EMASCULATION AND POLLINATION TECHNIQUES IN SUGARCANE

SUGARCANE (Saccharum officinarum) (2n = 80)

Cross pollination is the rule in sugarcane. Self male and female sterility, protogyny and hanging down of anthers away from the stigma at the time of anthesis promote self pollination. Usually anthesis will be in early morning between 5 am and 6 am.  Maximum anthesis between 6 am and 8 am.  Stigma protrudes out first and anthers dehisce afterwards.  Flower opening will be from top to downwards.  It will take about 10 days for complete opening of spikelets.  Flowering in sugarcane is location specific and influenced by environment.  Natural pollination is by wind (Anemophily)

Selfing 

Selfing is done by covering the arrow with a bamboo frame work or cage which is covered with muslin cloth or polythene paper. Such a cover is commonly called lantern. It prevents accidental cross pollination. The lantern has to be supported by bamboo poles. The lantern has to be opened once in a day to reduce the temperature that my build up inside during the day time. This is done preferably during the afternoon hours between 12am and 4pm. Usually the cover has to be retained in position till the seeds are set. Within one week or 10 days we can get selfed seeds. This selfing method is followed in Sugarcane Breeding Institute, Coimbatore.

Crossing

Hybridization is very difficult.

1. It is mostly vegetatively propagated.  Some varieties seldom flowers outside tropics.  Some varieties flowers once in 6 to 8 months.  It is highly controlled by photoperiods.
2. Spikelets are minutes.  So, hand emasculation is not possible.
3. Self sterility of both pollen and ovule predominates in almost in all the varieties.
4. Hot water treatment can not possible.
   

Hybridization methods

1. Coimbatore method

During flowering period, the sugarcane stem will be cut leaving one or two bud.  The cut stem can be transferred to a mud pot having moist mud.  Within 10 days the buds will develop into roots and there will be good root system.  This can be transferred to the breeding block.  In the crossing block, the male and female plants are covered with commonlantern.  Free shedding pollen over female plant will occur.  We can harvest both selfed and  crossed seeds from the female parent.  The selfed seeds can be identified by chromosome number by raising it in the nursery.  Selfed seeds thus removed retaining crossed seeds.

2. Marcotting method

During flowering, cut around the stem and tie a polythene bag with nutrients (growth medium).  The bud near cut end give rise to roots.  This can be cut and used for hybridization purposes.  This method is called marcotting.  Practiced in TNAU, Coimbatore and Sugarcane Breeding Institute, Coimbatore. 

3. Lantern method

Providing Lantern for a female plant before anthesis starts.  From the desired male parent cut the arrow.  That arrow can be introduced into the Lantern and shaken up and thereby crossing can be effected.  This will be repeated for 2-3 days in order to have more seed set.

4. Hawaii method (Sulfurous acid Technique)

A sulfurous acid solution keeps the inflorescence alive for several weeks.  Here, we cut both mal and female flowering arrows along with small portion of stem.  These cut end will be immersed in a vessel containing 0.01% sulphuric acid and 0.01% phosphoric acid.  The cut end at the lab is brought nearer and effect cross pollination.  They absorb the weak acids.  We have to add weak solution daily to replace the acid taken by stem.  Once in a week we have to completely change the solution.  This is done for 20-30 days.  During this time, the seed will mature.

In modified method of this, the female plant alone is cut and kept in weak acid at the time of flowering the male parent can be brought nearer and the pollen can be shed by shaking as done in Lantern method.