Rev. Biol. Trop., 44(3)/45(1): 23-28,1996-1997

Responses of sorne Nigerian vegetables to plant growth regulator treatments

�ukaila Kadiril, Fatimah Mukhtar2 & David Adejare Agboola' ,-

Department of Biological Sciences, University of Agriculture, Abeokuta, Nigeria. Department of Biological Sciences, Bayero University, Kano, Nigeria.

(Rec. 4-XI-1994. Rev. 24-VIII-1995. Acep. 18-1-1996)

Abstract: The effects of single and combined growth regulator treatments of indole-3-acetic acid (IAA), gibberellic acid (GA3) and coconut milk on plant height, yield, chlorophyIl and vitamin contents of Abelmoschus esculetus L and Solanum gilo L were investigated. The single growth regulator treatments consisted of 50mglL, l00mglL of IAA and GA3 and 10%, 15% of coconut milk. In case of combined growth regulator treatments, the treatments were 100mg/L IAA + 100mglL GA3,IOOmglL ¡AA + 15% coconut milk and lOOmglL GA3 + 15% coconut milk. Control vegetable plants were sprayed with water. Single treatments of lOOmglL IAA,IOOmglL GA3' 10% and 15% coconut milk result­ ed in significantly increased plant height, chlorophyIl contents and yield of A. esculentus, H. sabdarijJa and S. gilo while only conbined treatments of 100mglL IAA + 10% coconut milk and lOOmglL GA3 + 15% coconut milk had such an effect on A. esculentus and S.gilo but not on H. sabdarijJa. Moreover, singletreatments of IOOmglL GA3 and 15% coconut milk caused significantIy higher vitamins A, B6 and C contents of treated plants whereas the combined treatments produced such an effect on only vitamin C contents oi treated plants. Growth regulator treatments of 100mglL GA3 and 15% coconut milk were consistentIy the best out of the entire growth regulator treatments tried with the treated plants having the greatest plant height, yield, chlorophyIl and vitamin C contents.

Key words: Nigerian vegetables, plant growth regulators, plant growth, chlorophyll and vitamin contents.

Plant growth regulators are known to influ­

Gibberellic acid has been used to stimulate

ence growth and development at very low con­

stem and petiole extension in rhubarb, celery

centrations but inhibit plant growth and devel­

and water cress (Thomas 1976). Treatment of

opment at high concentrations (Jules et al.

radish and onion seeds with auxin or a mix­

1981). Plant physiological processes are under the

ture of gibberellic acid (GA 3 ) and kinetin have been found to increase the germination

control of growth regulators. Examples of these

of the seeds (Thomas 1976). Monthly foliar

are plant rooting and propagation, dormancy

spraying of geranium (Pelergonium grave­

initiation and breaking, promotion of flower­ ing, setting of fruit fall, regulation of plants'

olens) resulted in increased plant height and herb production (Mohammed et al. 1983). Spraying of datura plant (Dature innoxin)

chemical composition and mineral uptake from soil and conferment of resistance on plants

planted in different salinity concentrations

against pests and harsh environmental factors

with chlormequat, ethephon or kinetin was

(Nickell 1978).

found to enhance plant growth alkaloidal and

Recently, researches have shown the stimu­

soluble sugar contents of leave and reduce the

latory effects of growth regulators in the vege­

harmful effect of salinity on the plant (Abdel­

tative g r o w t h a n d y i e l d of vegetables.

Rahman & Abdel-Asiz 1983). Application of

24

REVISTA DE BIOLOGIA TROPICAL

gibberellic acid, 4-chloroindole and 6-benzyl aminopurine on to the standard petal and calyx of Vicia faba varo major before or after tripping was found to significantly enhance pod set (Rylott and Smith 1990). Likewise, spraying of Vicia faba cv. Troy reproductive structure with indole-3-acetic acid, gibberellic acid or 6-ben­ zylaminopurine resulted in increased pod num­ ber (Clifford et al. 1992). In N igeria, spraying of vegetables with growth regulators to enhance their vegetative growth and yield is currently not being prac­ ticed. This is due to lack of informatíon on the optimum concentrations of growth regulators that could be used to enhance vegetables '

bIes. These were single and combined growth regulator treatments. The single growth regula­ tor treatments were IAA and GA3 (50mglL and 100mg/L) and coconut milk (10% and 15%) while the combined growth regulator treatments were based on the best results obtained from pro­ motional effect of single growth regulator treat­ ments on the vegetables. For the three vegetabJe types, the combined growth regulator treatments given were: 100mg/L IAA + 100mg/L GA3 ' lOOmglL IAA + 15% coconut milk and lOOmgIL GA3 + 15% coconut milk. For both the single and combined growth regulator treatments, 30ml of the various concentrations were applied on the planted vegetables by foliar spraying of 4 doses

growth and yield. The present study aims at

at 2 week-intervals commencing from 2 weeks

bridging up such an information gap with respect to three tropical vegetables; namely,

after sowing. The control vegetable plants were sprayed foliarly with 30ml water also applied in

Abelmoschus esculentus (Okra), Hibiscus sab­

4 doses at 2 week-intervals starting from 2 weeks

dariffa (sorrel) and Solanum gilo (egg plant).

after sowing.

Abelmoschus esculentus and H. sabdariffa are cultivated for their mucilaginous pods, young leaves and shoots which are eaten as cooked vegetables in soups and H. sabdariff a Calyx

Effeds of growth regulator treatments on plant height

that is used in preparing a refreshing beverage (Tridall 1983, Ughorogho & Shofoyeke 1983).

Chlorophyll content and yield: Sampling

Salanum gilo is cultivated for its fruits and

of the treated vegetables and controls was car­

leaves which are eaten raw as vegetables and

ried out at 9 weeks after sowing. Plant heights

for the seasoning of other foods (Yoyock et al.

w e r e measured using a metre rule. Fresh weights of the fruits produced by the treated

1988).

and control plants of A. esculentus and S. gilo were recorded in 3 replicates and the averages MATERIALS AND METHODS

Planting of seeds: Seeds of A. esculentus,

taken. Leaves of treated and control plants of H. sabdariffa were harvested and the chloro­

phyll extracted using 80% acetone. The chloro­

H. sabdariffa and S. gila were sown on seper­

phyl1 contents were determined by following

ate prepared beds at 4 seeds per hole. There

the method of witham et al. (1971).

were seven beds of 2 x 2m each per vegetable of 2 x 2m each per vegetable for the combined

Effects of growth regulator treatments on vitamin contents: Fruits of treated vegetables

for the single hormonal treatments and 4 beds treatments with a distance of 0.5m in between

and controls were harvested at 9 weeks after

beds. the number of beds were replicated thrice

sowing, dried in an oven at 80°C for 48h,

and weeding was carried out regularly. During

ground into powders and the powders used for

the study period, the land area of the prepared beds had a mean temperature of 30 ± 3°c, rela­

analysed using the method of Beols and Troet

vitamins content determination. Vitamin A was

Growth reguiator treatments: The growth

(1959) by boiling 19 powder sample with a mixture of 30ml ethanol and 3ml 85%KOH for 30mins. Vítamin B analysis was carríed out 6 according to the method of Heochberg, Melnic

regulator employed in the experiment were indole- 3 -acetic acid (IAA), gibberellic acid

hydrolysed with 4N HCL in a boiling-water

tive humidity of 58 ± 10% and average day length of 12.5 ± 0.5h.

(GA3) and coconut milk. Two types of growth regulator treatments were given to the vegeta-

and Oser (1944) in 19 powdered samples being b a t h for lh. T h e c o louring d y e w a s 2 , 6 dichloroquinoquinoechloroimide reagent which

M. Kadiri et aL: Nigerian plant growth

complexes with pyridoxine at pH 5.7 to form reddish brown chromophore that absorbs at

25

chlorophylls a and b contents (Atanasiu et al 1983). Singh et al (1984) likewise obtained sig­

620nm. The determinantion of vitamin C was

nificant increase in the number of grains per

carried out using the method described by Lambert and Muir (1983) by 500mg of each

panic1e, % filled spikelets and yields of rice sprayed at anthesis with kinetin and IAA.

completely

Stuart and Cathey ( 1 9 6 1 ) explained t h a t

homogenised in lOml of 4%HCL in a blender.

increases i n plant height b y growth requlator

powdered

sample

being

The colouring dye was 2,6-dichloroindophenol

treatments are due to the fact that they enhance

which on titration forms a pink colour with

stem elongation of plants.

Vitamin C.

Plants of A. esculentus and H. sabdariffa treated with lOOmg/L GA3 and 15% coconut

RESULTS AND DISCUSSION Significant increases in plant height and

milk had significantly higher vitamins A, B 6 and C contents than the control plants (Table 3) . Similar result of increased total soluble sugar content in leaves of Datura innoxia treat­

yield were observed in A. esculentus and S. gilo

ed with varied concentrations of chlormequat

gi ven single treatments of IOOmg/L IAA,

and ethephon was observed by Abdel-Rahman & Abdel-Aziz (1983). Dybing & Lay (1982)

IOOmg/L GA3' coconut milk and combined treatments of lOOmg/L IAA + 15% coconut

found that application of growth regulators on plants improves the plants' quality in terms of

milk and 100mgIL GA3 + 15% coconut milk (Tables 1 and 2 ). R esults of significantly

oil, latex, sucrose and protein contents, fruit

increased plant height and chlorophyIl content

colour and fatty acid composition.

were also obtained for H. sabdariffa given sin­

The combined growth regulator treatments

gle treatment of 100mgIL IAA, gibberellic acid

of the v e g e t a b l e s resulte d in significant

anc coconut milk (Table 1). Similar results of

increases in only the vitamin C contents of

plant height stimulation were observed by

the vegetables (Table 4). Of all the growth

Currah & Thomas (1979) upon application of

regulator treatments applied on A. esculentus.

lOOmg/L GA 3 on carrot plant. Spraying of

kinetin on Datura innoxoa plant at 1 mg/L,

H. sabdariffa and S. gUo. 100mg/L GA3 and 15% coconut mil k treatments consistently

5mg/L and 10mg/L was f o u n d to cause

p r o d u c e d p l a nts w i t h t h e g r e a t e s t p l a n t

incresed vegetative growth (Abdel-Rahman & Abdel-Aziz, 198 3) . Similarly, GA3 spraying

was found to stimulate production of flowers in

lettuce (Metzger 1988). Biddington & Dearman

height, yield, chlorophyIl and vitamins con­

tent (Tables 1,2, 3 and 4). The possible rea­ sons for this could be that GA3 induces cell elongation and coconut milk is a crude source

(1987) also observed that GA3 application increased the growth of bean and leaf length of

of cytokinin and therefore a cell division pro­

lettuce. The auxin, naphthoacetic acid and the

coconut milk is being reported to have a

moter. This is probably the first time that

c y t o kinin, 6 -b e n zyl-amino-purine when

growth promotion effect when sprayed on

sprayed onto the open flowers Solanum melo­

plants. The significance of the present study

gena either singly or in combinatíon were like­ wise observed to increse the number of fruit set

is that single treatments of lOOmg/L GA3 and 15% coconut milk could be used to spray A.

as w e l I as t h e total weights of the fruits

esculentus, H. sabdariffa and S. gUo in order

( O Iympios 1976 ) . Spraying of kinetin o n

to enhance their vegetative growth, vitamins

Chlorella vulgaris 1 5 7 was found t o increase

content and yields.

RE VISTA DE BIOLOGIA TROPICAL

26

TABLE l

Mean plant height (cmlplant), chlorophy/l contents (mg/g fresh leaj) and yields (g fresh fruitlplant) of A. esculentus, H. sabdariffa and S. gil0 given single treatments of various concentrations of 1M, GA, and coconut milk at 9 weeks afier sowing

Treatment

A. esculentus

S. gilo

H. sabdariffa

(mg!L)

Plant height

Yield

Plant height

IAA (50)

15.8cd

14.Od

37.7e

IAA (lOO)

18.3C

19.9b

GA 3 (50)

24.2b

GA3 (lOO)

Plant height

Yield

0.61e

13.8d

8.8e

38. 3e

O.72b

22.6ab

15.5ed

54.2b

0.76b

21.6b

45.3a

17.Oc

56.2ab

0.91a

17.7e

15.4a

10% Coeonut milk

19.9be

19.2b

55.8ab

0.91a

17.7e

15.4a

15% eoconut milk

23.3b

26.4a

60.9a

1.08a

24.5a

17.3a

Control (water)

12.5d

7.6a

25.9a

0.6Oc

7.6e

6.4d

Chlorophyli eontent

11.4b 9.8be

Means followed by the same letter(s) within any column are not significantly different at p= 0.01 by Dunean's Multiple Range Test.

TABLE2

Mean plant height (cmlplant), chlorophyll content (mg/g fresh leaj) and yield fruitlplant) of A. eseulentus, H. sabdariffa and S. gilo given combined treatments IAA, GA3 and coconut milk (CM) at 9 weeks afier sowing

Treatment

A. esculentus

H.sabdariff

S. gilo Plant height

Yield

0.86b

15.6b

8.9b

25.3a

0.91ab

21.0a

1O.8b

16.1a

26.6a

l .02a

23.7a

12.9a

7.6c

24.4a

0.6Oc

8.Oc

6.4e

(mg!L)

Plant height

Yield

Plant height

IAA (lOO) + GA3 (lOO)

20.6b

9.5b

24.2a

IAA (100) +15% CM

21.1b

15.4a

GA3 (lOO) + 15% CM

25.7a

Control (water)

12.2e

Chlorophyll eontent

Means followed by the same letter(s) within any eolumn are not signifieantly diffe�nt at P = 0.01 by Dunean's Multiple RangeTest

M. Kadiri et aL: Nigerian plan! growth

27

TABLE 3

Mean vitamins A. B6 and e contents (mg/100g dry malter) offruits of A. esculentus. H. sabdariffa and S. gilo given single treatments of lAA. GA3 and coconut mi/k al 9 weeks after sowing Treatment

A. esculentus

H.sabdariffa

S.gilo

(mglL) Vit.A

Vit.B6

Vit.C

Vit.A

Vit.B6

Vit.C

Vit.A

Vit.B6

Vit.C

52.8b

14. 1a

38.8ab

37.4c

IAA (lOO)

5.2b

13.9b

41.8c

2 1.6b3

GA3 (lOO)

5.8b

18.5a

53.6b

22Aab

37.6a

S9.lb

14.7a

39Aa

70.0b

15% Coconut milk

8.3a

18.6a

68.8a

2S. l a

38.9a

74.2a

lSAa

43.9a

80.Sa

Control (water)

S.Ob

12Ab

3 1.Sd

l S.7c

33.7b

34.Sc

14.0a

34.5b

35.8c

6. 1ab

Means followed by the same letter (s) within any colurnn are not significantly different at P Range Test.

=

0.0 1 by Duncan's Multiple

TABLE4

Mean vitamin A. B6 and e contents (mg/lOOg dry matter) offruils of A. esculentus. H. sabdariffa and S. gilo coimbined treatments of 1AA, GA3 and coconut mi/k (cm) al 9 weeks after sowing Treatment

H. sabdariffa

A. esculentus

S.gila

(mg/L)

Vit.A

Vit.B6

Vit.C

Vit.A

Vit.B6

Vit.C

Vit.A

IAA (l OO) + GA3 (lOO) IAA (lOO) + 15% CM

S.Oa

12.4c ISAb lS.Oa 12.4c

40.2c SO.4b 62.5a 3 1.5d

lS.8a 16.2a 16.7a 15.7a

33.8a 34.9a 3S.Sa 33.7a

43.5b SS.Oa S6.3a 34.5c

14.0a 14.8a lS.Oa 14.0a

GA3 (lOO) + 15% CM Control (water)

S.2a SAa 5.0a

Means followed by the same letter(s) within any colurnn are not significantly different at P Range Test.

'"

Vit.B6 34.8b 38.Sa 4O.6a 3 4.5b

Vit.C 36.9c 60.4b 75.6a 35.Sc

0.0 1 by Duncan's Multiple

REVISTA DE BIOLOGIA TROPICAL

28

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