Lucerne (Medicago sativa L.) establishment after inoculation with different carriers of Ensifer meliloti on five sowing dates

Abstract

The effect of sowing date (21/10/10, 9/11/10, 8/12/10, 13/01/11 and 3/02/11) and seed inoculant (ALOSCA®, coated and peat seed) on the establishment and growth of seedling and regrowth ‘Stamina 5’ lucerne (Medicago sativa L.) crops was examined in a field experiment at Ashley Dene farm, in Canterbury. Lucerne establishment was successful across all sowing dates and seed treatments, including the bare seed control, with populations >200 plants m⁻². Total dry matter yields ranged between 0.59 t DM ha⁻¹ for sowing date 5 to 2.6 t DM ha⁻¹ for sowing dates 2 and 3. These low yields were due to volumetric soil moisture was below wilting point (9%) for over two months for the two earliest sown crops. For sowing dates 3 to 5 the declining autumn photoperiod (14.9 to 14.1) appeared to increase partitioning to roots which increased the phyllochron from 53 to 80°Cd per leaf. Inoculation treatments had no effect on lucerne development or dry matter production. The higher plant populations established from coated seed (287 vs. 212 plants m⁻²) did not result in any yield advantage for any crop. Isolation, extraction and genetic characterization of the bacteria in the seed treatment determined that Ensifer meliloti (Dangeard) was present in all three seed treatments. The same processes applied to root nodules from lucerne plants grown under each seed treatment produced ~14 genotypes including from bare seed. Both the indigenous species of Rhizobium sp. and E. meliloti were identified. These results suggest that lucerne can be successfully established in both spring and autumn and that adding an inoculant to the seed provided no benefits to lucerne establishment or production in the establishment season, on this dryland farm.