Biofumigation Efficacy of Spider Plant (Cleome gynandra L.) Accessions on Nematode Control in Tuberose (Polianthes tuberosa L.)

Tuberose(Polianthes tuberosa L.)is a perennial summer flower grown by smallholders in Kenya for export.However,its production and export volumes have declined drastically due to nematodes infestation.This study evaluated the effect of Cleome gynandra accessions on nematode management on tuberose.Experiment was carried out at Egerton University,Kenya using a randomized complete block design with four replications.The treatments were C.gynandra namely“Simlaw”,“Egerton”,“Taastrup”,“PS”and“IP8”,applied at 6 kg/m^(2) and compared with Brassica napus,solarization and untreated control.Data was collected on growth and yield parameters,nematode infestation and quality of tuberose.Data collected was subjected to analysis of variance at p≤0.05 and means separated using Tukey’s test.Biofumigation with Cleome gynandra accessions helped to reduce nematode population by 34%,gall numbers by 83% and galling index by 96%when compared with the control.Use of biofumigation helped to improve plant height and leaf number of tuberoses by 16% and 87%,respectively,when compared with the control.Use of biofumigation helped to improve spike length by 32%,marketable spikes by 80%,and flower yield by 90% and reduced nonmarketable spikes by 95% when compared with the control.Based on the above results,use of Cleome gynandra accessions and other biofumigants such as rape seed can be used to manage nematodes and improve growth,yield and quality of tuberose.

Control of Southern Root-knot Nematodes on Tomato and Regulation of Soil Bacterial Community by Biofumigation with Zanthoxylum bungeanum Seed

Biofumigation is an environmentally friendly strategy used to control nematodes and plant diseases.The volatile oil of Zanthoxylum bungeanum has high insecticidal and antibacterial activity.However,it is not known if the seed of Z.bungeanum is a suitable material for biofumigation to control southern root-knot nematodes(SRKN)on tomato,and how it may regulate the soil bacterial community structure.We used pot experiments in the greenhouse to determine the effects of Z.bungeanum seeds on SRKN,plant growth parameters,soil physicochemical and microbial characteristics.A total of 26 volatile components,including nematicidally active substances,were identified from Z.bungeanum seeds.Z.bungeanum seed biofumigation significantly reduced the SRKN population by 88.89%and 81.55%on the 50th and 100th day after transplanting,respectively.Compared to the control,the total soluble sugar,soluble solids,soluble protein,titratable acid,root activity and the fruit yield per tomato plant increased significantly.The content of soil alkali-hydrolyzed nitrogen,available potassium and the soil enzyme activities were also significantly increased.The soil bacterial diversity and the co-occurrence network complexity were increased by Z.bungeanum seed biofumigation.Relativelymore keystone OTUs in biofumigation soil had potential plant growth-promoting capabilities.The function of Z.bungeanum seed increasing tomato production in SRKN-infected soil depends on directly killing SRKN and improving soil properties.These results indicate that Z.bungeanum seed can be used as both a nematicide and a high quality organic fertilizer in tomato production.