Background and Aim
Albus lupin has in recent years enjoyed a resurgence in popularity around the Geraldton region. This has come on the back of the release of the new varieties Andromeda and Amira. Strong prices have also been a major driver of the increased area sown.
In Autumn 2015 at a workshop organised by Pulse Australia growers were keen to explore the options of lower seeding rates and wider rows as a means of cutting input costs and combating fungal diseases including anthracnose and sclerotinia. Previous wide row trials on albus lupin showed they were less suited to wide rows than narrow leaf lupin. However, these trials were run in the dry 2006 and 2007 years and as such yields were variable.
The aims of the trial were to test the yield response of albus lupin to lower than normal seeding rates and wider than normal row spacings. We were also wanted to see if using low seeding rates and/or wide rows would reduce the incidence and impact of fungal diseases including sclerotinia and anthracnose.
Trial details
The trial was sown at Moonyoonooka, (15 km east of Geraldton) using the albus lupin cultivar Amira. Treatments included 3 seeding rates, 60, 90 and 120 kg/ha and 2 row spacings of 22 and 44 cm. We had four plots of each treatment which were 20 m long by 3.0 m wide. The trial was sown on the May 5 and measurements included; establishment counts, ratings of ground cover and flowering percentage, biomass cuts, yield and grain quality.
Results
The trial was sown into drying soil on May 5 and most seed germinated on soil moisture at this time. The next significant rainfall occurred on May 17 and rainfall over the season was well below the long term May to October average of 382 mm.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | GSR May-Oct | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain (mm) | 0.00 | 12.2 | 87.2 | 37.6 | 16.4 | 54.0 | 54.4 | 48.6 | 9.8 | 0.8 | 184.0 |
| Av. Temp (oC) | 33.6 | 32.5 | 30.6 | 28.0 | 24.6 | 23.3 | 20.9 | 25.1 | 25.3 | 27.7 |
Establishment ranged from 5 to 26 plants/m2 depending on the treatment . These plant numbers were very low given the seed rates used. The proportion of seed which actually emerged ranged from 70% for the 120 kg/ha rate on 22 cm spacings to 30% for the 60 kg/ha rate at 44 cm spacing. Averaged over the seed rates the emergence per cent was 67 for the 22 cm rows and 37 for the 44 cm rows. With the seeding conditions being very dry it is likely that some of this difference was the result of increased competition between albus lupin seedlings in the 44 cm row spacing. However other changes in seeding procedure such as changed sowing depth or soil throw may also have occurred. We confirmed these plant populations by counting stems after harvest as a double check.
Overall the plants grew as expected according to the imposed treatments. In wider rows, plants took longer to achieve canopy closure, which has been shown previously to reduce radiation interception and biomass. There was very little fungal disease observed which was not surprising given the dry winter conditions. No difference in disease was observed between seed rate and row spacing treatments.
The overall site yield was very good at 2250 kg/ha. The range in yields from different treatments was large, the highest yielding treatment at 2757 kg/ha and the lowest at 1773 kg/ha.
There was a reduction in yield at the wider row spacing; 2024 kg/ha in 44 cm rows compared to 2475 kg/ha in 22 cm rows. There was also a reduction in yield with reduced seed rate; 60 kg/ha of seed produced 1991 kg/ha, 90kg/ha of seed produced 2253 kg/ha and 120 kg/ha of seed produced 2505 kg/ha. As discussed conditions were difficult for establishment and these seed rates correspond to very low plant populations of 8, 14 and 21 plants/m2.
At both 22 and 44 cm row spacings the yield loss with reduced seeding rates followed a similar response. For 22 cm rows the function y (yield kg/ha) = 9.1x + 1653 fitted the data well R2 0.9 where x = seed rate in kg/ha. For the 44 cm rows a linear function was also fitted y (yield kg/ha) = 8.0x + 1303 R2 0.9. (Figure 2).
Because of the dry conditions fungal disease were not evident, therefore we could not assess the impact of row spacing and density on foliar diseases.
Conclusions
Yield was highest in the narrow row/high seed rate treatment and lowest in the wide row/low seed rate treatment and followed a consistent trend of reduced yield with wider spacing and lower seed rates. These results and the results of 2006 and 2007 trials indicate that albus lupin is not well adapted to wide rows. Hence the reduction in yield loss to fungal pathogens by sowing in wide rows would need to be substantial to justify moving to wide rows.
Acknowledgements
Thanks to Stephanie Boyce, Jo Walker and the Geraldton RSU for trial management and measurements and Len and Daryl Hamersley for supplying the site.