| In order to screen the optimal onion cultivar and intercropping date for pepper/onionintercropping cultivated on organic substrate under plastic tunnel, the field experiment wascarried out and an investigation was conducted to explore the effect in pepper/onionintercropping system. The main results and conclusions are as follows:(1) The agronomic characters of different onion cultivars and intercropping dates hadgreat differences. Cv5805had advantage in standing plant height, cv5803had advantage inmaximum green leaf length and pesudostem diameter, cv T had advantage in green leafnumber. Considering the intercropping date, the average value of all agronomic charactersdecreased with the delay of intercropping date. Immature bolting rate of cv T and cv5805were the highest and lowest respectively. Immature bolting rate of onion decreased with thedelay of intercropping date. Comparison of three varieties, cv5805had the highest yield andthe yield of cv T was the lowest.Considering the intercropping date, D2had the highest yieldand net income, D1had the lowest yield. Therefore, in Guanzhong area of Shaanxi provinice,cv5805and11-02were recommended as the appropriate onion variety and intercroppingdate.(2) In the single stage of pepper, the bacterial number of intercropping treatment was lessthan that of monoculture at early growth stage. On the contrary, it was higher than that ofmonoculture at late growth stage. The fungi number of intercropping treatment was less thanthat of monoculture and actinomycetes number was greater than that of monoculture. Theavailable nitrogen of intercropping treatment was more than that of monoculture at earlygrowth stage and was less than that of monoculture at late growth stage. Substrate pH value ofintercropping treatment was always higher than that of monoculture and EC value was alwayslower than that of monoculture. Alkaline phosphatase and cellulose enzyme activity ofintercropping treatment were higher than that of monoculture. Urease activity was higher thanthat of monoculture at early growth stage and less than that of monoculture at late growth stage. Intercropping sucrase activity was greater than that of monoculture only at fruit setstage. At the symbiotic stage of pepper/onion, the number sequence of bacteria, fungi,actinomycetes was in order of T2>T1>CK1>CK2. Available nutrient content of CK1and CK2were greater than T1and T2, T2had the least available nutrient content. Substrate pH valueorder of four treatments was T1> CK1> T2> CK2, substrate EC value of CK1and CK2were greater than T1and T2. The order of four substrate enzyme activity wasT2>T1>CK1>CK2.(3) Three antioxidant enzymes activity in pepper leaves of intercropping treatment weregreater than that of monoculture and MDA content was less than that of monoculture.Chlorophyll content of intercropping pepper was less than monoculture. Nutritional quality ofpepper intercropping was higher than monoculture. Every harvest period yield and total yieldof intercropping treatment were significantly higher than that of monoculture. Single fruitweight of intercropping pepper had advantage. Bolting rate and yield of intercropping onionwere lower than that of monoculture. Land equivalent ratio of intercropping system wasgreater than1and had significant yield advantage.To sum up, pepper intercropping onion in substate under plastic tunnel increased thenumber of substrate microorganisms, the activity of pepper leaves enzyme and pepper quality,at the same time, mitigated the pepper continuous cropping obstacles in plastic tunnel, whileincreased economic efficiency. Bolting rate of cv5805in2013was about10percentagehigher than that rate in2012in the Guanzhong area of Shaanxi Province, but failed earlymaturity as we expected. The onion variety suitable for intercropped with pepper in substrateneed to be further screened. There was competition between pepper and onion inintercropping system. Therefore, pepper/onion intercropping system under plastic tunnel needto be further investigated and optimized. |
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