Flowers development

While low irradiance levels often limit the number of flowers developed, duration of the light period perhaps more frequently dominates in the floral development phase. In any event, an unsuitable carbohydrate nitrogen balance under either long or short photoperiods can limit the number of flowers that reach the pollination stage of development. 

El Hinnawy (1956) has reviewed the relation of macronutrient nutrition to flower initiation. He concluded that variations in macronutrient levels may greatly influence the time of appearance of floral buds, the rate of subsequent floral development, the number of flowers produced and the stamen—pistil ratios but there was no alteration in initiation of floral primordia in photoper-iodically sensitive plants. 

There is now strong evidence that iron is very important in floral development in Xanthium (Smith etal. 1957). When Fe was supplied iron deficient plants after six photoinductive cycles, normal staminate inflorescence development occurred but the pistillate inflorescences were abnormal and reduced in number. If Fe was not added to the — Fe plants following photoinduction, many of them died. It is not possible at this time to say if Fe is directly or indirectly involved. Most probably, however, the effects are indirect and reflective of the importance of Fe in cytochromes, ferredoxin, nitrate reductase, and sulfite reductase as well as several other enzymes that are essential in cellular function. 

The pistil is the last of the floral structures to be differentiated during flower formation. In some dioecious species, such as Lychnis dioica, pistil initiation is linked to the presence of a sex chromosome (Westergaard 1958). In many species, however, sexual expression is more subject to modification by environmental factors acting on metabolic processes. This aspect has been studied frequently in monoecious members of the Cucurbitaceae. In these species, as in other monoecious types, light and temperature are particularly potent factors influencing the production of stamens and/or pistils. 

How do photoperiod and temperature bring about their effects on sex expression A definite answer is not known. Since it is known, however, that ethylene treatment stimulates the development of pistillate flowers in cucumbers (Minina and Tylkina 1947, Sims and Gledhill 1969, Rudich et al. 1969), it is hypothesized that under short photoperiod and chilling temperature conditions metabolism of methionine is tipped toward ethylene generation. It is now feasible to test this hypothesis and it should be tested. 

The diameter of the head of the inflorescence ranges from 1.3 to 1.8 cm (six clones) and the mean number of seed per plant from 0.45 to 163 (Swanton, 1986). In wild clones, 9% of the biomass by the end of the season had been allocated to the flowers and fruit (Westley, 1993). If sexual reproduction was blocked, there was a substantial increase in biomass allocated to asexual means of reproduction in the form of more and larger tubers. Flowers in the late fall (November 1, Ontario, Canada) contained 2.46% N, 0.51% P, 2.02% K, 1.21% Ca2+, and 0.68% Mg2+ (Swanton and Cavers, 1989). 

Biology and Chemistry of Jerusalem Artichoke Helianthus tuberosus L. 

---

When mitosis is blocked by colchicine, the treated cells may be left with an extra set of chromosomes. Plants with extra sets of chromosomes are typically larger and more vigorous than normal plants. Flowers developed in this way may grow with double the normal number of petals, and fruits may produce much larger amounts of sugar. 

Clark SE, Running MP, Meyerowitz EM 1993 CLA VAT A 1, a regulator of meristem and flower development in Arabidopsis. Development 119 397-418 Clark SE, Running MP, Meyerowitz EM 1995 CLA VA TA 3 is a specific regulator of shoot and floral meristem development affecting the same processes as CLA VATA 1. Development 121 2057—2067... 

There is accumulating evidence for cooperation of the CSN and cullin-based complexes in specific developmental processes [96]. First insight has been provided by studies on auxin response where the CSN interacts with SCF , modulating its activity [55]. Similarly, binding of the CSN to other cullin-based complexes regulates their activity in mediating various developmental processes such as flower development, and plant defense responses [97, 98]. 

X. W., Wei, N. The COP9 signalosome interacts with SCF UFO and participates in Arabidopsis flower development. Plant Cell 2003, 35, 1071-1082. 

Craker, L. E. Decline and recovery of petunia flower development from ozone stress. HortScience 7 484, 1972. 

Stitch K, Eidenberger T, Wurst F, Forkmann G (1992) Flavonol synthase activity and the regulation of flavonol and anthocyanin biosynthesis during flower development in Dianthus caryophyllus. Z Naturforsch 47C 553-560... 

Only a general indication of phenotype is given, and the full changes identified may include production of anthocyanin earlier in flower development than normal, increased anthocyanin production only under stress conditions, small increases in flavonoid levels in tissues already producing flavonoids, ectopic flavonoid production, changes in levels of nonflavonoid phenylpropanoids. 

The greenhouse and growth-chamber experiments indicated that S. divinorum is an obligate short-day plant. Plant height is a minor factor in flower development, as several (growth chamber) specimens were less than 0.5 m tall when they flowered. Pollination experiments showed that the mint is probably self-sterile, but it remains to be demonstrated that S. divinorum will set viable seed. 

Small molecule carboxylates are an important class of compounds that plants produce to attract pollinators,44 defend against herbivory,45 7 regulate the cell cycle,48,49 and induce defense responses.50 5 Often these compounds are esterified and volatilized. Plants utilize the emission of volatile esters as chemoattractants and signaling molecules. Classes of volatile compounds include the salicylates and jasmonates, which are ubiquitously distributed in the plant kingdom. Jasmonic acid, salicylic acid, and their methyl ester derivatives, are intimately involved in cell regulation and help control such developmental processes as seed germination, flower development, fruit development, and senescence.14,17,53... 

JAs also play important roles in flower development.832 833 837 Particularly, the requirement ofJA biosynthesis for anther development was clearly shown by JA biosynthesis mutants 834-836 AOS and OPR3, two enzymes required for JA biosynthesis, are encoded as a single gene in Arabidopsis genome. An opr3 mutant in Arabidopsis,... 

In both the flowers develop at least two sets of leaves (either on one or two plants of the same species) called sporophylla or sporophyll leaves, the stamens and carpels. The stamens or stam-inal leaves are also termed microsporophylls. The carpels or carpellate leaves are alscx known as megasporophylls. 

The order of flower development is termed ascending when, as in the raceme, the blossoms open first at the lower point on the axis and continue to the apex. Examples White Lily, and many other... 

Branches with small masses of galls. Cause Ash flower gall mites. These tiny mites attack male flower clusters on white ash Fraxinus americana). Infested flowers develop abnormally, producing galls that dry and remain on the tree. Spray branches and galls with dormant oil in late winter for control. 

The first key step in the biosynthesis of tropane alkaloids is the formation of the intermediate putrescine. Polyamines and, therefore putrescine, are found in plant cells and are implicated in growth, root, fruit and flower development, and in different stress phenomena. It is well known that plants synthesize polyamines from ornithine and arginine, unlike other eukaryotes like mammals, which only synthesize polyamines from ornithine. In plants putrescine is synthesized directly from ornithine, a reaction catalysed by ornithine decarboxylase (ODC, EC 4.1.1.17) and indirectly from arginine via agmatine catalysed by arginine decarboxylase (ADC, EC 4.1.1.19), Fig. (1). In Arabidopsis, it is known that the adc gene is required for the production of polyamines that are essential for normal seed development [103]. 

Flower Development Also Requires Spatially Regulated Production of Transcription Factors... 

These hairs vary in appearance those of the bracts and axes of the female flowers develop an elongated stem and resemble a tiny mushroom, while others (especially on the lower surface of the top leaves) lack the stem and have a flat, round head v/ith a masimum of ten cells (sessile glands). There is reason to believe that sessile glands are a distinct type and not an early stage of the stalked glands. All these cells lack chloroplasts and are colorless except for the amber oil produced in the head. Lesser amounts of cannabinoids are also produced by cells generally distributed throughout the epidermis of the plant (lactifers). ... 

When the trees reach maturity, sweet smelUng white or pink flowers develop in long, narrow sprays of between 40 and 50 flowers from which 4 to 15 nutlets form. These will eventually ripen into mature nuts encased in a woody shell surrounded by a green-brown fibrous husk. The shell surrounding the nut is extremely hard and difficult to crack open without damaging the nuts. For this reason, the commercial processing of the nuts was initially slow and only took off when a mechanized processing plant, to safely break the shells, was established in 1954. 

---