Understanding which traits allow one bean plant to perform better than others is a demanding task. But this is precisely what CIAT’s Idupulapati Rao, has spent more than 20 years doing. An Indian national, he is a plant physiologist with extensive experience in plant nutrition, and has been based in Colombia since 1989.

A major focus of his work has been adapting beans to climate change and soil problems, helping to develop climate-smart bean lines useful for crop breeders to develop new, improved varieties.

Rao is also an active member of scientific organizations such as the American Society of Plant Biologists (ASPB), American Society of Agronomy (ASA), Crop Science Society of America (Crop Science), Soil Science Society of America (Soils), New York Academy of Sciences (NYAS), and the International Union of Soil Sciences (IUSS).

His more than 160 papers published in refereed journals, 60 book chapters, 65 papers published in conference proceedings, 250 oral presentations/posters, and 3 co-edited books are the demonstration of how important it is for him to share knowledge.

The result of Rao’s two decades of dedication is his recognition as an expert, particularly for his contributions on plant mechanisms of remobilization of photoassimilates – in other words, those savings from utilization of CO2 and solar energy that a plant takes advantage of and mobilizes for pod formation and grain filling, resulting in higher yields under abiotic stress (heat, drought, and low soil fertility) conditions.

Photoassimilates to the rescue to overcome drought in bean production

Water saving and water spending: two plant strategies for coping with drought

Drought is the main abiotic limiting factor for bean production. Rao, along with peer bean breeders, found that, as far as drought resistance goes, genotypes can be classified into two groups: water savers and water spenders taking into account their use of water and traits such as carbon isotope discrimination, rooting depth, and extent of remobilization of photoassimilates.

Water saving genotypes

Water-saving genotypes present several desirable traits that allow them to save water, such as the capacity to close their stomata and produce smaller leaves, among others. They are efficient in remobilizing carbon to produce grain. Such varieties are suitable for semi-arid or sub-humid environments, such as those found in Central America, Africa, and southern Mexico.

Water spenders genotypes

Water spenders have a deep rooting system that maximizes their water uptake to aid pod-filling and grain production under conditions of water-stress. They are suitable to areas of Central America, South America, and Africa, especially those with irregular rains or prolonged dry spells rains, and soils with good water storage capacity.

In outstanding genotypes, success in responding to challenges posed by drought –– seems to rely largely on the strategic combination of desirable traits, according to the environment in which they are grown. This is the key to advancing specific varietal improvement, based on the most suitable agro-ecological zones in which to sow.

Plants with deep roots are able to remain hydrated and fresh. They also have an appropriate rate of growth despite environmental stress; good pollen formation and pollination; and a better remobilization of photoassimilates to develop their pods and fill their grains. All of these desirable traits contribute to higher yields under high-heat and drought conditions.

Beans are not Rao’s only passion. Another line of research that continues to excite him is the sustainable intensification of forages in livestock systems to improve production and protect the environment.

Hence his interest in research on biological nitrification inhibition (BNI), a chemical mechanism that significantly reduces the conversion of nitrogen in fertilizers into nitrous oxide – a greenhouse gas roughly 310 times more potent than CO2.

In 2009, in close collaboration with the Japan International Research Center for Agricultural Sciences (JIRCAS), Rao and his team generated field evidence for the concept of BNI through identification of a compound in the roots of Brachiaria humidicola forage grasses that inhibits nitrification in soil.

In 2015, a consortium was created for researching on BNI. It is formed by three Centers of the CGIAR Consortium – the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), the International Maize and Wheat Improvement Center (CIMMYT), and CIAT- and JIRCAS.

That is how, JIRCAS-CIAT partnership demonstrated residual effect of BNI from B.humidicola pasture on maize productivity and nitrogen use efficiency; JIRCAS-ICRISAT alliance invested their efforts in a proof of concept for BNI function in sorghum; and JIRCAS-CIMMYT has been developing low-nitrifying and low-N2O emitting wheat production systems.


Nitrogen fertilizer

applied is not recovered by the crops. Amounts to a direct annual economic loss of US$ 90 billion

“This is a unique opportunity to be part of a center of excellence in agricultural research, which is also a meeting point for a great team of scientists with whom I share the conviction that we can make a difference for millions of bean producers and consumers around the world.”

Idupulapati Rao

Plant Nutritionist and Physiologist, CIAT

Cultivating the next generation of researchers

Topics such as crop resistance to pests and diseases; tolerance to drought, heat, and low soil fertility; higher yields; and seeds with increased iron and zinc concentration make up CIAT’s bean research portfolio.

This agenda is enriched by “igniting the brains of young scientists,” points out José Polanía, a young scientist at CIAT, telling how training new researchers occupy a significant share of Rao’s day.

Polania is referring to the undergraduate, master’s, and doctoral students located at CIAT’s headquarters in Colombia or in other countries as far away as Australia, and who receive feedback on the progress of their research on a daily basis from Rao; extra homework to further stimulate their restless minds; and constant support in their field observations, the formulation of hypotheses, and the structuring of scientific documents. All of this is thanks to “his strong devotion to teaching,” emphasizes Polanía.

Among Rao’s outstanding pupils are Andrés Felipe Rangel, a specialist in plant nutrition currently working in Yara, UK; Louis Butare, leader of the bean project from the HarvestPlus initiative; Néstor Chávez, University of Costa Rica; Juan Andrés Cardoso, specialist in tropical forages and climate change at CIAT; and José Polanía himself, with whom Rao recently published the paper titled Physiological traits associated with drought resistance in Andean and Mesoamerican genotypes of common bean (Phaseolus vulgaris L.).

“He is a man with a huge working capacity and an unalterable temperament, who has yet to learn to say no, and whose door is always open to offer assistance to anyone who needs it.”

John Miles

Plant Breeder, CIAT

And what does he do when he’s not working? “I play tennis with Colombian friends and I watch football and baseball games,” says Rao.

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