根结线虫对文冠果苗木根系结构与生长及矿质养分分布特性的影响北大核心CSCD

以根结线虫侵染的文冠果一年生苗木为材料,观察分析苗木根系的形态和显微结构,植株生长发育以及主要矿质养分在苗木中的分布特性,并分析不同矿质元素与线虫侵染的关联关系,以揭示根结线虫对文冠果苗木生长发育的影响机制。结果表明:(1)受根结线虫侵染的文冠果苗木根系形成根结,依据根结发生程度分为0(对照,正常植株)、2、3、4级;与对照相比,具有根结的文冠果苗木根系解剖结构特征主要表现为皮层相对较厚,木质部排列扭曲,导管较少,射线数目较少且分布不均匀;韧皮细胞内含物明显较多;多个巨细胞及细胞空腔主要存在于韧皮部。(2)具根结的苗木株高和地径较对照均增加,且株高增幅达显著水平(P<0.05)。(3)具根结苗木根、茎、叶部位的N、P含量均较对照下降,根部降幅达显著水平(P<0.05),其中具2~4级根结的根部N含量分别较对照显著下降7.8%、16.0%和29.5%,P含量分别显著下降15.6%、7.1%和43.3%;根部Fe含量、Zn含量显著上升,2~4级根结根系中Fe含量较对照分别增加1.56倍、0.81倍和3倍,Zn含量分别增加1.11倍、1.56倍和1.78倍;具3和4级根结的苗木根系中K含量较对照显著增加(P<0.05),具2和4级根结的苗木叶片中K含量较对照分别显著下降61.5%和47.0%。(4)苗木根部、茎部N元素含量对于根结线虫侵染的响应最明显,且其含量随侵染程度的增大而降低,叶部Mg元素含量与根结线虫侵染率、K元素含量与整株苗木生物量均呈显著负相关关系(P<0.05)。该研究为根结线虫对文冠果苗木养分吸收利用及运转的影响提供了一定的理论依据。

Effect of Root knot Nematodes on Root Structure, Growth and Mineral Nutrient Distribution Characteristics of Xanthoceras sorbifolia

Taking the annual seedlings of Xanthoceras sorbifolia infected by root knot nematode (Meloidogyne incognita) as materials, we observed the morphology and microstructure of root system, plant growth and development and the distribution characteristics of main mineral nutrients in the seedlings, analyzed the relationship between different mineral elements and nematode infection, and clarified the effect of root knot nematode on the growth and development characteristics of X. sorbifolia seedlings. The results showed that: (1) root knots were formed in the seedlings infected with root knot nematodes, which were divided into grade 0 (control, normal plants), grade 2, grade 3 and grade 4 according to the degree of root knot occurrence. The root anatomical structure of X. sorbifolia plants with root nodes showed typical changes: the cortex is relatively thick, the xylem is twisted, the vessels are less, and the rays were less and not evenly distributed. The contents of phloem cells were significantly more. Several giant cells and cell cavities were mainly found in phloem. (2) Compared with the control, the height and ground diameter of seedlings with root knot increased significantly (P<0.05). (3) The contents of N and P in roots, stems and leaves all decreased, and the contents of N in roots with grade 2, 3 and 4 roots decreased by 7.8%, 16.0% and 29.5%, and the content of P decreased by 15.6%, 7.1% and 43.3%, respectively, compared with normal plants. The contents of Fe and Zn in roots increased significantly. The content of Fe in roots of different roots increased 1.56, 0.81 and 3 times, respectively, and the content of Zn in roots increased 1.11, 1.56 and 1.78 times, respectively, compared with normal plants. Compared with normal plants, K content in roots of seedlings with grade 3 and 4 root knots significantly increased (P<0.05), while K content in leaves of seedlings with grade 2 and 4 root knots significantly decreased by 61.5% and 47.0%, respectively. (4) Overall analysis showed that N content in roots and stems had the most obvious response to root knot nematode infection, and its content decreased with the increase of infection degree. There was a significant negative correlation between leaf Mg content and infection rate, and K content and seedling biomass (P<0.05). This study provided a theoretical basis for the effect of root knot nematodes on nutrient uptake and utilization of X. sorbifolia seedlings.