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苗期为棉花对磷吸收最敏感时期,然而现有研究未能明确土壤有效磷含量对苗期棉花干物质积累和碳氮代谢的影响以及适宜的土壤有效磷含量。本研究以“中棉所79”为供试品种,采用盆栽试验,研究了不同土壤有效磷水平下,五叶期棉苗干物质质量、碳氮代谢、功能叶片叶绿素含量及磷的吸收和利用。结果表明,随着土壤有效磷含量的增加,棉苗干物质质量逐渐增加,根冠比逐渐降低;土壤有效磷含量在9.0 mg·kg~(-1)时,棉苗干物质质量达到最大值,根冠比最小;过高的磷素营养对干物质质量的积累没有显著促进作用。叶片叶绿素含量随着土壤有效磷含量的增加呈现出先增加后减少的趋势,在土壤有效磷含量为7.2 mg·kg~(-1)时达到最大值。各处理棉苗中的蔗糖、可溶性糖、淀粉和氨基酸总量先随着土壤有效磷含量的增加呈显著增加趋势,在9.0mg·kg~(-1)时达到最大值,随后开始下降但差异不显著。土壤有效磷含量的增加可以促进棉苗的磷吸收量和磷根效率比,抑制磷利用效率,但对磷转移效率没有显著影响。因此,低磷会降低棉花幼苗叶绿素含量、糖含量和氨基酸总量,导致棉花生长受到抑制,适宜棉花幼苗生长发育的土壤有效磷的临界含量为9.0 mg·kg~(-1)。
The seedling stage is the most sensitive stage for cotton to absorb phosphorus. However, the available studies failed to clarify the effects of soil available phosphorus on cotton dry matter accumulation and carbon and nitrogen metabolism at seedling stage and the suitable soil available P content. In this study, “Zhongmiansuo 79” was used as tested varieties, pot experiments were conducted to study the effects of different soil available P levels on dry matter quality, carbon and nitrogen metabolism, chlorophyll content and phosphorus uptake in functional leaves And use. The results showed that with the increase of soil available P, the dry matter mass of cotton seedlings increased gradually and the ratio of root to shoot decreased gradually. When available phosphorus was 9.0 mg · kg ~ (-1), the dry matter mass of cotton seedlings reached the maximum , And the ratio of root and shoot was the lowest. Excessive phosphorus nutrition did not significantly promote the accumulation of dry matter. The content of chlorophyll in leaves increased first and then decreased with the increase of soil available P content, reaching the maximum at 7.2 mg · kg -1 soil available phosphorus content. The total amount of sucrose, soluble sugar, starch and amino acids in cotton seedlings increased significantly with the increase of soil available P content, reaching the maximum value at 9.0 mg · kg -1 and then decreased, Not obvious. The increase of soil available P could promote the phosphorus uptake of Pm and the ratio of P to P, inhibit the utilization of P, but had no significant effect on P transfer efficiency. Therefore, low phosphorus could reduce the content of chlorophyll, sugar and total amino acids in cotton seedlings, resulting in the inhibition of cotton growth. The critical content of soil available phosphorus suitable for cotton seedling growth was 9.0 mg · kg -1.