International soybean variety experiment; sixth report of results, 1978

This volume reports the results of the sixth ISVEX, primarily through the 153 statistical tables which comprise the bulk of the document. During the sixth ISVEX, conducted 2/78-3/79, a large number of cultivars with a diverse genetic composition were evaluated under a wide range of environmental conditions at 185 sites in 76 countries. Seeds and materials were prepared and shipped with instructions for management and data collection to cooperating scientists who in turn provided land, labor, and fertilizer. The 36 cultivars, including 16 cultivars from previous ISVEX trials, were selected for agronomic performance, maturity group classification (O-IX), seed availability, uniform seed quality, and adaptability to program design. Experiment sites were divided into environmental zones defined according to latitude and altitude. Cooperators collected data on: yield days to flower and to maturity, nodule number and weight, plant height at maturity, lodging and shattering scores, plants harvested, pods per plant, seed weight and quality, and protein and oil contents of the beans. Data were then analyzed, using standard statistical techniques. The sixth ISVEX found that yields ranged from 1320-3035 kg/ha, indicating that varieties should be selected on the basis of local trials. The intervals between planting and flowering and between flowering and maturity were significantly correlated. The number of pods per plant was relatively stable, while seed weight was quite variable. In addition, seed quality was not good. Lastly, the range in protein and oil content was small.