A herbage investment strategy has been developed based on the key elements of FAR's Research and Extension Strategy and Portfolio. The Herbage strategy is revised and updated each year in response to industry requirements. The key investment areas are: physiology, crop management, farming systems, environment and value added products.
Impact of harvest technology on yield
The type of machinery and the way it is used to harvest seed crops can have a big impact on harvested yields. Research by FAR and the Seed Industry Research Centre (SIRC) is investigating how different types of machinery, or even different harvest speeds can affect harvest yields in ryegrass and clover.
Opitmising cutting times for cocksfoot seed harvest
Classical seed moisture (SM%) testing by rubbing out seeds is difficult with cocksfoot. This 2018/19 trial evaluated two pre-harvest descriptors, (i) whole seed head moisture and (ii) seed rachis browning, and related these two parameters to three cutting dates in an attempt to find an objective method to define optimum cutting time. This preliminary trial found that the time of cocksfoot cutting influenced seed yield, with the greatest seed yield occurring when the crop was windrowed at 29% seed head moisture content or when approximately three quarters of the heads (72%) contained a rachis that was greater than 50% brown or when just under half (43%) were greater than 90% brown.
Plant growth regulators
Plant growth regulators (PGRs) have been the focus of investigations in perennial ryegrass seed crops for many years. An increase of seed yields in perennial ryegrass of up to 50% has been connected to the application of plant growth regulator Trinexapac-ethyl (Moddus®). A number of FAR trials showed an application rate of around 1.6L is ideal when applying PGRs to seed crops in New Zealand. Better dry matter partitioning to the harvested parts increases harvest index and as a result yield increases. This partitioning leads to changes in harvest components and most notably increases seeds per spikelet (better seed retention) and seed head density. Reduced lodging is a result of stem shortening which in turn is caused buy the inhibition of gibberellic acid biosynthesis during stem extension. The total of post-harvest biomass is not reduced by Moddus. Photosynthetic efficiency and seed yield is reduced by lodging while secondary vegetative growth is increased.
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For Richard Chynoweth's paper entitled "Reduced stem length increases perennial ryegrass yield", please click the following link:
The major nutrient required for a high yielding ryegrass seed crop is nitrogen (N) assuming other soil nutrient levels are in the optimum range. N is also the major nutrient which can be lost though leaching to ground water or runoff in surface water. Over the last 30 years there has been a significant amount of research undertaken to determine the nitrogen requirements of ryegrass seed crops in New Zealand (NZ). Prior to 2000, research to establish the N requirements of ryegrass seed crops, e.g. responses and nitrogen use efficiency, was in the absence of the plant growth regulator Trinexapac-ethyl (e.g. Moddus). Since Trinexapac-ethyl became widely used by growers the optimum N rate for maximum yield in perennial ryegrass has been shown to be 185 kg/ha made up of, on average, of 40 kg N/ha as late winter soil mineral N and 145 kg of applied N. This is supported by 17 trials over five years and further trials each year since 2013.
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Irrigation Management - Response to drought
In many crops, early season drought can reduce number of flowers/ears being produced at harvest. This may result from slower tiller/branch initiation or from tiller death depending on when the drought occurs. In practice, this response varies from season to season depending on winter/spring rainfall. Drought later in the season reduces the number of seeds that set and the final size of those seeds, therefore minimum thousand seed weights become important. White clover is different. Restricted early season irrigation/water supply reduces leaf area and increases the number of flowers which emerge above the canopy. Following peak flowering yield is driven by seed number and seed weight. The response to irrigation varies depending on the seed crop (Figure 1). For example perennial ryegrass and red clover follow a linear increase in seed yield up to the fully irrigated point, compared with white clover, where a reduction occurs in fully irrigated plots.