Potential Of Some Maize Varieties (Lines) To Induce Germination Of Orobanche Spp.

Orobanche cumana and Orobanche aegyptiaca are two devastating root parasitic weeds,causing enormous crop losses in our country. Maize (Zea mays L.) has the potential toinfluence the growth of other crops through releasing certain allelochemicals. In this study,some maize inbred lines and commercial maize varieties were used as donators, and O.cumana and O. aegyptiaca were used as receptors. Cut-root assay, hydroponic, pot and fieldexperiments were conducted to test the stimulation of maize verieties on Orobanche spp., andfinally screened out the best “trap crop” for these two parasitic weeds.We screened four maize hybrids and their parental lines for their ability to induce O.cumana germination. In the cut-root experiment, the root and root residues of maize couldinduce O. cumana germination and there were significant differences, it showed that somegermination stimulants were produced during the early stage of germination. In the pot andfield experiments, rhizosphere soil, rhizosphere soil extracts, root extracts, and shoot extractsfrom three of the four maize hybrids and their parental lines induced significant O. cumanagermination as well.The ability to induce germination varied significantly among maize hybrid and inbredlines. The hybrid3255×335and both of its parents generally induced the highest O. cumanagermination rates. It is important note that the ability to induce germination of O. cumana hadnot been a selection criterion in the breeding program from which these maize lines came.The genetic mechanism for the production of allelochemicals that induce O. cumanagermination needs to be analyzed. Plant breeders have used a similar approach to developmaize lines with greater resistance to another root parasitic weed, S. hermonthica. We proposethat a breeding program could be developed to produce maize varieties with greater ability toinduce O. cumana germination.We further studied the potential of maize varieties to induce germination of O. aegyptiacabased on the results that maize could induce O. cumana germination. We used somecommercial maize varieties for screening out the best variety which could induce O.aegyptiaca to germinate suicidally, and provided a basis for control of O. aegyptiaca in theparasitic field. The ten maize varieties could induce O. aegyptiaca germination and presented consistentrule in the cut-root and hydroponic experiments. Changcheng799and Zhengdan958had thestrongest stimulatory effect on O. aegyptiaca, while Luyu13and Zhengyu203had the loweststimulatory effect. We just studied these four varieties in the pot experiment and theunanimous results were also received. This could be regarded as a basis for extend test in thefield in future.We observed that root extracts generally induced higher germination rates than shootextracts, it coincides with the report that strigolactones were mainly synthesized in roots andtransported to shoots. We also found that methanol extracts generally induced highergermination rates than distilled water extracts.In our preliminary test, O. cumana and O. aegyptiaca could not parasitize on maize. Thisstudy proved that the hybrid3255×335had the strongest stimulation on O. cumana, whileChangcheng799had the strongest stimulation on O. aegyptiaca. Therefore, using them as“trap cop” is feasible. In addition, other researchers who engaging in control of Orobanchespp. found that alfalfa, hot pepper, sweet potato and green bean could be as “trap cop” for O.aegyptiaca after long-term screening practices, and sweet potato had the most obvious effect.So we can use maize and sweet potato for spreading experiment at the same time, plantingthem in front stubble of the crops in the field where O. aegyptiaca occurred, and observewhich is better for control of this root parasitic weed.We researched the induction of different maize varieties (lines) on O. cumana and O.aegyptiaca systematically, and we found that maize could be as “trap crop” for both twoweeds. This could provide a new thought for control of the "malignant weed". It can not onlyimprove the maize yield, but also reduce the use of herbicides by using the maize allelopathyto control the weeds of Orobanche spp.. Meanwhile, it can reduce the contamination ofpesticides to the environment. Therefore, we can call this “one kind of typical ecologicalagriculture”.