Effect of bunch-covering methods on maturity bronzing, yield, and fruit quality of bananas in North Queensland

Abstract

The timing of bunch covering during the development of bananas was examined to find the optimum for fruit quality and reduction of maturity bronzing. Bunch covers, either open or sealed, were applied at various stages of bunch development. The experiments were carried out at South Johnstone, North Queensland. Sealed covers increased the severity of maturity bronzing whenever they were applied. Sealed covers applied for the period either before or after finger diameter of the third hand had reached 2.7 cm increased maturity bronzing, but not by as much as when covers remained sealed throughout bunch filling. These data indicate that sealed covers increase maturity bronzing throughout fruit growth. Maturity bronzing was slightly less when open covers were applied as the last female bract lifted on the bunch (early), compared with a week or so later when the fingers had curled up. Bunch weight was not increased by the application of open covers, but the use of sealed covers increased bunch weight by up to 9%. This was due to increased finger length along the entire bunch. The application of covers (both open and sealed) at earlier than conventional times increased finger length at the proximal end of the bunch, the effect being greater the earlier covers were applied. Open covers reduced the time taken from bunch emergence to harvest by 5-11 days compared with no covering. Very early and early covering gave the largest reductions. Sealed bunch covers delayed harvest by up to 16 days compared with no covering. There was a non-significant reduction of 2-4 days in fruit greenlife, related to the delay in bunch filling caused by sealed covers. Sealed covers led to some fruit abnormalities, including severe spotting by Deightoniella sp., slightly s-shaped fruit, and dull fruit appearance. Early application of open bunch covers is recommended to reduce maturity bronzing. This treatment also increases finger length, and bunch filling time is reduced by about 1.5 weeks. This effect suggests sensitivity to the environment during and soon after bunch emergence.

Effect of Pulp Cell Number and Assimilate Availability on Dry Matter Accumulation Rate in a Banana Fruit [ Musa sp. AAA group 'Grande Naine' (Cavendish subgroup)]

“…This was particularly noticeable in our early bagging treatment and is in accordance with results obtained by Daniells et al (1992). In our experiment, early bagging was applied 1 week after¯ower emergence, i.e.…”

“…2 weeks before the end of cell division. According to our results and those of Daniells et al (1992), earlier bagging would allow an increase of fruit weight and size on the upper hands. It would be worthwhile investigating whether a similar eect could be obtained on lower hands by modifying the size of the bag ( for instance using a longer bag).…”

“…However, the growth rate of banana fruit also seems to vary with the source/sink ratio during fruit growth. Removal of hands (thereby decreasing the sink size: Meyer, 1975;Daniells et al, 1994;Johns, 1996), leaf shading (reducing resource availability: Israeli et al, 1995) or bunch bagging (increasing sink demand by elevating the air temperature: Turner and Rippon, 1973;Ganry, 1975;Johns and Scott, 1989a, b;Daniells et al, 1992;Jannoyer and Chillet, 1998;Turner, 1998) modify fruit growth rates and, consequently, the commercial harvest date.…”

Efeito do ensacamento de cachos de banana 'Nanicão' na produção e no intervalo entre inflorescência e colheita

“…A mudança da fase de desenvolvimento vegetativo do meristema apical para o estádio floral geralmente ocorre de três a quatro meses antes da emergência da inflorescência no ápice da planta (Turner, 1972a(Turner, , 1972b, podendo chegar a mais de seis meses Sampaio & Simão (1970), Daniells et al (1992) e Salomão (1995) com as cultivares Nanica, Williams e Mysore, respectivamente. No entanto, Cann (1965), Robinson & Nel (1984) e Galán Saúco et al (1996 registraram aumentos significativos de massa em relação a cachos ensacados da cultivar Dwarf Cavendish.…”

“…O acondicionamento em sacos de plástico de cachos de banana, em início de desenvolvimento, pode contribuir para aumento da massa dos cachos, redução do intervalo entre a emergência da inflorescência e a colheita, melhoria visual dos frutos, aumento do Simão (1970), Daniells et al (1992) e Salomão (1995), nas cultivares Nanica, Williams e Mysore, respectivamente, não encontraram diferenças em relação a massa de cachos ensacados e não ensacados.…”