PHYSIOLOGIA PLANTARUM, VOL. 19. 1966, 417-421

The Effect of Simulated Caterpillar Damage onCO2 Fixation and Transloeation in Banana Leaves

ByBARBARA E. JOHNSON and W. A. BRUN

Central Research Laboratories, United Fruit Company, Norwood, Massachusetts(Received January i, 1966)

Abstract

A study was undertaken to see how a small hole in a leaf such as caused hy atecditig cateri>illiir will influence photosynlhesis and translocation in the remainingleaf ti.ssue. Banana leave.s were exposed to C'^ O^ at various intervals before andafter holes were made in the leaves with a cork borer. Radioautographs were takento study the extent of CO^ fixation and translocation.

Results show that photosynthesis is impaired for only 24 hours. I>

418 BARBARA E. JOHNSON AND W. A. BHUN

Figure 1. Assimilation chamber and monitor-ing device u.sed for '^C0> firation. .1; Coni-piV-ssed air with 300 mt;/l COg. B: Waterimbhter. C: Series nf sulfiiric nciil Imlihies.D: Constant temperature wiittT t)atti. E: Flowmeter. F: "CO^ generator rontaitiiniJ .Na^ '^ COasolution. G: Syringe ciuitainiiig 11(^ 1. tt: Cir-cutating water pump. !: Water jaeket of as-simitntion chnmber. J: Assimitation cliamberson upper and tower surfaces of Ivai. K: Ba-nana leaf. L: Coot-white fluoresccnl tubes.M: Infra-red CO2 analyzer. N: Strip chart re-corder. O: Exhaust to outdoors.

Material and MethodsThe following work employed leaves of Musa acuminata L. var. Hort. Gros Michel,

a commercially important variety.COo fixation. Two 1 cm holes were punched out with a cork horci in indi-

vidual leaves of greenhouse-raised plants. One hole covered a major vein, the othercovered minor veins. At designated times afterward, 0 hours to 10 days, the leafwas placed in an assimilation chamtior, as sliown in Figure 1. The plant was chirkenedfor 45 minutes prior to run to insure total stomatal closure. In the case of 0 hoursthe holes were punched out immediately after this dark period. The area contain-ing the holes was exposed to a humidified airstieam of 300 mg/t COo in air flowingat 0.5 !/min. The leaf wus lighted hy a hank of four cool-white fliioiescent tubes atc. 38,000 lux. When photosynthesis levelled to a .steady rate. 10 uc of ''COo was gen-erated into the airstream in small bursts over a period of 10 minutes.

At the end of the run, the exposed area was cut out from the rest of the leaf andradioautographed against a jjicce of X-ray film for 24 hours at -20".

Translocation. The same technique was used except that the holes were [junchedout immediately after exposure to "COo. Samples were taken at 24-hour intervalsafterward.

Results

CO2 fixation. The leaf sample exposed to "CO2 0 hours after punchingthe holes appeared to have hands of non-fixation as wide as the diametersof the holes extending from fhe niidrih lo Ihe leaf margin parallel to theveins (Figure 2.\). This effect persisled, Ihough with decreasing iulensily.through 24 hours after punching the holes (Figure 2B). Forty-eight hours

. Plant., 19. me

EFFECT OF SIMULATED CATERPILLAR DAMAGE 419

Figure 2. Rmiioautographs of leaf areas exposed to '*C02 at different times after piinchim/hote.i. A: 0 hours. B: 24 hours. C: 48 hours. I): 10 days.

alter punching' Ihe holes, this effect disappeared and a fairly unilorm fixa-tion pattern was apparent (Figure 2C). The experiments were followedthrough for 10 days with no reappearance of these bands of non-fixation(Figure 2 D).

Slight chlorosis appeared in an area at the margin of the leaf just belowthe holes after 4 days, hut there seemed to he no ohvious effect on Iheamount of CO2 fixation present.

A darkened leaf was exposed to "CO2 as a check. No fixation or adsorp-tion occurred.

Phvsiol. Plant.. 19.1066

420 BARBARA E. JOHNSON AND W. A. BRUN

R r e 3. Railinnuln(/rnphs of lenj areasluiri'cxlett tit (lifftTcnt times

EFFECT OF SIMULATED CATERPILLAR DAMAGE 421

The observation of a very marked area of non-fixation, such as occurredat 0 hours, might simply he catised hy tnlal stoniatal closure wilhiu Ihatarea. Iirun (2) found that cotuplele stomalal clo.siu'f was reached at about.'iO minutes alter the vascular system was interrupled hy culling. This appearsto he just what has happeiied here. The 30 minule lag period observed hyBrun is covered by the 45 minutes the plant, in this experiment, was in thedark prior to tbe riui.

By 24 hours ai'ltM' punching the holes, the appearance of spotty fixationin the affected area can probably he altributed lo a partial revival of sto-matal function. Samples at 48 bours and longer show apparent completerecovery of stomatal function. For tbis lo occur, alternate pathways of waterstipply mtist have been established.

Caterpillar damage in these .small areas only affects the immediatelydiuuaged area. The areas .surrounding Ihose holes completely recover theittnclions of stomatal movement and photosynthesis.

If the theories estahlished thus far are correct, it is fair to assume thatalternate pathways also are estahlished for the trauslocation of pholosyn-thates out of the leaf as has been ol>served.

More extensive work needs to he dune as to how nuu'h damage can heinflicted on the leaf and still have it recover function in all undamaged areas.

The presetit addresses of the authors are: liarliara E. Johnson, Department ofBotany, University of Hawaii, Honoluht, Hawaii and W. A. Brun, Departmenl ofAgronomy and Plant Genetics, University of Minnesota, LSI. PattI, Minnesota.

References

I. Brun. \V. A.: Photosynlhesis and transpiration from upper atid lower surfaces of in-lact baiijuui k-avcs. Planl Physiol. 3(3: ;!WI-405. 1961.

'2. Photosynlhesis and trans[)iration of haniina leaves a.s affected by severing the vas-cular system. Ibid. 36:577-r)80. 1961.

3. Harrison, J. O.: Notes on the life hislory and hahits of Ceramidia Imtlcri Moeschler,a pest of bananas. Ann. luitoni. Soc-. Amer. 52: ;S51-iir)4. 1959.

4. Merino, M., Merino, G. & Hernandez. D.: Efecto del toxiifeno en el comate de la orugade la hoja del hutiano, Ccraniidia viridis (Druce). Turrialba, Rev. Intcram,Ciencias Agr. 9:123-126. 1959.

5. - Iifecto del toxafeno en el control del caterpilar, Ceramidia viridis de la hojadel banano. Cienc. y Nat. 3:35-39. 19(iO.

P/iysiot. riant., 19, 1366