Prairie Agriculture Machinery Institute results adapted by Laura Schmidt, Production Specialist – West, MPSG – Spring 2022 Pulse Beat
MAINTAINING PEA GERMINATION and careful handling of pea seed are top of mind this spring. The goal is to maximize the number of seeds that make it to produce viable, healthy plants.
An MPSG-funded study was conducted by PAMI to determine the effects of fan speed and moisture content on pea seed quality (germination, vigour and seed coat damage). The original goal of this study was to compare varieties with differing seed sizes and equipment with different distribution systems, but the methods were adjusted due to logistical constraints.
Larger air seeders (>60 ft) typically require higher air velocity for adequate seed distribution and to prevent plugging. As such, there was a desire to know if greater fan speeds result in increased damage to pea seed and how seed moisture content might impact damage.
Pea seeds at three different moisture contents (dried to 11.4%, as received at 13.6% and wet at 15.1%) were run through a stationary air drill at three different fan speeds representing low (FSL), medium (FSM) and high (FSH) speeds. Fan speeds were determined by using the manufacturer-recommended speed as the FSM (4250 rpm), then varying the speed approximately 8% lower and higher to achieve FSL (3900 rpm) and FSH (4600 rpm).
A 65-ft, 2010 Bourgault Paralink Hoe Drill 3310 with a 6550 cart was the chosen air drill. This drill contained six secondary manifolds, each with a total of 11 openers, resulting in 66 total openers across the drill. This drill represents a sort of ‘worst case scenario’ for potential seed damage. A second drill was initially planned to be tested as well. However, due to logistical constraints, the second drill was removed from the scope of the project.
AAC Carver yellow pea seed was used. The seeding rate in these trials was 222.7 lbs/ac (3.7 bu/ac), calculated to target approximately 7.4–8.4 live plants/ft2 (or 3.5–3.8 bu/ac). The fertilizer used was MES15, at a rate of 20 lbs P205/ac, resulting in 59.7 lbs/ ac of product (or 19.8 lbs/ac of P205). Each treatment was run for the equivalent of 0.5 seeded acres with a targeted ground speed of 3.0 mph. Germination, vigour and seed coat damage (via soak test) were assessed before (Table 1) and after (Table 2) treatments.
RESULTS: MOISTURE > FAN SPEED
Surprisingly, varying fan speed did not significantly affect seed germination, vigour or seed coat damage. Seed moisture was the primary factor determining seed damage (Table 2).
Seed moisture content had the most significant impact on germination, vigour and seed coat damage (percentage of damaged, wrinkled and smooth). Pea seed that had been dried to moisture contents below recommended levels (11.4% seed moisture) had significantly lower germination and vigour (a more than 10% decrease) compared to the “as-received” seed (13.6% seed moisture) and the wet seed (15.1% seed moisture). Reduced germination and vigour will negatively affect plant stand and plant establishment, reducing crop yield potential. These results reflect similar findings from previous PAMI research on air seeder distribution and seed
damage to wheat, canola and soybeans, where drier soybean seeds (8% seed moisture) resulted in poor germination compared to 13% seed moisture.
Wet seed also displayed a significantly higher percentage of wrinkled seeds and a significantly lower percentage of smooth seeds, compared to the other two moisture contents.
Ensuring seed moisture content is at the recommended level is imperative for good seed germination, vigour and seed coat quality. These results indicate that initial moisture content, before running the seed through the drill, is an important factor for maintaining seed quality and establishing a successful crop.
To obtain the desired moisture content, it is recommended to pay close attention to proper storage and to monitor pea seed moisture by moving the grain during storage, as necessary. Though differences in fan speed did not affect the seed quality, manufacturer-recommended speeds are suggested to maintain productive performance to reduce the risk of plugging at low fan speeds and the potential for more accurate seed distribution at recommended speeds versus high speeds. ■