Sweetpotato is grown throughout the year in Mozambique but drought affects storage root yield and biomass productivity. The objectives of this research were to estimate the impact of genotype 9 environment interactions (G 9 E) in sweetpotato and select genotypes based on drought indices such as geometric mean, percent yield reduction, drought sensitivity index and harvest index. A total of 58 clones were evaluated during the dry season of 2006, 2008 and 2009. Two treatments were applied for this multi-year trial: full irrigation and without irrigation at the middle of root initiation growth stage. The field layout was a randomized complete block design with three replications. 'Jonathan', 'Resisto' and 'Tanzania' were the check cultivars in each treatment. Storage root and vine yields were recorded at harvest in the trials. Harvest index was computed from the yield data. The analysis of variance, regression and the additive main effects multiplicative interaction (AMMI) analyses, plus phenotypic coefficient of variation and ecovalence were used for dissecting the G 9 E and assessing the stability of each clone. Treatment, genotype 9 treatment and genotype 9 year (G 9 Y) interactions had highest contributions to the variation in storage root yield observed among clones. The stability of harvest index was significantly correlated with the absolute AMMI's IPCA1 and IPCA2 values for storage root yield. Cultivar performance varied within treatments. Four clones had significantly higher storage root yield (t ha -1 ) than 'Tanzania', the best check cultivar under drought. In conclusion, storage root yield (t ha -1 ) was negatively affected by drought and G 9 Y interaction. Harvest index stability and the geometric mean may be key to identify clones with storage root yield stability and high storage root yield under both treatments. At least two environments should be used at early breeding stages to consider harvest index in the early breeding cycle.

SUMMARYSweetpotato breeding requires at least 5 years to obtain an advanced breeding clone for further testing with the goal of cultivar release. An accelerated breeding scheme (ABS) can be feasible if the genotype × year interaction is low. The objectives of the present study were to describe an ABS for sweetpotato and to investigate the efficiency of this breeding scheme for selecting high-yielding and well-adapted orange-fleshed sweetpotato (OFSP) cultivars with high β-carotene (BC) content. More than 198 500 seeds from two crossing blocks were germinated and rapidly multiplied for evaluation in observation trials at four breeding locations in Mozambique. Breeding clones with storage root yields above 10 t/ha were advanced to preliminary and advanced yield trials across four sites and for 3 years. As a result, 64 high-yielding OFSP breeding clones were selected and evaluated in four mega-environments following a randomized complete block design with three replicates at Angónia, Chókwè, Gurúè and Umbelúzi. Data from multi-environment trials were subjected to single site and combined analysis of variance as well as to stability analysis. The genotype × environment interaction was highly significant for storage root and vine yields, dry matter (DM) and BC content. Storage root yield and DM content for 15 OFSP breeding clones ranged from 14·9 to 27·1 t/ha and from 24·8 to 32·8%, respectively. BC content, iron and zinc ranged from 5·9 to 38·4, 1·6 to 2·1 and 1·1 to 1·5 mg/100 g dry weight, respectively. The OFSP breeding clones also met the culinary tastes required by local consumers in Mozambique. The proposed ABS seems to be an attractive scheme for genetic enhancement of sweetpotato.

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Open Agriculture. 2017; 2: 280-291 were mentioned respectively by 43 %, 21 % and 20 % of households as their preferred varieties. All households consumed OFSP roots. However, more than 50% of households consumed OFSP from April to October. Fifty six percent of households sold OFSP roots which generated an average income of 48 USD per household per year. The use of lowland areas for vine conservation has increased and vine management has improved. Consequently, production area has increased by 23%, root yield has increased by more than 100%, from 6.0 t/ ha as average national yield to 15.5 t/ha, average yield for the survey, and the period of consumption from own production has also increased to seven months. Awareness campaigns will continue to promote year round production of OFSP. Abstract: The objective of this study is to evaluate the use of lowland areas for vine conservation to improve the availability and access of planting material during the main planting period and subsequently improve access to Orange Fleshed Sweetpotato (OFSP) roots for consumption and income. The study was implemented in 8 districts in Niassa province in early December 2015, among 271 households (HH), where 77% of these households had children under 5 years and 34% of the respondents were women. These households were selected randomly among households that had received OFSP planting material between 2013 and 2015. Data about vine conservation, use of lowland areas, OFSP consumption and income from OFSP were collected and analyzed using SPSS. Results were compared with the baseline survey results from 2013. Eighty seven percent of households have access to lowland areas. The households using lowland areas for vine conservation increased from 41% in 2013 to 58% in 2015 and the use of small garden plots from 14% to 26%. The households conserving vines in upland fields dropped from 56% in 2013 to 7% in 2015. About 53% of households still planted in June (beyond the main planting season) while 24% continued to plant year around. However, cultivation on small plots dominated from March to December, mainly for vine multiplication. Delvia, Irene and Gloria varieties