Back Plant populations for maize silage

Date: 12 April 2018

Plant breeding and selection of maize hybrids for superior stress tolerance has contributed significantly to achieving higher and more consistent silage and grain yields. One of the outcomes of improved stress tolerance is the ability of modern maize hybrids to deliver increases in yield from higher plant populations.

Higher plant populations increase competition among individual plants for sunlight, water and soil nutrients. This may result in lower individual plant yield but increases yield per hectare by optimising the relationship between the key yield components:
• Number of plants per hectare

• Number of cobs per hectare

• Number of kernels per cob

• Weight of each kernel

New Zealand Planting Rate Recommendations Pioneer® brand products planting rate recommendations are based on assessed yield potential of both the growing environment and the host paddock. This affords growers, particularly in medium and high yield environments, the opportunity to optimise their crop yield with modest increases in plant populations.

Every year, Pioneer conduct trials to test how new hybrids respond to changing population rates. These trials focus on the agronomic science of plant population and are invaluable in understanding how hybrid yield responds to changing plant populations. At the same time it is essential to maintain a focus on other key responses such as the impact of stalk and root strength on lodging and changes in silage quality, particularly grain content.

The findings from the research trials are further tested in ‘extension’ strip trials on farm and under grower management practices to ensure the research responses are carried into commercial practice. Many growers and contractors throughout New Zealand
actively follow Pioneer’s Product Advancement Trial (PAT) programme and the ongoing population strips of new commercial hybrids and as a result apply to the specific hybrid recommendations made in the trait
table.

Planting Rate studies

Waikato 2016-2017
A series of three replicated small plot trials were planted in the Waikato to characterise the yield response of P9911 and P0640 at plant populations between 75,000 and 150,000 plants/hectare. The trials were planted and harvested using specialised small plot equipment but in other respects normal farm management practices were applied. The yield responses are shown in the graph below.

The population for maximum yield was not reached but the optimum economic population when the retail value of seed and silage value (25 c/kgDM) are considered was 130,000 plants per ha. It should be noted that the recommended populations for these hybrids in the trait table are 100,000 to 115,000 for P9911 and 95,000 to 110,000 for P0640. These actual recommendations balance yield, agronomic, silage quality and economic considerations.

 Lower North Island 2013-2014

A similar series of trials were conducted in the Lower North Island on P8805 and P9721 and the yield responses are shown below.

The population for maximum yield was 135,000 plants/ha while the optimum economic population was 120,000. Once again it should be noted that the recommended populations for these hybrids in the trait table are 105,000
to 120,000 for P8805 and 104,000 to 115,000 for P9721. Again, these actual recommendations balance yield, agronomic, silage quality and economic considerations.

 Interesting to note

It is also interesting to note that the shape of the yield curve was consistent between hybrids within a growing region. The actual planting population you decide to apply will be influenced by your own input costs, the hybrid selected, expected growing conditions and the realistic yield expectation of your paddock.

The populations reported here are established plants per hectare at harvest. Actual seeding rates should be increased slightly to take into account plants losses that may result from seed bed and growing conditions at the time of planting.

If you require any assistance with this important management process please give us, your local merchant or contractor a call.