Sugarcane

Egypt


Biological Characteristics

 

The vegetation period of sugarcane ,from planting to blossoming (10-24 months) , includes five basic stages : 

                1) Sprouting (Forming sprouts)

                                        

  •  When cultivated commercially, sugarcane is propagated only vegetatively by stem parts ( Cuttings ) or by  whole stems.
  •   Seed propagation is employed only in selection.
  •   Planting cuttings should have at least three buds
  • When the stem grows, the terminal bud inhibits the lower buds which are in a dormant stage and do not germinate.
  • After the stem is cut into pieces , the inhibiting effect of the terminal bud ceases , the buds wake up from their dormancy, and begin germinating , if conditions are favorable.
  • The germination rate of buds differs , depending on their position on the stem.
  • The quickest to germinate are the buds in the upper part of the stem, where the content of nitric substances is higher and the sucrose (it is called saccharose also ) to total reducing sugars ratio is lower ( as compared with the buds in the central and the lower parts of stems).
  • To stimulate germination of buds in the lower and central parts of the stem, the cuttings are soaked in warm water ( 50 C) for two hours.
  •      The buds begin germinating at temperatures never below 10 C,
  •    at 10 to 20 C germination is very slow
  • At 25 to 33 C it is the most rapid ( 10 to 15 days) .
  • Germination begins when the primary roots appear from the root zone of cutting; then the bud begins to grow.
  • The cutting breaks through the soil layer and emerges into the open world.
  • The sprouting phase ( the beginning is marked by 10% and the complete stage by 75% pf sprouts) is thought to commerce when two leaves appear on the stem.
  •  One plant may have as many as 60 primary roots.
  • When the second leaf appears, the plant begins to develop its own secondary roots.
  •  Normal sprouts can develop only if the soil moisture is optimum, 70-80% of field water capacity.

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   2)    Tillering

  • Tillering of sugarcane in the tropics begins soon (in about 15-20 days) after the first sprouts appear.
  • The secondary sprouts are formed from underground buds.
  •   At first, the underground buds of plant cutting begin to grow; then, the underground buds of  the daughter sprout from secondary runners, which , in turn, give rise to tertiary sprouts, and so on .
  • The early-ripening varieties of sugarcane are specific in the rapid growth of leaf foliage surface and high capacity of  tillering .
  •  In these varieties, tillering lasts for 4-6 months, and finishes after the row contact.
  •   In the late-ripening varieties of sugarcane , tillering lasts long as 6-8 months.
  • Every new sprout appears in 2 to 4 days.
  • Under field cultivation each plant develops :
  •    In the strong-bushy varieties 20 to 40 sprouts
  •   In medium-bushy 15 to 25 sprouts
  • And in weakly-bushy 8 to 12 sprouts.
  •  When highly crowded (up to 30 thousand plants per hectare = 12600 plants/feddan "acre") the tillering coefficient sharply decreases (10 runners per plant).
  • In less crowded plantings crowded (10 thousand plants per hectare = 4200 plants/feddan "acre"), it increases (25 runners per plant).
  •   All sprouts which appear before the rows contact, as a rule, develop into normal commercial stems.
  • Tillering is retarded after the rows contact, and soon ceases completely.
  • Sprouts formed after the rows contact become yellow and die off.
  • The root system of sugarcane is formed during the tillering phase.
  •   Each runner has an autonomous root system.
  • Up to 60 main roots are formed on the central sprout.
  • The number of roots on the secondary, tertiary and quarternary runners decreases.
  • On one plant the roots may reach a total of 500.
  •  The optimum conditions for normal tillering of sugarcane should provide   for high heat requirements (25-30 C) and moisture supply (soil moisture 77 to 80% of field water capacity ) , as well as good illumination and nutrients availability.

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      3)    Intensive growth of shoots

  • Period of intensive growth begins after the row contact.
  • During this stage lasting 5 to 8 months in the major regions of sugarcane cultivation, the basic yield of the crop is formed.
  • Daily length increments in runners are from 1 to 2 centimeters and more, monthly increments may be as high as 50 to 60 centimeters.

Sugarcane plants normally vegetate at this stage, if properly supplied with heat and moisture. 

                       

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      4)     Ripening ( Maturation)

  • Sugarcane begins ripening in 2 to 3 months before harvesting.
  • The most important factors determining the maturation rate of this crop are soil moisture and temperature.
  • If these factors are decreased , the growth processes are retarded while the synthesis of sucrose  increases because a lesser amount of products of photosynthesis is necessary for the formation of the vegetative organs, and more carbohydrates as sucrose are stored.
  • In tropical countries , sugarcane matures in the dry season.
  • Its maturation is determined by a definite sucrose level in the stems (up to 14-16% stem mass) and a low level of reducing sugars.
  • The commercial ripening of stems can be identified quite reliably by the ratio of refractometry indices of juice taken from the seventh-eighth internodes and lower (0.95-0.98).
  • In tropics, by harvesting  time the sugarcane stems accumulate on the average up to 14-16% sugar; in subtropics 8-12% sugar.

                        

 

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        5) -Blossoming:

  •  Blossoming begins at the end of the commercial ripening stage of sugarcane .
  • This is followed by sprout lignification and a decrease of sugar content in the stems.
  • The bulk of sugarcane varieties develop few or no inflorescences.
  • The sugarcane in the tropics blossoms most frequently in dry season.
  • The number of  inflorescences sharply decreases when waterings or nitrogen dressings during the ripening stage are diminished.

                          

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