Cultivated bananas (dessert, cooking, beer bananas and plantains) are a food source for millions of people around the world. Its cultivation spans over 120 countries from the tropics and subtropics across five continents and is not only a staple food for over 400 million people in developing countries of the South America, Southeast Asia and Africa, but also a real source of income [1].

Its cultivation predominates in the lowlands of the humid tropics of Africa, including the Democratic Republic of Congo, Congo Brazzaville, Gabon, Cameroon, Nigeria, Ghana, Ivory Coast, Guinea and Liberia. Over 90% of bananas produced in Africa are consumed locally [2].

However, serious parasitic threats currently weigh on the production of this crop. Among these threats, fungal diseases, bacterial diseases, nematodes, viral diseases and insects are reported in banana growing areas and have a considerable impact on production. To this end, it is reported that viral diseases occupy the first place in the drastic drop in the yields of banana cultivation. The low yields in Africa are explained by the attacks of pests and diseases that affect banana cultivation. Parasites and pests reduce yields by their action on growth, on the number  of  productive  plants  and  on  the quality of fruits, even make part and all of the harvest unfit for consumption. They can even prohibit the cultivation of a variety or a plant species in a given region [3]. Viral diseases are always generalized infections of the plant, except for the meristems. They are transmissible by plant material and in particular during in vitro multiplication, if drastic precautions are not implemented. However, transmission can occur easily from reservoir hosts and vector agents [3].

Bananas (Musa spp) play an important role in food security in the Democratic Republic of Congo [4]. It constitutes the fourth major fruit harvest in the world after citrus fruits and apples [3]. From a production point of view, banana comes second after cassava [5]. However, in the east of the country, bananas occupy the first place in terms of production with 85% of the total production of fresh material, followed by cassava and beans [6].  In 2015, the production of bananas and plantains in the DRC was estimated by the FAO at 1,528,690 tons, including 322,000 tons for bananas, a decrease in production. The total cultivated area is 600,000 hectares with an average yield of around 3 tons per hectare; this production still remains very low compared to world production [7].

In mountainous Kivu, bananas are produced in the hut system and play a major role there from a social, cultural, environmental and economic point of view. That is to say, in traditional compost pits placed around the hut receiving household waste for soil fertilization. Local beer drawn from bananas generates money for the benefit of agricultural farmers, facilitates all customary ceremonies in the village, including events of weddings and mourning [8]. And the research results indicate that in the African Great Lakes region, and under good conditions, 30 to 40 tons of bananas per hectare per year can be produced [8]. Banana tree occupies the first place in terms of cultivated area [6]. Although the yield of bananas is still low, production varies between 4 and 10 tons per hectare per year. Among these threats we find bacterial (bacterial wilt), fungal, viral diseases, nematodes and pests such as weevils (Cosmopolites sordidus) are reported in cultivation areas and have a considerable impact on decreasing the production of the banana [9]. The presence of black Sigatoka or black leaf streak disease causes a 30 to 40% reduction in yield [7] and bacterial wilt disease completely affected the banana plantation [8].

The lack of improved propagation materials of good quality and in sufficient quantity. The use of healthy and sufficient planting material is a major factor limiting the promotion of the cultivation of bananas and plantains. However, tissue culture allows the production of healthy rejects in sufficient quantity. The high cost (plus at least one dollar per seedling) of reject produced in vitro limits access to small farmers [10]. The technique of seedlings from fragments (PIF) or macro propagation is a simple and less expensive technique for the rapid and mass production of banana shoots. The corm (Cormus) will be cut into quarters. The stump shards are placed on a light, well-drained substrate in a container called a propagator. The burst of strain will give rise to one or more suckers, two to three months after they are propagated. These vegetative propagated products or clones are genetically and vigorously similar to the plant from which the starting strain was used. The plants thus produced are extracted from their substrate. They are individualized and weaned from the burst of strain from which they originate [11].

Banana cultivation is practiced in the study environment, in particular the Cirunga group in Lwami. It is subject to attack by bacteria constituting, not only a brake for the overall security of the soil, but also for the economy and social life of the peasants. In addition, this problem is aggravated by the fact that the propagation of bananas is done exclusively by sucker’s ie n limited number of suckers per plant due to the apical dominance which exists in the banana tree.

The overall aim of this research was to improve banana production in South Kivu in general. Specifically, to assess the growth rate of bananas multiplied and weaned in situ with macro propagation located at Lwami in the Cirunga area and to determine the number of banana suckers and leaves ex situ in the study environment.

Study area

The Lwami site is an improved seed multiplication center belonging to the Provincial Inspectorate of Agriculture and dating from the metropolitan era. It is located in the Cirunga area, Kabare chiefdom, Kabare territory (Latitude: 2° 30′ and 2° 50′S, Longitude: 28° 45′ and 28° 55′E, South-Western of the Kivu Lake) at the South Kivu province, eastern part of DR Congo).  The study area Lwami is limited in the North by Bushwira, to the south by the Bugobe, to the east by the municipality of Bagira and in the West by the chiefdom of Nindja. The Cirunga group includes the following streams Kagulye, Nyakakungudwe, Cicongo, Mana and  Nshenshero. The relief of the Cirunga area includes valleys. It is characterized by an average altitude of 2,250 m of cold climate, with natural vegetation made up of wild grasses.

Biological Material and Substrates

The banana bulbs came from Minova, in Kalehe territory, in disease-free pilot fields, set up by the Provincial Inspectorate of Agriculture of South Kivu, with funding from the ICRC / BUKAVU, from 2012 to 2017. The characteristics of the varieties used in this work are presented in Table 1.

The substrates used for this work are humus and manure from the Kabare Pilot Agricultural Farm (FAP) while sawdust is provided by the carpentry workshop Located in Muhungu la Voix. The substrate is prepared in advance; the humus has been mixed with manure of organic matter composed of 6: 3 is preferable i.e. 6 Kg of humus against 3 Kg of manure (Figure 14).

Table 1. Characteristics of varieties

The mixed substrate is sterilized for 12 hours in a drum. After sterilization, the substrate should cool for 24 hours before use in the propagator.

The hotbeds are built under 50% shade according to the width of 1.2 m x 5 m in length) x 1 m in height. These breeding grounds or propagators are well protected. They should be clean and completely covered with clear plastic. Humidity and temperature must be controlled so that there is good recovery of the bulbs. Figure 7 (Photo below) shows the construction of the propagators.The hotbeds are three-quarters full with sawdust; previously sterilized by steam. The bulbs used come from healthy bayonet shoots of the varieties (FHA 17, 21, 23 and CIBULULA) are the most recommended. However, plants ready for or in disease free production which are not infected with weevils and nematodes may also be used. The healthy harvested bulbs are shoveled to remove the roots or trimmed, then washed to remove plant debris and soil. The bulbs prepared are dried in the shade for 24 hours before being planted in humid rooms (greenhouse).  After trimming the bulbs, they are immersed in boiling water for 30 seconds before the leaves are peeled. It is necessary to avoid exceeding 30 seconds of sterilization in boiling water because the buds are often damaged (Sterilization). The upper leaves are removed 2mm from the bulb base with a sharp knife to expose any buds and / or the meristem. Sterilized bulbs are subjected to scarification. It consisted of incising the buds with the tip of a sharp knife to stimulate the buds to give several seedlings. The bulbs prepared are planted at intervals of 5 to 10 cm apart depending on the size of the bulbs and covered with a layer of sawdust of 2 cm.

In the field, dung or farmyard manure was used at the rate of 5 kg per hole intended to receive them for young banana plants. The hotbed is well watered immediately and afterwards, watering is carried out 2 to 3 times a week depending on the humidity of the environment. The shoots are observed at a rate of 3 to 4 weeks depending on the variety and the climatic conditions: larger seedlings are re-scarified to obtain secondary plants, seedlings with more than 2 to 3 leaves are weaned and put in pots to promote root development, the hotbed always remains clean and covered, spraying of insecticides and fungicides against pests (insects and fungi). The duration of the bulbs in the propagator is 75 days and, in the grow, out shed is 80 days or 5 months. This operation is conditioned by the presence of the roots. The seedlings are weaned with the roots and planted directly in the pots then, put under grow-out sheds. Acclimatization consisted of putting the weaned seedlings under a grow-out shed. The movement of the seedlings put under the grow-out shed to a new field is done by wheelbarrows, basins and / or boxes. The ground is prepared beforehand by digging holes 40 cm long x 40 cm wide and 40 cm deep, in which we put 10 kg of well-rotted farm manure (dung) or compost. The seedlings are then placed in the holes and well covered with soil up to the neck, starting with the surface layer. A few weeks after installation or placement, mulching is recommended.

In short, the intermediate steps are the first scarification (five weeks after germinating), the second scarification (three weeks after the first scarification), the weaning and rooting (three weeks after the second scarification) and acclimatization (seven weeks). Seedlings are ready for planting between 12-18 weeks from the day of installation. The seedlings resulting from macro propagation are more fragile than the suckers. The planting or final establishment took place on October 20^th, 2020 at a spacing of 3m x 3 m.

Statistical Analysis

 All data was coded, entered and then analyzed using R (R Core Team, 2018) and Microsoft Office Excel 2010 (Microsoft Corporation, Redmond, WA, USA). The descriptive results were expressed in the form of a graph then by analysis of variance with a single criterion (ANOVA 1). The ANOVA was used for the comparison of the means of the height and collar diameter of the bananas pseudostem as well as the number of offspring and banana leaves emitted and the Tukey multiple comparison of the means was made at 95% confidence level.

Multiplication rate in propagators

The multiplication rate in the propagators of the varieties is presented in table 2

Table 1 shows that the multiplication rate in the propagators of the FHIA 23,21 and 17 banana varieties respectively are high compared to the CIBULULA variety, that is to say the dessert banana (15,5), plantain (6, 4) and cook (5.3) have  a high the multiplication rate than the beer banana (1).

Pseudostem Collar D iameter 

The graphs below show the pseudostem collar diameter at 10 cm from the ground of the banana trees. The variety FHIA 17 is more vigorous than the others, followed by FHIA 21 then by FHIA 23 and finally by CIBULULA.

Let us ANOVA1 statistically analyze the data of these graphs (Figure 1). The summary of analysis of variance of bananas pseudostem collar diameter of bananas is presented in Table 3.

The difference is not significant in banana pseudostem collar diameter between the varieties: the bananas pseudostem is the same at the level of the circumference of the pseudostem at 10 cm from the ground of the banana trees.

The graphs show the bananas pseudostem heights varying according to the varieties 180 cm for FHIA 23, 170 cm for FHIA 21 and FHIA 23 and, 135 cm for CHIBULULA.

tables fonts size 8

Let us ANOVA 1 statistically analyze these data Figure 2 and the summary of the analysis of variance of bananas pseudostem height is presented in Table 4.

The difference is significant between the pseudostem height of the varieties of banana tree: the size of the plants differs between them. Let us compare the means two by two using Tukey's method. Table 5.

Table 2: Multiplication rate in propagators

Table 3:  ANOVA summary

Table 4: ANOVA summary

Significant. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘’ 1

Table 5:  Comparison of means

 FHIA 21 has a larger size than CHIBULULA and FHIA 17 but it has the same size as FHIA 23. The latter has a larger size than CHIBULULA and FHIA 17 too.

Table 6: ANOVA summary 

Significant. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘’ 1

Figure 1: Pseudostem collar diameter

Figure 2: Bananas pseudostem height

Figure 3: Number of offspring

Table 7. Comparison of means 

 FHIA 21 has a large number of offspring as CHIBULULA and FHIA 17 but it has the same number of banana rejections as FHIA 23. The latter has a large number of offspring than CHIBULULA and FHIA 17

Figure 4: Number of banana leaves emitted

Table 8. ANOVA summary

Let us ANOVA 1 statistically analyze these data Figure 3   and the summary of the analysis of variance of the number of offspring is presented in Table 6.

The difference is significant between the number of offspring: the number of rejections differs between them. Compare the means two by two using Tukey's method Table 7.

Number of banana leaves emitted

The Figure 4 shows the number of banana leaves emitted.

The summary of the analysis of variance for the number of banana leaves emitted is presented in Table 8.

The difference is not significant between the numbers of banana leaves emitted into varieties, i.e. the number of banana leaves emitted is the same.

The multiplication rate in the propagators of the dessert banana FHIA23 (15.5), the plantain banana FHIA 21 (6.4) and cooking banana FHIA 17 (5.3) respectively are high compared to the beer bananas CIBULULA (1). These results could be explained by the use of fertilizer (Belfakih et al. ,2013). For example, Bora (2013), working on the effect of different concentrations of coconut milk on the proliferation of these three cultivars, obtained the average of 5.4 for Gros Michel, 5.4 for Figure Rose and 5.7 for Yangambi km 5 without coconut milk treatment.

FHIA 21 and FHIA 23 have a larger size and a large number of offspring than CHIBULULA, FHIA 17 in ex situ culture. These results agree with that of Smith et al [12]. The height growth of the plantain does not have the same characteristics as the leaf growth. It took place in a single positive phase until flowering. This observation is general to most cultivars [13]. The maximum height of plantains obtained in Azaguié with fertilizer was 296 cm against 250 cm for the Azaguié plot without fertilizer. This difference can once again be explained by the effect fertilizers. In the Yamoussoukro plots, plantains on average measured 326.5 cm in height in the plot with fertilizer and 318 cm in the plot without fertilizer. These results are far superior to those of Tezenas Du Montcel [14].

The number of banana leaves emitted is the same as well as the pseudostem size of bananas in ex situ culture. The growth in the fertilized plot was short and rapid. These results could be explained by the use of the fertilizer stimulates the leaf meristem and allows the plantain to complete its crop cycle more quickly in the fertilized plot, unlike that without fertilizer. Belfakih et al. [15] obtained similar results by working on the effect of salinity on the growth of two varieties of banana "large dwarf" and "small dwarf" and their mineral nutrition in Morocco. Pattison et al. [16] also obtained similar results in Australia. These results are still within the range of those obtained by Lassoudière, Anno [17], Dagba [18], Turquin [19] and Tixier [20].

The results of this study the multiplication rate in situ (propagators) of the dessert banana(FHIA 23) (15.5), plantain(FHIA 21) (6.4) and cooking banana(FHIA 17 ) (5.3) respectively are high compared to the beer banana(CHIBULULA) (1).In ex situ cultivation, FHIA 2 and FHIA 23 have a large size than CHIBULULA and  FHIA 17. In addition, they have a large number of offspring as CHIBULULA and FHIA 17 but FHIA 2 and FHIA 23 have the same number of offspring as well as large size. Additionally, the number of banana leaves emitted is the same as well as the size of the bananas pseudostem in ex situ cultivation. At the end of this work, the multiplication of banana seedlings is an asset in the middle of South Kivu to have the suckers quickly exempt from diseases. This work recommends that the Agriculture Inspectorate to make banana rejections available to farmers, allowing them to multiply this crop and the results of this work available to other students, extension agents and researchers, NGOs with the fruit crop extension service to disseminate these banana rejections.

ACKNOWLEDGEMENTS

We would like to thank Mr Jean Augustin Rubabura for correcting this paper and all workers of IPA/South Kivu for their support and all field Agent for the collect data for this study. Thanks, are also due to all CICR for their support in funding.

COMPLIANCE WITH ETHICAL STANDARDS

Conflict of interest: We declare that there is no conflict of interest with the publication of this manuscript. No human/animal participants were involved in the preparation of this manuscript.

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