S03 - Session P1 - Effects of fruit cooling, harvesting frequency and timing on organic seed production quality of eight tomato genotypes

Authors: Joelle Herforth-Rahmé *, Patricia Schwitter

Organic production is increasing since several years as an answer to environmental and consumer concerns. The development of organic farming in Europe is however limited by different factors including limited availability and poor quality of seeds. Moreover, rules on the use of propagation material in organic agriculture are changing, and it becomes necessary to insure that organic seed production can meet the increasing demand. Propagation of own seeds promotes genetic biodiversity, but is time consuming and can interfere with harvesting. Reducing the number of seed extractions per season would allow organic producers to keep their workload within acceptable boundaries. However, it is necessary to verify whether reducing the number of extractions does not negatively impact seed quality and quantity. A regular harvest would remove fruits from the plants and reduce the probability of disease development. This topic is unfortunately rarely addressed in research. Within the H2020 BRESOV project, in a greenhouse trial with eight genotypes of tomato and three repetitions per genotype, we evaluated the effect of different harvest regimes on seed yield and quality during two consecutive years. One treatment consisted of regular fruit harvest and extraction of seeds from harvested fruits, while in the other treatment, harvest was only punctual and seed extraction was therefore done on fruits of different and advanced maturity. In addition, for two of the eight genotypes, the fruits regularly harvested were kept in cold storage and extracted alongside fruits harvested at different time points. In both years, the seed extractions were carried out early, mid and late in the season. Among the parameters we measured are fruit yield per plant, number of seeds per kg of fruit and thousand seed weight (TSW). Once all seed extractions were completed, we performed germination tests. The first results indicate no significant difference in the seed yield and seed germination between the fruits frequently harvest and those harvested only every three weeks. Cooling the fruits had no effect on seed germination. Fruits harvested late in season have a tendency to yield more seeds n although lighter n than those of fruits harvested earlier in the season. The fact that cooling the seeds does not affect seed quality makes it easier for seed producer the collect the fruit part of their usual harvest schedule and store them in order to extract all fruits at once.