Báo cáo lâm nghiệp: from the simple application of a mixture of to more gibberellins integrated explanations

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Promotion of flowering in conifers: from the simple application of a mixture of to more gibberellins integrated explanations...
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Báo cáo lâm nghiệp: " from the simple application of a mixture of to more gibberellins integrated explanations"Promotion of flowering in conifers:from the simple application of a mixture of gibberellins integrated explanationsto moreM. Bonnet-MasimbertINRA Station dAm6lioration des Arbres Forestiers, Ardon, 45i60 Olivet, FranceIntroduction factors interact extensively. In fact, in order to get a more reliable response, the hormonal treatment of conifers has gen-Flowering induction in trees is still an erally been associated with different kindsimportant problem for both the supply of of cultural treatments. Thus, in the field, itseed and breeding programs, which have is generally possible to enhance the natu-to face the long juvenile phase and irregu- ral flowering cycle of a tree in good yearslar flowering so common in most forest or in good flowering clones but it is still dif-trees. Many recent reviews indicate clearly ficult in off years or with recalcitrantthat induction of flowering is now possible clones. In greenhouses, it is possible toin many conifers in a more or less juvenile have a better control of some of the envi-stage (Owens and Blake, 1985; Pharis ronmental factors and to obtain moreand Ross, 1986; Pharis et al., 1987; Bon- reproducible results. This is one reasonnet-Masimbert, 1987; Bonnet-Masimbert why containerized indoor orchards areand Zaerr, 1987). In most cases, the treat- now proposed as a favorable alternative toments are based on the use of gibberellins conventional soil-based orchards (Ross(GAs), especially the mixture of GA4 and et al., 1985).GA7, which were demonstrated to be theactive gibberellins for Pinaceae species The details of the various applied treat-(Pharis, 1975). ments will not be discussed in this review. However, the problem of stimulation and They are amply documented in the pre- of flowering in forest seed viously quoted reviews. Owens and Blakeregulationorchards is still far from a general solution. (1985) presented a general review of all the reproductive processes from floral ini-These difficulties are due to the fact that, tiation to seed development. Pharis et al.,in opposition to photoperiodic or thermo- (1987) paid special attention to the effectperiodic herbaceous plants, the floweringof woody perennial species involves of exogenous applications of GAs and cul- tural treatments on variations in endo-undoubtedly a multifactorial regulation genous GAs. They discussed the specificwhere environmental and physiological no low polarity GAs after rootand not pharmacological action of less revealed whereas they were found up to 6polar GAs on flowering. Also, the relation- flooding, weeks after one stem injection of GA4/7ship between flowering and shoot growthor bud vigor was discussed. Ross and (Pilate, 1987). Both treatments produced the same floral response, which mightPharis (1987) presented recent concepts mean that compounds other than GAs areof sex expression in conifers. Other plant also able to stimulate flowering or thatgrowth regulators (PGRs) were consid- flooding produced a deferred induction,ered by Bonnet-Masimbert and Zaerr possibly by retarding the differentiation of(1987). Practical treatments (i.e., tech- ...