外源甘氨酸促进火龙果根系生长和养分吸收

根是植物的重要营养器官,控制水分和养分的吸收,很大程度上影响了作物的产量,因此,健康庞大根系网络的建成,对促进作物生产具有决定性意义。火龙果（Hylocereus polyrhizus）属于仙人掌科量天尺属,是热带地区重要的经济作物,具有很高的食用价值和工业价值,近年来其在热带和亚热带地区的种植面积呈现出急剧扩大的趋势。火龙果是浅根系作物,而关于如何促进火龙果根系生长的研究依然非常匮乏。氨基酸态氮是植物重要氮源,对改善根系生长和作物品质有重要作用,而外源氨基酸态氮如何影响火龙果根系生长以及养分吸收尚无相关报道。本研究以‘软枝大红’火龙果为研究对象,在水培条件下,分析了不同外源氨基酸态氮（甘氨酸、谷氨酸、精氨酸）对火龙果幼苗根系和养分吸收的影响,探究适合火龙果生长所需的外源氨基酸类型。结果表明：甘氨酸处理条件下,火龙果幼苗地上部分生物量和侧枝长度分别为18.12 g/株和59.0 cm,显著高于无机氮（NH₄⁺+NO₃^?）、谷氨酸或精氨酸等处理。地上部养分吸收量也显著受氨基酸类型的影响,甘氨酸处理氮、磷、钾以及中微量元素的吸收量均显著高于其他氨基酸处理。同谷氨酸和精氨酸相比,甘氨酸处理显著促进了根系的生长,幼苗总根长和根表面积分别达到2578 cm/株、401 cm²/株,但低于对照无机氮处理。甘氨酸处理火龙果幼苗根系FTIR光谱在1604 cm^?1和1380 cm^?1波数附近的透射率均高于其他处理,表明甘氨酸处理降低了火龙果根系氨基酸等物质的含量,可能由于含氮素等物质更多向地上部分配引起。综上所述,同谷氨酸和精氨酸相比,甘氨酸能显著促进火龙果幼苗根系生长,并提高地上部生物量以及养分吸收。

Exogenous Glycine Promotes Pitaya (Hylocereus polyrhizus) Root Growth and Nutrient Absorption

Root is important organ for plant nutrient absorption. Controlling the absorption of water and nutrients greatly affects the yield of crops. Therefore, the establishment of a large and healthy root network is of decisive significance for promoting crop production. Pitaya (Hylocereus polyrhizus) is a perennial climbing plant belonging to the cactus family and the genus Hylocereus, with high nutritional value and commercial value. Pitaya is a shallow-rooted crop, and the root system is one of the important factors that determine plant growth. The growth of the root system also determines the yield of the crop. With the rapid expansion of dragon fruit planting areas in tropical areas, research on the absorption of nitrogen by dragon fruit roots is still very scarce. Amino acid nitrogen is an important nitrogen source for plants and plays an important role in improving root growth and fruit quality. However, there is no relevant report on how exogenous amino acid nitrogen affecting pitaya root growth and nutrient absorption. In this study, pitaya Ruanzhi was used as the research object. Under hydroponic conditions, the effects of different exogenous amino acid nitrogen (glycine, glutamic, arginine) on the root system and nutrient absorption of pitaya seedlings were analyzed. Meanwhile, the most suitable type of exogenous amino acids for the growth of pitaya were explored. The results of the study showed that under the conditions of glycine treatment, the aboveground biomass and lateral branch length of dragon fruit seedlings was 18.12 g/plant and 59.0 cm, respectively, which were significantly higher than that of inorganic nitrogen (NH₄⁺+ NO₃^?), glutamic acid and arginine. The nutrient absorption of the above ground was also significantly affected by the types of amino acids. The absorption of nitrogen, phosphorus, potassium and trace elements in the treatment of glycine was significantly higher than that of other treatments. In the underground part, compared with glutamic acid and arginine, glycine treatment significantly promoted the growth of roots. The total root length and root surface area of seedlings reached 2578 cm/plant and 401 cm²/plant, respectively, but lower than that of the control inorganic nitrogen treatment. The transmittance of FTIR spectra of pitaya seedling roots treated with glycine was higher than that of other treatments at the wave numbers of 1604 cm^?1 and 1380 cm^?1. The content may be caused by the redistribution of nitrogen to the aboveground. In summary, compared with glutamate and arginine, glycine can significantly promote the root growth of pitaya at the seedling stage, resulting in increased above-ground biomass and nutrient absorption.