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Saturday, June 29, 2013

Induce fruiting of mangoes by spraying with Potassium nitrate discovered by a Filipino

Mango is one of the most priced tropical fruit in the world. Technically, mango is a fleshy stone fruit belonging to the genus Mangifera, consisting of numerous tropical fruiting trees in the flowering plant family Anacardiaceae. It is native to Asia such as India, Philippines, Pakistan and Bangadesh. It has been distributed worldwide to become one of the most cultivated fruits.

Mango Consumption

Mangoes are generally sweet, although the taste and texture of the flesh varies across cultivars, some having a soft, pulpy texture similar to an overripe plum, while the flesh of others is firmer, like a cantaloupe or avocado, or may have a fibrous texture. Mangoes are widely used in cuisine. In the Philippines, unripe mangoes may be eaten with bagoong. Dried strips of sweet, ripe mango (sometimes combined with seedless tamarind to form mangorind) are also popular. Mangoes may be used to make juices, mango nectar, and as a flavoring and major ingredient in ice cream and sorbetes, and milkshakes. Sweet glutinous rice is flavored with coconut, then served with sliced mango as a dessert. In other parts of Southeast Asia, mangoes are pickled with fish sauce and rice vinegar. Green mangoes can be used in mango salad with fish sauce and dried shrimp. Mango with condensed milk may be used as a topping for shaved ice.

Eating mango fruits are good for one’s health. Raw mango consists of about 81.7% water, 17% carbohydrate, 0.5% protein, 0.3% fat, and 0.5% ash. A 100 g (3.5 oz) serving of raw mango has 65 calories and about half the vitamin C found in oranges. Mango contains more vitamin A than most fruits.

Production and Cultivation

The Food and Agriculture Organization of the United Nations estimates worldwide production at nearly 35,000,000 tonnes (39,000,000 short tons) in 2009. The aggregate production of the top 10 countries is responsible for roughly 80% of worldwide production. India is the biggest producer of mangoes.

Mango tree is well adopted to tropical and subtropical environmental conditions. It can be cultivated until up to 1300 m above mean sea level. However, commercial cultivations are limited to areas below 600 m above mean sea level. Optimum temperature for mango cultivation is 27-30C. Mango is successfully cultivated in areas where annual rainfall range from 500-2500 mm. For a successful crop, most important thing is the distribution of rainfall rather than the amount. A dry period of 3-4 months is an essential prerequisite for successful flowering of mango. Rains at flowering may affect yield due to pollen wash off. Mango can be cultivated in a wide range of soil conditions. A well drained soil with 2 M depth is the best. Soil pH must be 5.5-6.5. Soils with high clay content or with frequent water logging are not suitable for successful cultivation of mango.

However, erratic fruiting habits make mango cultivation challenging: being very seasonal, mango trees bear fruit only one month in a whole year. Sometimes they bear fruit well in one year, but do not bear fruit at all in the next year. To overcome these challenges and make mango cultivation more commercially viable, in the early 1970s Philippine horticulturalist Dr. Ramon Barba set out to develop a chemical solution to induce early flowering in mango plants.

Research and Development of Potassium nitrate Flower Induction

Already as a student, Dr. Barba, who holds degrees in plant propagation and horticulture, was very interested in the problems of mango production: “We already had a unique practice in the Philippines of using smoke to bring on flowering. But it was a tedious practice, and expensive. So as students we were all thinking, ‘how can we make the mango flower?’” he recalls.

During in his years as a BS in Agriculture student in the University of the Philippines Los Banos in Laguna, he did research and established that the presence of ethylene in the smoke was responsible for the flowering effect. “But you cannot just use ethylene – it is a gas, you would have to cover the tree”, Dr. Barba points out. So, he started experimenting with other chemicals: “Potassium nitrate was low on the list, but I included it because I know from other studies that there is a link between potassium nitrate and ethylene”, he says.

To deepen and continue his research, he entered and got a scholarship in the University of Georgia where he had done various experiments to induce flowering of plants using gibberillic acid and Potassium nitrate. He finished his degree in MS in Horticulture (with distinction) in the year 1962. He continued his studies in the East-West Center in Hawaii and got his doctorate degree in Plant Physiology, specializing in Tropical Fruits and Tissue Culture in 1967.

He encountered many criticisms of his proposal to induce flowering of mangoes. However, with the help of Mr. and Mrs. Jose Quimson of Quimara Farms in San Antonio, he had continued his research. Out of 400 trees of 10-20 years old, he succeeded in conducting his experiments and got good results. Mango trees bear flowers from 1 week to a month after being sprayed with Potassium nitrate. “The process was very simple. You just get one kilo of potassium nitrate, put it in 100 liters of water, spray it on the plant once – and within a week you can see the buds forming. In two weeks the buds are already forming into flowers. It was... unprecedented. I have never seen any reaction so spectacular”, he said. Spraying mango trees with the liquid doubles or triples the yield, in addition to making them fruit at different times of the year.

In further research, Dr. Barba analyzed whether forcing mango trees beyond normal fruiting had any impact on them and found that they were affected: “After eight years of induction they are 15 percent smaller than those that are not treated. But there was no bad effect, no damage to the mango. Trees that have been sprayed with potassium nitrate for more than 30 years are still producing”, he reports. He published his research in a paper entitled Induction of Flowering of the Mango by Chemical Spray.


Overjoyed with his revolutionary invention that any grower could use, Dr. Barba completely forgot to protect his discovery: “I forgot all about the patenting aspect – until I read in the paper that somebody else had patented potassium nitrate for mango flower induction. I said, ‘But how can this be? I think I discovered it; everybody in the scientific community thinks I discovered it; and here it is patented!’”

He immediately contacted the Philippine patent office, who confirmed that they had received an application, but that no patent had been granted yet. With the help of a lawyer, he applied for a patent and contested the existing application. “Fortunately because of the records I had, I could show that the invention was mine. So the process went through and the patent office gave me the patent”, he recalls.

However, he is well aware of the risk he incurred in not protecting his invention straight away: “If a patent had been granted, then the other person would own my invention. I would not be recognized as the inventor, so would lose the credit scientifically and lose any financial possibility”.

During the process, he learnt that patents can do many things: “Patenting both protects your rights and helps you make the benefits of your invention available. Patents give some inspiration because the reward is there, and the recognition. In the Philippines there needs to be more information, more education about it. If we could introduce the subject in school science classes it would be a big step”, he says.

Business Results

The use of potassium nitrate to induce flowering in mango plants has revolutionized the Philippine mango industry: “It has been said that no single plant commodity has benefited as much from a single technology as the mango has from potassium nitrate induction. From 1974, when it was virtually neglected, it has become our number one fruit crop”, reports Dr. Barba. “The effects are felt in all areas related to mango production. Everybody has benefited: the companies selling pest control chemicals, the people who harvest, the people who package, the people who bring the fruit to market, and the people who make baskets for mangoes”, he continues.

Today, with an annual production of about 900,000 tons, the Philippines are among the top ten mango producers worldwide, making the crop one of the country’s top exports. Dr. Barba’s mango flower induction method is now used in many countries around the world. He has received numerous prestigious awards for his research, including the IBM-DOST Award in 1989, the DA-Khush Achievement Award in 1995, the Crop Science Society of the Philippines Best Paper Award in 1974 and 1981, and the Gamma Sigma Delta Achievement Award in 1995. What he finds most rewarding is the impact of his discovery: “I am very proud of having invented the potassium nitrate technology. As a scientist, I feel that one technology that has a positive impact on agriculture justifies a lifetime of research”.

One Creative Idea, One Patent, Many Positive Effects

Patenting helped Dr. Barba disseminate his invention: the security that he had all the rights to his discovery enabled him to share his technology with a maximum number of people by choosing not to enforce his patent. His ingenuity has contributed to increasing food security and has benefited a wide range of communities involved with mango growing, in particular in developing countries, where most mangoes are grown.


  1. Thank you Dr. Barba,
    Your invention is so much useful to farmers like me. I am from india. Hear also its giving so nice result. Any one wants to discuss on that please contact me on ""
    Thanks again

  2. I just heard about inducing mangoes from a Philippino friend. I grow fruit seedlings and distribute them to farmers. Going to give this a try. Eager to hear if it works on other fruit trees as well. Thank you. Tom

  3. nice..could u help me for a seminar /training for mango spraying management?

  4. i wanted to train my workers or let them for several skills in spraying mango for a better fruit production..we already started the game"spraying"...if somebody could be as mentor pls help to recommend, no.09099601102.