Crop development and root distribution in lesser yam (Dioscorea esculenta): Implications for fertilization

A growth analysis study involving monthly excavation of Dioscorea esculenta plants revealed that the root system developed fully in the period before tuber initiation, and extended radially for a distance between 2.3 and 4.3 m. Primary roots initially remained in the top 10 cm of the soil profile, but descended to approximately 30 cm near their full extension. Tuber number increased from initiation around 21 weeks after planting (WAP) until maximum vine growth was reached around 33 WAP, but tuber dry weight continued to increase throughout the senescence period of the vine, to 45 WAP. Tubers lost dry matter but not fresh weight during dormancy in the soil, to 55 WAP. The results indicate that a distance of at least 4.5 m is required to separate experimental fertilizer treatments, and that post-establishment burial of fertilizers around the mound or ridge risks damage to roots near their base, while inter-row application is accessible to roots and may be preferable

Understanding the cocoa genetic resources in the Pacific to assist producers to supply the growing craft market

The Pacific countries of Fiji, Samoa, Solomon Islands, and Vanuatu account for less than 2% of the world?s cacao dry bean production. To capitalise on the rapidly expanding origin craft cocoa market, understanding the genetic attributes of Theobroma cacao in the Pacific is essential. A six-year ACIAR-funded project collected 1647 dried leaf samples from research stations and smallholder farms to identify the population ancestry of T. cacao in the partner countries. Using SNP marker profiling, the study identified germplasm high in Amelonado, which represents the majority of material throughout the Pacific. However, the study also identified samples high in the remaining nine genetic groups, including Criollo, Nanay, IMC (Iquitos), Guiana, Parinari (Marañón), Nacional, Ucayali (Contamana), LCT EEN (Curaray), and Purus, which were distributed throughout the Pacific. The results, if utilised in local selection trials, could reposition growers in the Pacific countries, allowing them to supply the growing origin craft cocoa market, with genetically unique beans. Cocoa genetics was one aspect of a project incorporating production and postharvest research to refocus the commodity based cocoa industry to a supplier of high-quality beans of unique Pacific cocoa origin to the rapidly expanding craft ?bean to bar? cocoa industry