Short communication. Effective pollination period in ?RedChief? and ?Golden Delicious? apples (Malus domestica Borkh)

Due to the significant variation in the initial fruit set of apples among seasons and producing regions of Chihuahua, Mexico, it is important to determine the cause(s). Apple fruit yield is strongly determined by the initial fruit set, which is the result of a series of physiological events, such as pollination, pollen tube growth, ovule longevity and fertilisation. During one or two seasons, in the two main apple-producing regions in the state of Chihuahua, México, the effective pollination period (EPP) was evaluated in �Golden Delicious�, �RedChief Delicious� and �Golden Delicious Tardío,� a regional mutant of Golden Delicious. Daily manual pollinations after the full pink stage were made with �Snow Drift� pollen to determine the EPP. The initial fruit set at 30 days after the last day of hand pollination was evaluated. A daily sampling of flowers was used to measure the pollen tube growth (average growth of 11.70 mm at 96 h) in the pistil and ovule viability in the ovary. The EPP lasted 6 days for RedChief Delicious, 4 days for Golden Delicious, and 10 days for Golden Delicious Tardío. The average ovule longevity of 63% seemed to be a limiting factor for Golden Delicious, leading to a reduced initial fruit set.En el estado de Chihuahua, México, existe una gran variación en el amarre inicial del fruto de manzana entre los diferentes ciclos y regiones productoras, por lo que es importante establecer alguna(s) causa o causas de ello. La producción en el manzano está determinada fuertemente por el amarre inicial de frutos, y éste es el resultado de una serie de eventos fisiológicos como polinización, crecimiento del tubo polínico, longevidad del óvulo y fecundación. Durante uno o dos ciclos, el periodo de polinización efectiva (EPP) se evaluó en �Golden Delicious�, �RedChief Delicious� y �Golden Delicious Tardío�, un mutante regional de Golden Delicious, en las regiones de mayor producción de manzana en el Estado de Chihuahua, México. Para determinar el EPP, se llevaron a cabo polinizaciones manuales diarias, después del estadio de rosa completo, con polen de Snow Drift. Se evaluó el amarre inicial de frutos a los 30 días después del último día de polinización manual. Se tomaron muestras diarias de flores para determinar el crecimiento del tubo polínico (crecimiento promedio de 11,70 mm a las 96 h) en el pistilo y la viabilidad de los óvulos en el ovario. El EPP observado fue de 6 días para �RedChief Delicious�, 4 días en �Golden Delicious� y 10 días en �Golden Delicious Tardío�. La viabilidad del óvulo, un promedio de 63%, pudo ser un factor limitante para �Golden Delicious�, el cual redujo el amarre inicial de fruto

Comunicación corta. Periodo de polinización efectiva en manzano (Malus domestica Borkh) "Red" y "Golden Delicious"

Due to the significant variation in the initial fruit set of apples among seasons and producing regions of Chihuahua, Mexico, it is important to determine the cause(s). Apple fruit yield is strongly determined by the initial fruit set, which is the result of a series of physiological events, such as pollination, pollen tube growth, ovule longevity and fertilisation. During one or two seasons, in the two main apple-producing regions in the state of Chihuahua, México, the effective pollination period (EPP) was evaluated in "Golden Delicious", "RedChief Delicious" and "Golden Delicious Tardío", a regional mutant of Golden Delicious. Daily manual pollinations after the full pink stage were made with "Snow Drift" pollen to determine the EPP. The initial fruit set at 30 days after the last day of hand pollination was evaluated. A daily sampling of flowers was used to measure the pollen tube growth (average growth of 11.70 mm at 96 h) in the pistil and ovule viability in the ovary. The EPP lasted 6 days for RedChief Delicious, 4 days for Golden Delicious, and 10 days for Golden Delicious Tardío. The average ovule longevity of 63% seemed to be a limiting factor for Golden Delicious, leading to a reduced initial fruit set.En el estado de Chihuahua, México, existe una gran variación en el amarre inicial del fruto de manzana entre los diferentes ciclos y regiones productoras, por lo que es importante establecer alguna(s) causa o causas de ello. La producción en el manzano está determinada fuertemente por el amarre inicial de frutos, y éste es el resultado de una serie de eventos fisiológicos como polinización, crecimiento del tubo polínico, longevidad del óvulo y fecundación. Durante uno o dos ciclos, el periodo de polinización efectiva (EPP) se evaluó en "Golden Delicious", "RedChief Delicious" y "Golden Delicious Tardío", un mutante regional de Golden Delicious, en las regiones de mayor producción de manzana en el Estado de Chihuahua, México. Para determinar el EPP, se llevaron a cabo polinizaciones manuales diarias, después del estadio de rosa completo, con polen de Snow Drift. Se evaluó el amarre inicial de frutos a los 30 días después del último día de polinización manual. Se tomaron muestras diarias de flores para determinar el crecimiento del tubo polínico (crecimiento promedio de 11,70 mm a las 96 h) en el pistilo y la viabilidad de los óvulos en el ovario. El EPP observado fue de 6 días para "RedChief Delicious", 4 días en "Golden Delicious" y 10 días en "Golden Delicious Tardío". La viabilidad del óvulo, un promedio de 63%, pudo ser un factor limitante para "Golden Delicious", el cual redujo el amarre inicial de fruto

Evolution in the photosynthetic oxygen rate of a Cd-resistant strain of Dictyosphaerium chlorelloides by changes in light intensity and temperature

Environmental factors such as temperature and light are the most determinants in the photosynthetic productivity in microalgae. However, under extreme of these conditions, certain resistant microalgae strains possess additional abilities such as growth in the presence of high concentrations of metals and some can improve in combinations of more than one abiotic stress. Therefore, the aim of this research was to evaluate the efficiency in photosynthetic production through the oxygen balance to variations in photon intensity, and under temperature changes in a Cd-resistant strain (DcRCd100) compared to the wild-type strain (Dc1Mwt) of Dictyosphaerium chlorelloides. The results showed that the DcRCd100 strain has the maximum efficiency at 200  μmol m−2 s−1 on photosynthesis net (Pn) (96.32 ± 3.63% nmol O2 ml−1 min−1) as the threshold light saturation, and an adaptation to maintain this maximum photosynthetic gross (Pg) rate at 30 °C (94.99 ± 10.03% nmol O2 ml−1 min−1) due to possible modifications in the photosynthetic apparatus that is reflected in the net evolution rate of O2 to deal with such evaluated conditions. While, Dc1Mwt strain its maximum photosynthetic efficiency was at 300 μmol m−2 s−1 and 21 °C (97.72 ± 2.99 and 99.85 ± 0.30%nmol O2 ml−1 min−1, respectively) and in optimal response to the oxygen balance that is normally achieved by this mesophilic genus. These results provide a new prediction of mechanisms in the oxygen evolution in photosynthesis that rules the correlation between resistance and adaptation to extreme abiotic conditions in metal resistant strains of eukaryotic microalgae.Mexican National Council for Science and TechnologyMexican University the BeneméritaUniversidad Complutense de MadridCentenaria Universidad Michoacana de San Nicolás de Hidalgo (México)Sección Deptal. de Farmacología y Toxicología (Veterinaria)Fac. de VeterinariaTRUEpu