Wheat Yield Potential
Increasing in Marginal
Areas
Wheat yield
gains in favorable and marginal |
In the last two decades, wheat yield potential has risen more rapidly in marginal than in more favorable environments. Data from CIMMYT’s International Spring Wheat Yield Nursery (ISWYN) and the Elite Spring Wheat Yield Trial (ESWYT) indicate that wheat yield potential in drought-prone environments rose by about 3.1% per year from 1979 to 1995, or approximately 80 kilograms per year. In contrast, wheat yield potential in irrigated environments rose at about 1% (62 kilograms) per year (see figure).
What does this mean for farmers in marginal areas in any given year? It means considerable yield gains. In marginal areas in 1997, for example, the wheat production increase resulting from replacing older improved varieties with newer ones was about 1.85 million tons. What caused wheat yield potential to grow so fast in marginal areas? In some cases, newer, higher yielding wheat varieties developed for favored areas finally became available (or “spilled over”) to farmers in more marginal areas. CIMMYT’s Veery wheats, for example, were originally developed for favorable environments about two decades ago, but they have adapted well to most marginal environments. The Veery wheats and their descendents have yielded better than other cultivars in both high-yielding environments and under reduced irrigation.
In other cases, breeders working in innovative programs for marginal environments crossed varieties with high yield potential to cultivars that could resist drought. For example, Nesser, a wheat bred from the high-yielding CIMMYT variety Jupateco 75 and the drought-tolerant Australian variety W3918A, has performed well in the dryland environments of West Asia and North Africa.
These environments have also benefited substantially from research spillovers. Using data from ISWYN, researchers documented that varieties bred locally for specific environments had significant yield advantages only for those environments, whereas CIMMYT-related wheats demonstrated significant yield advantages across several environments.*
Projected growth in wheat productivity in high-potential environments is not likely to meet the growing demand for wheat over the next 20 years. Given increasing population pressure in the developing world, declining investments in irrigation, and many other factors, improved productivity in marginal areas could be the key to food security in the coming years.
* See M.K. Maredia and D. Byerlee (eds.), The Global Wheat Improvement System: Prospects for Enhancing Efficiency in the Presence of Spillovers (Mexico City, CIMMYT, 1999).
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For more information: Michael Morris (m.morris@cgiar.org) |
©
CIMMYT
October 2001