Influence of fitohormones in the nutrient medium on the proliferation at the microplants of blue honeysuckle cultivars (Lonicera caerulea L. var. kamtschatica)

The proliferation activity of blue honeysuckle microplants of cultivars ‘Krupnoplodnaya’, ‘Goluboye vereteno’, ‘Pavlovskaya’, ‘Volkhova’ at micropropagation stage is determined by hormonal composition of nutrient medium and genotype. An increase in concentration of 6-BA in MS medium from 0.2 to 1.5–2.0 mg/l leads to an increase in micropropagation rate from 1.91 to 3.26–3.57. The maximum micropropagation rate for cultivars ‘Krupnoplodnaya’ (3.43–3.47) and ‘Goluboye vereteno’ (4.11–4.23) was given at MS medium with addition of 1.5 and 2.0 mg/l 6-BA, for cultivars ‘Pavlovskaya’ and ‘Volkhova’ (2.80 and 3.90 respectively) – at medium with addition of 1.5 mg/l 6-BA. It is possible to increase micropropagation rate due to the joint use of two growth regulators: 6-BA (1.5–2 mg/l) and GA3 (1.0 mg/l). The use of gibberellic acid leads to formation of axillary branch, intensification of growth by increasing the length of internodes of shoots, which makes it possible to further divide long microshoots into microcuttings with two to three nodes.It was found that use of TDZ actively stimulates proliferation of blue honeysuckle shoots and allows to obtain a high micropropagation rate (up to 12) at lower concentrations (0.3–0.6 mg/l) than use of 6-BA in high concentration – 1.5 and 2.0 mg/l (micropropagation rate was 2.80–4.23 depending on cultivar). However, TDZ inhibits growth of microshoots in length, forming a conglomerate, which is an accumulation of small shoots that are not suitable for rhyzogenesis stage, and therefore their subsequent elongation on a hormone-free medium is necessary. The use of TDZ in two consecutive subcultures for cultivating of blue honeysuckle is not desirable, as it leads even more to formation of small shoots.

Effect of Cooling of Medium on Fruit Set in High-bench Strawberry Culture

We demonstrated the effect of cooling of the medium on the fruit set of strawberries (Fragaria × ananassa Duch.) grown on high benches for forcing culture. The cooling by water evaporation promoted by a fan enabled to cool the medium by an average of several degrees compared with no cooling. When runner plants were transplanted in late summer, cooling accelerated flower bud emergence almost 10 days on the primary axillary branch compared with plants grown in uncooled medium. Also, with cooling, fruit was harvested from the inflorescence of the primary axillary branch almost 10 days earlier. We expect that this technique will allow early transplanting around the end of summer and will shorten the time between fruit set on the terminal inflorescence and that on the inflorescence of the primary axillary branch.

Morphological and anatomical development in the Vitaceae. VIII. Comparative development of three Cyphostemma (Vitaceae) species reveals important vegetative and reproductive differences among the species

Vegetative and floral development of Cyphostemma simulans (C.A. Small) Wild & Drummond, Cyphostemma juttae (Dinter & Gilg) Descoings, and Cyphostemma mappia (Lam) Galet were compared using epi-illumination light microscopy and paraffin sectioning. Cyphostemma simulans is a liana with leaf-opposed tendrils and inflorescences, which both arise from the shoot apical meristem, whereas the other two species are shrubs that lack tendrils and their main shoot terminates in an inflorescence. A shoot apical meristem of C. simulans can be overtopped by an inflorescence, making the architecture appear to develop like a sympodium, which is the architecture shared by the other two species. On the other hand, a terminal inflorescence of C. juttae or C. mappia can be placed in a leaf-opposed position by a precocious axillary branch, making the architecture appear to develop like a monopodium, which is the typical architecture of the Vitaceae. The floral development of all three species is similar in early ontogeny, except for a difference in calyx development between C. mappia and the other two species. Later developmental differences of the septum and gynoecium, in addition to flower colour and phenology, are distinct characteristics that distinguish flowers of each species. Therefore, this study is the first to demonstrate differences in the floral characteristics of Cyphostemma. In addition, it shows how each architecture type (monopodium or sympodium) can resemble the other and so provides stronger evidence about how the unique architecture of the Vitaceae has originated.

THE EFFECT OF PHOTOPERIOD ON AXILLARY BRANCH DEVELOPMENT AND FLOWER PRODUCTION OF A NEW GUINEA Impatiens HYBRID

The influence of photoperiod and temperature on the production of flowers by a New Guinea hybrid Impatiens, cv. Starburst, was investigated. Delayed flowering below 20 °C was due only to effects on flower bud development. Although flower initiation was day-neutral, the number of flowers produced was significantly influenced by photoperiodic control of axillary branch elongation. In 8-, 14- or 16-h photoperiods axillary branches on the lower nodes remained compact but in a 12-h photoperiod the axillary branches elongated, and flower production on these axillary branches was enhanced. Night-break (NB) treatments indicated that this was a photoperiodic effect. This photoperiodic control of plant growth habit provides a means of regulating the rate of flowering of this cultivar.Key words: Impatiens, photoperiod, flowering, apical dominance

Analyse du système ramifié de Phaseolus vulgaris: particularités du gradient morphologique gemmaire

An analysis of the branching pattern in a dwarf so-called determinate variety of Phaseolus vulgaris L. has been attempted. A distinctive organogenetic gradient displayed by the axillary buds is described. The number of leafy nodes on the first-order axillary branch, before its termination by a double raceme, decreases as its level of insertion on the main stem increases. This modification in the axillary organogenesis culminates in the appearance of the simple axillary raceme, apparently coinciding with the bracteal transformation at the next axil on main stem. However, not all the stages in the reduction of axillary structures were observed. These facts are discussed in relation to the concepts of comparative isomorphic development of main stems and first-order axes, and certain correlations regulating cauline morphogenesis.

Temperature Effects on Growth and Leaf Production in Three Weed Species

Sicklepod (Cassia obtusifoliaL. ♯6CASOB), hemp sesbania [Sesbania exaltata(Raf.) Cory ♯ SEBEX], and showy crotalaria (Crotalaria spectabilisRoth. ♯ CVTSP) were grown in controlled-environment greenhouses with day/night temperatures of 23/17, 26/20, 29/23, and 32/26 C. Plant height, leaf area, and total dry weight at 53 days after planting increased significantly with temperatures between 23/17 and 29/23 C in sicklepod and showy crotalaria, and between 23/17 and 32/26 C in hemp sesbania. In all species, leaves were produced more rapidly as temperature increased. Axillary branch leaf production was greatest at 29/23 C in sicklepod, and at 29/23 and 26/20 C in showy crotalaria; hemp sesbania showed little axillary branch development. Total dry-matter production in all species was closely correlated with leaf area duration, but not with net assimilation rate. Differences in total main stem leaf area in all species were primarily due to differences in leaf number rather than to differences in leaf size at maturity.