木薯物质累积特征及其施肥效应研究

以传统品种华南205及新育品种华南5号为材料，通过田间试验，研究了木薯生物量与产量累积规律，探讨了品种改良及施肥措施对木薯物质形成规律的影响。结果表明，不同品种生物量累积动态相似，生长前期生物量累积缓慢，且以地上部分为主，到8月中下旬块根快速生长，物质累积速率迅速提高，累积重心由地上部逐渐转移到地下部; 不同品种间物质累积速率及分配比例有所差异，分枝早且多、茎叶生长旺盛的大株型品种(华南5号)物质累积速率大于小株型品种(华南205)，但地上部分生物量比例相对较高，降低了收获指数。氮素是木薯物质形成累积的主要养分限制因子，其次是钾素，磷素影响最小。氮、磷、钾配合施用(1.0∶0.4∶1.0)可显著提高木薯物质累积速率及产量，不同木薯品种物质累积对施肥依赖程度不同，可能与品种的营养需求量、根系发达程度有关。

Characteristics of Dry Matter Accumulation and Effect of Fertilizer Application in Cassava

The field trials were conducted at two sites nearby the Tropical of Cancer to investigate the influence of variety and fertilization on dry matter formation and accumulation of cassava. Two varieties of newly developed SC5 and conventional SC205 were used with five fertilization treatments including NP (1.0:0.4:0), NK (1:0:1), PK (0:0.4:1.0), NPK (1.0:0.4:1.0) and CK (no fertilizer application). Results indicated that the dry matter accumulation patterns were similar for both varieties. From transplanting to early August, dry matter accumulation mainly allocated in above-ground parts. When tubes started rapidly growing from mid August, the allocation of dry matter accumulation was shifted from above-ground to underground parts, and there was a difference between two varieties in accumulating velocity and distributing proportion of biomass. SC5 had larger crown with many earlier developing branches and leaves compared with SC205, resulting in more biomass accumulation in above-ground parts, thus reducing harvesting index. For fertilizer application, N was the most significant factor to increase dry matter, following K and P. Combining application of NPK (1.0:0.4:1.0) significantly enhanced accumulating velocity of dry matter and tube yields of cassava. There were some difference between two varieties in dry matter accumulation depended on NPK fertilizer application, and probably related to their nutrient demands and root developing level.