Grain Yield Stability and Nutritive Traits in Bean Landraces From NE Italy.

Phaseolus vulgaris seeds reached Northern Italy around 1530 AD. After centuries, considerable diversity can be observed in sub-alpine areas of Friuli (Northeast Italy). Since 2001, putative landraces and populations  have been collected, characterized and maintained on farm and/or ex situ by the University of Udine Genebank (FAO code: ITA368).  Segments of the bean collection have been annually evaluated in multi-location field trials. Results from a dataset including three landraces and two commercial varieties, i.e. the checks used in 12 year/location experiments, are presented here. Grain yield, seed macro- and micronutrients concentration, seed water absorption and teguments to seed mass ratio are considered in the analysis. For seed nutrient concentration, samples were acid treated following the EPA method 3052 and analyzed by an ICP-OES (Varian Inc., Vista MPX). The small-seeded landrace 'Cesarins' showed high (on average 3.16 Mg ha^-1) and fairly stable grain yields; conversely, the Borlotto-type commercial variety ‘Pegasus’ (2.17 Mg ha^-1) appeared to have low and unstable yields. Linear regressions between grain yield and number of seeds m^-2 for small-seeded and large-seeded materials, indicate a steeper regression coefficient for the small-seeded group. Indeed, ‘Cesarins’ and ‘Kondor’, i.e. the two small-seeded materials, outperformed the others in the unusually dry 2003 season. Seed protein was higher in wet seasons; a large variation across environments was observed in the Borlotto-type ‘Pegasus’. The range of Fe and Zn concentration in seeds was larger across environments (Fe 45–125;  Zn 30-66 mg kg^-1) than across landraces (Fe 66– 85;  Zn 42–47 mg kg^-1). Indeed, compared to large-seeded Borlotto types, the two micronutrients were consistently in the low range for small-seeded materials. ‘Cesarins’ had the highest Ca concentration (2.09 g kg^-1 ), ‘Pegasus’ the lowest (1.20 g kg^-1). The  high Ca content of ‘Cesarins’ seeds could be related to the excellent texture of these traditional beans after cooking.