不同类型水冷苗床的根际降温效果及其对番茄穴盘苗生长的影响

为了降低夏季蔬菜集约化育苗时幼苗的根区高温环境，利用地下水作为循环媒介,设计了用于根区降温的水冷苗床。试验分别采用金属梯形管（M）和塑料圆管（P）作为冷水管，以未采用根区降温的苗床为对照，研究两种水冷苗床的根区降温效果及其对番茄幼苗生长的影响。结果表明，两种水冷苗床番茄幼苗根区日均温、白天均温和最高温度均显著低于对照苗床（P＜0.05）。M式和P式苗床番茄幼苗根区日均温分别为23.2℃和26.0℃，全天根区温度高于25℃的历时为8.3h和11.6h，分别比对照苗床减少7.5h和4.2h。水冷苗床显著促进了番茄幼苗生长和干物质积累，提高了番茄幼苗茎流速率、根系呼吸速率和光合能力，M式和P式水冷苗床番茄幼苗单株干质量依次为4.52和3.90mg，分别比对照（2.85mg）增加58.6%和36.8%（P＜0.01）。两种水冷苗床番茄幼苗的壮苗指数和根冠比均显著高于对照。综合根区降温效果和番茄幼苗生长来看，M式水冷苗床更有利于番茄幼苗的生长。

Root-zone Cooling Effect of Different Water-cooled Seedling Bed and Its Effect on the Growth of Tomato Plug Seedlings

In order to alleviate high root-zone temperature injury on intensive seedling production during hot summer. A water-cooled seedling bed was designed, in which underground water was used as the natural coolant. Two different water-cooled seedling beds were exploited in this experiment. Metal stainless steel tube(M-type cooled-bed) and plastic tube(P-type cooled-bed) were used as cooling tube respectively. The seedling bed without root cooling system was used as control(CK).The cooling effect of two different water-cooled seedling bed and its effect on the growth of tomato seedling were investigated. The results showed as follows: the cumulative temperature, mean daily temperature and mean daily maximum temperature of the root-zone both in M and P-type cooled-bed were lowered significantly compared with those of non-cooled seedling bed(CK). The mean daily temperature of M and P-type cooled-bed were 23.2℃ and 26.0℃. The mean high temperature duration of M and P-type cooled-bed above 25℃ was 8.3h and 11.6h per day, which were shortened by 7.5h and 4.2h respectively compared with control’s seedling-bed. The growth rate and dry mass accumulation of tomato seedling both in M seedling-bed and P seedling-bed were enhanced significantly, and sap flow velocity, root respiration rate and net photosynthetic rate were also improved. Dry mass of per plant of tomato seedling in two cooled-bed were 4.52mg(M) and 3.90mg(P), which were increased by 58.6% and 36.8% respectively compared with control. Tomato seedling healthy index and the ratio of root to shoot both in two cooled-beds were apparently higher than control. Water-cooled seedling bed was an effective way to lower the root-zone temperature and it could improve tomato seedling growth during hot summer. The M-type cooled-bed was more beneficial to enhance the growth of tomato seedlings.