| Industrial seedling has become one important form of seedlings production in our country. While moisture would affect the growth and development of seedlings, as well as the quality, few studies have been devoted to moisture absorption and migration of seedlings under the industrial seedling.Melon(Cucumis melo var.reticulatus Naud.) were studied by such means as MRI to investigate the properties of substrate moisture and moisture absorbing of seedlings, the effect of temperature and irrigation amount on moisture transfer, and the laws of growth and development of seedlings. This research was intended to provide theoretical basis and reference for the substrates optimization and the exact of condition management. The main results as follows:The properties of various substrates and moisture of seedlings were distinctly different. The moistureholding capacity and content of T6(Peat: perlite: vermiculite = 9: 3: 1) was better than the others. The binding force given from particles within the substrates to the moisture was relatively small, so that the moisture within the substrates maintained high degree of freedom which was conducive to absorption and utilization of moisture. Namely that substrates T6 had the physical characteristics, which was conducive to seedlings to absorb moisture.The growth and physiological indicators of melon, cultivated from different substrates, showed that the seedlings cultivated from T6 substrates had higher value in some indicators than other kinds of substrates for example root surface-area, moisture content and degrees of freedom moisture ratio. In addition, the transpiration rate of this kind of seedlings was relatively high, which indicating that liquidity of moisture in seedlings maybe more large, and the rate of absorption was relatively high.Different cultivation temperatures had significantly affection on moisture absorption of root and moisture transport in seedlings. With 35? treatment(day temperature / night temperature of 35?/ 15?), the substrates lost moisture quickly, the ratio of free moisture that had high liquidity and freedom decreased, and the root updated moisture more difficult. Namely that the 35? temperature treatment reduced the moisture absorption capacity of the seedlings, which leaded to the absorption of the moisture became more difficult. Compared with the normal temperature treatment, the bond moisture proportion of substrates under 15? treatment showed no significant difference, but increased to some extent with the increasing moisture viscous force. Meanwhile, the root activity and absorption area were lower than those under normal temperature treatment. As the results, 15? treatment affects root moisture absorption to some extent, as well as the moisture transferring from root to leaf, so leaf stomatal conductance and transpiration rate decreased than which under the normal temperature treatment.The moisture condition of substrate and related indicators of seedlings showed some difference under various irrigation quantities. After treated by low irrigation quantity(substrates moisture is 60% of moisture-holding capacity), substrates moisture and free moisture proportion of T6 were significantly lower than others treatments.Root surfacearea, root length and activity, showed significant reduction, so root system was harder to absorb moisture. In addition, leaf stomata tended to be closed and transpiration rate was relatively lower, which illustrated that irrigation quantity had great impact on both moisture absorption and transferring of seedlings. After treated by high irrigation quantity(substrate moisture is 100% of moisture-holding capacity), substrates moisture and free moisture proportion of T10 were higher than others treatments. However, high irrigation quantity influenced growth development and metabolic activity of seedlings, consequently affecting moisture absorption and transferring of seedlings. After treated by moderate irrigation quantity(substrates moisture is 80% of moisture-holding capacity), substrates moisture and free moisture proportion of T10 were higher than others treatments. At the same time, leaf stomatal conductance and transpiration rate of seedlings were significantly higher, consequently moisture absorption and transferring rate were also better. |
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