A study on the effects of low temperature pre-sowing treatments and ageing on the germination performance of different tomato seed lots : a thesis presented in partial fulfilment of the requirements for Master of Agricultural Science (Seed Technology) at Massey University,Palmerston North, New Zealand

Abstract

Although the total germination capacities were not significantly different, ten different tomato seed lots differed in their vigour. LTPST caused signifi­cant improvement in germination rate both in high and low vigour seed lots of different cultivars of tomato seeds tested without altering their germination potential. The degree of improvement in germination rate was positively related to the initial germination rate of the seed lots and it was even possible to predict the effectiveness of the treatment based on the initial T5O of un­treated seeds. Despite the treatment always causing a significant improvement in germination rate, the improvement in uniformity was lot-dependent and the treatment had little or no effect on initial seedling growth.

Increased SMC and temperature caused rapid loss of viability and ger­mination rate during storage. The effectiveness of LTPST treatment before ageing differed with seed lot and subsequent ageing conditions used. The application of the LTPST after ageing restored the germination rate to that of unaged untreated seed but as expected had no effect on loss of viability. The survival pattern of tomato seeds under rapid ageing followed a normal distribution and parameters of survival curves were in agreement with the norms of the general viability model for orthodox seeds. On the basis of these results of LTPST on aged seeds, it is argued that factors affecting loss of seed vigour may be different from those causing loss of seed viability during storage.