Recovery and utilization of applied nitrogen by a diallel set of progenies of Lolium perenne L.

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Abstract
Five selected clones of Lolium perenne were selfed and the ten possible diallel crosses, without reciprocals, made. The progenies were grown in a split-plot design in which whole plots comprised the four nitrogen rates (0, 225, 450 and 675 kg/ha of N) and sub-plots the fifteen progenies, square planted at 0·25 m.The percentage of the applied nitrogen recovered, and the utilization of the nitrogen by the plant, were measured. Data were collected from four harvests in each of two consecutive years. The diallel was analysed by Griffing's (1956) Method II, Model II.There were significant effects for nitrogen rates, progenies and their interaction for both ‘recovery’ and ‘utilization’, but years were significantly different for ‘recovery’ only. The effect of applied nitrogen was mainly linear and it was the linear effect of applied nitrogen which interacted most with the progeny effects.Significant g.c.a. and s.c.a. effects were found but they varied between nitrogen rates and years. For ‘utilization’ the interaction nitrogen rates x g.c.a. was significant on two year means but there was no significance for the nitrogen interaction with s.c.a. The g.c.a. values obtained for both parameters did reveal some trends between the five parents.The presence of significant additive and non-additive genetic variation is discussed in relation to a plant breeding programme.