Effects of high temperature on pea (Pisum sativum) seed quality and attributed traits : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science, in Plant Breeding at Massey University, Manawatu, New Zealand

Abstract

The experiment was set up in a randomised complete block design with four replicates and two pea cultivars (Greenfeast vs. Snow pea), at two different temperature regimes (25/15-35/25°C and 25/15°C). The objective of this study is to investigate the effect of high temperature on seed quality, germination and evaluates the changes in the protein and total soluble sugar content of pea seeds in response to high temperature. The high temperature had significantly reduced flower number, flower accumulation number, pod number and pod accumulation number. The pod number of Greenfeast was highest at day 104.10 at 15/15°C than Greenfeast at 15/25-35/25°C whereas Snow pea pod number was significantly higher at day 91.97 at 25/15°C than at 25/15-35/25°C and the rate of increase was higher for the Greenfeast at 25/15°C, followed by Snow pea t 25/15-35/25°C with the highest correlation (R2=0.73). The pod accumulation rate (K) for Greenfeast was lower than other treatments, with maximum peak at day 98.73. The highest correlations are detected between pod accumulation rate (k) Snow pea at 25/15°C and Greenfeast at 25/15-35/25°C (R2=0.96). There were more Snow pea seeds germinated at 25/15ºC in the first 5 days while the final germination rate was not significant between combination treatments (F3,28=0.92, P=0.4421). High temperature reduced Snow pea dry shoot weight at 25/15-35/25°C compared to Greenfeast which had a low significant dry shoot weight at 25/15°C. Root dry weight of both cultivars was reduced with high temperature (25/15-35/25°C) compared to the low temperature (25/15°C). In terms of protein and sugar content, Greenfeast had the highest protein content and higher sugar content than Snow pea at 25/15°C temperature regime.