MARDI Res. Bul l . (1986) I4( l ) , 47-51

DEVELOPMENT OF CUCUMBER SEED FROM FLOWERING TOMATURITY

A.S. HALIMATHUL SAADIAH* and B, JUNAIDAH*

Keywords: Seed moisture content, Germinability, Seed length, Seed dry weight,Development, Physiological maturity.

RINGKASAN

Kaj ian pembentukan bi j i t imun (var iet i MTi 2) tc lah di ja lankan. Bunga-bunga di tanda dan buahdipet ik sc lang schar i schingga buah matang. Si fat-s i fat yang dikaj i termasuk kandungan kelembapanbi j i . keupavaan bercambah, panjang dan bcrat b i j i ker ing. Kematangan f is io logi d idapat i ber laku 31 -

33 har i selepas per ingkat bunga dan pada kandungan kelembapan 38 pcratus. In i merupakan masa yangpal ing baik untuk kut ipan bi j i benih sctc lah mengambi l k i ra corak pembentukan bi j i dan faktorkerosakan di ladang. Bi j i segar mempunvai kcupayaan percambahan l7 har i selepas berbunga dancorak percambahan menunjukkan kewujudan masa rehat .

INTRODUCTION

Harvest date has great influence onseeds during processing, storage quality andf ie ld emergence. The seeds should reach ther ight s tage of matur i ty at harvest to ensuregood qual i t l ' and establ ishment af tergerminat ion. Considerable number ofstudies on seed development andmaturat ion had been carr ied out on qrasses(Mncl- rsren. l t )43; Gnngr, . 19,56) and gra incereals (Hnnln l and Popr. . 1922; Bnnrr- r - ,1941 ; A lon rc r . 19 ,13 : Fnev . Rue l andWIccRxs. 19-58) . Simi lar s tudies had a lsobeen done on seeds of cot ton (Sl tutpsclx .1935 : JnuEs and SAN{ rR Aenp l -A r . . 1965 :TuracRnR. laN and R,r r . rRSanrv. 1979).saf f lower (Lr ' r . - t rc ; r -n and URrE. 1964). feu 'f o res t spec ies (Bnn re l . 1912 : 1971 .BoNNTER, 1976 ) . r ubbe r (Se rHreuN. CHINand Hon . 1981 ) . l ong bean (CHtx . 1981 )and ok ra (CHnuHeN and BHnNo ,A ,n r . l 97 l ) .From these studies. var ious factors had beenfound to be associated wi th maturat ion.Thev were seed moisture content , seed s ize,dry mat ter content and germinabi l i tv .Alnntcu (1943) in h is s tudies on corn foundthat drv mat ter weight of the gra in was thebest cr i ter ion of re lat ive and actualmatur i t ies in corn. On the other hand.BoNNER (1916) observed that atphysio logical matur i ty . as indicated by,

normal germinat ion, carbohydrate contentin acorns of shumard and whi te oaks was25Vc and 407e respectively.

The understanding of events tak ingplace dur ing seed development andmaturat ion would be verv usefu l in seedoperat ions. This would be an advantage indecid ing the r ight s tage or t ime to harvestfor h ighest seed v ie ld and qual i ty ' .In format ion is lack ing for vesetable seeds assuch th is s tudv was conductecl to c tbta ininformat ion on the devclopment andmaturat ion of cucumber seed.

MATERIALS AND METHODS

Cucumber (var ietv MTi 2) was f ie ldplanted in December 198;1. The seeds usedwere taken f rom foundat ion seed lotor ig inated f rom breeder seed obta ined f romMARDI S ta t i on , Ja lan Kebun . Ke lang .Cul tura l pract ices as recommended byMARDI were fo l lowed. On 11 Januar l ' 198,5about 300 freshly opened female flowerswere randomlv tagged to a l low per iodicharvest of developing f ru i ts unt i l matur i tv .The first harvest was done on the fifth davafter tagging. Three fruits were harvestedon a l ternate dav for a durat ion of s ix weeks.On each harvest. seeds from the three fruitswere extracted and pooled. Samples were

*Central Rescarch Laborator ies Div is ion, MARDI. Scrdanq. Selansor. Malavsia.

47

taken for subsequent maturity tests andmeasurements. Fresh and oven-dried seedswere tested for germination according to theprocedures recommended in ISTA rules(ANoN., 1985). For moisture determinat ion,seeds were oven-dried at 105'C for 24 hoursand moisture content was computed fromthe differences in weight before and afterdrying and expressed as a percentage of theoriginal wet weight of the seeds. For drymatter weight, sample consisting of 30 seedswere placed in the oven at 105'C for 24hours. The seed length was obtained fromthe average measurement of 30 seeds. Alltests and measurements were replicatedfour times. At every harvest, the skin colourof all the fruits were also recorded.

RESULTS AND DISCUSSION

Five days after the flowering stage, thedeveloping seeds had very high moisturecontent of above 90% (Figure 1). As theseeds developed the moisture content

rc< Seed length

.+ Seed moisturc

r--+--r Seed drv weisht

decreased gradually unti l the 25th day, afterwhich it remained quite constant throughoutthe rest of the development. This trend wasalso observed in other seed types. In a two-year study on sorghum seeds, KEnsrtruc,Srrcr lnn and Pnulr (1961) repor ted thatthe moisture content was above 80Vo afterpoll ination and dropped to below 207o, 50days later. Similarly in corn, the seedmoisture content was 74.3Vo 20 days afterferti l ization and by the time of huskingwhich was 123 days after anthesis, it haddecreased to 22.17c (KoEslEn. Dur. rcuNand BunusoN, 1934).

Seed length increased very rapidly inthe first nine days after f lowering to reach10.48 mm long and then remained wi th inthe range of 10.48 - 13.50 mm (Figure 1) .Drv matter accumulation began to increaseonly after the seed had attained its maturedsize. This increment was gradual and themaximum was reached about 31 - 33 daysfrom flowering (Figure I ). SHaw and

( , . f J

' 6

rl 6 5'5

a

EE

c

;0 . J

9 1 1 1 3 1 5 1 7 1 9 2 1 2 3 2 5 2 7 2 9 ) 1 3 3 3 5 3 7 3 9 4 t 4 3

Days after flowering

Figure 1. Development of cucumber seed at various intervals from flowering.

Loovls (1950) in their works on corndescribed development at this point as thephysio logical matur i ty .

Some of the seeds were found to becapable of germination 17 - 21 days afterflowering. The abil ity to germinate beforephysiological maturity was also observed inthe other seed types. Seeds of barley(Hnnren and Popa, 1922) and bromegrass(Gnnee, 1956) could germinate as early asfive days after poll ination. In this investiga-tion, it was found that the germinationcurves for both dried and fresh seedsshowed similar pattern (Figure 2). Therewere sudden r ises in germinat ion percentageon the 21st and 23rd day for the dried andfresh seeds respectively, reaching the peakon the 25th day after f lowering. At thispoint, 90o/o of the seeds had germinated.However, the germination dropped sharplyafter the 25th day and by the 33rd day, lessthan I07o of the seeds had germinated. Thisphenomenon had not been reported in thematuration studies of other seeds in theliteratures reviewed. The ungerminatedseeds did not show any sign of death ordisease. Lost in the abil ity to germinate inthe seemingly viable seeds suggested thepossible occurrence of dormancy. One of

the possible causes of dormancy isimpermeabil ity of seed coat. Dormancy ofthis nature was reported to be caused bycutin deposit in the nucellar layer of theseed coat of watermelon (TuonNroN, 1968)and suberin deposit in the testa of grasses'seeds (ANoN., 1969). Impermeabi l i ty couldbe due to gases or water. Another l ikelyexplanation for the cause of seed dormancyis chemical inhibit ion. Presence or suddenincrease in the level of inhibitor might haveprevented the germination process. Furtherinvestigation should be carried out todetermine the real cause of the dormancv.

It is a well established fact that atphysiological maturity, seed would be at itshighest vigour. Safflower seed was found tobe physiologically matured at 28 days afterflowering and at thrs stage it also hadmax imum pe rcen tages o f o i l . ge rm ina t i onand iodine number (LErNlNcen and URrE,1964). However, at physiological maturity,seed moisture content is too high forharvesting as in cotton (56%) (JnuEs andSnvrn AnneL-AL, 1965), okra (56%)(CHauHnN and BHnruoenr, 1971) andbromegrass @7Vo) (Gnnne, 1956). Seedsharvested at too h igh a moisture contentcould increase the cost and time of drvins.

100

\a

. E 6 0E' =trL

lo 40

a

a

Days af ter f lower ing

Figure 2. Germination of cucumber seed at various intervals from flowering.

0 17 19 2t 23 25 2't 29 31 33 35 37 39 41 43

For this reason these seeds are normallyallowed to dry on the plant to below 30%moisture content before they are harvested.In th is s tudy, the moisture content ofcucumber seed at physiological maturity was38Vo (Figure 1) and remained quite stablethereafter. Perhaps the seed moisture wouldnot drop fur ther or would take a long t imeto do so as the seeds are embedded in themucilage and surrounded by the juicy

mesocarp. It is thus no advantage in thiscase to delay the harvest beyond the point ofphysio logical matur i ty . Fur thermore at th isstage, the fruit could be very heavy (up to 1kg) and unless good support is g iven. i twould end up rest ing on or touching theground and become rotten, thus delayedharvest would l ike ly increase the loss.However, the germinat ion percentage at thepoint of physiological maturity was as low asl07o and thus the seeds harvested could notbe used for immediate sowing. Themaximum seed germination (90%) occurredon the 25th day after f lowering (Figure 2)and before the attainment of maximum dryweight . These immature seeds, thoughhaving good germinat ion would l ike lyproduce weak and less vigorous seedlingsthat have poor chance of survival under lessfavourable environment. Another dis-advantage of harvesting at this point is thehigh moisture content of seed (52%) whichcould give rise to drying problems.

AI.DRICH, R.S. (1943). Matur i ty measurements in cornand indicat ion that grain development cont inuesaf ter premature cut t ing. " I . Am. Soc. Agron. 35,667 - 80.

ANoN. (1969). Report of the grass seed sub-commit tee.Proc. Ass. Off. Seed Analysts N. Am. 59,20.

In conclusion, taking into account seedmoisture content, germinabil ity and risk off ie ld deter iorat ion, the best harvct ing t imefor cucumber seed would be 31 - 33 daysafter f lbwering at the point of physiologicalmaturity. At this stage, the fruit would bedark brown with lots of netting pattern onthe skin surface (Table 1). Seeds obtainedcould be dormant and that after - ripeningor treatment would be required to break thedormancy before the seeds could be used forsowing.

Table 1. Changes in the skin colour of thedeveloping cucumber fruit

No. of days

from flowering

Fruit colour

5

7

9 , 1 lt ? t (

1 7r o , r ) 1 ) 5 ) 71 q 1 l 1 1 1 5 1 7

39. .11

Green

Whit ish green

Green wi th l i t t le yel lowing

Yel lowish green

Brownish yel low

Brown wi th l i t t le net t ing pat tern

Darke r brown wi th net t ing pat tern

al l ovcr the f ru i t

ABSTRACT

The development pat tern of cucumber seeds (var iety MTi 2) was invest igated. Flowers weretagged and harvest ings were carr ied out at one day interval unt i l f ru i t matur i ty . Characters studiedincluded seed moisture content , germinabi l i ty . seed length and seed dry weight . I t was found thatphysio logical matur i ty was reached 31 - 33 days af ter f lower ing at moisture level of 38 per cent . Thiswould be the best t ime to do harvest ing for seeds, af ter consider ing var ious developmental pat terns aswel l as r isks of f ie ld deter iorat ion. Fresh seeds were capable of germinat ion l7 days af ter f lower ing butthe germinat ion pat tern suggests the occurrence of dormancy.

REFERENCES

ACKNOWLEDGEMENT

Appreciat ion is extended to Dr. ChewBoon Hock. Co-ord inator of Plant ScienceUni t for construct ive comments on themanuscript.

- (1985). The germination test. Seed Sci. &Technol. I3(2), 421 -63.

Benre l , A .T . (1941) . Green seeds in immature smal lgrains and their relat ion to germination. J. Am.Soc. Agron.33,732-8.

50

- (1972). Maturat ion of sweetgum and American

sycamore seeds. Forssa Scl . 18. 223-31.

- (1974). Maturat ion of acorns of cherryback.

water and wi l low oaks. Forest Sci . 20.238 12.

BoNNER, F .T . . ( 1976 ) . Ma tu ra t i on o f shumard and

whi te oak acorns. Fbre. i / Sci . 22 (2) . 1,19 -5-+.

CHer - r s rN . K .S . and Bu r : . rDaR t . Y .M . ( 1971 ) . Pod

development and gcrminat ion studies rn okra.

Indian J. agr ic. Sci . 41,852-6.

Cu rN , H .F . ( 1981 ) . The e f f ec t o f t imc o f ha rves t i ng on

seed storabi l i ty ' and subsequent performance of

long bean. Acta Hort ic t t l turae l l I .249 53.

FRr - - y . K . J . , RUAN and Wt r ; t ; rNs . ( 195 f i ) . D ry we igh t

and germinat ion of developing oat sceds.

Agron. 1.50. 2,+8-50.

GnAeE . D .F . ( 1956 ) . Ma tu r i t y i n smoo th b romeg rass .

Agron. J. / t8.253-6.

H rn le r . H .V . and PopE . M .N . ( 1922 ) . The ge rm ina -

t ion of bar ley seeds harvested at d i f fercnt stagcs

of growth. J. Hered.13, 72-5.

J r v r s . D .H . and S ,qv l n ABDET- -A t - . M . ( 1965 ) . Somc

aspects of seed and bol l maturat ion in cot ton.

Proc. Ass. Off. Seed Anal,v-sts N. Am. 55, 151-

62.

Kers t i ng . J .F . , S r t cx r r . n . F .C . and Peu l t . A .W.(1961). Grain sorghum caryopsis developmcnt

1. Changes in drv weight . moisture perccntagc

and v iabi l i ty . Agron. J. 5J. 36-8.

KoEn ren . B . . DuNc t ' x , G .H . and BL rR l . t soN . W.L .( 193.1) . Matur i ty of seedcorn in re lat ion to

yie ld ing abi l i tv and disease in infect ion. J. Arn.

Soc. Agron. 26,267-74.

LE rNrNcF .R . L .N . and Un r - , A .L . ( 196 .1 ) . Deve lopmen t

of safflower seed from flowering t() maturit\'.

C rop Sc i . 4 , 83 -6 .

Mecl-rsren. D.E. (1913). The ef fect of matur i ty on the

viabi l i tv and longevi tv of the seeds of Wcstern

range and pasturc grasses. J. Am. Soc. Agron.

35 .442 -53 .

SaxHreux , M .H . . Cu t x . H .F . and Hon . Y .L . ( ' l 98 ' l ) .

Frui t and seed development in Hevea (Clone

RRIM 600) in Malaysia. J. Rubb. Res. Inst .

M alal-sia 29(2). l0l - 10.

SHau . R .H . and Lo t - r v t s . W .E . ( 1950 ) . Bases f o rprediction of corn yields. Pl. Pht'siol. 25, 225

S tnpsoN . D .M . ( 1935 ) . Do rmanc l ' and ma tu ra t i on o f

cot ton seed. J. Agr ic. Res. 50.129-34.

Ture.c j , rn,r :e.N. C.P. and Rntutes,qv ' r . K.K. (1979).

Studies on seed maturat ion in twct short durat ion

cotton var. MCU 7 and PRS 72. Seed Researt'h

7(2). 87 -et .

TsonNroN. M.L. (196U), Sccd dormancv in watcr-

mclon. Ci t ru l l is Vulgar is Shrad. Prac. Ass. Of l .

Seed Anal , -sts N. An. 58. 80-.1.

Accepted for publication on 15 January 1986

) l