Some plants are able to tolerate salinity using salt glands on the leaf surface, which secrete excess salts transported into the leaves. Rhodes grass (Chloris gayana Kunth) reportedly possesses such salt glands, but the features of secretion remain unclear. In the present study, we compared the ability of Rhodes grass salt glands to secrete sodium and potassium with the aim of clarifying the preference of cations for secretion. In both whole plant experiments and detached leaf experiments, NaCl treatment increased Na + secretion and KCl treatment increased K + secretion. When the ratios of the amount of secreted ions to their concentration in the leaves were compared between Na + and K + , the ratio was greater with Na + than K + .

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In 1993 a field experiment was conducted to determine the influence of seeding date on flowering and seed production of velvetleaf at Kyushu National Agricultural Experiment Station, Nishigoshi, Kumamoto, on thick high humic Andosols (Melanudands). Velvetleaf seeds were seeded monthly from April to November in plots fertilized in advance at 1kg N, 1kg P2O5 and 1kg K2O/a with a compound fertilizer. Flowering and seed production of the emerged plants were evaluated. Flowering was observed in the April to August seeded plants and mature seed production in the April to July seeded ones. Days from seeding to first flowering, plant height and plant age in leaf number, and days from seeding to initiation of the production of mature capsules were decreased with the later seeding dates, and both flowering and seed production showed short-day photoperiodic response. The number of seeds produced per plant ranged from 2,214 in the April seeded plants to 424 in the July seeded. Weights of 100 seeds ranged from 866mg in the plants in the May seeding to 993mg in those in the July seeding, and the seeds produced by the plants seeded in April and July were heavier than those seeded in May and August. Thus, in Kyushu, velvetleaf emerging from April to July was able to efficiently produce vigorous seeds due to the short-day photoperiodic response, and plants emerging in April might cause the most serious problem by producing a large amount of seeds.

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