Path and correlation analysis of perennial ryegrass (Lolium perenne L.) seed yield components

Abstract

Maximum perennial ryegrass seed production potential is substantially greater than harvested yields with harvested yields representing only 20% of calculated potential.Similar to wheat, maize and other agriculturally important crops, seed yield is highly dependent on a number of interacting seed yield components. This research was performed to apply and describe path analysis of perennial ryegrass seed yield components in relation to harvested seed yields. Utilising extensive yield components which included subdividing reproductive inflorescences into five size categories, path analysis was undertaken assuming a unidirectional causal-admissible relationship between seed yield components and harvested seed yield in six commercial seed production fields. Both spikelets per inflorescence and florets per spikelet had a significant (p < .05) direct effect on the overall seed yield; however, total path correlation coefficients showed that inflorescence size had the largest positive influence on seed yield via its indirect effects on other seed yield components. Our results will allow seed producers, seed production researchers and plant breeders alike to more efficiently increase harvested seed yield.) is used extensively in temperate pastures as a production source of high-quality grass for feeding animals or as turf for home lawns, golf courses and recreational areas. However, perennial ryegrass seed crops are biologically inefficient at producing seed (Elgersma, 1990b).Seed production is a key trait for all forage and turf grass species (Boelt & Studer, 2010). Grassland is estimated to cover approximately 72 million hectares within the European Union (EU) with grass production estimated at a total value of 23 billion Euro (ESA, 2016). Denmark is the largest grass seed-producing country within the EU. To ensure economic sustainability of new improved cultivars within today's market, detailed understanding of seed production and the interaction between dynamic yield components is required to improve the efficiencies of the biological system (Studer et al., 2008;Wilkins & Humphreys, 2003).Seed yield is highly dependent on various seed yield components starting with tiller production and reproductive induction. Reproductive tillers, inflorescences or seed heads are all terms used to define the same morphological unit: a modified panicle. After a period of cool weather and increasing day lengths, tillers will undergo secondary induction and develop to form a single inflorescence. As perennial ryegrass has the ability to asexually produce daughter tillers, Havstad, Aamlid, Heide, and Junttila (2004) investigated the transmission of the reproductive stimuli from primary to daughter tillers and concluded that daughter tillers did not necessarily have to be directly exposed to inducive conditions. However, problematic toThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is pr...

Potential Effects of Awn Length Variation on Seed Yield and Components, Seed Dispersal and Germination Performance in Siberian Wildrye (Elymus sibiricus L.)

“…Our results also showed an association between spikelets per inflorescence and traits determining seed yield potential such as seed size, seeds per inflorescence and TSW. These findings are consistent with a previous study that spikelet number has a significant direct effect on seed yield [6]. Moreover, evidence in wheat [13] and barley [4] suggested no relationship between awn length and spikelet number.…”

“…These results reflect that seed size and seed weight were the most important seed yield components in Siberian wildrye populations. Similarly, the experiments by Hebblethwaite and Ivins [33] and Abel et al [6] stated TSW contributed to greater harvestable seed yield in ryegrass (Lolium perenne L.). In wheat, awns increased grain size and thereby harvested grain yield [9,34].…”

“…A balance and interaction between different yield components may be the key factors that regulate and affect seed yield. Furthermore, seed yield is affected by the interaction of seed yield components, genetic mechanisms and agronomic and environmental factors [2,6,31]. Analyzing this interaction in different grass species would be a valid method for identifying awns' impact on seed yield.…”

“…However, the grass is biologically ineffective at producing seeds and there are considerable seed losses even in suitable growing conditions [2]. Fluctuations in seed development and subsequent yield in Siberian wildrye, as in many other grass species, may be influenced by growing conditions, physiological processes underlying assimilates production and partitioning and molecular genetic factors [6,7]. Consequently, forage breeders have mainly focused on increasing biomass yield and enhancing forage quality [8].…”

“…Seed yield in grasses is known to be associated with a number of seed yield components, such as spikelets per inflorescence, seeds per inflorescence, seed size and seed weight and seems impossible to achieve realized seed yields without considering these traits [6,9,10]. A number of considerable works have shown awns are positively associated with larger seed size and thereby increased yield in less favorable conditions [11,12].…”