Studies on the Photoperiodic Responses and Seed Production of Chinese Matgrass (Cyperus malaccensis Lam.)

Abstract

It is generally accepted as impossible to produce seed of Chinese matgrass under the natural conditions in Japan where the temperatures in autumn are too low. Studies were made in order to find out the possibility of seed production of Chinese matgrass by speeding up its flowering date at high temperature in summer (evading cool climate in autumn), through due photoperiodic treatment by making the best use of the responses of Chinese matgrass to photoperiodism. Effects of photoperiodic treatment on the heading date, stem growth, seed setting, and viability of seed obtained were examined. The test results can be summarized as follows: (1) Long-day (24hours) treatment promoted stem elongation. In case where long-day treatment was started in June, the promoting effect was greatest, but no heading was found in the case of long-day treatment plot. (2) Short-day (8 hours) treatment inhibited stem elongation. The inhibiting effect was remarkable in case where short-day treatment started in June was continued lasting for long days. The earlier the short-day treatment was started, the more in the number of stems per hill. Short-day treatment hastened the heading date, but the later in the start of short-day treatment, the less in the number of days from the start of treatment to the flowering date, and the more in the number of spikelets on the stems. (3) It was, after all, clarified that the seeds produced from the spikelets bearing flowers during the period ranging from mid-July to late August and collected in late September had germinating ability. Particularly, excellent seeds were produced from the spikelets bearing flowers during the period from late July to early August. For producing such excellent seeds, the short-day treatment started in early July is deemed most effective. (4) Seeds of excellent quality were 1.4 to 2.2mm in length, 0.3 to 0.5mm in width, 0.2 to 0.3mm in thickness, and about 120 mg in 1, 000 grain weight.