overtime sink and source relationship in sweetpotato


Sweetpotato is one of the most important root crops in the world with more than 133 million tonnes produced worldwide annually (Baafi, E., K., et al., 2016). The crop is versatile in Uganda and is used in various food preparations with other staples. However, on-farm yield is still very low (4 t/ha) compared to attainable yields under improved circumstances (30 t/ha), despite giant strides made through breeding to release 23 high yielding and disease resistant cultivars in the country. The majority of farmers still prefer their landraces which are low yielding and more susceptible to diseases and pests (Abidin et al., 2004). The decision to adopt a new cultivar is quit complex, related to field and yield performance as well as end-users’ preferences (Sugri et al., 2012). In cassava, early maturity was the most frequent attribute desired by farmers in the transitional ecological zone of Ghana and several studies have revealed that late bulking is the single most important reason for the rejection and abandonment of cassava varieties in African countries (Okechukwu RU, 2009). However, in sweetpotato, farmers tend to select continuous storage root forming and bulking varieties to allow continuous harvesting for home food security and for benefiting from in-ground root storage. Hence the importance of these underutilized traits in sweetpotato. In East African countries, households like ‘continuous storage root formation and bulking’ varieties because they produce a few storage roots each day over a long season. The appropriateness of this type of varieties for domestic use should be exploited for increased home food security. Small scale farmers gradually sell sweetpotato to procure small daily needs in families like salt, soap, oil, school material for children, etc. Therefore, Commercial potential of these types of varieties are of high value especially for women as they are in charge of these daily familial needs.

Breeding for early maturity (determinate growth habit) and high yield (indeterminate growth) has been one of the principal tasks of breeders in many crops, however, breeding for such in sweetpotato, a vegetatively propagated crop, has not been given much attention and few studies have been reported. It is well recognized that differences in early (determinate) or late (indeterminate) storage root formation and bulking among sweetpotato varieties exist. However, little attention is paid to the selection of parents in breeding for continuous storage root formation and bulking (CSRFAB) in sweetpotato. The level of variability of CSRFAB in the Ugandan sweetpotato germplasm, the inheritance and genetic correlation of DSRFAB and ISRFAB of the trait are unknown. The relationship between DSRFAB and ISRFAB controlling genes and its magnitude in yield improvement in sweetpotato should be the priority of future research programs.


Leaf Photosynthesis MultispeQ V1.0


Measures many photosynthesis-related parameters in <15 seconds, including:

  • Chlorophll Fluorescence: Phi2, PhiNPQ, PhiNO, NPQt, qL, LEF
  • Relative Chlorophyll: SPAD
  • Proton Motive Force: ECSt, vH+, gH+
  • Absorbance at: 450, 535, 605, 650, 730, 850, 880, and 940nm.
  • Leaf Thickness (in mm), angle, and cardinal direct...


  1. (Multiple Choice)



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