Bamboo flowering is a peculiar phenomenon. Bamboos grow vegetatively for a species-specific period before flowering, seeding and dying. Most bamboo plants flower only once in their life cycle. Some species of bamboo flower only once every 40 to 50 years.
There is something mysterious about bamboo flowering. All members of a species or at least of a particular clone, wherever they happen to be, will flower simultaneously. This means forests of bamboo separated by hundreds of kilometres will flower simultaneously. Scientists are not sure how or why this happens.
They theorise that the rhizomes of the bamboo have some kind of "memory" or an imperturbable inner clock ticking away until the preset alarm goes off simultaneously. In this quiet cacophony, all the bamboo plants burst into bloom simultaneously. After flowering, they all die in some kind of a "mass suicide." Dying after flowering is a characteristic phenomenon of monocarpic flowering, which bamboos share as a member of the grass family.
Based on this flowering behaviour, bamboos can be classified into three groups. Those bamboo species that flower annually or nearly so, bamboos with gregarious and periodic flowering and bamboos with irregular flowering patterns. Most woody bamboos are semelparaous, flowering gregariously, seeding at long intervals of many years and dying thereafter. The seeds thus produced after long intervals have an extremely short life. The time interval between two successive flowerings is species specific.
In Schizostachyum elegantissimum , (a Javanese species), and Arundinaria wightiana, the period is three years. In Phyllostachys bambusoides , a Chinese species, it is 120 years while Bambusa vulgaris has a cycle of 150 years. The next bamboo flowering in northeast India is expected around year 2003-04.The mysterious pattern of bamboo flowering does not fit within the parameters of popular flowering theories in which environmental factors such as photoperiod, temperature and stress plays an important role. The en masse post-flowering death of bamboos has disastrous consequences, both ecological and economical.
The flowering and seeding at long intervals makes the propagation of bamboos through seeds and improvement by hybridisation difficult. It also threatens wild life, in particular the Giant Panda in China, which lives almost exclusively on bamboo shoots.
Considering the intimate relationship between bamboos and the Asian people, the government of India is, for once, taking the phenomenon of bamboo flowering seriously.
The Planning Commission is working on an emergency plan to combat the likely consequences of bamboo flowering, expected around 2003-04, especially in Mizoram, where 49 per cent of the geographical area is covered by bamboo plants.
A bamboo policy, the first of its kind in the country, is being formulated for the state of Mizoram. This would be a working plan to tackle issues like bamboo harvesting. The union government has also directed the state administration to increase food stocks and to store these provisions in rodent-proof silos.
Mizoram too, is taking preparatory measures. It has suggested cutting down bamboo plants, which will be economically exploited. The Planning Commission has sanctioned Rs 4 crore to establish a bamboo-processing unit.
To combat the menace of rats following bamboo flowering, the local administration plans to initiate offering a monetary reward for every rat killed. Similar incentives in the past resulted in villagers killing more than 2.5 million rats annually at the peak of flowering.
Officials are also debating measures, such as replacing flowering varieties of bamboo with non-flowering ones. Botanists, however, believe that the only way to avert famines, associated with bamboo flowering, is to teach farmers to plant crops that rats do not eat, such as ginger and turmeric, during the periods when vast fields of bamboo are expected to flower.
Whether these measures will work, only time will tell.
The writer heads the Tissue Culture Pilot Plant at the National Chemical Laboratory, Pune