In this article we will discuss about the characteristics of phylloplane microflora.
Since phylloplane microflora is exposed into the environment, it is constantly influenced by meteorological factors.
Therefore, microflora develop certain characteristic features so that it can cope with environment:
(i) Morphological Characteristics:
The phylloplane inhabitants possess morphological characteristics for their survival. These include the development of pigment in their mycelia, spores, pycnidia, apothecia, cleistothecia for protection against strong light and desiccation. The dark pigments act as light screen. These pigments are often referred to as melanin.
(ii) Physiological Characteristics:
Phylloplane fungi possess a number of physiological characteristics discussed as below:
(a) Nutrition:
Phylloplane microfungi have ability to decompose cellulose by producing cellulases. In addition, pectinases, cutinases, proteases have also been estimated in many fungi e.g. Alternaria alternata, Aureobasidium pullulans, Botrytis cineria, Cladosporium herbarum.
(b) Radiations:
Besides certain exceptions, high intensity light inhibits mycelial growth, while light (of normal intensity) is not harmful to phylloplane fungi. The UV portion of spectrum plays a significant role. Fungi containing melanin pigment are resistant to UV exposure as compared to those containing hyaline mycelia.
Hyaline spores of Aureobasidium and Sporobolomyces are killed by exposure of UV for five minutes, whereas dark spores of Alternaria and Epicoccum survive even after exposure for 35 minutes. High intensity of UV radiation becomes lethal to microorganisms.
(c) Relative humidity:
During rain and dew formation, high relative humidity on leaf surface is found. But when there is wind the microenvironment is reduced. Therefore, phylloplane fungi get advantages at low levels of relative humidity. Generally, a faster growth rate of the germ tube and mycelium of some fungi occurs at 100% relative humidity. Even some could not grow below 93% of relative humidity.
(d) Temperature:
Generally, the phylloplane fungi are mesophilic growing at temperature 20-25°C. Even some fungi (e.g. Alternaria alternata, Aureobasidium pullulans, Cladosporium herbarum, and Botrytis cinerea) can grow below 0°C.