Productivity of rice, world's most important cereal is threatened by high temperature stress, intensified by climate change. Development of heat stress-tolerant varieties is one of the best strategies to maintain its productivity. However, heat stress tolerance is a multigenic trait and the candidate genes are poorly known. Therefore, we aimed to identify quantitative trait loci (QTL) for vegetative stage tolerance to heat stress in rice and the corresponding candidate genes. We used genotyping-by-sequencing to generate single nucleotide polymorphic (SNP) markers and genotype 150 F8 recombinant inbred lines (RILs) obtained by crossing heat tolerant “N22” and heat susceptible “IR64” varieties. A linkage map was constructed using 4,074 high quality SNP markers that corresponded to 1,638 recombinationally unique events in this mapping population. Six QTL for root length and two for shoot length under control conditions with 2.1–12% effect were identified. One QTL rlht5.1 was identified for “root length under heat stress,” with 20.4% effect. Four QTL were identified for “root length under heat stress as percent of control” that explained the total phenotypic variation from 5.2 to 8.6%. Three QTL with 5.3–10.2% effect were identified for “shoot length under heat stress,” and seven QTL with 6.6–19% effect were identified for “shoot length under heat stress expressed as percentage of control.” Among the QTL identified six were overlapping between those identified using shoot traits and root traits: two were overlapping between QTL identified for “shoot length under heat stress” and “root length expressed as percentage of control” and two QTL for “shoot length as percentage of control” were overlapping a QTL each for “root length as percentage of control” and “shoot length under heat stress.” Genes coding 1,037 potential transcripts were identified based on their location in 10 QTL regions for vegetative stage heat stress tolerance. Among these, 213 transcript annotations were reported to be connected to stress tolerance in previous research in the literature. These putative candidate genes included transcription factors, chaperone proteins (e.g., alpha-crystallin family heat shock protein 20 and DNAJ homolog heat shock protein), proteases, protein kinases, phospholipases, and proteins related to disease resistance and defense and several novel proteins currently annotated as expressed and hypothetical proteins.

The bean weevil (Acanthoscelides obtectus Say) is an aggressive post‐harvest pest of the common bean (Phaseolus vulgaris L.). Bean common mosaic virus (BCMV) and Bean common mosaic necrosis virus (BCMNV) are important seedborne diseases of dry bean in the Americas and Africa. The development of bean lines that combine resistance to BCMV, BCMNV, and bean weevils can help to reduce yield loss during the growing season and avoid seed damage during storage. AO‐1012‐29‐3‐3A, (Reg. No. GP‐299, PI 675563) is a multiple virus and bean weevil‐resistant bean germplasm line adapted to the humid tropics; it was developed and released cooperatively in 2015 by Sokoine University of Agriculture, Oregon State University, the USDA‐ARS, and the University of Puerto Rico. AO‐1012‐29‐3‐3A has a determinate growth habit and a dark red kidney seed type similar to the cultivar Rojo, which is commercially acceptable in Tanzania. AO‐1012‐29‐3‐3A possesses the I and bc‐12 genes that confer resistance to BCMV and BCMNV. AO‐1012‐29‐3‐3A produced a mean seed yield similar to the checks USLK‐1 and ‘Badillo’ in three trials planted in Puerto Rico. Seed of AO‐1012‐29‐3‐3A had greater levels of threonine, proline, analine, valine, lysine, methionine, and crude protein compared with the check cultivar Badillo. AO‐1012‐29‐3‐3A should serve as a useful source of resistance to the bean weevil, BCMV, and some pathogroups of BCMNV.

Solanum aethiopicum L. is indigenous to Africa and constitutes an important vegetable. Morpho-agronomic traits were used to study diversity among 44 accessions of S. aethiopicum groups to identify traits of high discriminatory ability and donor parents with specific or multiple traits for introgression and utilization in breeding programmes. Field experiments were conducted from 2008 to 2010. The principal component (PC) analysis of morpho-agronomic data indicated high discriminatory ability for fruit calyx length, fruit length and leaf length. On PC1, fruit length showed positive and significant correlation coefficients with leaf length, fruit calyx length and width. An independent association was recorded among fruit width, fruits per infructescence and seed yield (t/ha). Ordination (biplot) and grouping (dendrogram) revealed genetic variation and relatedness, phenotypic plasticity and geographical heterogeneity among the accessions within and among the clusters. Members of cluster 1 (group ‘c’) are a promising donor parent for multiple traits (earliness and fruit length), and members of group ‘b’ are superior for fruits per plant, fruits per infructescence and fruit infructescence per plant. Hybridization among distant clusters would provide an opportunity for bringing together gene constellations of diverse background. Earliness and fruit length were highly variable among the S. aethiopicum groups. The results are important for the breeding and selection of this crop.

Double blind field experiments and experimental auctions were conducted with bean and cowpea farmers in Tanzania and Ghana to gauge the relative demand for three types of seed products that differ in price and quality: certified, quality declared, and recycled. Whether the cost differential makes these seeds qualitatively different products as reflected in their perceived performance, and whether that translates into farmers' willingness to pay price premiums, are the research questions addressed by this study. Results indicate that, all else equal, there were significant differences in the perceived quality of the seed products evaluated. Farmers were willing to pay significantly more for their higher rated seed relative to their lower rated seeds. However, for a majority of farmers the magnitude of the premium they are willing to pay for a higher quality seed is less than the current price differential between certified seed and grain. Research and policy implications of these results for legume seed system are discussed.

Fruit flies (Diptera: Tephritidae) are among the most important pests damaging fruit crops growing in Tanzania. Demographic parameters for Ceratitis cosyra (Walker) and Bactrocera invadens (Drew, Tsuruta & White) are reported and compared. These include pre‐adult survival and development rates, adult survival and fecundity and population parameters such as the intrinsic rate of increase, and mean generation time. Population and biological parameters of the C. cosyra and B. invadens were measured in an environmental chamber at 25°C and 30°C with 75% RH and at room temperature ranging 23–28°C. The results showed that B. invadens had shorter embryonic, larval and pupal development times than C. cosyra independent of temperature. Life expectancy of male B. invadens was significantly greater than that of C. cosyra, while life expectancy of female B. invadens was greater than that of C. cosyra but not significantly. Average net fecundity was higher for B. invadens than for C. cosyra. Both species attained their highest intrinsic rate of increase and net reproductive rate at 30°C. B. invadens exhibited higher intrinsic rate of increase and net reproductive rate than C. cosyra at all temperatures tested.

Preliminary evaluations have shown that indeterminate new tomato breeding lines produce high yields of large fruits. Pruning systems have been reported to regulate tomato fruit size and overall yield performance. A study to evaluate the effect of pruning levels (non pruning, single stem, two stems and three stems) on plant developmental cycle, yield, and quality of five indeterminate tomato breeding lines and one commercial cultivar was conducted from November 2009 to March 2010 at the Horticulture Unit of Sokoine University of Agriculture, Morogoro, Tanzania. Results showed that two stem pruned plants gave the highest number of marketable fruits per plant. The highest number of non marketable tomato fruits per hectare was observed in unpruned plants. Tomato lines differed in their performance, with the longest period of harvesting, highest number of flowers flowers, highest percentage of fruit-set, the highest yield, high number of marketable fruits observed in lines P20-(03) and 186-2(06), which is probably a result of their genetic characteristic. It was concluded that, the large fruit size of the new tomato breeding lines can be reduced to meet consumer's needs without reducing yield by two and three stem pruning in lines P20-03 and S186-2(07).

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