Carnegie Institution of Washington Publication Volume 49-51

Carnegie Institution of Washington Publication Volume 49-51

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1906 edition. Excerpt: ...plants experimented with, so long as an ample supply of water was provided for the roots, thus allowing the excessively high transpiration to be kept up. WATER REQUIREMENT FOR GERMINATION. Seeds of Fouquieria splendens were planted in Stender dishes containing soil of several different water contents and note made of their germination. In soils containing 5 and 10 per cent of water by volume the seeds failed to germinate. In the latter soil the wings and outer layers of the seed coat softened and became somewhat like moist paper, but in the former such signs of absorption were hardly perceptible. In a soil containing 15 per cent of water the seeds germinated at last, although germination occurred much sooner in the 20 per cent sample. They germinated earlier in moister soils up to 40 per cent, but were soon destroyed by fungi in 30 per cent and above. It thus becomes evident that, at the temperatures of the summer rainy season, Fouquiemla seeds require for germination a moisture content in the soil of about 15 per cent, while they germinate and develop well in soils of higher moisture content up to about 25 per cent. Seeds of Cereus g'igante'u.s were found to germinate well in 15 per cent soil and with higher moisture content, but soon died with apparent damping ofl: ' in soils of 25 per cent or above. _It was often noticed that the soil of Tumamoc Hill is full of spores of 1f_u 1_gi-angi.: bacteria, which develop very rapidly as soon as sufficient mois'ture'1s present. For comparison, a number of seeds pf. cultivated plants'-were-teageq. in the same way. Mexican beans (Phasqolgw) andjwheat (-Tyitgioym vulgare) germinated in 15 per cent and more vigorously in 20 per cent soil. The cultivated balsam (Impatiens) ge1=mina3; more

Product details

  • Paperback | 44 pages
  • 189 x 246 x 2mm | 95g
  • United States
  • English
  • black & white illustrations
  • 1236739817
  • 9781236739810