Background and aim
It is well known that delaying harvest after seed maturation can increase harvest losses and affect seed quality. Anecdotal evidence indicates that there are varietal differences in regard to the amount of seed that sheds or falls from the plant as whole pods. In particular Mandelup has a reputation for losing more seed prior to and at harvest than other varieties and this lead to the release of PBA Gunyidi. The aim was to see if new lupin varieties have higher harvest losses than old varieties.
Lupin varieties PBA Leeman, PBA Jurien, PBA Barlock, PBA Gunyidi, Mandelup and Gungurru were sown at Eradu on 28 April using a plot cone seeder. Plots were 10 metres long by 1.54 metres wide with buffers enabling complete randomisation of harvest timing. All plots were harvested with a Kingaroy plot header from the same direction.
Treatments were factorial six varieties by three times of harvest. This included a harvest timing control for each variety; harvested as soon as they were mature to minimise any seed or pod drop pre-harvest or during the harvest operation. The second time of harvest was two weeks after the first and the third was four weeks after that.
Overall yield was 2.5t/ha, which was exceptional given the late emergence and low rainfall. Variety yields differed (P <0.001) and averaged across harvest times PBA Jurien yielded more than all the other varieties (Figure 1). Generally the later released varieties yielded more than the older ones, for example, PBA Jurien yielded 588kg/ha or 26% more than Gungurru. It was interesting to note that harvest index differed significantly between varieties (P <0.05) with PBA Jurien and PBA Gunyidi having a higher HI than several of the other varieties. There was no significant difference in yield from the late October and mid-November harvest dates; with only a 41kg/ha reduction in yield from the two week delay in harvest. There was a significant reduction in yield at time of harvest 3384kg/ha less than harvest time one, or 15%. There were different variety responses to harvest date; some varieties yielded less at harvest time 3 while others did not (Figure 1).
Pre-harvest yield loss accounted for only 1%, 6% and 14% of the total yield lost for harvest times 1, 2 and 3, respectively. Hence the majority of yield loss occurred during the harvest operation.
Total yield loss measured in quadrats after harvest ranged from 178-500kg/ha or 7-24% of machine harvested yield. Yield losses were greater with each delay in harvest (P <0.001) and reached 20% at time of harvest 3, averaged across varieties. The varieties all averaged 12-16% yield loss across the harvest times however the varieties responded differently to harvest time (P <0.001). PBA Jurien and PBA Gunyidi had the lowest yield loss at harvest time three but these were still substantial losses at 14 and 16% of yield. It should be noted if new varieties lose the same percent of seed at harvest there will be a greater amount of seed on the ground due to higher overall plant yield, for example, averaged over the harvest times, the quadrat counts indicated that Gungurru lost 14% of yield or 292kg/ha while PBA Jurien lost 13% of yield or 367kg/ha (Table 1).
|Variety||Harvest time 1||Harvest time 2||Harvest time 3||Average|
|PBA Barlock||240 (9)||202 (8)||452 (21)||299 (12)|
|Gungurru||209 (8)||208 (9)||458 (24)||292 (14)|
|PBA Gunyidi||211 (8)||381 (15)||366 (16)||320 (13)|
|PBA Jurien||290 (10)||421 (14)||388 (14)||367 (13)|
|Mandelup||178 (7)||459 (19)||453 (21)||364 (16)|
|PBA Leeman||261 (10)||272 (10)||500 (23)||345 (14)|
|Average||232 (9)||324 (13)||437 (20)||331 (14)|
|P value variety||0.05|
|P vaule harvest time||<0.001|
|lsd harvest time||42|
|P vaule interaction||<0.001|
This trial highlights the advance in lupin breeding made over the past 20 years. Newer varieties had a higher harvest index and out-yielded older varieties. In particular, PBA Jurien yielded significantly more than all other varieties.
Machine harvested yield was reduced by 15% when harvest was delayed from late October to mid-December. This corresponded reasonably well to quadrat counts which showed average yield loss of 20% from December harvest. There was no evidence in this trial to suggest that PBA Jurien was less resilient to delayed harvest than other varieties.
The key message is that lupins should be harvested as soon as possible after maturity to minimise harvest losses.
Thanks to Larry Prosser, Stephanie Boyce and the DPIRD Geraldton Research Support Unit for managing this trial (17GE16) (GRDC project number: DAW00227).
PBA Leeman, PBA Jurien, PBA Barlock and PBA Gungidi varieties are protected under the Plant Breeders Rights Act 1994.