Preliminary Research On Potato Allelopathic Effect To Orobanche SPP.

With water culture method and then pot experiment,4commercial potato varieties(“Xiabodi”,“Qingshu168”,“Jizhangshu No.5” and “Kexin No.1”) as donors, sunflowerbroomrape (Orobanche cumana Wallr.) and melon broomrape (Orobanche aegyptiaca Pers.)as receptors, the germination rates of broomrape seeds induced by the extracts of rootexudates, rhizosphere soil and plant tissues were used to analyze allelopathy potential ofdifferent potato varieties on broomrape, and then those varieties causing high germinationrates were chosen. And the distinct proportion of sand and soil pot experiment with twovarieties (“Jizhangshu No.5” and “Kexin No.1”) was conducted to test the amount ofallelochemicals in earth secreted by potatoes under the treatment of different proportion ofsand and soil, thus proper potato varieties according to different regions could be chosen toprevent and kill off O. aegyptiaca seeds in the cropland. Lastly, the experiment of potatotissue cultured seedlings of5genotypes(T、W、SCI、SCII and NT) stimulating the germinationof broomrape seeds was conducted to provide theoretical basis for further study onallelopathic effect of potato tissue cultured seedlings on broomrape.The result of potato water culture experiment showed that root exudates, extracts of rootand aerial part of the4varieties were all able to induce the germination of O. cumana and O.aegyptiaca. The germination rates of O. cumana and O. aegyptiaca seeds induced bymethanol extracts were higher than water extracts, in other words, methanol extracts had thebetter effect. The stimulation of potato root exudates and plant samples on O. aegyptiacaseeds was stronger than which on O. cumana, allelopathy potential of plants reflectsfacilitation with low concentration and inhibition with high concentration. The treatment of“Kexin No.1” root exudates concentrated liquor with the concentration100mg/L on O.cumana seeds caused the highest germination (48.3%), and that of “Qingshu168” on O.aegyptiaca seeds also caused the highest germination (48.6%), significant difference existedamong the varieties.The result of different potato varieties pot experiment suggested that allelopathypotential of potato root was greatest at seedling stage, followed by blossom stage, and finallytuber formation stage; while which of aerial part showed greatest at tuber formation stage,then blossom stage, and last seedling stage. The germination rate of seeds treated with root extracts declined with the growth of potato, while which treated with aerial part extractincreased. This fact suggested that the germination stimulants of O. aegyptiaca in potatotransported from root to aerial part gradually, and remained in aerial part. Among those fourvarieties,“Xiabodi” had the strongest germination stimulation on seeds of O. cumana and O.aegyptiaca, the germination rates of O. cumana and O. aegyptiaca seeds induced by whoseroot methanol extracts at seedling stage were36.9%and48.5%respectively. In O. aegyptiacaserious damaging area,“Xiabodi” could be planted for5to8years with returning straw tocontrol the harm of O. aegyptiaca.The result of distinct proportion of sand and soil pot experiment showed the differencebetween “Jizhangshu No.5” and “Kexin No.1”. In the germination experiment of broomrapeseeds induced by the extracts of rhizosphere soil, the highest germination rate induced by“Jizhangshu No.5” was under the treatment with soil:sand ratio2:8, which induced by “KexinNo.1” was soil:sand ratio6:4.“Jizhangshu No.5” can secrete much germination stimulants ofbroomrape in the soil with high content of sands, while “Kexin No.1” is opposite. The amountof germination stimulants of broomrape secreted in soil is affected by soil texture. For thesandy soil area in the northwest of China, we can give priority to crop rotation with“Jizhangshu No.5” to prevent and kill off broomrape.In the experiment of potato’s tissue culture, the root exudates of5genotypes potatotissue cultured seedlings could not stimulate broomrape seeds to germinate under theexperiment condition, the extracts of plant could hardly stimulate the germination of the seedsof O. cumana but were able to stimulate the germination of the seeds of O. aegyptiaca.Significant difference was existed among different genotypes, the root methanol extracts ofgenotype “T” caused the highest germination rate (33.2%) of O. aegyptiaca seeds. Amongthese genotypes, transfer-gene style “T” and “SCI” caused higher germination rates of O.aegyptiaca seeds than wide type “NT”, which means transgenic potato tissue culturedseedlings probably harbor more stimulants inducing the germination of the seeds of O.aegyptiaca.