Cassava (Manihot esculenta Crantz) roots spoil 2 to 3 d after harvest because of postharvest physiological deterioration (PPD), which has remained an unsolved problem. Roots from different sources of germplasm were evaluated 5, 10, 20, and 40 d after harvest and some were found to be tolerant to PPD. Three genotypes showed zero levels of PPD even 40 d after harvest. Tolerance to PPD in roots with high carotenoid levels may be explained by their antioxidant properties. Irradiation of seeds in mutagenized populations may have silenced one of the genes involved in the expression of PPD. The tolerance to PPD found in other sources cannot be properly explained. The identification of several sources of resistance (and at least two different modes of action) suggests that now there are alternatives available for solving this problem, benefiting millions of resource‐limited farmers worldwide.

Improving total carotenoids content (TCC) in cassava roots is an important strategy to reduce vitamin A deficiency in human populations that rely on cassava as a source of energy in their diets. The high heritability for TCC in the roots allowed the International Center for Tropical Agriculture to implement a rapid cycling recurrent selection approach that reduced the standard length of each cycle from the ordinary 8 yr to 3. Data from successive evaluation nurseries suggested that gains have been made through time. However, no comparison of different cycles of selection has been made when representatives of each cycle were grown together. This study compares 4 to 5 clones representative of cycles of selection from 2004 to 2009. Results demonstrated significant gains for TCC as well as for total β‐carotene (TBC) expressed both in a fresh and dry weight basis. Although dry matter content (DMC) was not a selection criterion during the selection process, it increased with the successive cycles of selection. This suggests that indeed, simultaneous gains for TCC, TBC, and DMC are feasible. This finding is relevant for the important ongoing efforts at the International Institute of Tropical Agriculture and African National Programs to release biofortified cassava clones in Africa with adequate levels of dry matter content.

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Maize is a staple crop that has been the subject of biofortification efforts to increase the natural content of provitamin A carotenoids. Although significant progress toward increasing provitamin A carotenoid content in maize varieties has been made, postharvest handling factors that influence carotenoid stability during storage have not been fully established. The objectives of this study were to determine carotenoid profiles of six selected provitamin A biofortified maize genotypes at various developmental stages and assess the stability of carotenoids in maize kernels during controlled storage conditions (12 month period), including elevated temperature and relative humidity. There were no significant changes in the content of individual carotenoids within genotypes during kernel development from 45 days after pollination through the time of harvest. Carotenoid losses through traditional grain drying were also minimal (<9%). However, the stability of carotenoids in maize kernels over storage time after harvest was found to be dependent on both temperature and humidity, with variation observed among genotypes. Different forms of provitamin A carotenoids follow similar degradation rates. The genotype C17xDE3 had a degradation rate 2 times faster than those of the other genotypes evaluated (P < 0.001). These differences in carotenoid stability under controlled storage were attributed, in part, to observed differences in the physical properties of the kernels (surface area and porosity). These results support the notion that effective control of moisture content and temperature of the kernels during storage conditions is essential to reduce the speed of degradative reactions.

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