temperature regimes representing potential seeding dates in Lexington, KY. Materials and methods Germination studies were conducted in the Turfgrass Science Laboratory on the University of Kentucky campus in 2011. Nineteen commercially available cultivars were
Michael T. Deaton and David W. Williams
Martin Makgose Maboko, Isa Bertling and Christian Phillipus Du Plooy
cultivation medium. The recent more common occurrence of unfavorable weather conditions such as large rainfall and temperature fluctuations have resulted in the search for other means to optimize yield and quality of tomatoes. Amongst these is the use of
Arnon Dag, Smadar Boim, Yulya Sobotin and Isaac Zipori
important to balance the rates of harvest with those of oil extraction in the mill. The objective of the current work was to evaluate the effect of storage temperatures and duration on extracted oil quality from commercial, mechanically harvested orchards
Luisa Dalla Costa, Nicola Tomasi, Stefano Gottardi, Francesco Iacuzzo, Giovanni Cortella, Lara Manzocco, Roberto Pinton, Tanja Mimmo and Stefano Cesco
It is well known that soil temperature changes have a significant impact on the growth and development of plants both in agricultural and native ecosystems ( Bonan, 1992 ). During plant growth, optimum temperature is required below- and aboveground
Charles F. Forney
cranberry fruit are not clearly defined. In various handbooks published in the past 20 years, recommended storage temperatures range from 2 to 7 °C ( Hardenburg et al., 1986 ; Kader, 1997 ; Kasmire and Thompson, 1992 ; Lidster et al., 1988 ; Prange, 2004
Chikako Honda, Hideo Bessho, Mari Murai, Hiroshi Iwanami, Shigeki Moriya, Kazuyuki Abe, Masato Wada, Yuki Moriya-Tanaka, Hiroko Hayama and Miho Tatsuki
a , 2012 ; Iglesias and Echeverría, 2009 ). Anthocyanin synthesis in the fruit skin of red cultivars is affected by external biotic and abiotic factors, including nutrients, water stress, wounding, light, and temperature ( Ubi, 2004 ). The effect
Douglas A. Hopper, P. Allen Hammer and James R. Wilson
This paper details the development and verification of ROSESIM, a computer simulation model of the growth of `Royalty' roses (Rosa hybrida L.) based on experimentally observed growth responses from pinch until flowering under 15 combinations of constant photosynthetic photon flux (PPF), day temperature (DT), and night temperature (NT). Selected according to a rotatable central composite design, these treatment combinations represent commercial greenhouse conditions during the winter and spring in the midwestern United States; each selected condition was maintained in an environmental growth chamber having 12-hour photoperiods. ROSESIM incorporates regression models of four flower development characteristics (days from pinch to visible bud, first color, sepal reflex, and flowering) that are full quadratic polynomials in PPF, DT, and NT. ROSESIM also incorporates mathematical models of nine plant growth characteristics (stem length and the following fresh and dry weights: stem, leaf, flower, and total) based on data recorded every 10 days and at flowering. At each design point, a cubic regression in time (days from pinch) estimated the plant growth characteristics on intermediate days; then difference equations were developed to predict the resulting daily growth increments as third-degree polynomial functions of days from pinch, PPF, DT, and NT. ROSESIM was verified by plotting against time each simulated plant growth characteristic and the associated experimental observations for the eight factorial design points defining the region of interest. Moreover, one-way analysis of variance procedures were applied to the differences between ROSESIM predictions and the corresponding observed means for all 15 treatment combinations. At 20 days from pinch, significant differences (P < 0.05) were observed for all nine plant growth characteristics. At 30 and 40 days from pinch, only flower fresh and dry weights yielded significant differences; at flowering, none of the 13 selected responses yielded significant differences. These graphical and statistical comparisons provide good evidence of ROSESIM's ability to predict the growth response of `Royalty' roses over a wide range of constant environmental conditions.
Fisun G. Çelikel and Michael S. Reid
The respiration of cut flowers of gerbera (Gerbera jamesonii H. Bolus ex Hook.f. `Vesuvio') and sunflower (Helianthus annuus L.) increased exponentially with increasing storage temperature. Poststorage vase life and negatively gravitropic bending of the neck of the flowers were both strongly affected by simulated transport at higher temperatures. Vase life and stem bending after dry storage showed highly significant linear relationships (negative and positive, respectively) with the rate of respiration during storage. The data indicate the importance of maintaining temperatures close to the freezing point during commercial handling and transport of these important commercial cut-flower crops for maximum vase life.
P. Lootens and J. Heursel
The short-term effects of photosynthetic photon flux (PPF), day/night temperatures and CO2 concentration on CO2 exchange were determined for two Phalaenopsis hybrids. At 20 °C, the saturating PPF for photosynthesis was 180 μmol·m-2s-1. At this PPF and ambient CO2 level (380 μL·L-1), a day/night temperature of 20/15 °C resulted in the largest daily CO2 uptake. Higher night temperatures probably increased the respiration rate and lowered daily CO2 uptake in comparison with 20/15 °C. An increase in the CO2 concentration from 380 to 950 μL·L-1 increased daily CO2 uptake by 82%.
Md. Shahidul Islam, M. Jalaluddin, James O. Garner, M. Yoshimoto and O. Yamakawa
Sweetpotato leaves contain biologically active anthocyanins that have significant medicinal value for certain human diseases and may also be used as natural food colorants. Foliar anthocyanins and their relative abundance were investigated in leaves of sweetpotato cultivars `Shimon-1', `Kyushu-119', and `Elegant Summer' grown under artificial shading and different temperature conditions. High-performance liquid chromatography profiles of the cultivars tested showed similar peaks but with peak areas differing with cultivar, temperature and shading. The relative quantity of individual anthocyanin was YGM (Yamagawamurashaki)-1a> YGM-4b> YGM-1b> YGM-5a> YGM-0d> YGM-0a> YGM-2> YGM-0c> YGM-3> YGM-6> YGM-5b> YGM-0b> YGM-0f> YGM-0e> YGM-0g. Seven were peonidin and eight cyanidin derivatives. The highest anthocyanin contents were found in plants grown at a moderate temperature (20 °C) with lower levels at 25 and 30 °C. The leaves of plants grown in full sun accumulated significantly more total as well as the major individual anthocyanins than plants grown in 40% and 80% shade. The results indicate that growing sweetpotatoes at moderate temperatures and without shading facilitates the accumulation of anthocyanins in the leaves. The anthocyanin composition of the leaves is discussed relative to their physiological function in human health.