The Studies On Container Selection Of Chinese Pine And North China Larch Seedlings Under Sub-irrigation

Sub-irrigation is relatively new in containerized seedling production, it can reduce the amount of water and fertilizer needed for producing high-quality plants. In order to find out the most suitable container for Chinese pine and North china larch under sub-irrigation, a nest-designed trial was conducted to test the effects of container types and sizes. There were hard plastic container with sizes of 3.8cm(diameter)X14cm(length),3.8cm(diameter)X21cm(length); non-woven fabrics container with sizes of 4.5X10,4.5X15; black plastic container with sizes of 10X10,10X15. Morphological index, root system, contents of N, P, K and the water consumption index were analyzed. The results showed:1) Hard plastic container with the length of 21cm was the most suitable one for growing Chinese pine seedlings under subirrigation. Seedlings in hard plastic container had the largest shoot height (15.41cm) and root collar diameter (2.65mm), the QI was 0.23. The contents of N in leaf and shoot were 11.30mg and 4.41mg, which was apparently larger than the other two container types. Also, the content of N in root (4.69mg) was in the highest level. The SRL was 1435.97cm.g’1, and the root length in 2 diameter class was as 3.5 times as that in non-woven fabrics. Hard plastic container with the length of 21cm provided more space for roots, so the dry weight of roots was 49% higher and the root length of fine roots was 97% higher than that of short hard plastic container. Besides, the total water amount used by long hard plastic container during sub-irrigation was only 451ml, but the WUE of long hard plastic container (4.95g/L) was the largest among all containers.2) Black plastic container with the length of 15cm suited the North China larch seedlings under subirrigation best. The shoot height was approximately 27 cm, the root collar diameter achieved 3.55mm and QI (0.17) were the largest among three container types. The contents of N, P, K in root were 9.48mg,2.14mg,5.15mg. No circled roots were observed and the root dry weight which was the highest among the three container types was 0.72g. The root length of the 2 diameter class was as 1.6 times as the hard plastic container and 2.5 times as the non woven fabrics container. Black plastic container with the length of 15cm stimulated the root growth, the root length of fine roots were 4 times higher than the short one. Besides, long black plasic container was only sub-irrigated 10 times.