Lettuce (Lactuca sativa L.) seedlings emerged from vermiculite tablets but did not survive in warm weather plantings (maximum daytime air temperature >32°C) under irrigated desert conditions. Final plant stands of 90% were obtained with modified seed tablets containing activated carbon and nutrient P in cool weather (maximum daytime air temperature <26°C).

Activated carbon stimulated seed germination of lettuce (Lactuca sativa L.) in soil and vermiculite. Stimulation was strongly dependent upon the moisture potential. Germinating seeds were shown to excrete an inhibitor into the micro-environment which cannot diffuse away rapidly at moisture potentials near the soil field capacity or at analogous potentials in vermiculite. Increasing the moisture potential or adding activated carbon caused rapid removal of inhibitor from the seed micro-environment.

(2-chlorethyl)trimethylammonium Chloride (chlormequat) sprayed on tipped Clusters of girdled ‘Cardinal’ grape (Vitis vinifera L.) at 250 to 1000 ppm during bloom increased the number of seeded berries per Cluster but reduced berry weight Heavy Cluster thinning increased berry weight on chlormequat treated Clusters. Succinic acid-2,2-dimethylhydrazide (SADH) did not increase seeded berry set or affect any of the other fruit characteristics measured at the concentrations tested. The synthetic cytokinin, 6-(benzylamino)-9-(2-tetrahydropyranyl)-9H purine (PBA), resulted in a marked increase in seeded berries at 300 ppm, but the number of shot-berries was also increased.

The rate and total germination of cucumber (Cucumis sativus L.) seeds incubated at 12°C was markedly increased by acetone infusion with fusicoccin (FC). Gibberellic acid (GA4/7) was less effective than FC but more effective than GA3 or (2-chloroethyl)phosphoric acid (ethe-phon) in promoting rapid germination. Infusion of GA4/7 alone or in combination with kinetin and/or ethephon into muskmelon (Cucumis melo L.) seeds increased total germination at 16°C The growth regulators were generally not effective in promoting low temperature germination of watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) seeds.