demonstrated that monoecious genotypes could be grown without pollenizers trees. Hence, the field of investigation was extended; detailed observations and investigations were made for specific variation characteristics and blooming data in 2014. Branches of
Qian Bai, Shuchai Su, Zhu Lin, Pingsheng Leng, and Wenhao Wang
Yuto Kitamura, Hisayo Yamane, Akira Yukimori, Hiroyoshi Shimo, Koji Numaguchi, and Ryutaro Tao
Prefecture, where the most popular cultivar, Nanko, usually blooms in the middle of February. However, the timing of the blooming stage varies depending on the year, with differences of up to 1 month. This fluctuation is an important factor affecting the
Xiaojie Zhao, Guihong Bi, Richard L. Harkess, Jac J. Varco, Tongyin Li, and Eugene K. Blythe
), inflorescence stems, rhizomes, and roots. Reblooming or remontant irises (a subclass of I. germanica ) are capable of blooming more than once per growing season. Use of reblooming iris for cut flower production has the potential to make TB iris cut flowers
I. Citadin, M.C.B. Raseira, F.G. Herter, and J. Baptista da Silva
Differences in heat requirements for blooming and leafing were investigated in peach [Prunus persica (L.) Batsch] using artificially chilled excised shoots and potted trees. `Della Nona' and `BR-1' have high heat requirements; `Planalto', `Sunlite', and `Eldorado' are intermediate; and `Precocinho' and `Riograndense' have low heat requirements. Prolonged chilling enhanced leafing more than blooming. Flower and vegetative buds have different heat requirements during ecodormancy.
Craig E. Kallsen and Dan E. Parfitt
full bloom flowering dates for male and female cultivars are shown for 5 years in Table 1 . ‘Tejon’ flowering dates were coincident with the early blooming female ‘Gumdrop’ ( Kallsen and Parfitt, 2017a ) in 2016–18. During the low chill years of 2014
Warner Orozco-Obando* and Hazel Y. Wetzstein
Recently, the release of Hydrangea cultivars with the capacity to produce a second flush of blooms has created a great expectation in the ornamental industry. However, the lack of fundamental information on flower development of big leaf Hydrangea does not allow a descriptive explanation of why re-blooming capacity occurs. The objectives of this study were to characterize the timing and location of flower initiation and development in several H. macrophylla cultivars throughout an annual cycle. Four cultivars were evaluated: 2 exhibiting re-flowering capacity (Penny Mac-PM and Endless Summer-ES) and 2 without (Madame Emile Mouillere-MEM and Nikko Blue-NB). Plants were managed under outdoor nursery conditions and harvested at each of four different time periods. These periods represented key developmental stages: 1) Pre-induction: late summer, after completion of shoot expansion; 2) Post-induction: late fall, following short day and cold temperature exposure; 3) Dormancy: winter, post leaf abscission; and 4) Post-dormancy: early spring, just prior to bud break. At each sampling time, bud location (terminal or lateral) and stem origin (basal, lateral, terminal, or secondary) were established. All buds >;2 mm were dissected under a stereomicroscope and the degree of floral induction was determined. Floral primordial were initiated not only in the terminal buds but also within axillary buds. The degree of induction and development varied according to the stem origin, bud location and cultivar. Cultivars with re-blooming capacity had floral primordial initiated within buds at the first sampling period prior to receiving inductive conditions. This suggests they may have minimal or no photoperiodic/temp requirements for flowering.
I-Ling Lai, Chih-Wan Lin, Tsai-Yu Chen, and Wei-Hsin Hu
Begonia montaniformis × Begonia ningmingensis var. bella hybrids have high ornamental potential. Hence, the aim of this study was to determine the optimal conditions for the micropropagation of a Begonia montaniformis × Begonia ningmingensis var. bella F1 progeny by using various concentrations of plant growth regulators (PGRs) and varying light spectra in half-strength Murashige and Skoog (1/2 MS) medium. The results showed that the explant regeneration was optimal when the lamina was incubated in a medium supplemented with 2.0 μM N6-benzylaminopurine and 0.8 μM α-naphthaleneacetic acid (NAA). Under such conditions, 98% of the explants regenerated adventitious shoots after 8 weeks, and 41 buds were produced per explant on average. The mean shoot length was 9.6 mm, and on average, 4.5 shoots per explant were more than 2 mm long. Subsequently, the induced adventitious shoots were transferred into rooting medium consisting of 1/2 MS and various NAA concentrations. After 4 weeks, the shoots subcultured in this medium showed ≈93% root induction and an average of 3.5 adventitious roots per explant. Furthermore, the applied light spectrum significantly influenced shoot regeneration, and optimal results were achieved under an equal distribution of blue, red, and infrared light. The histological sections of shoots regenerated from direct organogenesis were observed through scanning electron microscopy (SEM). Afterward, the rooting adventitious shoots were subcultured in PGR-free medium for 8 weeks. The seedlings were successfully acclimated 4 weeks after being transferred to soil and bloomed after 11 months in a greenhouse. Thus, the PGR composition in micropropagation efficiently shortened the time to blooming from 25 to 16 months.
Ken W. Leonhardt
Ignasi Iglesias, Pere Vilardell, Joan Bonany, Elisabet Claveria, and Ramon Dolcet-Sanjuan
A new spontaneous mutation of the pear variety Dr. Jules Guyot, named `IGE 2002', was selected from a pear growing area in Catalonia. The clone was established in vitro from a 40-year-old tree, a highly recalcitrant material unable to root by cuttings. An in vitro micropropagation protocol, with an average multiplication rate of 5, a 90% rooting, and an acclimation of 79% of the plantlets, was defined. Self-rooted plants were grown in two experimental stations, covering two distinct fruit growing areas. The main agronomic characteristics of the clone `IGE 2002' were evaluated during six seasons, 1997 to 2002. Blooming and harvest period were at a similar time than `Dr. Jules Guyot'. Soluble solids concentration and acidity are also similar to `Dr. Jules Guyot'. However, at the same harvest time, a lower fruit firmness of `IGE 2002' in comparison to `Dr. Jules Guyot' indicated an advanced ripening. In addition, a finer flesh texture of `IGE 2002' than `Dr. Jules Guyot', distinguished the former from the later variety. Important differences between both plot sites were found on cumulative fruit yield, fruit size, and fruit size distribution, of `IGE2002' grown on its own roots. However, the site did not affect the fruit quality parameters. Superior fruit yields were associated with higher vigor and yield efficiency of the self-rooted variety.
J.M. Alonso, J.M. Ansón, M.T. Espiau, and R. Socias i Company
Almond (Prunus amygdalus Batsch.) blooming date is determined by the temperatures during the dormancy period, from the onset of endodormancy to just before blooming. In this work we have developed a model, based on several years data, to estimate the mean transition date from endodormancy to ecodormancy in 44 almond cultivars covering the whole range of almond bloom, through the significance of correlation coefficients between the temperatures occurring during dormancy and the date of full bloom. The estimation of this date for each cultivar has allowed the calculation of its chill and heat requirements. It was found that most cultivars have chilling requirements between 400 and 600 chill units, whereas the span of heat requirements was wider, from 5500 to 9300 growing degree hours Celsius. Some cultivars show high chilling requirements and low heat requirements whereas others show opposite requirements. These differences confirm the wide almond adaptability to different climatic conditions and offer the possibility of being utilized in breeding programs. The good fit shown by the application of this model in the prediction of bloom time may sustain its application in chilling and heat requirement estimation in other fruit species if blooming dates and climatic data for several years are available.