EFFICIENCY IN THE USE OF PHOSPHORUS, NITROGEN AND POTASSIUM IN TOPLESS FABA BEANS (VICIA-FABA L) - VARIABILITY AND INHERITANCE

In a field experiment with topless faba beans, parental inbred lines a nd F-1 hybrids of a 7 x 7-diallel were evaluated for traits related to the P, N and K efficiency. In addition, the parental inbreds were cul tivated in a pot experiment at two P levels (100 vs. 700 mg P per pot) . Significant heterosis for grain yield, uptake and utilization effici ency of nutrients in the field experiment highlighted the enhancement of nutrient efficiency in the hybrids. Amongst both parental inbreds a nd hybrids, significant genotypic variation was found for nearly all r ecorded traits. In the diallel analysis, the GCA effects generally pro ved to be highly significant and in most cases considerably higher tha n the SCA effects. In the pot experiment, grain yield ranking of the p arental Lines at the high P level (= P700) was very similar to that in the field experiment, whereas at the low P level (= P100, = P deficie ncy) the ranking of the Lines changed considerably. Correspondingly, t he P level-line interaction was highly significant. High tolerance tow ards P deficiency was found for those two parental inbreds derived fro m cultivars bred under Syrian conditions. At the high P supply, P effi ciency was more favoured by a high P uptake, but at P deficiency by a high internal P utilization.