Impact of narrow row spacing on grain yield, seed quality and weed competitiveness in sorghum
Impact of narrow row spacing on grain yield, seed quality and weed competitiveness in sorghum
Author: Trevor Philp (Pacific Seeds) | Date: 23 Jul 2018
Key message
In a tough season sorghum grown in narrow rows didn’t not reduce the yield or increase lodging, narrow row sorghum did reduce weed populations and has potential to increase fallow efficiency.
Introduction
Grain sorghum is currently grown in three main row widths in the north eastern Australian grain belt, 150cm, 100cm and 75cm. Broadly the higher the yield potential and the more reliable the environment the narrower the row spacing.
There has been a renewed interest in narrow rows in field crops due to two main factors
- Weeds with resistance to one or more herbicide mode of action group.
- Improving ground cover to drive improvement in the efficiency of subsequent fallows.
Little data is available for Australia on the effect of narrow row spacing in grain sorghum on yield, grain quality, suppression of weeds and improvement in fallow efficiency. There is also no data on narrow row sorghum planted with precision planters.
Summary
In the 2017-18 season nine grain sorghum trials were conducted to measure the effect of row spacing on yield grain quality and weed populations. Six trials compared 50cm, 75cm and 100cm rows, one trial compared 50cm and 100cm rows and two trials compared 50cm, 75cm and 150cm rows.
All configurations were sown at the same plant density using a single hybrid. Only eight trials were harvested, with the trial at Felton abandoned due to lodging. The Felton site was assessed for weed competition and was the only site that had significant weed populations to assess.
No grain quality data is available at this stage.
A significant difference in grain yield was measured at two of the eight sites, one at Tamworth and one at Goondiwindi, no significant difference between the row configurations was measured at any of the other sites.
Row width had a significant effect on weed population at the Felton Site, with weed population reducing with row width.
An across site analysis of the five sites comparing 100cm, 75 cm and 50 cm was conducted. No difference in grain yield was measured between row configurations.
The 2017-18 sorghum season was below average for yield, with grain size also reduced. Most spring planted crops suffered high levels of stress in the grain fill period, due to no rainfall in January.
Trial analysis description
The trait of yield (kg/ha) was analysed in two ways, firstly with row width included as a fixed effect (model 1: Best linear unbiased estimate BLUE) otherwise known as least square mean. This gives an estimate of the mean yield of the each of the treatments.
And secondly with row width included as a random effect (model 2: Best linear unbiased prediction BLUP). The BLUP value is used to estimate/predict the difference between row widths.
Only the BLUPS are reported.
Results
Table 1. Locations, row widths compared and sowing rate by site
Location | State | Row widths compared | Plant density/ha |
|---|---|---|---|
Clifton | QLD | 100, 75, 50 cm | 85,000 |
Felton | QLD | 100, 75, 50 cm | 75,000 |
Brookstead | QLD | 100, 75, 50 cm | 85,000 |
Pampas | QLD | 100, 75, 50 cm | 85,000 |
Yelarbon | QLD | 150, 75, 50 cm | 65,000 |
Goondiwindi | QLD | 150, 75, 50 cm | 65,000 |
Yallaroi | NSW | 100, 75, 50 cm | 85,000 |
Tamworth | NSW | 100, 75, 50 cm | 75,000 |
Premer | NSW | 100, 50 cm | 85,000 |
Table 2. Individual trial results, grain yield by row width
Location | Row width | BLUP kg/ha | RANK | Rel mean % | se | Rep number | CV% | h2 | P.value |
|---|---|---|---|---|---|---|---|---|---|
Goondiwindi | 50CM | 3262 | 1 | 132.9 | 58 | 2 | 3.37 | 0.99 | 0.16 |
Goondiwindi | 75CM | 2214 | 2 | 90.2 | 58 | 2 | - | - | - |
Goondiwindi | 150CM | 1886 | 3 | 76.9 | 58 | 2 | - | - | - |
Premer | 50CM | 7462 | 1 | 100.0 | 70 | 3 | NA | NA | NA |
Premer | 100CM | 7462 | 1 | 100.0 | 70 | 3 | - | - | - |
Pampas | 50CM | 3655 | 1 | 108.2 | 263 | 3 | 30.22 | 0.24 | 0.28 |
Pampas | 75CM | 3173 | 3 | 94.0 | 263 | 3 | - | - | - |
Pampas | 100CM | 3303 | 2 | 97.8 | 260 | 3 | - | - | - |
Brookstead | 50CM | 3075 | 1 | 103.2 | 186 | 3 | 20.01 | 0.22 | 0.32 |
Brookstead | 75CM | 3039 | 2 | 102.0 | 186 | 3 | - | - | - |
Brookstead | 100CM | 2828 | 3 | 94.9 | 181 | 3 | - | - | - |
Yelarbon | 50CM | 1947 | 2 | 94.8 | 177 | 3 | 15.52 | 0.89 | 0.19 |
Yelarbon | 75CM | 1626 | 3 | 79.2 | 177 | 3 | - | - | - |
Yelarbon | 150CM | 2588 | 1 | 126.0 | 177 | 3 | - | - | - |
Tamworth | 50CM | 6469 | 3 | 97.0 | 52 | 2 | 1.12 | 0.95 | 0.18 |
Tamworth | 75CM | 6770 | 2 | 101.5 | 42 | 3 | - | - | - |
Tamworth | 100CM | 6771 | 1 | 101.5 | 42 | 3 | - | - | - |
Yallaroi | 50CM | 4480 | 1 | 101.8 | 139 | 3 | 9.39 | 0.15 | 0.34 |
Yallaroi | 75CM | 4321 | 3 | 98.2 | 149 | 2 | - | - | - |
Yallaroi | 100CM | 4396 | 2 | 99.9 | 144 | 2 | - | - | - |
Clifton | 50CM | 2972 | 3 | 100.0 | 26 | 2 | 0.23 | 0.03 | 0.04 |
Clifton | 75CM | 2972 | 1 | 100.0 | 26 | 4 | - | - | - |
Clifton | 100CM | 2972 | 2 | 100.0 | 26 | 3 | - | - | - |
Table 3. Across site result, Clifton, Pampas, Brookstead, Yallaroi, Tamworth, and Premer
Treatment | est_blup | rank_blup | rel_blup | se_blup |
|---|---|---|---|---|
100CM | 4627 | 1 | 100 | 0 |
75CM | 4627 | 1 | 100 | 0 |
50CM | 4627 | 1 | 100 | 0 |
Table 4. Weed population by row spacing at harvest, Felton Site 2018
Row width | Subscript | Weed count blup | Rank blup | Rel % | se_blup | ||
|---|---|---|---|---|---|---|---|
100CM | a | 49.8 | 1 | 175.6 | 3.2 | CV% | 19.861 |
75CM | b | 23.5 | 2 | 82.8 | 3.2 | h2 | 0.974 |
50CM | b | 11.8 | 3 | 41.6 | 3.2 | P.value | 0.166 |
Discussion
Overall these trials demonstrated no consistent significant difference in yield by row width, although only one hybrid was tested at a single planting rate.
Two sites showed significant difference in row spacing, Goondiwindi showed a clear advantage in the 50cm rows against the commercial standard row spacing of 150cm. This advantage was created due to less lodging in the 50cm, the 50cm rows appeared to create more biomass early and ran into stress earlier than the 150cm rows. The earlier stress resulted in less yield potential, and reduced height, no rainfall occurred in the grain fill period which resulted in the higher yield potential treatment to lodge.
The Tamworth trial had a similar environment but stressed earlier and then was relieved by late rain, which favoured the 100cm rows over the 75 and 50cm rows.
In all sites row canopy closure occurred much earlier in the 50cm row configuration, providing better ground cover. Water use and water use rate wasn’t measured in these trials, but the 50cm rows may use soil water at a faster rate in the vegetative phase and potentially increase the chance of stress prior to flowering.
The combination of an appropriate hybrid and plant density and the 50cm row spacing has the potential to improve the sorghum crops competition against weeds, reducing weed seed set and improving yields. This system has potential to improve the fallow efficiency of the overall system, as well as lifting the sorghum yield and reliability in most seasons.
Further work to assess the impact on yield and quality is needed and work is needed to assess the effect on the fallow efficiency after the sorghum crop. Detailed economic analysis is needed to determine the cost benefit of purchasing a narrow row precision planter.
Contact details
Trevor Philp
Summer Grains Agronomist
Pacific Seeds
Mb: 0427 568 517
Email: trevor.philp@advantaseeds.com