|Whitehead, Sharon - UNIVERSITY OF READING, UK|
|Summerfield, Rod - UNIVERSITY OF READING, UK|
|Ellis, Richard - UNIVERSITY OF READING, UK|
|Wheeler, Tim - UNIVERSITY OF READING, UK|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 24, 1999
Publication Date: N/A
Interpretive Summary: The accumulation and partitioning of biomass and nitrogen among germplasm representing a genetic gradient from wild species progenitors to current high yielding varieties was examined over a two year period at two locations. The data indicate that yield improvements in lentil have come about from consistent increases in the ability of the germplasm to produce biomass, the total weight of the plant material and improvement in the ability of the germplasm to partition that biomass to the valuable protein- seeds. However, with the seed yield benefits, the data indicate that the proportion of nitrogen partitioned to the seeds has gradually increased such that it now appears to be at a limit and that further increases in seed yields will have to come from additional increases in biomass. The encouraging part of the study is the indication that biomass and seed yield production are likely to continue with selection.
Technical Abstract: The accumulation and partitioning of biomass and N throughout the domestication of lentil (Lens culinaris Medik.) has been examined using a genetic 'gradient' comprising three representatives each of Lens orientalis (Boiss.) progenitors, landraces, pre-1980 cultivars and modern germplasm. All twelve genotypes were sown at Pullman, WA USA in 1996 and 1997, and at Reading, UK in 1997. The progenitors produced meager biological yields (averaging 0.72 t ha-1) and poor harvest indices (HI=0.19), and so their seed yields were also small (0.11 t ha-1). Productive landraces had substantially better biological yields (3.52 t ha-1), improved HI (0.34) and so larger seed yields (1.13 t ha-1). Further increases in biological and seed yields have resulted from genetic selection of cultivars (5.11 and 1.32 t ha-1), respectively). The development of modern germplasm by hybridization has further increased seed yields (1.95 t ha-1). Strong and positive correlation between seed yield and biomass has persisted throughout domestication. The proportion of N in above-ground tissue which is found in mature seeds [i.e. N harvest index (NHI)] has increased more rapidly than has HI for dry matter. Given the small concentrations of N in dead leaves and stems at reproductive maturity (averaging 1.68 and 1.16%, respectively) it is unlikely that NHI will increase further. Future seed yield improvement will therefore depend on increased N accumulation. Reliance on N2 fixation must be supported by increased canopy photosynthetic capacity and therefore on vegetative biomass an advantageous correlation between seed yield and residue production seems likely to persist as crop improvement continues.