High-temperature effects on seed germination of fourteen Kentucky bluegrass (Poa pratensis L.) cultivars

M. Giolo¹ ³, A. Dalla Montà¹, E. Barolo¹, F. Ferrari², R. Masin³ and S. Macolino³

¹Council for Agricultural Research and Economics, Via Ca' Nova Zampieri 37, IT 37057 S.G. Lupatoto (VR), Italy
²Council for Agricultural Research and Economics, Via Emilia km 307 19, IT 26838 Tavazzano (Lodi), Italy
³Department of Agronomy, Food, Natural resources, Animals and Environment, Padova University, Viale dell’Università 16, IT 35020 Legnaro (PD), Italy
*Correspondence: roberta.masin@unipd.it

Abstract:

Kentucky bluegrass (Poa pratensis L.) is a perennial cool-season grass commonly used for sport and ornamental turfgrasses in transition zones. It is a rather difficult species to establish due to slow germination and the relatively moderate growth rate of seedlings. Early autumn is considered the best time for sowing Kentucky bluegrass in temperate regions. Spring sowing is not recommended as low soil moisture and high temperatures can have a negative impact on germination. However, unavoidable circumstances often force turfgrasses to be sown in spring with high probability of failure. The risk of failure may increase in the near future as a consequence of climate change, so more knowledge is required on the ability of Kentucky bluegrass cultivars to germinate at high temperatures. A laboratory study evaluated the germination response of fourteen cultivars selected among those most used in northern Italy. They were compared in a conditioning chamber under five regimes of alternating temperatures (20/30 °C, 23/33 °C, 26/36 °C, 29/39 °C, 32/42 °C). Germination was recorded weekly starting from sowing. The germination patterns were similar up to 26/36 °C. At 29/39 °C only five cultivars had a germination of over 50%. At the highest temperature regime none of the cultivars had more than 3% germination. It is concluded that only when very extreme high temperatures occur, growers need to pay attention to the choice of cultivars to avoid problems during the germination-emergence phase, but based on the climate change scenario this is likely to happen with greater frequency in the future.

Key words:

Effect of clippings management on turfgrass sward productivity and nitrogen content in the clippings and soil

K. Kauer¹, H. Raave², R. Viiralt², T. Köster³, M. Noormets-Shansky²,T. Laidna², I. Keres², A. Parol² and A. Selge²

¹Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences,Kreutzwaldi 1, 51014 Tartu, Estonia; e-mail: karin.kauer@emu.ee
²Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences,Kreutzwaldi 1, 51014 Tartu, Estonia
³Agricultural Research Centre, Teaduse 4/6, 75501 Saku, Estonia

Abstract:

The maintenance of turfgrass sward includes mowing and fertilization. Every year turfgrass sward produces a sizeable amount of clippings containing large amounts of nutrients which will be available for plants during the decomposition process. The aim of this research was to study clippings decomposition speed, the effect of returned clippings to the turfgrass sward’s clippings yield and total nitrogen content in clippings and soil. The study was carried out on turfgrass sward (seed mixture composition Festuca rubra rubra 50% and Poa pratensis 50%). The turfgrass clippings were either removed after cutting or returned to the plots. The clippings yield and nitrogen content in the clippings were measured after every cutting. The soil samples from different plots were analyzed for total nitrogen at the beginning and the end of the growing season. The decomposition dynamics of clippings was studied using the litterbag technique. Also the nitrogen mineralization from decaying material and the concentration changes of cellulose and lignin were studied during 12 weeks.The results showed that the turfgrass clippings mass and the content of nitrogen decreasedduring the decomposition process very quickly. The degradation of cellulose takes place after about 30% of initial weight decomposition. During the 12 week study period we did not fix the beginning of lignin decomposition. Higher productivity was obtained in treatments where clippings were removed. N content did not differ in plant from plots where clippings returned or removed but N content in soil of plots with clippings returned decreased compared to N content in soil of plots where clippings were removed.

Key words:

cellulose, clippings, decomposition, lignin, N mineralization, turfgrass