Agronomic performance and water-soluble carbohydrate expression of selected ryegrasses at two locations in New Zealand

Abstract

Agronomic trials at cool (Gore) and warm (Palmerston North) temperate sites in New Zealand tested ten United Kingdom-bred (six diploids, four tetraploids) and two New Zealand-bred diploid ('Bronsyn', 'Impact') perennial and long-term hybrid ryegrasses (Lolium perenne, L. boucheanum) over two trial periods. Dry matter (DM) yields and persistence were better at the cool site but differential expression among cultivars for water-soluble carbohydrates (WSC) and yields was small compared with the warm site. The tetraploid cultivars generally had the highest concentrations of WSC but also on occasions had higher levels of crown rust, moderate DM yields and poorer persistence compared with diploids. Two of the tetraploid cultivars will be of value for their high WSC and good agronomic performance at the cool site. Some of the diploid UK cultivars expressed higher WSC and had similar or higher annual DM yields than some of the NZ-bred cultivars, and had high levels of resistance to crown rust. Overall, differences among cultivars in expression of WSC were small. Some differences occurred for seasonal DM yields with some UK cultivars having lower winter yields.

Botanical survey of perennial ryegrass-based dairy pastures in three regions of New Zealand: implications for ryegrass persistence

“…Similar DM yield of diploid cultivars bred for high sugar levels and standard diploid cultivars in a multi-site comparison in New Zealand have been reported (Edwards et al 2007;Hume et al 2010).…”

“…Research to date has focused on their DM yield, quality and impact on livestock performance (Edwards et al 2007;Hume et al 2010). Similar DM yield of diploid cultivars bred for high sugar levels and standard diploid cultivars in a multi-site comparison in New Zealand have been reported (Edwards et al 2007;Hume et al 2010).…”

“…Reduced tiller density of tetraploid cultivars may therefore compromise their persistence in New Zealand dairy pastures. Other authors have reported that tetraploid cultivars are less persistent and have poorer DM yields than diploid cultivars (Roegiers et al 1988;Thom et al 1998;Hume et al 2010). Mortality of tetraploids is of particular concern in environments such as Waikato which are prone to summer drought (Lancashire 1985).…”

Does the “high sugar” trait of perennial ryegrass cultivars express under temperate climate conditions?

“…Moreover, Hume et al. () found similar productivities between the HSG AberDart and the diploid standard cultivar Bronsyn across three years of evaluation in a warm site but significant differences were observed in a cooler site (both in New Zealand) during the same period. Moreover, even though the HSG and standard cultivar had similar DM yields in the first year, the HSG had greater productivity on the second and third year, and as an average of the whole period, again showing an interaction of the site of evaluation with the genotypes tested.…”

Harvest management based on leaf stage of a tetraploid vs. a diploid cultivar of annual ryegrass

“…In studies that contrast the results of our study, environmental factors (e.g., nutrient and water availability, irradiance and temperature) may have played a significant role (e.g., Humphreys et al., ). Variation in concentration of WSC due to genetic differences has been reported for ryegrass (Humphreys, ; Smith et al., ) and that tetraploids generally have greater WSC concentration than diploid ryegrass (e.g., Hume, Hickey, Lyons, & Baird, ; Smith et al., ) because of the larger cells and higher ratio of cell content to the cell wall of tetraploids compared to diploids (Stewart & Hayes, ).…”