African Crop Science Journal African Crop Science Society ISSN: 1021-9730 EISSN: 2072-6589 Vol. 7, Num. 4, 1999, pp. 349-353

African Crop Science Journal, Vol. 7. No. 4, pp. 349-353, 1999

Effect of spacing, stage and method of desuckering on bunch size and yield of banana cultivar Kibuzi(AAA-EA)

M. Odeke, P.R. Rubaihayo and D.S.O. Osiru
Department of Crop Science, Makerere University, P.O Box 7062 Kampala, Uganda

Code Number: CS99025

ABSTRACT

Two experiments using banana (Musa sp.) cultivar Kibuzi were established to determine the effect of plant spacing, height of suckers at removal and method of desuckering on growth, bunch weight and yield. In the first experiment, cultivar Kibuzi was planted at recommended spacing of 3 x 3 m. Two suckers per stool were maintained and extra suckers were removed at heights of 300 mm, 500 mm and 1000 mm by digging them out or cutting the suckers at soil level. In the second experiment, cultivar Kibuzi was planted at spacings of 2.5 x 2.5, 3 x 3 and 3.75 x 3.75 cm giving plant populations of 1600, 1111 and 711 stools ha^-1, respectively. Plant height, pseudostem girth, both at 50 and 100 cm, and total number of standing leaves were significantly (P< 0.05) increased by desuckering at 300 mm while the method of desuckering had no significant effect on these growth parameters. Yield parameters were also significantly (P<0.05) influenced by stage of desuckering. The results also indicated that plant spacing and number of suckers retained per stool have no significant effect on height and pseudostem girth of the plant crop of bananas.

Key Words: Growth parameters, Musa sp., plant density, plant height, Uganda

RÉSUMÉ

Deux essais utilisant le cultivar Kibuzi ont été établis pour déferminer l’effect de l’espacement, la hauteur des rejets à l’enlèvement et la méthode de dedrageonnage sur la croissance, le poid/taille du régime et le rendement. Dans le premier essai, le cultivar Kibuzi a été planté à l’espacement recommendé de 3 x 3 m. Deux rejets par poquet ont été maintenus et des rejets supplémentaires ont été enlévés à la hauteur de 300 mm, 500 mm et 1000 mm en deterrant au niveau du sol. Dans le deuxième essai le cultivar Kibuzi a été planté aux espacements de 2.5 x 2.5; 3 x 3 et 3.75 x 3 cm donnant des populations de 1600, 1111 et 711 poquets ha^-1 respectivement. Les résultats indiquent que la hauteur de la plante, l’épaisseur de pseudo-tige, les deux à 50 et 100 cm, et le nombre total de feuilles ont augmenté significativement (P<0,05) par le deterage à 300 mm pendant que la méthode de déterrement n’a pas eu d’effect significatif sur ces paramètres de croissance. Les paramètres du rendement n’ont pas été influencés significativement (P<0,05) par le stade de déterrement. Les résults indiquent aussi que l’espacement des plantes et le nombre de rejets maintenus par poquet n’ont pas eu d’effect significatif sur la hauteur et l’épaisseur de la pseudo-tige des plants de banane.

Mots Clés: Epaisseur, paramètre de croissance, Musa sp., densité des plantes, hauteur de la plante, Uganda

Introduction

Banana (Musa spp.) is one of the most important food crops in Uganda, and is a staple food crop for over 7 million people (Gold et al., 1999). Despite its importance, banana yields have continued to decline due to poor agronomic practices, pests, diseases and the use of unimproved cultivars (Gold et al., 1999). Bananas are mainly sold as bunches and, to a lesser extent, as fingers yet the difference in prices between the large (>25 kg) and medium (20-25 kg) sized bunches is small (Mugisha and Ngambeki, 1995). This causes farmers who produce large sized bunches to lose income since they produce fewer bunches per unit area due to either wider spacing or fewer number of suckers left per stool. The medium sized bunches have an added advantage in that more can be loaded on trucks than large sized bunches.

Plant spacing, age/height of suckers to be removed and method of desuckering have a direct effect on bunch size as a result of inter- and intra-mat competition (Robinson, 1995). Stover and Simmonds (1987) reported that intra- mat competition is intensified when two or more suckers are allowed to develop and mature through creation of multiple sinks and intensification of root and rhizome competition for space, water and nutrients. They also suggested that bunch weight was decreased by 10-15% and harvest time increased by 3 weeks, when two suckers were left on a stool. The objectives of this study were to determine optimum spacing and number of suckers per stool that will give rise to the largest number of medium sized bunches, and to establish the best system of desuckering in order to achieve optimum yield of medium sized bunches for ratoon crops.

Materials and methods

The experiments were established at Makerere University Agricultural Research Institute, Kabanyolo (MUARIK) located at 0º28’N, 32º37’E and 1,150 m above sea level. The area has a bimodal mean annual rainfall of 1300 mm (Arnold, 1993) and has deep red tropical soils (Eutric Ferralsols) with a pH of 5.0 - 6.0 (Yost and Estwaran, 1990). Soil from the experimental plots was analysed before establishment of the experiment. The total amounts of P and K added were 22 kg P ha^-1 as SSP (granular form) and 226 kg K ha^-1 as KCl applied on a per mat basis and in split application at 6 month intervals.

In the first experiment, cultivar Kibuzi (AAA-EA) was planted at recommended spacing of 3 x 3 m. Two daughter suckers per stool were maintained and extra suckers were removed at heights of 300 mm, 500 mm and 1000 mm by two methods; digging (MD1) and cutting the sucker at soil level (MD2). The treatments were arranged in a split-plot design with three replicates. Method and stage of desuckering were assigned the main and subplots, respectively. Each subplot measured 9 x 9 m.

In the second experiment, cultivar Kibuzi was planted at spacings of 2.5 x 2.5, 3 x 3 and 3.75 x 3.75 m (1600, 1111 and 711 stools ha^-1, respectively), while 2, 3 and 4 suckers were maintained per stool. Extra suckers were removed at 300 mm height by digging. The experimental design was a split-plot with three replicates. Spacing was the main plot factor while number of suckers retained per stool was the subplot factor. The subplot size was 15 x 15 m.

Results and discussion

Soil analysis showed that there were nutrient deficiencies in both experiments 1 and 2 for Phosphorus (P), and potassium (K) and nitrogen (N) (Table 1). The critical values for these elements are 15.00 ppm for P and 0.44 m.e 100 g-1 for K. To meet the nutrient requirements of the banana plants 22 kg ha^-1 P (SSP) were applied in experiments 1 and 2 and 226 kg ha^-1 K (KCl) in experiment 2 during the long rains (March - July) of 1998.

Table 1. Nutrient level of the soil at the experiment site in Kabanyolo

Nutrient	Experiment 1	Experiment 2	Critical values*
Magnesium	1.40	2.23	< 0.88
Av.Phosphorus (ppm)	4.00	4.00	>15.00
Nitrogen (%)	0.18	0.15	> 0.20
Sodium (m.e/100g)	0.17	0.17	< 1.00
Potassium (m.e/100g)	0.50	0.15	> 0.44
Orgainc matter (%)	3.84	3.56	> 3.00
Soil pH	5.90	5.85	> 5.2

*Critical values as reported by Cottenie (1980), Tekalign (1991) and Anderson and Ingram (1993)

The effects of desuckering on banana growth parameters at 12 months after planting (MAP) are shown in Table 2. Plant height, pseudostem girth both at 50 and 100 cm, and numbers of functional leaves were significantly (P< 0.05) influenced by height of suckers at desuckering, with suckers desuckered at 300 mm consistently showing the best growth values and those at 1000 mm the worst. Delaying desuckering up to 1000 mm height enhanced intra-mat competition. Similar effects of intra-mat competition on growth and yield of banana have been reported by Stover and Simmonds (1987) and Robinson and Nel (1990).

Table 2. Effect of desuckering on selected growth parameters of banana plant at 12 months after planting

Desuckering stage	Growth parameters
	PH	G50	G100		LFNs		TLFNs
		(cm)	(cm)		(number)		(number)
T1 (300 mm)	223.3	51.9	42.5		7.6		10.1
T2 (500 mm)	217.0	49.4	39.9		7.3		9.8
T3 (1000 mm)	194.3	44.5	36.5		6.9		9.3
CV (%)	4.13	4.52	5.00		5.66		3.85
LSD (0.05)	11.65	2.93	2.64		NS		0.50

*PH, G50, G100 and LFNs are; Mean values for plant height, girth at 50 cm, girth at 100 cm and numbers of functional leaves and total number of standing leaves, respectively

Method of desuckering did not have significant effect on plant crop growth parameters (hence data not shown), although plants in MD1 plots tended to exhibit more vigorous growth compared to those in MD2. This was probably due to relatively low intra-mat competition in MD1 compared to MD2 treated plots, since MD1 involved digging out the entire sucker while in MD2 a sucker was cut at ground level and the rooting system left intact. Thus, plants in MD1 were still able to compete for assimilates, moisture and nutrients as they regrew, hence increasing intra-mat competition.

The yield parameters: bunch weight, weight of 2nd and 3rd hands, finger length and finger girth were significantly (P<0.05) influenced by the desuckering treatments (Table 3). This was attributed to more intra-mat competition for photosynthates and nutrients in plots desuckered at 1000 mm (T3) compared to 300 mm (T1). This is explained by the fact that finger girth and finger length (major determinants of bunch weight/size) were significantly (P< 0.05) reduced by delayed desuckering. Similar effects of intra-mat competition have been reported by Robinson and Nel (1990).

Table 3. Effect of desuckering on yield components during the plant crop cycle

Desuckering stage	Yield Parameters
	BWt	NHs	TNFs	HWt1	HWt2	HWt3	FL2	FG2
	(kg)			(kg)	(kg)	(kg)	(cm)	(cm)
T1 (300 mm)	17.9	7.7	126.1	2.70	2.90	2.60	18.6	14.1
T2 (500 mm)	16.7	7.5	123.8	2.70	2.60	2.60	18.0	13.6
T3 (1000 mm)	14.3	7.5	122.1	2.10	2.20	2.10	16.2	12.9
CV (%)	11.5	4.5	5.9	32.70	12.0	13.70	3.6	3.3
LSD (0.05)	2.50	NS	NS	NS	0.41	0.44	0.86	0.59

NS= Not significant at 5% probability level.
BWt, HNs, TNFs, HWt1, HWt2, HWt3, FL3 and FG3 are; Mean values for bunch weight, number of hands, total number of fingers, weight of 1st hand, weight of 2nd hand, weight of 3rd hand, and finger length and finger girth for the 2nd hand, respectively

The effects of the different spacings on growth prameters are shown in Table 4. All the growth parameters considered (except LFNs and TLFNs) were not significantly influenced by different spacing arrangements. The lack of influence of spacing on plant height, pseudostem girth could be attributed to mother plants of the plant crop cycle having no competition as the plants are exposed to sunlight for a greater part of their growth cycle and also minimum competition for nutrients, assimilates and moisture. Similar results have been reported by Obiefuna et al. (1982). Sauco Galan (1998) indicated that spacings of 2.0 x 3.0 m, 2.0 x 2.5 m and 2. 0x 2.0 m (giving plant populations of 1666, 2000 and 2500 plants ha^-1, respectively) with one follower per cycle had no significant effect on pseudostem girth, plant height, bunch weight, and number of hands during the plant crop cycle. However, significant differences were observed in the subsequent cycles (R1, R2, R3, R4 and R5). Lichtemberg et al. (1994) reported significant differences starting in the second ratoon cycle. Significant (P<0.05) values for TLFNs and LFNs were observed in this study. Similar results were reported by Robinson and Nel (1988).

Table 4. Effect of spacing on selected growth parameters of the plant crop at 12 months after planting

Spacing	Growth parameters
	PH	G50	G100	LFNs	TLFNs
2.50x2.50 m	208	46.5	38.5	4.47	7.69
3.00x3.00 m	206	45.9	38.8	4.52	8.22
3.75x3.75 m	216	46.9	38.9	5.69	7.19
CV(%)	5.09	4.49	5.22	5.52	6.40
LSD(0.05)	NS	NS	NS	0.35	0.55

*PH, G50, G100 and LFNs are; Mean values for plant height, girth at 50 cm, girth at 100 cm and numbers of functional leaves and total number of standing leaves, respectively

NS = Not significant at 5% probability level

The number of suckers retained per stool did not influence plant height, pseudostem girth, number of functional leaves and total number of standing leaves (data not shown). Similar results have been reported by Obiefuna et al. (1982) and Govea (1989) on mother plants. This was attributed to the fact that sucker emission occurs between the 5th and 6th month after planting by which time the mother plant has already achieved 70% of its total growth and therefore there is little influence of the treatments.

Conclusions

The results of the study have demonstrated the importance of desuckering in the management of banana plantations. Plant growth and yield were significantly influenced by stage of desuckering, while the method of desuckering did not have significant effect on growth and yield. Plants that were desuckered at 300 mm (early desuckering) consistently gave better results than those which were desuckered at 1000 mm (delayed de-suckering), suggesting the need to practice early desuckering.

The results have also indicated that plant spacing and number of suckers did not have significant effect on growth parameters during plant crop cycle due to minimum competition for growth resources.

Acknowledgement

The study was financed by the Rockefeller Foundation through Forum Grant RF 95007 # 75.

References

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