Philsurin develops sugarcane biofertilizer

Exciting developments are taking place in the search for a substitute for expensive chemical sugarcane fertilizers. Should the experiments succeed, the cost of fertilizer application may be greatly reduced in the future.

Long applied to rice, corn and other crops in the Philippines, biofertilizers have not been developed for sugarcane, notwithstanding that sugarcane also requires large amounts of fertilizers.

"The development of biofertilizer is justified by the rising costs of chemical fertilizers, not to mention the environmental and health damage associated with their application. Maximizing the usage of biofertilizer will eventually lead to the reduction of sugarcane dependence on chemical fertilizers. A corresponding savings in the amount of inputs will be derived," Philippine Sugar Research Institute Foundation, Inc. microbiologist Dr. Lucille C. Villegas said.

Armed with a Philsurin scholarship grant, Dr. Villegas conducted a study from 1998 to 2001 on the Isolation, Characterization and Investigations Into the Mechanism of Action of Plant Growth-Promoting Bacteria in Sugarcane.

Nitrogen-fixing microorganisms were sought, to be used as inoculants for development as biofertilizers. Microbial fertilizers carry microorganisms that help plants increase their mineral uptake, while promoting growth through nitrogen fixation and hormone production.

Nitrogen-fixing microorganisms convert the nitrogen present in the air into a usable form that plants may absorb and utilize for growth. A bacterium that aids in nitrogen fixation is rhizobium, which is present in legumes and peanuts.

Studies in Brazil have shown that sugarcane, like legumes, is capable of obtaining the nitrogen it needs from the air, for development which takes place in the presence of large numbers of nitrogen-fixing bacteria. These bacteria are called diazotrophic endophytes.

"We need to come up with superior strains of these bacteria to develop a viable nitrogen-fixing association with sugarcane. Our ultimate goal is to grow cane plants biotized with superior strains of diazotrophic endophytes," said Dr. Villegas.

The bacteria were isolated from surface sterilized tissues of sugarcane at Philsurin’s well-equipped biotechnology laboratory in the Victorias Milling Company’s premises. Tissue culture bioassays were performed to compare and determine the amount of nitrogen that the isolated bacteria would contribute.

The study yielded promising results. The number of tillers or shoots of the inoculated plants grown at a sub-optimal level of nitrogen were not much different from the plants grown at optimum level, confirming that bacterial inoculation was effective even in the early stages of growth.

Promising isolates of bacteria also were identified by the study, which determined their method of invasion and extent of colonization. Dr. Villegas found that the bacteria can be introduced in the micropropagation system, where large numbers of sugarcane are grown from plant tissues.

Pot experiments were then conducted to evaluate the effects of inoculation at various development stages of sugarcane. Four varieties of sugarcane (VMC 86-550, VMC 87-599, PS3 or VMC 84-524, and Phil 8013) were inoculated, grown in plastic cups and acclimatized in the nursery.

Philsurin has already scheduled the bacterization (the process of introducing the bacteria in plant tissues) plantlets to be used in field experiments, from September to October this year. By December, the planting of these canes will commence. The seedlings will be grown under natural environmental conditions, evaluated and monitored until the predetermined time of harvest.

A non-stock, non-profit organization created to undertake research development and extension functions, Philsurin, headed by director general Leon Arceo, is working to reduce sugar production costs by exploring new technologies.

"Philsurin is certainly changing the sugar industry’s profile in the Philippines. It could very well be the only research institute in the world undertaking this breakthrough experiment," James Ledesma, administrator of the Sugar Regulatory Administration, said.