No abstract

Thermoinhibition, or failure of seeds to germinate at warm temperatures, is common in lettuce (Lactuca sativa) cultivars. Using a recombinant inbred line population developed from a lettuce cultivar (Salinas) and thermotolerant Lactuca serriola accession UC96US23 (UC), we previously mapped a quantitative trait locus associated with thermoinhibition of germination to a genomic region containing a gene encoding a key regulated enzyme in abscisic acid (ABA) biosynthesis, 9-cis-EPOXYCAROTENOID DIOXYGENASE4 (NCED4). NCED4 from either Salinas or UC complements seeds of the Arabidopsis thaliana nced6-1 nced9-1 double mutant by restoring germination thermosensitivity, indicating that both NCED4 genes encode functional proteins. Transgenic expression of Salinas NCED4 in UC seeds resulted in thermoinhibition, whereas silencing of NCED4 in Salinas seeds led to loss of thermoinhibition. Mutations in NCED4 also alleviated thermoinhibition. NCED4 expression was elevated during late seed development but was not required for seed maturation. Heat but not water stress elevated NCED4 expression in leaves, while NCED2 and NCED3 exhibited the opposite responses. Silencing of NCED4 altered the expression of genes involved in ABA, gibberellin, and ethylene biosynthesis and signaling pathways. Together, these data demonstrate that NCED4 expression is required for thermoinhibition of lettuce seeds and that it may play additional roles in plant responses to elevated temperature.

Desiccant drying prior to hermetic storage extends viability and reduces bruchid (Callosobruchus chinensis L.) infestation of mung bean (Vigna radiata (L.

Purpose The purpose of this paper is to analyze the potential returns to value chain actors from employing desiccant bead drying and hermetic storage technology. Design/methodology/approach Information was collected from 175 different onion (Allium cepa L.) seed value chain actors in Nepal. Four different business models for the introduction of new bead drying and hermetic storage technology were compared to current practices through use of partial budgeting. Findings The increase in net income throughout the chain was quite similar in all four models, ranging from US$28.86 to 29.61 per kg of onion seed, making it difficult to say that any single model is best for all situations. However, there are differences in sharing of positive net income and negative net income for different actors in different models. Moreover, about US$5.85 million incremental return could be earned per year in Nepal from improved preservation of onion seed alone. Research limitations/implications This research assesses how to introduce a new technology, the dry chain concept to maintain seed quality, into the existing marketplace. Originality/value This paper focuses on the economics of a novel technology and compares different business models and scenarios.