适用植物根系生长观察的半固态凝胶配方筛选

Screening and application of semi-solid gel formula for root growth observation

【目的】植物根系是植物吸收土壤水分和养分的重要器官,研究植物根系有助于了解植物根系与地上部相互作用以及植物对环境变化的响应机制。本研究分析高分子吸水树脂(SAP)和卡波姆U20(U20)单配和复配的稳定性和植物生长安全性,尝试建立植物根系生长观察的半固态凝胶开放培养方法。【方法】借助根箱试验,以草本植物黑叶芋(Alocasia longiloba)和灌木鹅掌藤(Schefflera actinopylla)为试验对象,基于营养液和SAP与U20复配半凝胶配方,分析1/4 Hoagland’s营养液(CK)、0.3%SAP凝胶营养液(T1)、0.5%U20凝胶营养液(T2)、0.4%U20+0.3%SAP凝胶营养液(T3)和0.5%U20+0.2%SAP凝胶营养液(T4)的稳定性以及在这些培养介质中植物生长、叶片叶绿素、根系形态变化和养分吸收差异。【结果】放置5周后,各处理培养介质均没有观察霉变和长菌现象,T1、T2和T3出现水化或絮凝分层,T4与CK一样性质稳定且澄清透明。动态观察叶片叶绿素变化发现,同一时间内,鹅掌藤各处理SPAD值和总叶绿素含量均与CK无显著差异,黑叶芋各处理SPAD值也均与CK无显著差异(P>0.05)。与CK相比,T1和T2均对鹅掌藤和黑叶芋根系生长产生抑制作用,T1和T2处理鹅掌藤总根长分别显著降低了51.59%和47.48%(P<0.05),根表面积分别显著降低了30.59%和32.27%(P<0.05);黑叶芋总根长分别显著降低了44.72%和45.86%(P<0.05),根表面积分别显著降低了29.23%和27.75%(P<0.05)。T1和T2处理的鹅掌藤和黑叶芋的生物量累积以及氮磷钾吸收也显著低于CK。T3和T4中两种植物的总根长、根表面积、氮磷钾吸收和生物量累积均与CK无显著差异(P>0.05);与CK中根系多下垂于营养液不同,T4中根系舒展自然,侧根和细根均呈一定角度展开在半固态凝胶中,较好的模拟了根系在土壤介质的生长状态。【结论】0.5%U20+0.2%SAP凝胶营养液可在较长时间内保持稳定的半固态凝胶状态,较好满足了模拟植物根系在土壤中生长的要求,并且短时间内在该营养液中植物生长、叶片叶绿素、根系形态变化和养分吸收与纯营养液无显著差异,可考虑选择该凝胶配方来建立植物根系生长观察的半固态凝胶开放培养方法。

[Objective]Plant roots are important functional organs for plants to absorb soil moisture and nutrients.Studying plant roots helps to understand the interaction between plant roots and shoots and the response mechanism of plants to environmental changes.In this study,the stability and plant growth safety of single and compound of polymer absorbent resin(SAP)and carbomer U20(U20)were analyzed,and a semi-solid gel open culture method for plant root growth observation was established.[Method]Alocasia longiloba and Schefflera actinopylla were used as experimental plants,and a root box experiment was conducted with nutrient solution and SAP and U20 compound semi-gel formula.The 1/4 Hoagland's nutrient solution was used as the control(CK).The stability of 1/4 Hoagland’s nutrient solution(CK),0.3%SAP gel nutrient solution(T1),0.5%U2O gel nutrient solution(T2),0.4%U2O+0.3%SAP gel nutrient solution(T3)and 0.5%U2O+0.2%SAP gel nutrient solution(T4)were analyzed.The changes of root morphology,leaf chlorophyll,and nutrient uptake in these solutions were also explored.[Result]No obvious microbial contamination was observed in the solution of each treatment,flocculation and stratification occurred in T1,T2,and T3 during 5 weeks.The solution of T4 was as stable and clear as that of CK.Results of dynamic observation in leaves chlorophyll changes showed that there were no significant differences in SPAD value and total chlorophyll content between each treatment and CK at the same time in Schefflera actinopylla,and there was no significant difference in SPAD value between each treatment and CK in Alocasia longiloba(P>0.05).Compared with CK,T1 and T2 inhibited the root growth of Alocasia longiloba and Schefflera actinopylla.For Schefflera actinopylla,T1 and T2 significantly decreased the total root length by 51.59%and 47.48%and root surface area by 30.59%and 32.27%(P<0.05).Compared with CK,T1 and T2 significantly decreased the total root length of Alocasia longiloba by 44.72%and 45.86%,and the root surface area of Alocasia longiloba by 29.23%and 27.75%(P<0.05).Also,T1 and T2 showed significantly lower biomass and the contents of nitrogen,phosphorus,and potassium in shoots and roots than those of CK(P<0.05).There were no significant differences in total root length,root surface area,the contents of nitrogen,phosphorus,and potassium,and the biomass of shoots and roots in Alocasia longiloba or Schefflera actinopylla among T3,T4,and CK.Different from CK in which roots showed drooping growth,T4 provided a better condition to spread the roots of Alocasia longiloba or Schefflera actinopylla.The growth state of roots in soil medium was well simulated in T4 in which the lateral roots and fine roots were spread at a certain angle.[Conclusion]The nutrient solution with 0.5%U20+0.2%SAP can form a stable semi-solid gel for a long time.This semi-solid gel can better meet the requirements of simulated plant root growth in soil than others.Moreover,the growth of Alocasia longiloba or Schefflera actinopylla in this semi-solid gel showed no significant differences in plant biomass,leaf chlorophyll,root morphological changes,and nutrient absorption compared with those in the pure nutrient solution in a short time.The nutrient solution with 0.5%U20+0.2%SAP can be used to establish an open culture method with semi-solid gel for plant root growth observation.