The optimum models for cultivationg the seedlings of Dahurian Larch (Larix gmelim Rupr. ) were studied in the central nursery of Tahe Forestery Bureau from 1989 to 1993. The resultswerc as follows The optimum...The optimum models for cultivationg the seedlings of Dahurian Larch (Larix gmelim Rupr. ) were studied in the central nursery of Tahe Forestery Bureau from 1989 to 1993. The resultswerc as follows The optimum models of the main morphological standards of the seedlings were30000 kg /hm2 of' decomposed' ash for improviong soil, 70,000 kg/hm2 of excrement and 1,500 kg/hm2of' calcium superphosphate as basal fertilizer , and 500 kg/hm2 of (NH4)2HPO4 and 220 kg/hm2 of'urea as top dressing. During growth perlod of the seedlings, the growth was greatly checked when thesoil water suction (SWS) was uithin 50 ~ 73. 3 kPa or below 10 kPa but greatest when SWS waswithin 30 ~ 40 kPa in initial growth stage and within 10-20kPa in last growth stage. The method for determining the optimum sowing time is to measure the depth of soil thawing, accumulated temperature abovc 5℃ both at 5 cm of the depth of of soil and in atmosphere. In Tahe region, the optimumsowing trme for Dahurian larch for Dahuria larch is about on May 10 when the depth of soil thawing, the accumulatedtemperature above 5℃ at 5 cm of the depth and the accumulated temperature above 5℃ in atmosphere reaches 40 cm. abovc 46℃ and abovae 56℃ respectively. The optimum seedlings density forthis region is 600-800 individuals/m2.展开更多
文摘The optimum models for cultivationg the seedlings of Dahurian Larch (Larix gmelim Rupr. ) were studied in the central nursery of Tahe Forestery Bureau from 1989 to 1993. The resultswerc as follows The optimum models of the main morphological standards of the seedlings were30000 kg /hm2 of' decomposed' ash for improviong soil, 70,000 kg/hm2 of excrement and 1,500 kg/hm2of' calcium superphosphate as basal fertilizer , and 500 kg/hm2 of (NH4)2HPO4 and 220 kg/hm2 of'urea as top dressing. During growth perlod of the seedlings, the growth was greatly checked when thesoil water suction (SWS) was uithin 50 ~ 73. 3 kPa or below 10 kPa but greatest when SWS waswithin 30 ~ 40 kPa in initial growth stage and within 10-20kPa in last growth stage. The method for determining the optimum sowing time is to measure the depth of soil thawing, accumulated temperature abovc 5℃ both at 5 cm of the depth of of soil and in atmosphere. In Tahe region, the optimumsowing trme for Dahurian larch for Dahuria larch is about on May 10 when the depth of soil thawing, the accumulatedtemperature above 5℃ at 5 cm of the depth and the accumulated temperature above 5℃ in atmosphere reaches 40 cm. abovc 46℃ and abovae 56℃ respectively. The optimum seedlings density forthis region is 600-800 individuals/m2.
