The High-Yielding Mechanism Of Line Pepper/Wheat Intercropping And Viruses Identification Of Line Pepper In Shaanxi

The line pepper is one type or variant within annual chili pepper species (Capsicum annuum L.). This type of pepper has been grown with a large area in China's Shaanxi, Gansu, Xinjiang, Sichuan, Chongqing, Hunan, Guizhou, Yunnan and other provinces (cities, districts) for a long time. In Guanzhong region of Shaanxi Province, line pepper plant has a long history. Since1970's, the large-scale cultivation has been formed and the annual grown area is about 40 000～50 000 hm2, the highest year may overrun 70 000 hm2. The intercropping with wheat is the main cultivation pattern in Guanzhong west region of Shaanxi Province. Usually, this cultivation pattern has significantly effect in increasing yield. To explore high-yielding mechanism of line pepper / wheat intercropping, provide a theoretical basis for further optimization of this cropping patterns, at the same time, find out the virus disease status of line pepper seeds and plants and provide reference for viral disease prevention and control, two aspects were carried out in this study: (1) Under the intercropping conditions, the pepper transplanting shock period and the diurnal variation of canopy light intensity were measured. At the same time, the plant height, stem diameter, leaf area index, leaf chlorophyll content, leaf photosynthetic rate, virus disease incidence rate, yield and other agronomic and physiological traits of pepper were measured as well. (2) The viral disease pathogens and diseases in line pepper-producing areas of Shaanxi province were identified.The main test results are as follows:(1) Intercropping with wheat can significantly shorten the transplanting shock period (generally shorter 2~3d) of line pepper.(2) During symbiosis period, the daily average light intensity received by intercropping pepper was significantly lower than that of monoculture pepper, but most times in one day could meet the needs of capsicum photosynthesis. Under the intercropping belt of east-west direction, pepper receiving more direct sunlight than the belt of north-south direction.(3) Under intercropping, the leaf area index of line pepper was significantly higher than that of monoculture, and is 1.6~2.0 times of monoculture. When wheat was harvested, this difference was reduced, but until the end of line pepper harvest the difference still exists.(4) The leaf chlorophyll content of line pepper under intercropping is significantly lower than that of monoculture. In the 32nd day, the difference has basically disappeared.(5) The leaf net photosynthetic rate of line pepper under intercropping was significantly higher than that of monoculture. The difference was reduced gradually after wheat harvested. In the 20th after wheat harvested, the difference between the two was no longer significant. The leaf net photosynthetic rate diurnal curve of monoculture pepper present both peak, and there is a clear "midday depression" phenomenon, intercropping pepper with a single peak curve, and there is not "midday depression" phenomenon.(6) Under intercropping, the plant height of line pepper was significantly higher than that of monoculture. In 32nd day, the difference is still exists and significant. Under intercropping, the leaf length and width of line pepper was significantly higher than that of monoculture. The difference in leaf length and width, which was grown after the end of the intercropping conditions, disappeared.(7) Compared with monoculture, the intercropping can reduce the virus disease rate of line pepper, and the reducing rate is 50% to 60%.(8) The results showed that the yield of 4 pepper lines was increased in different levels, and the increasing range of yield is15% to 21%.(9) In the 4 line pepper lines (L1, L2, L3, L5) and 2 treatments (intercropping and monoculture), the items determined of the L2 are essentially the highest, and the other three lines were no significant differences in regularity.(10) The 28 line pepper seed samples were determined by ELISA. The 14.29% were positive to TMV, and the 39.29% were weakly positive to TMV. The 7.14% were positive to CMV, and the 46.43% were weakly positive to CMV. No sample was positive to PVY, and the 3.57% were weakly positive to PVY. The seedlings of 5 seed samples, which were selected randomly from 28 samples, were used to determine broad bean wilt virus (BBWV) by RT-PCR. The CP gene of BBWV was not amplified. This indicated the seed samples did not carry BBWV or the virus was too less to cause seedling disease.(11) The 32 line pepper leaf samples, which were collected in June 2007, were determined by ELISA. The results showed that 78.1% carried the virus, and 28.1% carried more than one virus. The 12.5% were positive to TMV, and 28.1% were weakly positive to TMV. The 12.5% were positive to CMV, and 34.4% were weakly positive to CMV. The 3.57% were positive to PVY, and 15.6% were weakly positive to PVY. The 32 line pepper leaf samples, which were collected in September 2007, were determined by ELISA. The results showed that 87.5% carried the virus, and 46.9% carried more than one virus. The 25.0% were positive to TMV, and 31.3% were weakly positive to TMV. The 18.8% were positive to CMV, and 34.4% were weakly positive to CMV. The 15.6% were positive to PVY, and 21.9% were weakly positive to PVY. These results suggested that the virus infection rate is higher than that in September in Shaanxi line pepper areas.(12) About the regional distribution of 3-kind viruses determined, the 81.3% of samples collected from Baoji in September 2007 carried viruses, the 87.5% of samples collected from Xianyang in September 2007 carried viruses, and the 100.0% of samples collected from Weinan in September 2007 carried viruses. These results indicated that samples from Weinan carried more viruses, the Xianyang district followed, and the Baoji district was lesser.Based on the results, follow conclusions can be educed:(1)Shorter transplanting shock period, faster recovery growth, more function leaves, higher leaf area index, bigger leaves, lower virus infection rate are the main high yield mechanism of line pepper under intercropping. Although there is shading under intercropping and the light intensity of scattered light is lower, the light intensity of direct light can meet the need of pepper photosynthesis in generally. Although the pepper leaf chlorophyll content (SPAD value) and photosynthetic rate are lower under intercropping, the differences were disappeared soon after the wheat was harvested. Plus higher leaf area index and lower virus infection rate, the fruit yield of 4 pepper lines under intercropping was significantly higher than that of monoculture, and yield increased 15% to 21%.(2) In the Shaanxi main producing areas of line pepper, the main viruses carried by line pepper seeds are TMV and CMV, the PVY and BBWV are very little; in the September, virus disease incidence was higher than that in June; the virus disease was heavier in the east area of Guangzhong, followed by the central, and western light.