The effects of nitrogen concentration and moisture content at harvest on the germination and vigour of perennial ryegrass and tall fescue seeds: A dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Science (Honours) at Lincoln University

Abstract

A series of laboratory tests and field trials were conducted to determine the effects of seed nitrogen (N) concentration and seed moisture content (SMC) at harvest on the viability, vigour (accelerated ageing, interim germination and seedling fresh and dry weights) and field emergence of perennial ryegrass (Lolium perenne L.) and tall fescue (Festuca arundinacea Schreb.) seeds. Standard germination (SG); (chilling + KN0₃ - ISTA 1993) and accelerated ageing (AA) tests after harvest did not show differences in viability or vigour. However, untreated germination (i.e. no chilling or KN0₃) was much lower than SG, indicating dormancy in all treatments. Chilling increased germination more effectively than KN0₃. After 6 months storage standard germination did not show any viability differences between low and high seed nitrogen concentrations. Accelerated ageing (interim germination) showed that high nitrogen seeds had significantly greater vigour than low N seeds. This effect was apparent in other vigour measurements. Chilling, and to a lesser extent KN0₃ treatments, obscured the detection of vigour differences between low and high N seeds. Differences in seed moisture content at harvest produced no consistent significant differences in viability, vigour or field emergence of ryegrass or tall fescue seeds. High N ryegrass seeds had greater field emergence under less favourable conditions than low N seeds. AA tests were able to predict the advantageous effects of high N seed, while SG, in most cases, could not predict seed N effects on vigour and field emergence. These results suggest using recommended germination protocols (ISTA 1993) may obscure vigour effects caused by experimental treatment differences.