ABSTRACT

This study was carried out to determine the carbon (C) allocation of tree components following water stress in radiata pine (Pinus radiata) seedlings. The seedlings were exposed to various water contents (low, moderate and high soil water content) for 30 days and labelled with ¹⁴CO₂ gas for six hours on the 31st day. Biomass in all seedling components (foliage, stems and roots) was significantly higher in the moderate soil water content treatment than in the low soil water content treatment, while seedling biomass did not significantly differ between the moderate soil water and high soil water content treatments. The shoot/root ratio of seedlings decreased when soil water content decreased. The C concentrations of radiata pine seedlings were not affected by the soil water content, whereas the soil water stress-induced difference in the C allocation of seedlings was attributed to differences in seedling biomass. The translocation of pulse-labelled ¹⁴C from the foliage to the roots was enhanced by low soil water content. The distribution of ¹⁴C was highest in foliage, followed by roots, stems and soil. The results indicate that soil water content was one of the primary factors influencing biomass allocation in the early growth of radiata pine seedlings.

摘要

进行这项研究来确定水分胁迫后辐射松（Pinus radiata）幼苗中树木成分的碳（C）分配。将幼苗暴露于各种水分含量（低，中和高土壤水分）30天，并用¹⁴ CO ₂标记第31天加气6个小时。中度土壤水分处理中所有幼苗成分（叶子，茎和根）的生物量均显着高于低土壤水分处理，而中度土壤水分处理和高土壤水分处理之间的幼苗生物量无显着差异。当土壤含水量降低时，苗的根/根比降低。辐射松幼苗的碳含量不受土壤含水量的影响，而土壤水分胁迫引起的幼苗碳分配的差异归因于幼苗生物量的差异。土壤含水量低，增强了脉冲标记的¹⁴ C从树叶到根的转运。分布¹⁴碳在树叶中最高，其次是根，茎和土壤。结果表明，土壤含水量是辐射松幼苗早期生长中影响生物量分配的主要因素之一。