植物生长延缓剂对壳菜果苗木生长和营养元素分布的影响

Effects of plant growth retardants on growth and nutrient elements of Mytilaria laosensis seedlings

【目的】研究植物生长延缓剂烯效唑(S_(3307))、多效唑(PP_(333))、矮壮素(CCC)对壳菜果苗木生长和营养元素分布的影响,从中筛选出矮化效果较佳的植物生长延缓剂,为壳菜果苗木生长的调控提供科学依据。【方法】采用田间栽培法,以半年生速生树种壳菜果实生苗为研究对象,于2021年7月9日、8月9日和9月9日对其叶面分别喷施不同质量浓度S_(3307)(50,100,150,200 mg/L)、PP_(333)(600,900,1200,1500 mg/L)、CCC(1000,1500,2000,2500 mg/L),以喷施清水的处理为对照(CK),10月9日取样,测定不同处理苗木的生长指标(苗高、地径、叶片厚度、叶面积),各径阶(细根(直径(d)<1 mm)、中根(1 mm≤d<2 mm)、粗根(d≥2 mm))根系形态(长度、体积、表面积)和干质量及营养元素(N、P、K)含量。【结果】S_(3307)、PP_(333)和CCC总体上均能延缓壳菜果苗木苗高和地径生长,降低高径比,增加叶片厚度,减小叶面积,其中1200 mg/L PP_(333)矮化效果较优。总体来看,与对照相比,3种植物生长延缓剂处理壳菜果苗木根系总长度、总体积、总表面积均降低,对各径阶根系形态(长度、体积、表面积)也有明显影响,其中900 mg/L PP_(333)处理的壳菜果总根长、总根表面积及总根体积均最小,分别为1273.88 cm、238.70 cm^(2)和6.85 cm^(3)。与对照相比,3种植物生长延缓剂均明显降低了壳菜果苗木各器官鲜质量、干质量和含水率,增加了根冠比,其中150 mg/L S_(3307)处理苗木质量指数最大,含水率最小,分别为0.86和62.13%。与对照相比,3种植物生长延缓剂处理壳菜果苗木叶片N和P含量明显增加,根N含量和P含量明显降低,苗木各器官K含量总体降低,其中1200 mg/L PP_(333)处理N含量整体较高,50 mg/L S_(3307)处理P含量整体较高,对照K含量整体较高。【结论】在壳菜果苗木生产培育中,叶面喷施适宜质量浓度的S_(3307)、PP_(333)和CCC均可延缓苗木生长,影响苗木的干质量和N、P、K含量以及根系形态,提高苗木质量,其中喷施1200 mg/L PP_(333)对壳菜果的矮化效果较佳。

【Objective】The effects of plant growth retardants of uniconazole(S_(3307)),paclobutrazol(PP_(333))and chlorophyll(CCC)on growth and nutrient elements distribution of M.laosensis seedlings were studied and the retardant with best dwarfing effect was screened to provide basis for regulating growth of M.laosensis seedlings.【Method】The M.laosensis seedlings of semi-annual fast-growing tree species were selected in field cultivation.On July 9,August 9 and September 9 in 2021,the foliage was sprayed with different concentrations of S_(3307)(50,100,150 and 200 mg/L),PP_(333)(600,900,1200 and 1500 mg/L)and CCC(1000,1500,2000 and 2500 mg/L),using clear water as control(CK).Samples were collected on October 9,and the growth indicators of seedlings(seedling height,ground diameter,leaf thickness and leaf area)in different treatments were measured.Root morphology(length,volume and surface area)of different diameter steps(fine root(diameter(d)<1 mm)),medium roots(1 mm≤d<2 mm)and thick roots(d≥2 mm)),dry mass and contents of nutrient elements(N,P and K)were also determined.【Result】S_(3307),PP_(333)and CCC all delayed the growth of seedling height and ground diameter,reduced height-diameter ratio,increased leaf thickness and reduced leaf area in general,with the best effects in the 1200 mg/L PP_(333)treatment.Overall,total length,total volume and total surface area of root system of M.laosensis seedlings were decreased by plant growth retardants,and the root system morphology(length,volume and surface area)of each diameter class was changed.The 900 mg/L PP_(333)treatment had the smallest total root length,total root surface area and total root volume of 1273.88 cm,238.70 cm^(2)and 6.85 cm^(3),respectively.Compared with the CK,plant growth retardants significantly reduced fresh weight,dry weight and water content of each organ of M.laosensis seedlings,while increased the root-shoot ratio.The 150 mg/L S_(3307)treatment had the highest quality index of 0.86 and the lowest water content of 62.13%.The contents of N and P in leaves of M.laosensis seedlings were significantly increased by plant growth retardants,the contents of N and P in roots were significantly decreased,and the contents of K in various organs were generally decreased.The 1200 mg/L PP_(333)treatment had high N contents,the 50 mg/L S_(3307)treatment had high P contents,while the CK had high K contents.【Conclusion】In the production and cultivation of M.laosensis seedlings,foliar spraying of S_(3307),PP_(333)and CCC with suitable mass concentrations can improve seedling by delaying growth and affecting dry mass,N,P and K contents and root morphology.The 1200 mg/L PP_(333)treatment had the best dwarfing effect.