Toward a Drought-Resilient Sorghum: Q&A with Innovation Lab Director Andrew Paterson
This Q&A with Andrew Paterson, Director of the Feed the Future Climate-Resilient Sorghum Innovation Lab, is part of a series for climate, weather and resilient agriculture month this May on Agrilinks. The Innovation Lab is advancing drought and heat tolerance of sorghum and, in parallel, transforming production systems to reverse losses of ecological capital.
Agrilinks: What are the lab’s goals and what have you achieved so far?
Paterson: Despite some delays, we’ve made a lot of progress toward two broad goals: improved drought tolerance of sorghum and producing multiple crops of sorghum from single plantings.
Sorghum is pretty drought tolerant as crops go; however, drought is still the single most limiting factor affecting production in the US and worldwide. It is widely grown in Africa as food and in the US as animal feed.
In Ethiopia and Mali, we inherited some populations that gave an early start in breeding progress. We have one drought-tolerant cultivar released already and another expected from these initial populations. We are also beginning to evaluate several panels of new populations that we developed, specifically targeted to drought.
Agrilinks: Why is perenniality of the crop important, and what advances have you made?
Paterson: Row crop agriculture is hard on the soil, as plowing, cultivation, and wind and rain exposure contribute to soil degradation and erosion. For some time researchers have sought to develop grain crops, ideally perennials, that could yield multiple crop cycles from single plantings to reduce tillage and protect the soil. Growing perennials like grasses on the Great Plains may not only mitigate losses but also reverse them.
To this end, we’ve worked with two sets of germplasm that are wild relatives of sorghum. One species has the same chromosome number as sorghum; however, it is only weakly perennial and has limited tolerance of cold conditions. There is another, Sorghum halepense, or Johnson grass, which you might know as a weed – it is a stronger perennial and has the ability to survive cold and dry conditions.
The weakly perennial material has been cross bred to a panel of leading African cultivars and progeny. These crosses were evaluated in several African countries, and we were pleasantly surprised to find they produce a second crop as well as some yield increases, which was unexpected since the relative was not domesticated. One line crossed with each of four African cultivars gave an average of 22 percent yield increase.
We knew the more strongly perennial materials could survive a cold season, but we didn’t know if they could survive a dry season. A total of 96 lines were selected and grown out in Mali and left to see if the crop would survive the eight-month dry season. Around half of the lines had at least some survival. The experiment is an important proof of concept.
Agrilinks: So what does this all mean for sorghum farmers in Africa and beyond?
Paterson: In addition to our proof of concept, we have found a means to overcome a "ploidy" barrier (which relates to the number of chromosomes in a species) between the strongly perennial relative and African sorghums. Now that we know how to make crosses with most sorghums, we can take a quantum leap towards perenniality of this crop. We can now cross improved perennials directly to the African germplasm, enabling us to infuse quality characteristics into their gene pools, which will lead to very sustainable cultivar releases down the road.