Adaptation of field pea varieties to organic farming across different environments of Italy

Abstract

This study aimed to support field pea (Pisum sativum L.) breeding strategies for organic systems of southern European environments, by assessing the size of genotype × environment interaction (GEI) due to spatial and temporal factors across climatically contrasting regions and identifying plant characters associated with genotype adaptive responses. Twelve recent varieties were evaluated for grain yield and other traits in six organically managed environments (three sites × two cropping years) of northern, central and southern Italy. GEI for grain yield was large, with the variety × site × year interaction greatly exceeding the variety × site interaction. This finding, and the similar magnitude of the mean genetic correlations for variety yields across pairs of sites (rg = 0.56) and pairs of years (rg = 0.51), indicated the difficulty of exploiting variety × site interaction effects by breeding for specific climatic regions. Pattern analysis highlighted the large inconsistency across years for GEI pattern of the sites from central and southern Italy. GEI also complicated the targeting of varieties, owing to inconsistent top-performing material across years according to additive main effects and multiplicative interaction (AMMI)-modelled yields. Higher genotype mean yield was strictly associated (P < 0.01) with lower weed proportion (hence, greater competitiveness against weeds: r = –0.96), taller plants (r = 0.89) and larger seeds (r = 0.78), with looser associations with lower susceptibility to lodging and ascochyta blight. These traits, which also contributed to preferential adaptation to the moisture-favourable environments of northern Italy, could be selected in breeding widely adapted varieties.

Pea genomic selection for Italian environments

“…The main limitation of this study lies in the limited number of test environments it was based upon. However, the observed GEI pattern for pea grain yield, implying modest GEI across geographically-distant Italian locations and high GEI across test years as a consequence of marked year-to-year variation for low winter temperatures, confirmed earlier results relative to different sets of recent varieties grown in a larger number of Italian environments [34, 36]. Those studies and the current one indicate the possible occurrence in northern Italy of absolute minimum temperatures in winter below the threshold of − 8.5 °C that was reportedly associated with sizeable plant mortality of relatively winter-hardy pea [43].…”

“…Four F 6 plants per line were grown in a non-heated glasshouse to collect DNA samples for line genotyping and to produce seed, which underwent one additional generation of multiplication before use for phenotyping. In addition, the evaluation work included the three parent cultivars, as well as the cultivar Spacial that displayed excellent adaptation across organically-managed environments of northern and central Italy in recent variety trials [36].…”

“…A thorough verification of the value of GS to predict estimated breeding values for pea grain yield requires to take into account GEI effects, which may be large across autumn-sown environments of southern Europe [34–36]. Particularly for Italy, GEI proved to be largely affected by year-to-year variation for timing and extent of winter cold stress, whose effect can be highly damaging in specific years both in subcontinental-climate and Mediterranean-climate areas [15].…”

Development and Proof-of-Concept Application of Genome-Enabled Selection for Pea Grain Yield under Severe Terminal Drought

“…However, wide GE interaction across environment mean yields in the range of 1-3 t/ha was repeatedly observed in cool-season cereals [36,37]. In pea, GE interaction for grain yield was reportedly modest for advanced breeding lines and elite cultivars across different drought-prone environments of Australia [38] but was large for different pea material across environments of Southern Europe [28,[39][40][41] as well as within a different European region such as Poland [42].…”

“…In particular, this study included 96 lines for the A × I population, 92 for K × A, and 100 for K × I, for which enough seed was available for sowing in both North-African environments. In addition, the evaluation trials included the three parent cultivars, as well as the recent cultivar Spacial, which is characterized by excellent adaptation to Italian environments [41].…”