Environmental effects on several CAM plants which bring than IN CAM (when plants show diurnal fluctuations in the concn of titratable acid) and OUT OF CAM (when acid concn remain low with no diurnal fluctuation) were studied. Change in photoperiod alone caused the greatest amplitude of the acid fluctuation from 23.8 to 1.8 meq acid/100 g FW in Kalanchoe daigremontiana as compared to either Kalanchoe tubiflora or Sedum telephoides. The K/Ca ratio varied from a high when IN CAM to a low when OUT OF CAM in the 3 species. The plasma emission spectrograph analysis of the leaf tissue grown in the specific environment showed the presence of high levels of Mn, B, Cu, Zn, Na, Al and Si in some CAM plants.The elemental analyses of CAM plants showed 1.8 to 14.7% K.
Peach seed (Prunus persica (L.) Batsch, cv. Elberta) were stratified at 0°C in peat moss and analyzed for GA3 and GA7 at weekly intervals for 4 weeks and at 4 week intervals for 16 weeks. Percentage germination increased as GA3 and GA7 increased during stratification. The suggestion is made that there is a conversion of GA7 to GA3 during stratification and the biosynthesis is temperature dependent.
Reduction of irrigation level on leatherleaf fern [Rumohra adiantiformis (G. Forst) Ching] to 150 cm/year from 311 cm/year (recommended rate) had no effect on frond yield or fresh weight and increased vase life on 3 of 7 harvest dates. Nitrogen sources of urea or NH4NO3 did not affect frond yield or fresh weight, but there were some minor variable effects on vase life.
Four herbicides, alone and/or in combination, were evaluated for weed control in beds of leatherleaf fern [Rumohra adiantiformis (G. Forst) Ching]. Fair winter weed, predominantly chick weed [Stellaria media (L.) Cyr.], control was obtained with simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] at 2 kg active ingredient (a.i.)/ha, simazine + metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] at 1.1 + 2.2 kg a.i./ha and oxadiazon [2-terf-butyl-4-(2,4-dichloro-5-isopropoxyphenyl)-Δ2-1,3,4-oxadiazolin-5-one] + simazine at 1.1 + 1.1 kg a.i./ha. Oxadiazon + simazine, oxadiazon + metolachlor at 1.1 + 2.2 kg a.i./ha, and simazine + metolachlor controlled spring weeds. All herbicide treatments gave fair weed control in summer. Except for simazine applied alone, none of the treatments injured leatherleaf fern visibly. Oxadiazon + metolachlor, oxadiazon + simazine, and simazine + metolachlor reduced winter weeding times. All combination treatments reduced spring weeding times, but none of the treatments reduced summer weeding times. No treatment reduced fern yield or affected average frond weights. Frond length and frond weight were positively correlated (r = 0.74).
The influence of photosynthetically active radiation (PAR) and temperature on net photosynthesis and dark respiration was determined on leatherleaf fern [Rumohra adiantiformis (G. Forst) Ching] grown under 73% polypropylene shade. The maximum photosynthesis rate of 7.5 mg CO2 dm-2 hr-1 occurred at 500 μE m-2s-1 PAR. The light compensation point was 44 μE m-2s-1 PAR. A temperature of 20°C and 1000 μE m-2s-1 PAR was most favorable for net photosynthesis of leatherleaf fern. Use of the antitranspirant, a paraffin wax emulsion (Mobilcer A), at a 2% concentration reduced dark respiration by more than 50% and reduced net photosynthesis considerably compared to the control at 40°.
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