Texas, USA 2010 - International Herbage Seed Group

Effect of date and rate of nitrogen fertilization on state of nutrition,photosynthesis rate and yielding of lawn cultivar of red fescue (Festuca rubrassp. commutata) grown for seedsM. SzczepanekDepartment of Plant Cultivation, University of Technology and Life Sciences in Bydgoszcz, Kordeckiego20 C, 85-225 Bydgoszcz, PolandMalgorzata.Szczepanek@utp.edu.plAbstractNitrogen concentration in leaves at the beginning of growth responds to nitrogen rates applied inautumn, which gives a possibility of using this indicator for predicting needs for springfertilization. Diversification of the chlorophyll index at the beginning of shooting according tofertilization level in early spring can be useful for determination of the supplementary rate. Inrespect of seed yield, in the first production year applying of 20 kg N ha -1 in autumn and 40 kgha -1 in spring during starting of growth is sufficient. For maintaining a similar productivity in thesecond year, at the autumn application of 20 or 40 kg N ha -1 it is necessary to apply not less than60 kg ha -1 in early spring.IntroductionAvailability of nutrients, mainly nitrogen, is the basis for plant productivity. Monitoring of soilnitrogen availability (Hart et al., 2007), the chlorophyll index (Fotyma & Bezduszniak, 2000) ornitrogen content in plants (Gislum & Boelt, 1999) is useful for the optimization of nitrogenfertilization. The aim of this study was to assess the state of nutrition, photosynthesis rate andyield of red fescue grown for seeds under conditions of varied rates and times of mineralnitrogen fertilization.Materials and methodsThe study was based on a strict field experiment located in the Kujawy and Pomerania region(53°09‟ N; 17°35‟ E). It was established on a podzolic soil of a content of 10.2 NO 3 - and 3.57NH 4 + mg kg -1 D.M. of soil. A lawn cultivar of chewing red fescue was sown in 2004 and 2005and then utilized for two successive years (respectively, 2005-2006 and 2006-2007). Afterharvesting the cover crop (spring barley) in the establishment year or seeds in the productionyears mineral nitrogen was applied at rates of: 20, 40 or 60 kg ha -1 (autumn fertilization). At theend of March/beginning of April, directly before the start of growth, 40, 60 and 80 kg N ha -1 wasapplied in a single rate or divided into half with application of 40 kg ha -1 at the beginning ofshooting. State of plant nitrogen nutrition was determined based on total nitrogen content inleaves (the Kjeldahl method) and the chlorophyll index (leaf greenness) using a217