds had higher germination percentage than the field and room temperature stored seeds. High germination was recorded in both lower and moderate temperatures (15/25 and 20/30°C) in light conditions. Sterilization of the seeds by NaOCl had a negative effect on the speed and germination percentage under all storage conditions, and it changes light and temperature requirements of seeds for germination. Conclusions Germination of C. prophetarum is sensitive to incubation light and temperature as well as to the seed storage conditions. The germination ability of stored seeds indicates that seed storage behaviour of C. prophetarum is orthodox. Light and temperature requirements for seed germination reflects a suitable place, habitat, and time for seedling emergence of C. prophetarum. The effect of NaOCl treatment on the germination may be associated with concentration and exposure periods of seeds. Therefore, we suggest that when using NaOCl for seed sterilization or to stimulate the germination, caution must be taken for using its concentration and exposure time, especially for species with thin and soft seed coats like C. prophetarum. Further studies on seed germination ecology would help to understand better the adaptive strategy of the C. prophetarum in the arid desert environments.

The Di2/pet variant in PETALOSA gene underlies a major heat requirement-related QTL for blooming date in peach (P. persica L. Batsch)

Environmental adaptation of deciduous fruit trees largely depends on their ability to synchronize growth and development with seasonal climate change. Winter dormancy of flower buds is a key process to prevent frost damage and ensure reproductive success. Temperature is a crucial environmental stimulus largely influencing the timing of flowering, only occurring after fulfillment of certain temperature requirements. Nevertheless, genetic variation affecting chilling or heat-dependent dormancy release still remains largely unknown. In this study, a major QTL able to delay blooming date in peach by increasing heat-requirement was finely mapped in three segregating progenies, revealing a strict association with a genetic variant (petDEL) in a PETALOSA gene, previously shown to also affect flower morphology. Analysis of segregating genome-edited tobacco plants provided further evidence of the potential ability of PET-variations to delay flowering time. Potential applications of the petDEL variant for improving phenological traits in peach are discussed.

Experimental Study on Biogas Digester Combined with Solar Heating System

In order to solve the problem of low gas production of biogas digester fermented at natural temperature in winter and possibly freezing biogas digester in northern cold areas, the biogas digester combined with solar heating system is proposed to maintain the normal fermentation temperature of biogas digester and ensure the continuous and efficient gas production of biogas digester throughout the year. Through the experiment and analysis of the system, in cold area, the temperature of biogas digester can be maintained above 12.5 °C, which can meet the temperature requirements of normal fermentation in biogas digester, so it is concluded that developing solar heating biogas digester project is feasible in cold area.