Floral initiation

Sugarcane Sower initiation is dependent on day length, temperature, age, moisture, and variety, and can be prevented by chemical applications at, or very close to, the date of floral initiation. The effective chemicals have been of two types (a) photosynthetic inhibitors, such as 3-(p-chlorophenyl)-1,1-dimethylurea (monuron), or (b) leaf-burning, contact chemicals. The very effective bipyridylium herbicides 6,7-dihydrodipyrido[l,2-a 2, r-c]pyrazidinium dibromide (diquat) and 1, l -dimethyl-4,4 -bipyridinium bis (methyl sulfate) (paraquat) combine the two properties, although the... 

Within less than two decades after the discovery of photoperiodism in 1920, the hypothesis developed that one or more specific flowering hormones are responsible for floral initiation (23,36-39). 

Stages of maturity 1 = floral initiation 2 = nearly full flowering, 3 = full flowering, primary umbel young green fruit, 4 = past full (lowering 50% (lower. 50% fiuit,... 

Depending on form, species, and climate, the plant may remain in the rosette stage for as short a period as 30 or as long as 210 days. However, once the day length and temperature trigger floral initiation, the plant bolts rapidly. The development stages of the summer turnip rape have been documented by Harper and Berkenkamp (1975) (Fig. 2). Summer rape follows a similar pattern (Fig. 3). 

Tucker, S. C. (1987). Floral initiation and development in legumes, pp. 183-293 in Stirton, C. H. (ed.). Advances in Legume Systematics. Kew Royal Botanic Gardens, Kew. 

Fig. 10. Individual monoterpenes from the midstem leaves of peppermint as a function of growth. (A) Floral initiation (B) flowers open (C) full bloom (D) end of bloom (from Burbott and Loomis, 1969).

Under non-inductive conditions, the GAs in question should be limiting in the apex. Conversely, experimental reduction of endogenous GA levels should inhibit or prevent floral initiation under inductive conditions. 

Heide, O. M., Sonsteby, A. Floral initiation in black currant cultivars (Ribes nigrum L.) Effects of plant size, photoperiod, temperature, and duration of short day exposure. Scientia Horticulturae 138, 1, 2012. 

Floral initiation is best studied at the microscopic level. The fact is, floral initiation often occurs and is unrecorded because abortion takes place or there is failure of the flower initials to develop to the macroscopic level where detection is easy with the unaided eye. There are many pieces of evidence that this is true. One was provided by Naylor (1941) with the photoperiodically sensitive cocklebur plant (Xanthium pennsylvanicum). He found that even when the plants were severely deficient in nitrogen or phosphorus or potassium they differentiated floral primordia after the leaves received an appropriate photoperiodic treatment. However, floral development did not occur. If dissection of stem apices had not been carried out, floral initiation would have gone undetected and the plants would have been recorded as vegetative. 

Regardless of how one views the phenomenon of floral initiation, it is clear that when a plant changes from the vegetative to the reproductive phase many... 

DEVELOPMENTAL REGULATION OF STEROL AND PENTACYCLIC TRITERPENE BIOSYNTHESIS AND COMPOSITION A CORRELATION WITH SORGHUM FLORAL INITIATION... 

Moench in various stages of development. Evidence for the developmental regulation of the amounts and biosynthesis of these polycyclic isopentenoids and its correlation with floral initiation have been obtained in this and our previous studies.Sterol and FT composition of individual fully mature leaf blades was determined at various stages in the life cycle of S. bicolor (L.) Moench cv. G499 GBR (Figure 1). 

Since the level of cholesterol was highest in the vegetative apices before their transition to flowering (Table 1), and cholesterol levels actually decreased during floral differentiation, it is also possible that cholesterol is in some way associated with the process of floral initiation. For instance, there is some evidence in the literature that the flower-inducing hormone may be an isopentenoid or steroid-like compound Various steroids occur in plants, and cholesterol has been shown to be a key intermediate in their biosynthesis Ojll. Thus, it is possible that cholesterol was being used to make steroids, which may be involved in floral induction. 

SPDS activity is inhibited by a competitive inhibitor cyclohexylamine (CHA). In early studies on plant polyamines, treatments of thin-layered tissue cultures of tobacco with CHA have been shown to inhibit floral initiation but to be reversed by spermidine application (Kaur-Sawhney et al. 1988). On the other hand, CHA treatment results in a drastic increase in the level of purescine but has little or no effect on the level of spermidine and spermine in other plant systems such as the vegetative organs of Arabidopsis (Stes et al. 2011) and germinating pollen of kiwifruit (Scoccianti et al. 2013). 

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