Research On Induction Of Orobanche Spp. Seeds Germination Of Hemp(Cannabis Sativa L.)

Broomrapes (Orobanche spp.) are root holo-parasites lacking chlorophyll. Some ofbroomrape species are weedy, causing severe yield losses in important crops. Orobanchecumana results in serious losses in sunflower planting area in our country, whereasPhelipanche aegyptiaca hampers the development of tomatoes and hami melon productionsin Xinjiang Uygur Autonomous Region in China. It is reported that “trap crop” or “catchcrop” is potential method to control broomrape problem.The hemp (Cannabis sativa L.) is a kind of oil crops in northweast region, and it haspotential to be used introducing the Orobanche germination, as the farmers in the northernshaanxi province commonly plant hemp within a rotation after sunflower to reduce thedemage from sunflower broomrape (O. cumana). According to the foreign reports, the hempin our country is a host of broomrape, while the European cultivars of hemp are nohost whichcannot be parasiticed. However, the hemp in the northern Shaanxi, is rarely found beingparasited by broomrapes.To find whether the hemp in our country is a host and if it has the ability to induce theseeds of sunflower broomrape and melon broomrape germination, we used hemp as donators,and seeds of O. cumana and P. aegyptiaca as receptors in this study. Under pot conditions,the effects of fertilizer and the influence of the difference between parts and the growthperiods on the inducing ability of hemp were analyzed.The results indicated that the distilled water extracts of the rhizosphere soil of the hempdisplayed a higher germination rate of melon broomrape than that of sunflower broomrape.And the stimulating effect on the melon broomrape reached the highest in the floweringperiod (27%), whereas the germination rate of the sunflower broomrape was <5%. The O.cumana and p. aegyptiaca seeds germination induced by methanolic extracts were significantdifferences, the germination rete of P. aegyptiaca seeds induced by hemp was highest at thefast growing period (>20%). However, the inducing ability of hemp rhizosphere soil to sunflower broomrape was much lower than melon broomrape (<5%). It indicated that somegermination stimulants were existed in the rhizosphere soil of hemp. Root extracts, shootextracts and leave extracts can induced Orobanche seed germination as well, with the abilityof root> stem> leaf.The ratio of sand to soil also influenced the potential ability of hemp to inducegermination of O. cumana and P. aegyptiaca.2:8of the ratio was found to be the conditionthat hemp induced the highest germination (58%), while the inducing ability on P. aegyptiacawas much lower than that of O. cumana. Although the methanol extraction of hemp inducedhigher germination than the water extractions,2:8of the ratio of sand to soil was stillconstand with the results from both water and methanol extracts.The application of fertilizer influenced the ability of hemp to induce Orobanche seedsgermination. At the seedling period, the application of nitrogen and phosphorus increased theinducing ability of hemp comparing with no-fertilizar treatments. The root extraction inducedthe highest germination of O. cumana (30.7%-52.3%) and P. aegyptiaca (43.3%-82.3%)seeds. The methanol extraction of hemp stem with phosphorus applying treatment inducedhighest germination of P. aegyptiaca seeds(56.9%). At the flowering period, the nitrogenapplying treatment induced highest germination of O. cumana(28.8%and26.1%). However,the water extraction of hemp plant (root, stem or leaf) at the seedling period did not induce O.cumana seeds germination, whereas nitrogen and phosphorus applying treatment inducedhighest germination of both Orobanche seeds at the fast-growing and flowering period(50.8%and38.6%).This study had shown that the water/methanol extraction of both the rhizosphere soil andhemp plant could induce the germination of O. cumana and P. aegyptiaca seeds; the ratio ofsand to soil at2:8enhanced this inducing ability of hemp. The results suggested that Chinesehemp varieties were able to induce and parasited by Orobanche spp.. And the hemp may ableto be use as a catch crop at the fast-growing and flowering period with the application ofnitrogen and phosphorus fertilizer.