Cane Ripening

8/4/2019 Cane Ripening

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The Ripening of SugarcaneBY

F. COLMET DAAGE AND J. GAUTHEYROU, O.R.S.T.O.M., Y. LEMAIRE AND M. De POMPIGNAN, C.T.C.S.,SOBESKY AND J. SALETTE, I.N.R.A.(Presented by Mr. H. . Strang)

INTRODUCTIONSugarcane cultivation has a great economic mportancein Martinique and in Guadeloupe. Whereas some gentlyundulating windward areas have a fairly marked dryseason (Grande Terre, Marie Galante, South Martinique)most of the other areas get frequent and abundant down-pours during harvest. In 1966, this period has beenparticularly rainy and the observations made cannot thusbe compared with those of other years.Following these rains, which occurred during thereaping season, a decrease in the sugar content has oftenbeen observed although not systematically. This decrease

varies in magnitude.These unfavourable climatic conditions for sugarcanecultivation are not common in the other sugarcaneCountries. Therefore, the improvement of sugarcanematuration is a very important part of our researchprogramme.EFFECT OF NITROGENMany results of factorial experiments carried out inboth islands for many years show that if nitrogenincreases both in tonnage and the sucrose content asoccurs when deficiencies in tbis element are severe,supplementary applications to bring the yields in tons ofcanelacre to near the optimum, tend to lower the sugarcontent even when further increases in tonnage are stillpossible. As a result of climatic variations, optimumdosages of nitrogen vary from year to year. I t is, therefore,very difficult to establish permanent recommendationsfor nitrogen applications.

In certain elevated areas with overcast skies, heavyrains and soils with a higher organic matter content,experiments seem to show that less nitrogenous fertilisersare needed than in lower areas, and more so in the case offirst ratoons. An increase in the application of nitrogento successive ratoons seems necessary, particularly inheavy soils.

to reduce the basal dressing of nitrogen to the minimumaverage dose required and to correct the possibledeficiencies afterwards when the cane is well developed.One of the aims of the trials was to determine if suchhigh yields could be obtained whether nitrogen wasapplied on the soil or in urea solution in water on heleaves. Another object was to find out under whichconditions nitrogen could have depressive effects on hesugar content and whether it could be responsible forthose sudden drops in quality or cessation of sugarincrease which have been noted from time to time duringthe harvest.SOIL NITROGENThe study of the mineral nitric and ammoniacalnitrogen variations during a number of years in theFrench West Indies in the sugarcane and banana soils,shows that fertiliser applications were followed in somecases by a very moderate increase in mineral nitrogenlevels and in other cases by an increase which could bemuch higher than the quantity applied.

Furthermore, in soils regularly fertilised, suddenincreases of mineral nitrogen levels have been observedduring some periods of the year and particularly whenrains occur during the so-called dry season. Theseincreases can be very important sometimes in soilsheavily dressed. Annual variations are of very littleimportance in non-fertilised soils.A low mineral nitrogen level in the soils does notnecessarily mean that the soils cannot supply anynitrogen to the plant. It is the case when the plant uptakereaches or goes beyond the speed at which the mineralnitrogen of the soil is renewed. On he other hand, a highlevel of nitric nitrogen indicates with .certainty thepossibility for the plant to find readily available nitrogenin the soil if the uptake conditions by the root systemare favourable. This is what happens when the rains arefrequent enough during harvesting for the resumptionof growth.It seems that the wav to Drevent these imnortanthereas an excessive potash application, which canbe checked by the K levels in the juice, in the soil and in increases in nitrogen co&sts i n limiting, as much as

the third leaf O$ the previous crops, leads to cessar^ possible, nitrogen applications to the soils. This nitrogenexport of K ln JUlce and may cause Some losses Of sugar can be transformed into the organic form by the soilat the factory it seems impossible in a given area to micro-organisms and re-mineralised by way of veryforecast the quantity of nitrogen to be applied at planting complex processes.or ust after reaping. Dependingonthe climatic conditions Through foliar applications of nitrogen, itthe latter can be either insufficient to achieve optimum possible to avoid, except during the first weeksofcontent.

Thanks to aerial application of urea, it seems possible nitrogen level in the soils.gelds or excessive thus causing a drop in the sugar important ap lications of nitrogen to the soils and thusto maintain I:uring harvesting a very low mineral

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METHODS(i) Uptake of soil nitrogen by the caneAs a result of some preliminary experiments, it hasbeen possible to relate the variations in soil nitrogen tothose of certain forms of nitrogen in the plant. Thegraphs of Figure 1 show that an increase in nitricnitrogen levels in the soils is followed by an increase ofthe nitrogen obtained through simple distillation inpresence of magnesia of the sugarcane juice extractedwith a Waring blender. This method has, therefore, beenprovisionally chosen for the first experiments until moreprecise and varied determinations can be undertaken.The semi-quantitative paper chromatographic deter-minations of the various amino acids undertaken in 1966by Mr. Yot show that a close connection exists betweenvariationsof soluble nitrogen obtained by distillation andthose of the principal amino acids. Some delay insecuring the necessary ingredients has made it impossibleto make use of the new techniques already available.(ii) Experimental designsThe experiments comprise six repetitions of:

(a) Plots on which the nitrogen is applied to the soil inone or two applications after plantation or afterreaping.(b )Plots getting only 30 kgs. of N/Ha on the soil at thebeginning of the growth, then three or four sprays ofurea solution on the leaves amounting to 90 kg./Hafrom August to November.Each plot is split in two halves. One half is not reapedand is used for sampling during the ripening period, theother half is weighed and analysed after harvesting.During the ripening period, cane is sampled every 8or 15 days in each plot. Three portions of stalk areprepared for analysis, viz. three internodes from the basalpart, three internodes from the middle part and the 8-10internodes. Sucrose was determined by polarimetry.Reducing sugars, soluble nitrogen and the moisturecontent of 4-5 internodes were also determined.Soil samples were also taken at the same time in eachplot for the determination of nitric and ammoniacalnitrogen and moisture content.RESULTS AND DISCUSSIONS(i) Soilmineral nitrogenIn 1965, in most of the experiments laid out on plantcane, the soil nitric-nitrogen level remained somewhatlower during the harvest in the plots getting nitrogen onthe leaves than in those to which nitrogen was appliedon the soil.This was the case in the following experiments: GrandRavine, Grand Cesar, Girard, Loison, Fonds Boyer andPlateau.In the following experiments the levels remainedpractically identical: Ravine Negresse, Lemoine andDattier.In 1966, probably because of very heavy and steadyrains occurring from the beginning of February, themineral nitrogen levels remained fairly constant andidentical in the plots with foliar or soil application.

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In Martinique very few differences were observed. Itseems, however, that certain occurrences of high mineralnitrogen level during some periods cannot be altogethereliminated.(ii) Nitrogenlsugar relationAn important increase of the soil moisture followingheavy rains in 1966, was immediately followed by anincrease of soluble nitrogen in the stalk. This increasecan affect the three parts of the stalks: low, middle and8-10 internode simultaneously, or of one of these parts,only far more intensively.A sudden increase of the soluble nitrogen in the stalkis, in nearly all cases, followed either by a drop of thesucrose in the cane or by a slowing down of its accumu-lation. 8-10 internodes seem particularly affected. Sucroseof these internodes has constantly decreased in certainfields from the first rain in February to the end of theharvest. In some other plots, the accumulation of sucroseslowed down during a certain period but increased againfor a few weeks.Examples:

Loison-February rains causing an increase of the soilmoisture and of the soluble nitrogen and a slowingdown of the sugar formation in the lower and middlepart of the stalk followed by a resumption of the accumu-lation. In May there was a new peak of soil moisture andof the soluble-nitrogen n the cane, and a marked slowingdown of sugar formation in the lower and middle partof the stalk accompanied by a drop in the 8-10 internode.Ride-An appreciable increase of soluble-nitrogenfollowing the February rains caused a stoppage in theaccumulation of sucrose in the three parts of the stalk,particularly in the lower part and in the 8-10 internodes,with very little accumulation in the middle section. The4-5 internode moisture content remained over 90 per centfrom mid-February to mid-April and over 89 per centup to the end of the harvest.Plateau-High soluble nitrogen level caused a dropof sucrose in the three parts of the stalk. From thebeginning of March, although the 4-5 internode moisturewas over 90 per cent, the accumulation increased again.A new increase in the soluble-nitrogen of the stalk inApril was followed by a general slowing down in theaccumulation of sucrose and by a drop in the 8-10internodes.Girard-A noticeable slowing down of the accumu-lation of the sucrose in February accompanied by a smallincrease in the soluble-nitrogen and a 4-5 internodemoisture content of 90 per cent was followed by anincrease in the accumulation of sucrose followed by afurther stoppage in April.Dip-The 8-10 internode sucrose content droppedconstantly after the rains at the beginning of Februaryand the soluble-nitrogen in the stalk increased. After aslight slowing down during February, the accumulationof sugar continued until harvest.Fonds Boyer-A constant drop in sucrose followed therains at the beginning of February and soluble-nitrogenincreased in the 8-10 internodes. The accumulation of


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- EMOINE-II- T-V foliaire N SolFig. I

CanneLNitriguc - --

\\\ Sol\\ /r.\ ;\ I, \ ;LO

21/1 4 /2 18/2 4/3 18/3 1/4 16/4 29/4 13/5

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II

I1963 , .

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4 30r..,

3 AZOTE DU SOL ArNil

N mg p. 100 sol

- RAND RAVINE-Fig.

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* 6/3 20/3 1/4

269

CannezSol

16/4 29/4 13/5

N - T -N foliaire N Sol

AZOTE SOLUBLE 11

mg/litr

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1963 2(


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sucrose slowed down during February and increasedagain very slowly afterwards. The 4-5 internode moistureremainedin the region of 90 to 91 per cent.Dattier-A cessation of the accumulation of sucroseand an increase in soluble-nitrogen followed the firstrains in February. During March soluble-nitrogendropped and sucrose increased again; subsequently,further rains caused an increase in soluble-nitrogen, adrop in sucrose in the S-10 internodes and a retardationof sucrose accumulation in the lower part of the stalk.Pallabaty-A very high increase of soluble nitrogenfollowed the rains of February causing a cessation in theaccumulation of sucrose in the lower and middle partsof the stalk. This was followed by a slight increase. Therewas a continuous drop in the sucrose content of thehigher part of the stalk associated with a high level ofreducing sugars.Riz-There was a constant drop in the sucrose contentof the 8-10 internodes and a cessation of ripening in thelower and middle parts of the stalk.Basse Pointe-An increase of mineral nitrogen duringFebruary and March caused two decreases or slowingdown of the accumulation of sucrose with a little increasein the middle.Riviere Sales-Fromager-An increase in soluble-nitrogen caused a drop in the sucrose content of the stallcfollowed firstly by more rapid ripening and later by afurther drop during April.Parc 1 Boeufs-A slowing down of the ripeningprocess during February-March, followed by a distinctdrop in the 8-10 internodes.Champs (1964); Grand Ravine (1964); Lemoine (1964)and Ravine Negresse (1964)-In 1964, a high increase in

soluble-nitrogenin the lower part of the stallc and in the8-10 internodes, and an associated fall in sucrose contentwas observed.(Ci) Yields in tons of cane and of sugar

(a) Control of the foliar applicationsThe control of the eEciency of foliar applications hasbeen made by foliar diagnosis on the third leaf when the4-5 internode moisture content was over 90 per cent.A slightly lower level of nitrogen is often noted in theplots which have only received30 kgs. per Ha. of nitrogenon the soil and no foliar applications. Immediately afterthe first foliar application the levels tend to becomeidentical in the two treatments. The high values in mostcases are very close to or somewhat above the usuallyregarded optimum.One may often observe, though this is not invariablythe case, that foliar applications of nitrogen seem alsoto increase the foliar level of K and P.Foliar diagnosis is often inadequate to establish thetremendous importance of foliar applications.Because of having relied too much on foliar diagnosis,innumerous fields in Martinique in 1965, yields have beenconsiderably lower than those possible because ofinsufficient nitrogen foliar applications. An alternativemethod remains to be developed.(b ) In the following table the yields in tons cane perhectare, the extractable sugar per cent cane, and the totalyield of sugar per hectare for 1965 and 1966 are presented.One notes very frequently that an important increasein the tons of cane/Ha. without an associated decreasein the sugar content occurs in the plots which havereceived foliar application.

Guadeloupe1965I IPlateauGrand RavineFonds BoyerLemoineBois NeufGrand CesarLoisonRavine Negresse

Guadeloupe 1966PlateauFonds BoyerLoisonPallabatyDattierDigueRideGrand CesarMartiniqueParc BoeufsFromagerBasse PointeRizEloiseVinaigrerieFanfanPaquemarRamier

T.C./Ha.N5582907081794978

73897210570767680

109138132202124115175115131-

-5471875777.865274

-79. 88719874797690-

112118161181125118166118116-

S.E. %CN

10.8512.8711.1213.9912.511.2213.7613.96

13.5511.2513.568.8311.0912.3310.5011.33

9.568.3810.327.939.2611.79.2511.696.64

T10.1812.1411.0513.0712.611O713.8713.913.7211.2413.499.3111.2611.7210.5511.1-9.838.529.619.29.1911.549.1411.546.09-

T.S./Ha.N5.9810.5410.09.7710.158.756.710.91

9.9310.069.819.337.769.387.819.1

11.8811.5113.7016.2411.5313.4716.1513.478.66-

T5.538.689.557.519.719.547.1710.27

10.989.889.649.148.339.298.0699.97

11 o210.0s15.616.5711.5313.6115.2413.617.04-

VarietiesB.51129B.51129B.51129B.51129B.46364B.49119B.51129B.51129

B.51129B.46364B.51129B.51129B.46364B.51129B.51129B.49119

B.46364B.4636413.51129B.37172B.46364B.46364B.37172B.46364B.46364

-CP2RCP2RCP2RCP2R-1R1R1R1R1R1R1R3R

CP1R3R3R1R3R3R3R3R-

Type of soi lAllophanes gibbsiteFerralitique friableAlluvionsFerralitique friableGrumosol calcaireGrumosol calcaireFerrisolFerralitique friable

Allophane gibbsiteGrumosol calcaireFerrisolFerralitique friableGrumosol calcaireFerralitique friableFerralitique friableGrumosol calcaire

Alluvions lourdesAlluvions lourdes vertisolJeune sur cendres et poncesAlluvions lourdesAlluvionsAlluvionsAllophane gibbsiteVertisol magnsienVertisol

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One may say that in 1965 foliar applications of nitrogencaused a noticeable increase of cane and sugar yields(probably because of a better utilisation of nitrogen,during the boom period of growth) as compared to equalquantities applied on the soil, even though this dosagewas a little higher than the usual dose.In 1966, a year of exceptionally heavy rains during theharvest, yields have remained substantially the same,whether the nitrogen was applied on the soil or on theleaves.It is rather premature to suggest the exact reason forthese differences.CONCLUSIONSA relationship seems to exist between increases insoluble-nitrogen levels in the stalk and the retardationor actual cessation of sucrose accumulation.These increases in soluble-nitrogen in the stalk occurduring the ripening period when rain falls after a dry spell.Are these increases of soluble-nitrogen in the stalkresponsible for the slowing down of sucrose accumulationin the stalk? Sugar can in fact be utilised for the elabora-tion of amino acids and protein and utilised in respirationto produce the necessary energy.Within the scope of these experiments, Mr. Yot ofIFAC, has undertaken the detailed study of the aminoacids, organic acids and sugars, to determine whetherthe biological mechanisms found confirm our pre-liminary hypothesis.Should these increases in the soluble-nitrogen contentof the stalk be attributed to absorption of nitrogen fromthe soil or to a conversion of the canes protein reserves?If the first supposition were correct, one shouldendeavour to reduce the soils ability to supply nitrogento the plant during the ripening period as much aspossible, as we have tried to do by avoiding appreciableapplications of nitrogen to the soil, or by other methodsyet to be developed.It should be pointed out, however, that whereas theincrease of soluble nitrogen in the cane seems almostinvariably to coincide with rainy periods, such increasesin the mineral nitrogen level of the soil are only associatedwith rainy periods in certain cases. Determinations of themineral nitrogen content of the soil only indicate the levelin the soil at a particular amount however, and give noindication of the soils ability to supply nitrogen to theplant over an extended period. We hope to imp;ove thistechnique.In the event of the second hypothesis (according towhich the increase in the soluble-nitrogen level in thestalk would originate from the nitrogen reserves of theplant) being correct one should ensure that foliarapplications made to induce optimum growth during theboom stage should not be so large as to cause excessiveaccumulation of nitrogen which would remain, eventuallyhampering the ripening process. Would it be possibleto determine a critical period after which no foliarapplications should be made in order not to inhibit thebeginning of ripening?Dr. Nicltell of the H.S.P.A. had considered the use ofthe content in the stalk of soluble amino acids, or of

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some of them, to differentiate varieties with good andpoor juice quality, the excess of amino acids being anindication of the failure of the active leaves completelyto mobilise them, and thus resulting in their being foundas amino acids in the stalk. The study of the various formsof nitrogen at the end of the growth period may help tofkd a control method.In the meantime, it is already of considerable interestand importance to have established that similar highyields can be obtained either by foliar sprays of urea orby soil applications. It will therefore, be possible to putthe results into practice immediately since the aerialapplication method is already being largely utilised in theFrench Islands for herbicide and fungicide applicationsto bananas.

REFERENCES1. Hartt, Constance and Kortschak. Radioactiveisotopes in sugar cane physiology.2. Hartt, Constance and Burr, G. Factors affectingphotosynthesis in sugarcane.3. Lemaire, Y . , Colmet-Daage and Gautheyrou, J.

(1965). Exports of elements in the cane juice. I.S.S.C.T.12th Congress, Puerto Rico (in press).4. Nickell, L. G. and Baver, L. D. (Personal com-munication).

DISCUSSIONMr. Le Grand said, from the limited knowledge he had about theFrench islands in the Caribbean, he was not surprised that juicequality was affected by aerial application of urea.Harvest started in about January in both places, and an applica-tion of 20 kg. urea per hectare, about equivalent to 20 lb. of ureaper acre, in November when the cane was about 10 months old,might affect proper maturation of the cane.He knew that several field practices in the French West Indiesresulted from experience gathered in Puerto Rico, where pioneering

work with aerial application n that territory was started by CentralMercedita, on the south coast. Application of urea in this case wasmade as soon as the cane was closed in, when the cane was about3 to 4 months old. He felt, that a similar application and timingmight greatly reduce maturing difficulties n the French West Indies.One application of 30 kg . per hectare to 4-5-months-old cane mightbe more effective than the three split applications now applied.,No damage to the leaf surface should be feared with this rate ofurea to the foliage, since much higher rates of applications had beenreported without causing damage to the foliage.Dr. Evans commented that in Martinique and Guadeloupe theproblem was that during the harvesting season they had frequentheavy showers similar to those being experienced in Guyana thisyear. These resulted in significant drops in quality. In order to findout the reason for this, these experiments using aerial applicationat various times, were being carried out.Mr. Le Grand observed that there were two rather distinct zonesin both islands. The first area could be called wet, while the otherzone could be regarded as receiving a moderate to heavy rainfall.The latter zone was mainly used for bananas, while the drier areaswere often employed for growing sugarcane.Mr. Strang noted, according to the authors, that a large part ofthe sugarcane growing area received frequent and heavy downpoursthroughout the harvesting period.Mr. L. S. Birkett recalled that several years ago, he, along withhis co-workers, carried out soil investigations and found that it waspossible during boom periods of growth to get large variations inthe nitrate and ammonia-nitrogen levels in the soil within relativelyshort periods.

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Cane Ripening