Birte Komolong

The Pacific Islands (Melanesia, Micronesia, Polynesia) were the last region in the world to be colonized by modern humans. In their migrations, they dispersed asexually propagated food plants that were first domesticated in Melanesia and exposed them to further selection in diverse insular environments. Later, staple food crops were introduced from South America. In our search for research on genetic resources characterization and breeding conducted between 1950 and 2022, we retrieved 338 references on 13 crop species. All studies were examined, and a review is presented here. Relatively few were on genetic improvement (92 references) compared to those on morphological diversity (246 references). The paradox is that the Pacific is considered a region exposed to the climatic crisis, perhaps more vulnerable than any other region in the world. This paradox is surprising when we consider that most people in the Pacific are growing staple food crops, for household use and/or for local ma...

Virus diseases transmitted by aphids (Myzus persicae) and whiteflies (Bemisia tabaci) have been one of the major cause of yield decline in sweetpotato (Ipomoea batatas (L.) Lam) in sweetpotato producing countries including Papua New Guinea. In this study, the epidemiology of aphids and whiteflies was investigated at the National Agriculture Research Institute Momase Regional Center Bubia, in 2015. Virus-free sweetpotato variety of Beauregard was planted in two separated observatory plots on a field where different crops were grown. Virus vectors incursion were systematically sampled on weekly basis using binomial sampling technique throughout the growing period. It is observed from the result that virus vectors start moving into the crop soon after establishment of the sweetpotato plants. Incursions in particular happened from other crops growing adjacent to the sweetpotato trial plots. Whiteflies were observed to colonize sweetpotato plants all throughout the growing period but rarely occur with aphids. Whitefly and aphids population fluctuated at different times but generally peaked during high rainfall months and towards harvest. High population densities of vectors were discovered mostly at the edges of the trial plot with minimal virus symptoms expressed. In terms of sweetpotato virus management, these may suggest that farmers should clear weeds around the plots and grow non-host plant species (or lesser favored hosts) as barrier which may help in reducing incursion of vectors. It is suggested that planting materials for next planting should be obtained from inner plots rather than on the edges where plants are exposed to high population of vectors. Keywords: Vectors (Aphids and Whiteflies), Virus-free material of Beauregard, Virus, Host, Incursion, Population density, Re-infection

... Cause Sorghum Ergot in Australia Birte Komolong, Sukumar Chakraborty, Malcolm J. Ryley, and David Yates Abstract Ergot of sorghum affects seed production and grain usage in animal feed due to concerns about potential animal toxicity. ... Brisbane. Aus-tralia). ...

ABSTRACT Ergot, caused by Claviceps africana, has emerged as a serious threat to sorghum hybrid seed production worldwide. In the absence of gene-for-gene-based qualitative resistance in commercial cultivars, varieties with high pollen production that can escape ergot infection are preferred. Recent demonstration of differences in ergot susceptibility among male-sterile lines has indicated the presence of partial resistance. Using chitin-specific fluorescin-isothiocyanate-conjugated wheat germ agglutin and callose-specific aniline blue, this study investigated the process of sorghum ovary colonization by C. africana. Conidia germinated within 24 h after inoculation (a.i.); the pathogen was established in the ovary by 79 h a.i., and at least half of the ovary was converted into sphacelial tissue by 120 h a.i. Changes in fungal cell wall chitin content and strategic callose deposition in the host tissue were associated with penetration and invasion of the ovary. The rate of ovary colonization differed in three male-sterile lines that also differed in ergot susceptibility. This work demonstrates a possible histological basis for partial resistance in male-sterile sorghum lines that could lay the foundation for variety improvement through further breeding and selection.

The partnership, spanning ten (10) years, between the Technical Centre for Agricultural and Rural Cooperation (CTA) and the National Agricultural Research Institute (NARI) of Papua New Guinea has been fruitful. CTA, in fulfilling its mandated function, has been supporting a partner organisation in the Pacific Region and NARI, on the other part, has been a successful recipient of CTA’s support and making good use of the invaluable support offered by CTA

Four rice (Oryza sativa L.) varieties, NR 1, NR 9, NR 15 and NR 16 were provisionally released in 2003 by the National Agricultural Research Institute (NARI) for the lowland areas ranging from 0-1200 meters altitude. They were selected on the basis of grain yield, eating quality and pest and disease resistance from the first season of trials.. The varieties were tested by NARI for another two seasons at five different sites in the Madang and Morobe Province. The superior performance of the four NR varieties over the standard varieties TCS 10 and FB91 was confirmed in both seasons. The varieties NR 1, NR 9, NR 15 and NR 16 are recommended for final release to farmers in the Lowlands of PNG based on yield performance and taste.

Sweet potato is generally known as drought tolerant crop, however cannot withstand drought during initial planting and during initial growth stages including development and tuber intitiation and thus there is need to identify appropriate genotypes adapted to drought conditions. The aim of this study was to evaluate different sweetpotato genotypes subjected to drought stress to identify the most drought tolerant genotypes and select the best index for investigating sweetpotato genotypes under stress and non-stress conditions. Twenty four sweetpotato genotypes were screened for drought tolerance under the screen house. The trial was assessed using a randomised complete block design with three replicates. The analysis of variance showed significant differences in genotypes under drought stress condition. Five different drought tolerant indices including mean product, geometric mean product, stress tolerance index, tolerance and stress susceptibility index were used to identify high yi...

Sorghum ergot was first discovered in Australia in 1996. It affects seed production and grain usage in stock feed due to concerns of animal toxicity. Three species of Claviceps are known to cause ergot of sorghum with different epidemiological, animal toxicity, and management implications. Claviceps africana was identified as the causal agent but morphological differences between isolates raised the possibility of more than one species being involved. The major aim of this study was to identify the Claviceps species causing sorghum ergot and to determine the genetic diversity among isolates of the ergot pathogen from Australia and overseas. Symptom development, sequencing of the ITS1 region, and radiolabelled DNA amplification fingerprints (RAF) were used to confirm that ergot of sorghum in Australia is caused by C. africana. The morphology of sphacelia, microconidia, macroconidia, and secondary conidia of all 36 Australian isolates studied matched the description for C. africana an...

The aim of the presented investigation was to study chemical composition variation in starch, protein and minerals found in corms of ten taro cultivars from Papua New Guinea, South Pacific. The chemical analyses were performed on oven dried materials. The starch content ranged from 66 % to 79 %, mean content of crude protein was 3.72g/100g. Among minerals, K was the most abundant (1.77 %), followed by P (0.43 %), Ca (1230 mg/kg) and Mg (976 mg/kg). The analyzed materials could also be considered as moderate sources of Zn (22.10 mg/kg), Fe (19.63 mg/kg), and Cu (6.87 mg/kg). The content of Mn was rather low (5.12 mg/kg).