Standardization of Growing Substrates for Mass Production of Quality Planting Material in Banana Cv. Grand Naine via Macropropagation

Introduction

Banana (Musa spp.) is oldest among crop plants domesticated by humans. Bananas are consumed as ripe fruits, while plantains remain starchy even when fully ripe and require cooking to be palatable. Originally crops from humid tropics, they have acclimatized to a broad range of climatic conditions. It is tall, non-woody plant classified under the Musaceae family and Musa genus most edible bananas are seedless hybrids of Musa acuminata and Musa balbisiana. They grow from a false stem (pseudostem) and form fruit without pollination this process called parthenocarpy. The most widely grown type is the Cavendish, part of the Musa AAA group. The plant reproduces vegetatively by sucking, although some wild species also reproduce by seeds (Nayak et al., 2019) [4] . Approximately 90% of the vegetative propagation of banana is done mainly using sword sucking and the rest by using other planting materials such as fragments, cuttings and peepers (Suryanarayana et al., 2018) [10] . Naturally produced suckers are more likely to carry pest and diseases. Rapid production of propagating material could be achieved through various vegetative methods like in-vitro micropropagation. But it is not accepted by traditional small farmers. That's the reason, Macro-SPA is a relatively simple method, requires minimal investment in the configuration, is an excellent technique for producing high-quality, high-quantity planting materials, and the resulting plants are plant culture, etc. and have uniformity (Baiyeri et al., 2007) [2] . The goal of macro propagation is to overcome obstacles it enables the quick creation of additional planting materials that are disease and pest-free. Due to its increased output, the macro propagation technology has gained popularity and farmers are requesting a steady supply of high-quality planting materials. Macro propagation was developed as a substitute method that requires less money and expertise to get around the issue of micropropagation's high cost and skill requirements. A farmer-friendly technique that enhances field sucker output is macro propagation (Njau et al., 2011) [5] . [3,8,7] and the rate of sucker formation will be increased by complete or partial decapitation on plants grown in the field (in situ) or by separation of the bulbs (ex situ) (Baiyeri and Aba, 2007) [2] .

In the present study, attempts have been made to enhance the rate of plantlet production through macro-propagation by the addition of bio-fertilizer like VAM, Trichoderma viride, Azospirillum, Bacillus subtilis. Phytohormones (BAP and IBA) to the explants/substrate for breaking the apical dominance of banana for the production of number of side suckers from the corms and for thereby improved multiplication rate of banana suckers. Cocopeat as a substrate gives anchorage, moisture supply and aeration to the newly emerging roots from the decapitated and decorticated corm. Cytokinins such as BAP and kinetin are known to suppress the apical dominance during meristematic shoot formation of banana, thereby inducing both axillary and adventitious shoots.

Materials and Methods

The ). Healthy and disease-free sword suckers were selected. Collected rhizomes were pared to remove older roots including the superficial layers. The pseudo stem of mother corm or sword sucker was cut transversely 2 cm above the collar region. The apical meristem was removed using sharp pointed sterilized knife, leaving a cavity of 2 cm diameter and 3 cm depth. Corm was given criss-cross incisions to a depth of 1-1.5 cm ending down to a rhizome collar. These corms were dipped in 1 per cent Bavistin/carbendazim solution for about 5 minutes to eradicate surface pathogens. Treated corms were shade dried for 20 minutes. These corms were imposed with treatments and were planted in the initiation media by covering with the media 2-3 cm above the corm. Regular watering was done. The pseudo stem of plantlets grown from primary decapitated and decorticated corms were again cut transversely 2 cm above the collar region at 3 leaf stage without separating it from main corm. A 2 cm diameter by 3 cm deep void was left behind after the apical meristem of the secondary decapitated plantlets was scooped out. The little corm was covered with media 2 cm above it after having crisscross incisions that proceeded from 1 to 1.5 cm deep and ended at a rhizome collar, just as the primary decortication. Continue watering and weeding throughout the duration of evaluation. New plantlets growing from secondary decapitation and decortication were detached after 30 to 40 days, along with roots and a portion of corm at the 3-4 leaf stage. They were then planted as new individual plants for hardening in a new polybag filled with medium.

Results and Discussion Growth Parameter's Time taken for sprouting

The treatment T 5 [Cocopeat +VAM (30 g)] took minimum number of days for sprouting (17.10 days) which was significantly lower than other treatments. This treatment was statistically on par with T 3 [Cocopeat + Peatmoss] which took 18.98 days for first bud emergence. On the other hand, maximum number of days required for bud emergence was observed in T 9 [Garden soil (Control)] taking 26.36 days (Table 1). The treatment T 5 performed better due to the presence of optimum level of cytokinin (PGR) which help to induce early bud sprouting (Sajith et al., 2014) [8] . The similar results were reported by Thungon et al., (2015) [11] for macro-propagation in banana.

Plant height at saleable stage

At saleable stage treatment T 5 [Cocopeat +VAM (30 g)] showed maximum plant height (27.34 cm) as compare to other treatments. Treatment T 6 (24.73 cm) and T 7 (24.42 cm) found statically at par with T 5 . On the other side lowest plant height found in treatment T 9 [Garden soil (Control)] (20.43 cm) at saleable stage respectively (Table 1). The treatment T 5 was superior for good plant height might be due to presence of beneficial microorganism VAM, which improve the quality of the media, The physical composition of the growing medium significantly influences the availability of water, nutrients and air to the developing plantlets and also plays an important role in providing anchorage as well as determining the medium's nutrient and water retention capacity and there by improve the growth and development of plant. The similar results were reported by Abirami et al., (2010) as well as Tripathi et al., (2014), Rosales et al., (1998) [1,12,7] .

Leaves per plant at saleable stage Treatment T 5 [Cocopeat +VAM (30 g)] recorded the maximum leaves per plant at saleable stage (12.11) and treatment T 7 [Cocopeat + IBA 2500 ppm] (9.42) which is numerically followed by T 5 . The lowest number of leaves were found at saleable stage which is found in lowest leaves per plant at T 9 (7.20) (Table 1). Inoculation of VAM to the growing media has a positive impact on synthesis of various hormones like auxins, gibberellins and cytokinin which leads to increased cell division and multiplication. The result was in lined with previous findings of Abirami et al., (2010) and Tripathi et al., (2014) [1,12] .

Leaf width at saleable stage

The data presented in Table 1 indicating that, at saleable stage significant variation was observed in leaf width among different treatment and interaction effects. At saleable stage the maximum leaf width found in treatment T 5 (15.52), followed by treatment T 4 (11.94). The lowest leaf width was found in treatment T 9 (7.00, 7.96) [Garden soil (Control)] at saleable stage. It may be due to presence of microorganism VAM with Bacillus which enhances nutrient and water uptake, leads to improve plant growth and development, including larger leaves. This was in agreement with the finding of Sajith et al., (2014) [8] .

Leaf area at saleable stage

The data presented in Table 1. showing leaf area has been significant differences among the treatments due to use of different growth hormones and biofertilizers. At saleable stage treatment T 5 (163.81 cm 2 ) [Cocopeat +VAM (30 g)] was found highest leaf area and treatment T 4 (153.02) was found at par with T 5 . While lowest leaf area was found in treatment T 9 (140.85 cm 2 /plant). Adding VAM to the growing medium positively influences the production of hormones such as auxins, gibberellins and cytokinins, which in turn stimulate cell division and multiplication. Also, it aids in better nutrient absorption especially phosphorous and increases photosynthetic rate thus enhances growth (Usha et al., 2004). Ravani and Patel (2013) [13,6] . It also improves nutrient uptake particularly phosphorus and boosts the photosynthetic rate, thereby promoting overall plant growth (Usha et al., 2004) [13] .

Conclusion

On the basis of the present investigation on Standardization of Growing Substrates for Mass Production of Quality Planting Material in Banana Cv. Grand Naine via Macropropagation, it can be concluded that, highest plant height (cm) at saleable stage, leaves per plant at saleable stage, leaf width (cm) at saleable stage and leaf area (cm 2 ) at saleable stage was found in treatment T 5 with lowest time taken for sprouting (days).

References

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