Distribution of diploid and tetraploidLotus pedunculatusplants in moist, North Island hill country

Abstract

Abstract The proportions of diploid (2n) and tetraploid (4n) Lotus pedunculatus lines were determined at different hill country sites in southern North Island hill pastures by stomatal cell length measurements and by counting chromosome numbers. The area had been oversown 10–15 years earlier with both diploid G4703 (now ‘Grasslands Sunrise’) lotus and tetraploid ‘Grasslands Maku’ lotus seed. There was a greater frequency of diploid than tetraploid plants in the 506 plants sampled from different slope, aspect, and fertility classes. Tetraploid plants were more common on steeper slopes and north-facing aspects but the proportion of diploid:tetraploid plants was not affected by fertiliser treatments. These data are consistent with the hypothesis that plants with a large DNA content per cell nucleus and large cell size have a superior ability to grow in seasonally dry sites.