Sorghum hybrid evaluation trial in Liverpool Plains season 2013-14

Background

The Liverpool Plains is the primary high yielding sorghum production zone in the northern grains region. With the improvements in farming practices and the increasing adoption of sorghum throughout the north western districts of the northern grains belt, commercial seed companies have come under pressure of late, to produce sufficient quantities of seed in time for sowing. As a consequence growers and advisors are also coming under increasing pressure to make cultivar selections well in advance of planting windows. There is an increasing number of commercially available and near release experimental sorghum varieties entering the market place (>15) that are potentially well suited and adapted to the northern grains belt. A small proportion of these varieties have been evaluated by the commercial and public sector in the past providing robust agronomic support for the best placement of sorghum varieties by region. However, the agronomic performance of many other varieties is yet to be established. Currently, cultivar evaluation is generally conducted by the individual seed companies, where their experimental lines are evaluated against their commercial cultivars and maybe a limited number of competitor checks. Therefore it is difficult for growers and advisors to make informed cultivar decisions unless they only ever use a single companies cultivars.

The aim of these projects was evaluate a range of new and existing cultivars from all commercial sorghum seed companies throughout the Liverpool Plains. It is hoped that we can build on this single seasons worth of data in the future to provide data that can assist growers and advisors in making informed decisions about sorghum cultivar selection on the Liverpool plains.

Trial information

Four sorghum hybrid trial sites were established in the 2013-2014 season across the Liverpool Plains at “Romney Vale” Quirindi, “Mooki” Pine Ridge, “Noojee” Goran Lake and “Lambrook” Mullaley. Individual site information is collated in Table 1. The Quirindi and Mullaley sites had 20 variety entries while Pine Ridge and Goran Lake had 19 variety entries, with all sites having a mixture of commercial and experimental material. Planting dates ranged from the 4^th week in October till the first week in December. Maturity assessments on all varieties were made during the season at each of trial sites to give an estimate of days from planting to flowering. Trial plots were harvested using a KEW plot harvester. The growing season experienced higher than average temperatures which was combined with drier than average rainfall with many small, relatively ineffective rainfall events. To highlight the difficult season; Quirindi site received 15mm in December in three separate falls; one 4 mm fall in late January and 34 mm in February in two individual rainfall events. The February rainfall in the opinion of the authors occurred at the point of late grain fill and was relatively ineffective in increasing final yield.

Data from each of the trial sites was collated and included in an across sites analysis to compare grain yield, protein, screenings and test weight to give an indication of the differences between varieties grown on the Liverpool Plains in the 2013-2014 season. For the purposes of this paper we will focus on the results from the across sites analysis and only the near release experimentals and commercially available varieties. For these varieties there were 13 common varieties across the 4 trials while Dominator, MR Taurus, HGS 135 and HGS Exp 1 was only included at 2 of the trial sites. The analysis is also from a single season only, which should be taken into account when interpreting the results.

Table 1. Site information for the four sorghum hybrids Liverpool Plains trials in 2013-2014 summer.

Trial results

From all four trial sites average grain yield was 3.24 t/ha (Table 2.). The spread in grain yield between varieties wasn’t pronounced with approximately 1 t/ha separating the highest and lowest yielding variety. HGS114 and Tiger had the highest grain yield (3.72 t/ha) which was statistically similar to HGS Exp 1, MR Bazley, G33, G22, Dominator, MR Buster, MR Eclipse and HGS102. Enforcer had the lowest grain yield (2.73 t/ha) that was similar to HGS135, MR Scorpio, MR Taurus, Liberty, MR43 and G99.

There was little variation in grain protein or test weight between varieties. HGS114 and Tiger had lower protein concentration than a majority of other varieties. Grain protein levels averaging 12.2% indicates the nitrogen nutrition provided was more than adequate to achieve maximum yield. Tiger also had the highest average test weight (74.7 kg/hL) across the sites and was significantly higher than MR Bazley, G33, HGS135, MR Taurus, MR43, G99 and Enforcer, whilst being similar to all other varieties. On average all varieties were above the test weight minimum of 71 kg/hL for SOR1 specification. On average varieties did vary in the level of screenings but not to the point of falling out of the SOR1 specification of 11%. HGS135 and G99 had the highest screenings of all varieties, however, the HGS135 result is may be skewed by the fact that it was only at the Mullaley and Quirindi sites where average screenings were 9.4 and 3.9 %, respectively. In saying that G99 and HGS135 had screenings in excess of 19 % at Mullaley, which was 7 % higher than all other varieties.

Significant rainfall during March created a shelling out event throughout the region. Based on limited observations the authors believe that individual head maturity had the greatest influence on shelling out severity as opposed to variety maturity or planting date.

Table 2. Cross-sites analysis of yield and grain quality of sorghum hybrids from Liverpool Plains trials in 2013-2014 summer.

Means followed the same letter are not significantly different. LSD (P=0.5)

Maturity assessments were collected for all varieties in all trials however; the method used did differ with Mullaley and Quirindi using 50% of heads at 50% flowered. Goran Lake and Pine Ridge were scored using 50% of heads at 10% flower (Table 3.). The maturity of varieties is presented relative to MR43.

Enforcer and Liberty were the longest maturity varieties in all the trials, while Tiger, G99 and G33 were consistently quicker maturing varieties. The spread in maturity between the shortest and longest varieties was 11, 14, 13 and 6 days at Goran Lake, Pine Ridge, Mullaley and Quirindi, respectively. It is interesting that Quirindi had the least spread in maturity between varieties as it was planted at least 31 days earlier than all other sites. Some of the more noteable changes in variety maturity at the Quirindi site, Enforcer and Liberty were almost 5 days quicker relative to MR43 when compared to other sites.

Table 3. Relative difference in time to flower between sorghum hybrids and MR 43 across four sites on the Liverpool Plains in 2013-14

¹determined as 50% of heads at 10% flower

²determined as 50% of heads at 50% flower

Final yield was related to flowering date at Mullaley. However; this trend didn’t correlate at the other three sites, indicating factors other than variety maturity had greater influence on the final yield result.

Figure 1. Relationship between hybrid flowering date and grain yield at Mullaley and Quirindi

Outcomes

These trials have shown that HGS114 and HGS Exp1, both near release experimental cultivars, have performed well in comparison to current commercial standards. The 2013-2014 seasons were extremely tough with extremely warm temperature and below average monthly rainfall totals. The season may explain why existing commercial varieties such as Tiger, which is not widely grown, performed so well in the 2013-2014 season. This highlights the need to repeat the trials again through seasons to give a more reliable prediction of variety performances on the Liverpool Plains.

A word of caution

Before you read too much into these trials there are few words of warning to heed. While these trials are the culmination of 4 fully replicated trial sites, with over 300 plots involved; they are only the result of one season and a below average year at that. Winter crop evaluations are made up of many more sites, over several years to achieve a varietal rating outcome that is scientifically rigorous.

Acknowledgements

These trials were funded by GRDC under Commercial Agribusiness grants through applications by Hunt AG Solutions/Agricultural Consulting & Extension Services (combined) and AMPS Research. Trials were planted, monitored & harvested by NSW DPI, Kalyx, AMPS Research, Hunt AG Solutions and Agricultural Consulting & Extension Services.

Contact details

Jim Hunt
Hunt AG Solutions
Ph: 0429 721 367
Email: huntag@optusnet.com.au

Sam Simons
AMPS Research
Ph: 0417 729 031
Email: sam@agromaxconsulting.com.au