By Dr Antony Jarvie, Podsquad Pty Ltd (Independent consultant to Corteva Agriscience™ businesses)
Last season two of the Corteva Agriscience TM seed production units yielded more than six tons per hectare, and whilst it is nowhere near a world record, it provides us with an upper range of what is a locally achievable. In South Africa, we face a multitude of sub-optimal growing conditions that corrode our yield potential, culminating in us only achieving a national average yield of around 2t/ha - a far cry from the possible 6t/ha. Some of our conditions are not easy to optimise, whilst others have simple solutions that should be considered to increase yield and lower the risk of production. The use of good quality seed in soybean grain production is one such simple solution that offers yield benefits and lowers production risk.
An incident in the National Cultivar Trials during the 2003/04 season forever changed my view on seed quality. A variety that had consistently placed in the top position nationally, dropped to 7th in the 2003/04 season, without apparent warning. On investigation it was established that the seed source used in the trial, while having a 97% germination, had low vigour. In the field there was no visual warning of this yield drag because the germination appeared normal. The low vigour during initial growth phase silently drained enough yield to relegate the variety to 7th position at the end of the season. The valuable lesson I learned was that seed quality is a critical contributor to final yield. I was always aware of the dominant role of germination in seed quality, but this was the first time for me that the effects of low vigour had been separated from germination and rather painfully demonstrated.
The use of certified seed, widely across our production region, has the ability to raise the national average yield.
One of the benefits of using certified seed is that germination and vigour are tested in a standardised protocol to meet minimum production requirements. It must be noted that the vigour and germination tests are a mere snapshot in time. Soybean seed is sensitive to rough handling and adverse storage conditions. Any rough handling or poor storage conditions after certification can negatively impact on seed quality at planting and should be guarded against.
In the past, there have been two arguments against the use of certified seed which have driven the farm-saved-seed phenomenon. The first of these, has been cost. Historically, as more farmers retained their own seed, seed prices have risen to cover costs. As seed costs rose, even more farmers retained their own grain for seed. This unhealthy spiral has eventually been halted with the introduction of end-point royalty (EPR). In time, if the EPR is formulated correctly, seed costs will stabilise at a point where it is both affordable for farmers to plant certified seed and profitable for the seed-houses to invest in soybean cultivar development.
The other argument against certified seed was a belief that soybeans acquired adaptation to a farm or an area by being grown there. This fuelled the belief that farm-saved seed performed better than certified seed. In 2009 and 2010, in association with Grain SA, we designed and conducted a trial to investigate acquired adaption in soybean seed. The conclusion of this study was that there was very little evidence to support the notion that any adaptation was acquired. The strongest trend in the trial was that high-quality seed (regardless of where it was produced) performed well (regardless of where it was planted). Other findings included:
Most reputable seed-houses would have factored these trends into their certified seed production business. Understanding that the area that they choose to produce seed in is important and knowing how to deal with seasonal variations in rainfall, particularly at harvest time, is crucial to their success. Having the ability to match variety with location/planting date and having enough capacity to be able to choose only the best production units for seed is what delivers consistent quality over time. Most soybean farmers are specialist grain producers who concentrate their efforts on maximising grain yields, and not necessarily seed quality. High grain yield is no guarantee of good seed quality.
Considering the complexities and peculiarities of producing good quality seed consistently, it follows that farmers aiming to maximise their production and lower their risk should opt to use certified seed in place of farm-saved seed. I believe that the contribution of good seed quality to yield is widely understood and accepted. Using it as a standard practice will reduce the frequency of failure associated with seed of unknown performance that plagues our industry. Considering the level of farm-saved seed present in our market, the simple change to certified seed, on its own applied widely across the soybean production area, has the ability to raise the national soybean average yield. Very few discrete operational changes could have this significant an impact.
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