Pakistan Gardening Forum

Q.1 I have observed in my short span of gardening that purple flower color cultivar of an annual (petunia, stock, pansy dahlia etc), Is first to flower than other colors. Is it a coincidence or some science involved? if its coincidence it happens all the times

Q.2 Mali's by tradition recommend reducing water to promote flowering early. Is it valid as is the case with bolting?
But there are two aspects of this.
(a) Early flowering would mean soon the annual will be finished as it has not grown large enough or will it continue to grow?
(b) Should one continue watering as the time will come when one will not be able to meet the optimum water requirements as temperatures increase, such as spring changing into summer?

farhan137 wrote:
Q.2 Mali's by tradition recommend reducing water to promote flowering early. Is it valid as is the case with bolting?
But there are two aspects of this.
(a) Early flowering would mean soon the annual will be finished as it has not grown large enough or will it continue to grow?
(b) Should one continue watering as the time will come when one will not be able to meet the optimum water requirements as temperatures increase, such as spring changing into summer?

Q.1. About purple flowers blooming earlier- no idea. But why would this happen in the first place? Interesting observation.

Q.2 It seems that your Mali is really good :-). There are lots of studies on stress induced flowering. That stress may be lack of water, due to temperature, or nutrition. See for example the case of Citrus:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1075276/

Ahhh...the dependable Farooq Sb answering

Q.2 That is one part, other considerations remain. Stress induced flowering would than be bolting as the plants in discussion are annuals. Bolting of course means a quick demise. If the aim is just to achieve fewer quicker blooms than this theory would hold good, but not when one desire a healthy floriferous plant, not in hurry to die rather enjoying its stay . What say you?

Its interesting to note that you mentioned LACK OF NUTRIENTS, kindly elaborate how that would induce flowering?

And about Mali's ...they follow tradition without knowing the essence/reason and what happens is that actual cause is lost with sands of time. Mutilated. They have a long way to go.

For Q.2 I have not been able to get a definite answer but an interesting clue.

Anthocyanins(Blue Flower) are pigments responsible for flower colors. And the amount of these pigments and color they produce is varied by soil type/nutrients and PH. As color is dictated by Genes and variegated by above mentioned factors, it could be so that my soil/PH is more supportive of BLUES(if available in that annual).

This could be verified if some members have also observed appearance of some specific color earlier in his garden which would be because of the specific soil/PH of his garden.

farhan137 wrote:Ahhh...the dependable Farooq Sb answering

Q.2 That is one part, other considerations remain. Stress induced flowering would than be bolting as the plants in discussion are annuals. Bolting of course means a quick demise. If the aim is just to achieve fewer quicker blooms than this theory would hold good, but not when one desire a healthy floriferous plant, not in hurry to die rather enjoying its stay :-). What say you?

Its interesting to note that you mentioned LACK OF NUTRIENTS, kindly elaborate how that would induce flowering?

And about Mali's :-)...they follow tradition without knowing the essence/reason and what happens is that actual cause is lost with sands of time. Mutilated. They have a long way to go.

I would agree with you that why induce early flowering by stress? What was your Mali's rationale? Searching the causes of bolting reveals that bolting is also induced by light, temperature and water stress (http://apps.rhs.org.uk/advicesearch/pro ... px?pid=262).

The lack of nutrition inducing flowers was studied recently: http://www.ncbi.nlm.nih.gov/pubmed/20505356, but plant biochemistry is outside my field of specialization so I don't understand the exact reasons :-(

It was suggested by a passerby mali once he saw sweetpeas growing healthy but not flowering as yet, as compared to others growing elsewhere which he saw were smaller in size but flowering. He suggested to stop watering.

My answer to him was same that i don't want them to bolt sooner and would continue watering, i would like them to grow as healthy as possible till the time weather itself causes them to bolt. Healthier the plant, more the blooms.


Regarding lack of nutrients, what i understand.......
It is caused by salicylic acid which induces plant defense against various adverse factors ( in this case, salicylic acid signals flower production/bolting). BUT this lack of nutrient is not total lack of nutrients from start. "Its removal of nutrients which were present earlier to induce stress".......in other words to remove nutrients/fertilizer of a healthy plant to make it bloom.............But that would be very difficult in garden environment unless one is experimenting in pots.

farhan137 wrote:For Q.2 I have not been able to get a definite answer but an interesting clue.

Anthocyanins(Blue Flower) are pigments responsible for flower colors. And the amount of these pigments and color they produce is varied by soil type/nutrients and PH. As color is dictated by Genes and variegated by above mentioned factors, it could be so that my soil/PH is more supportive of BLUES(if available in that annual).

This could be verified if some members have also observed appearance of some specific color earlier in his garden which would be because of the specific soil/PH of his garden.

Farhan, the classic example of pH dependence of flower colours is Hydrangeas. They are red and blue in different pH. Your hypothesis may be valid about pH causing a purple colour, but it does not explain early bloom.

An excellent article here if you really want to go deeper for different colours of morning glory which changes its colour. Note that a unit increase in pH means a ten fold decrease in hydrogen ions- it is a huge number!


http://www.uni-regensburg.de/Fakultaete ... anth-e.htm

"The change in color of Ipomoea tricolor is an exceptional case supporting the pH theory. The 'Morning Glory' or 'Heavenly Blue' changes its color from purplish red in the bud to blue in the fully open flower (Picture 4). One and the same pigment, a triacylated anthocyanin, is responsible for both colors. By direct measurement of the vacuolar pH using a proton sensitive microelectrode, was demonstrated that the change of petal color is accompanied by an unusual increase of the vacuolar pH in the petal epithelium from 6.6 to 7.7. "

Regards,

Farooq

farhan137 wrote:
Regarding lack of nutrients, what i understand.......
It is caused by salicylic acid which induces plant defense against various adverse factors ( in this case, salicylic acid signals flower production/bolting). BUT this lack of nutrient is not total lack of nutrients from start. "Its removal of nutrients which were present earlier to induce stress".......in other words to remove nutrients/fertilizer of a healthy plant to make it bloom.............But that would be very difficult in garden environment unless one is experimenting in pots.

You are right that stress is induced by changing the conditions. It was a highly controlled recent study so it means that stress induced flowering is a recent research problem in plant physiology. Bolting is a economic disaster in the worst case.

My observations:

For the Q1, here i have observation that white and pinks bloom early in phlox, petunia, nicotina, stocks, gladiolus.. followed by purple and yellow and last is the red..

For Q2, part (a) i have experienced that early flowering annuals are always the longest blooming, provided they get the nutrition well and with deadheading.. without deadheading they are the first to die..
part (b) if the annuals are kept constantly moist, they will produce lush foliage and delay flowering.. there must be a dry period between watering..

For the plants you need foliage like leaf vgges, coleus etc you dont want early flowering so stress induced flowering is a big NO..

Plants in sunflower family show that early blooming reduces the quality of blooms as well as the number of blooms e.g. marigolds, dahlia, sunflowers, gaillardia, cosmos, tithonia etc

Regarding Q.1..............hmm,so Izhar is also experiencing same sequence of early blooms of specific color in specific plants. Interesting. I think it has something to to with the soil and PH.

Its again very interesting point by Izhar that Asteraceae or Compositae family must not be allowed to go to flower soon or the quality of blooms will suffer, i would vouch for this observation as i have observed same in case of sunflowers.