EFFECT OF SEED GERMINATION METHODS ON SEEDLING EMERGENCE AND EARLINESS OF PURSLANE (PORTULACA OLERACEA L.) CULTIVARS IN A HYDROPONIC FLOATING SYSTEM

Purslane (Portulaca oleracea L.) is a spontaneous wild forb particularly widespread in the Mediterranean Basin area. It contains high levels of a number of nutritionally important compounds, including several vitamins and -linolenic acid. The floating system is an easy and profitable growing technique for the cultivation of small-sized vegetal crops. The effect of different seed germination methods on the timing of seedling emergence and earliness of cultivars of purslane cultivated in such floating system was studied. Seeds were sown directly into 'styrofloat' trays containing vermiculite media. The followings cultivars were used: 'Golden purslane' and 'Summer purslane' from a commercial seed company, and the local accessions '01-215' and '0-294'. The following germination methods were tested: (T1) pre-germination treatment for one day in a germination chamber at 25°C and 95% relative humidity, (T2) pre-germination treatment for one day in a germination chamber at 25°C and 65% relative humidity, and (T3) trays directly transferred to flotation beds and maintained floating permanently on fresh tap water. Seedlings were grown in the floating system for 16 days. Two days after sowing (DAS) germination methods T1 and T2 and commercial seeds resulted in a higher percentage of emerging seedlings than method T3 and local accessions seeds, respectively. Commercial seeds germinated in T2 showed the highest final percentage of emergence. T1 and T2 methods and commercial seeds resulted in a higher emergence index than T3 and local accessions, respectively. Significant interactions between the germination method and cultivar were evident for the degree of emergence and germination index. "Earliness", measured as the number of developed pairs of leaves of purslane at harvesting (17 DAS), was not affected by any of the three germination methods, but was cultivar dependent. In general, germination methods T1 and T2 and commercial seeds increased purslane seedling emergence in the floating system, but did not affect earliness.