Effect Of Hypocotyl In Zostera Marina L. Seed On Early Seedling Growth

In the present study, we investigate the utilization and transformation of water andstorage nutrient substances in the hypocotyl of Zostera marina L. seed during earlyseedling growth. The changes of seedling survival rate, morphological characteristicsand storage nutrient contents in control and experimental groups in different growthstages of seedling were studied to find the function time and degree of hypocotylaffecting on early seedling growth, and the response of seedling to hypocotyl missing.The findings of the research not only provide information and support for thelarge-scale restoration of seagrass beds, but also offer theory basis to the developmentof protective measures on hypocotyl. The main results are summarized as follows:1. To investigate the utilization and transformation of water and storage nutrientsubstances in the hypocotyl of Zostera marina L. seed during early seedling growth,seedlings with and without hypocotyl were cultivated in the laboratory under thesimulated natural conditions. The results showed that during the seedling growthstages, main nutrient of seedling obtained from hypocotyl were sugar, protein andstarch; water absorption and nutrient decomposition during seedling growth can bedivided into several stages: rapid water absorption stage (0~17d), rapid nutrientdecomposition stage (0~27d) and stable water absorption and nutrientdecompositionstage (27d~).2. Seedling survival rate and morphological characteristics of Zostera marina L.seedling in control and experimental groups were compared to find the effect ofhypocotyl on early seedling growth. The results showed that the function time ofhypocotyl on seedling growth was about0~27d; compared to control group, thesurvival rate of experimental group which was wiped off hypocotyl when first leaflength was1cm fell by36.5%after cultivating for57d, and main morphological characteristics such as leaf length, shoot length and root length were fell by25.4%,28.9%and32.5%, respectively; compared to control group, the survival rate ofexperimental group which was wiped off hypocotyl when first leaf length was1cmand then continued to cultivate10d fell by18.0%after cultivating for57d, and leaflength, shoot length and root length were fell by12.1%,11.4%and13.6%,respectively.3. Storage nutrient contents of different parts of Zostera marina L. seedling werecompared to find the responding mechanism of seedling to hypocotyl missing. Theresults showed that the main storage nutrient were sugar, protein and lipid duringseedling growth stages; response of seedling to hypocotyl missing was to increase thecontents of sugar, protein and lipid. It is supposed that Z. marina seedling cannotgrow normally after wiping off hypocotyl even though some storage nutrient contentsincreased, or there were other functional mechanisms between hypocotyl and seedlinggrowth.