The bananas are thought to be particularly sensitive to changes in the environment. This review considers some historical and recent investigations into the response of the leaf, root and reproductive system to the environment. Monteith's analysis of the response of plants to intercepted radiation is appropriate for analyzing the productivity of bananas and plantains. The banana is sensitive to soil water deficits, and expanding tissues such as emerging leaves and growing fruit are among the first to be affected. As soil begins to dry, stomata close and leaves remain highly hydrated, probably through root pressure. Productivity is affected because of the early closure of stomata. We find the common belief that bananas use large amounts of water does not have a strong physiological basis. Improvements in water-use efficiency in irrigated plantations could come from a closer match between plant water use and the amount of water applied. We examine recent data on water-use efficiency of different banana cultivars and propose that agronomists, physiologists and breeders could quantify the amount of water available in each rain-fed environment and work towards directing more of that water through the plant. The banana is day neutral for floral induction, but photoperiods of less than 12 h are associated with a slowing in the rate of bunch initiation that is independent of temperature expressed as growing degree days. This may contribute to seasonal variations in banana flowering, even in more tropical environments with moderate temperatures. Key words: crop yield, leaf system, light, photoperiod, photosynthesis, reproductive system, root system, temperature, water supply Ecofisiologia de bananeiras (Musa spp.): Bananeiras são particularmente sensíveis a mudanças no ambiente. Nesta revisão, exploram-se alguns estudos clássicos e recentes sobre as respostas ao ambiente da folha, raiz e sistema reprodutivo dessa espécie. A análise de Monteith sobre as respostas das plantas à radiação interceptada mostrou-se apropriada para a análise da produtividade de bananeiras. Bananeiras são sensíveis ao déficit hídrico do solo, particularmente tecidos em expansão tais como as folhas em formação e os frutos em crescimento. Na medida em que o solo começa a secar, os estômatos se fecham e as folhas se mantêm altamente hidratadas, provavelmente devido à pressão radicular. A produtividade é afetada, em função do fechamento estomático. A crença geral de que bananeiras usam grandes quantidades de água não tem forte embasamento fisiológico. O aumento na eficiência do uso da água em cultivos irrigados pode advir de aumentos na densidade de plantio e quantidade de água aplicada. Examinam-se dados recentes sobre a eficiência do uso da água em diferentes cultivares de banana e propõe-se que agrônomos, fisiologistas e melhoristas possam quantificar a quantidade de água disponível nos vários ambientes de sequeiro, de modo a maximizar a eficiência do uso da água pela planta. A bananeira é uma espécie neutra para a indução floral, porém fotoperíod...

Pollen viability was examined by recording the number of viable as well as non-viable microspores in anthers just before anthesis, as it could be an efficient and rapid indicator of female fertility. It was thought that competency in meiotic restitution in microspores could indicate similar competency in megaspores. Pollen fertility was compared among seeded diploids and edible triploids of Musa and correlated with ovule fertility. Viability was examined using the Alexander’s pollen stain procedure. The seeded diploid species M. acuminata, M. balbisiana, and M. ornata had 3 times more viable pollen than the edible tetraploids (AAAB). M. balbisiana and M. ornata had significantly more viable pollen than M. acuminata. The tetraploids contained 3 times more viable pollen than the edible triploids AAA and ABB and 4 times more than the AAB cultivars. The genome A or B did not affect pollen viability within the triploid cultivars examined. The AAA triploid Gros Michel had the highest percentage of viable pollen at 13% and Green/Red the lowest at 3%. Pollen viability was influenced by meiotic disturbances and an association was made between viability of pollen and viability of embryo sacs. Pollen viability from anthers of Australian grown species and cultivars of Musa a. ssp. (undescribed subspecies) was compared with published reports of pollen viability from Indian grown species and cultivars. The pollen viability between the Indian cultivated and wild diploids of Musa a. ssp. was similar at 50–66%, but less than the pollen viability of Australian diploid Musa a. ssp of 84%. The Indian-grown triploid cultivars had 21–29% viable pollen and the tetraploids had 28% viable pollen, whereas the Australian grown triploids had 6–10% viable pollen and the tetraploids 29% viable pollen. There was a difference in pollen viability between genome groups and within genome groups. Different species and cultivars of Musa possess different levels of competency in the production of microspores, which correlated positively with levels of megaspore fertility in the same species and cultivars.

No abstract

Bananas and plantains (Musa spp.) may flower at any time of the year but they show seasonal variation in flowering. To determine whether photoperiod contributed to this seasonal variation, we calculated the thermal development units (DT) from planting to bunch appearance (flowering) using data from published planting date experiments in the tropics and subtropics. Minimising the coefficient of variation in DT across planting dates was used to evaluate the contribution of photoperiod and soil water balance to time of flowering. Coefficients evaluating sensitivity to photoperiod were estimated in some datasets and validated on independent datasets. Data on the rate of bunch appearance from four locations over several years were analysed to establish correlations between this, photoperiod and temperature. The time of bunch initiation was matched against photoperiod to determine whether short photoperiods delayed bunch initiation. Long photoperiods in the mid-vegetative phase hastened flowering while soil water deficits delayed it. Cultivars of the Cavendish subgroup (AAA) were more sensitive to photoperiod than the Maricongo cultivar (False Horn-type plantain, AAB). Long photoperiods during the reproductive phase were correlated with an increased rate of bunch appearance some 8 to 11 weeks later. Musa spp. show a facultative long-day response to photoperiod.

No abstract