The chrysanthemum is important ornamental crop mainly grown for the production of cut flowers, loose flowers and pot plants. The plant belongs to family Asteraceae and is popularly known as "Queen of the East". The utility and popularity of chrysanthemums have increased recently with the introduction of new cultivation technique "year-round production of chrysanthemums" based on scientific work conducted in the field of plant physiology, photoperiodism and genetics (Datta and Gupta, 2012).
In general, chrysanthemum is a qualitative short day plant. It flowers only when short photoperiods are available. But the demands for the flowers are more especially during occasions like New Year, Christmas, mother’s day, etc. If the farmer is able to produce during these peak consumption periods it fetches a lot to the farmer. For off-season cultivation, crops are grown in the protected structures because controlled environmental conditions (light, temperature, relative humidity, air composition) are required for growth and flowering of the crops.
Photoinduction and response group
Different varieties of chrysanthemums have different photoinduction requirements i.e. the number of light and continuous long dark periods (short days) required by the plant for coming into bloom after it has attained full vegetative growth. A combination of day and night is termed as one photoperiod. Different varieties require different photoperiods ranging from 8 to 15 weeks for coming into bloom. A variety requiring eight weeks of photoinduction period means it belongs to 8 weeks response group. The chrysanthemum varieties have been classified into different response groups ranging from eight to fifteen weeks depending upon on their respective photoinduction requirement. Determination of the response group is very much essential because artificial lighting and blackout dates have to be provided, based on the response group of the varieties chosen for cultivation.
Control of Environment
Selection of Cultivars: The right choice of cultivars is of paramount importance for successful cultivation for the off-season. Chrysanthemum varieties belonging to 8 to 9-week response groups were suitable for growing in high light intensity areas or season, while 12 to 14 weeks response varieties were preferred for those areas or season which received low light radiation.
Some of the cultivars which were evolved from National Botanical Research Institute (NBRI) can be grown for beyond the normal season of chrysanthemum. These cultivars are listed below. Likewise photo-thermo insensitive varieties like Pusa Anmol, Sensation can also be grown for year-round flowering without photoperiodic manipulation.
Name of cultivar |
Date of planting |
Blooming season |
Himanshu, Jwala, Jyoti |
January |
Summer |
Meghdoot, Varsha, Tushar |
February |
Rainy season |
Sharad, Sharad Shobha |
March |
Sept.-Oct. (Autumn) |
Sharad Kanti, Sharad Mala |
March |
Oct.-Nov. (Autumn) |
Traditional cultivars |
March |
Nov.-Dec. (Winter) |
Vasantika, Jaya |
July |
Dec.-Jan. (Winter) |
Illini Cascade |
August |
Spring |
It is very clear that both early and delayed blooming may be possible in chrysanthemum by creating artificial photoperiods. By manipulating the planting date and the light inside the protected greenhouses, the grower can coordinate the response of several varieties as per specific flowering dates and marketing requirements.
Authors:
Reference:
Datta, S.K. and Gupta, V.N (2012). Year round cultivation of garden chrysanthemum (Chrysanthemum morifolium Ramat.) through photoperiodic response. Science and Culture 78: 71-77.
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