000			02963nam a22002897a 4500
003			MX-TxCIM
005			20260123153440.0
008			260121s2025 ||||op||||00||0|eengdd
040			_aMX-TxCIM
041			_aeng
100	1		_aMulungu, K.H. _8001714131 _gSustainable Agrifood Systems _933325
245	1	0	_aVariety age and maize yield in Zambia : _bclimate-smart benefits of varietal turnover under production stress
260			_a[Mexico : _bCIMMYT, _c2025]
300			_a42 pages
500			_aOpen Access
520			_aAgricultural productivity growth in sub-Saharan Africa has stagnated despite sustained investments in crop improvement research, with maize yields showing concerning signs of decline since the 2000s. This study examines whether slow varietal turnover (the replacement of older varieties with newer improved varieties) constrains productivity growth in Zambian maize systems. Using nationally representative panel data spanning 2012-2019 and covering 11,065 plot-level observations from 8,369 households, we estimate the relationship between variety age and yield while controlling for household and plot characteristics through fixed and random effects models. First, we find that female-headed households use varieties 2-3 years older on average, pointing to equity concerns in variety access. Our analysis reveals that each additional year of variety age reduces maize yields by 8.5-20 kg/ha depending on model specification. These effects are substantially larger than previously documented in African contexts. Our results are robust to different causal identification strategies. The effects are highly heterogeneous across production conditions, with newer varieties providing greatest yield advantages under drought stress, late planting, low fertilizer application, and high temperatures, demonstrating successful incorporation of climate-smart traits in recent breeding efforts. However, newer varieties do not outperform older ones under pest and disease pressure, highlighting gaps in biotic stress tolerance. Economic analysis reveals benefit-cost ratios of 3.5-8.3 for adopting varieties one year newer than average age (13 years), indicating strong financial incentives for variety turnover. Our findings suggest that accelerating varietal turnover represents an important but underutilized pathway for agricultural productivity growth and climate adaptation in sub-Saharan Africa.
546			_aText in English
597			_dCGIAR Trust Fund _fBreeding for Tomorrow _uhttps://hdl.handle.net/10568/180573
650		7	_aMaize _2AGROVOC _91173
650		7	_aSeed _2AGROVOC _99893
650		7	_aMarkets _2AGROVOC _93765
651		7	_aAfrica _2AGROVOC _91316
700	1		_aCairns, J.E. _gGlobal Maize Program _8INT2948 _9879
700	1		_aDebello, M.J. _gSustainable Agrifood Systems _8INT3210 _9903
856	4		_yOpen Access through DSpace _uhttps://hdl.handle.net/10883/36812
942			_cRE _n0 _2ddc
999			_c69821 _d69813