| It is becoming more important to raise crop productivity in order to meet the increasingfood requirements of and increasing population all over the world. Intercropping is aneffective way of using several kinds of natural resources more effectively, such as nutrient,water, light and heat energy, and improving yield per unit of cultivated land. The key problemof intercropping is the interactions between above-and below-ground parts, to understand themechanism through the phenomenon. Above-and below-ground parts with differentseparation methods of the maize/soybean intercrop and sole crop were studied in a canopyexperiment with measurements of biomass and yield, nutrient uptake, soil moisture content,photosynthetic parameters, fluorescence parameters and SPAD value, to analyze resourcecompetition from above-and below-ground interaction, and provide a theoretical basis ofresource utilization by intercrops, to further determine the contribution to intercrops and soleresource competition from above-and below-ground interaction. The experiment comprisedof twelve treatments and four separation methods, including four maize/soybean1:1intercropping treatments, four sole maize and four sole soybean treatments, with shoot androot separation, no shoot or root separation (CK), root separation, and shoot separation. Themain results in two years were following as:1. The plant height and leaf area of intercropping maize is larger than which of sole maize,and the plant height in jointing stage and the leaf area in tasseling stage showed the fastestgrowth rate. The fastest-growing of intercropping and sole maize plant height and leaf area isT3and T7, respectively. The plant height and leaf area of intercropping soybean is smallerthan which of sole soybean, the plant height and leaf area in flowering stage showed thefastest growth rate. The slowest-growing of intercropping soybean plant height and leaf areais T3, and there was not obvious difference between the sole.Intercropping and sole maize had a character of “slower initially and faster afterwards” indry matter accumulation in individual plant, which increased rapidly after flowering stage. Theoverall trend of treatments in each period showed dry matter accumulation of intercropping is largerthan which of sole maize, but in contrast with soybean.The yield and its components of intercropping maize are larger than which of sole maize.T3had the highest value in intercropping maize, followed by T4, T2and T1. T7had thehighest value in sole maize, followed by T8, T6and T5. The yield and its components of intercropping soybean are smaller than which of sole soybean. T3had the lowest value inintercropping soybean, followed by T4, T2and T1, and there was not obvious differencebetween the sole.In terms of intercropping maize plant height, leaf area and dry matter accumulation, therewas no significant difference between the interaction of above-and below-ground (T3) andbelow-ground (T4); but there was significant difference between the interaction of above-andbelow-ground (T3) and above-ground (T2), more significant difference between theinteraction of above-and below-ground (T3) and no above-or below-ground (T1). In terms ofintercropping soybean plant height, leaf area and dry matter accumulation, there wassignificant difference between the interaction of above-and below-ground and below-ground(T3and T4); above-ground (T3and T2); no above-or below-ground (T3and T1), respectively.In the maize/soybean intercropping system, maize competition ability was stronger thansoybean, and there was promote effect on maize.In terms of sole maize plant height and leaf area, there was no significant differencebetween the interactions of above-and/or below-ground. But for sole maize dry matteraccumulation, there was no significant difference between the interaction of above-andbelow-ground and below-ground (T7and T8); and there was significant difference betweenthe interaction of above-and below-ground and above-ground (T7and T6), no above-orbelow-ground (T7and T5), respectively. In terms of sole soybean plant height, leaf area anddry matter accumulation, there was no significant difference between the interactions ofabove-and/or below-ground.For yield and its component of intercropping and sole maize, intercropping soybean, therewas no difference between T3and T4, T7and T8, significant difference between T3and T2,T7and T6, T3and T1, T7and T5. For yield and its component of sole soybean, there was nosignificant difference between the interactions of above-and/or below-ground.2. There are the same trends among intercropping maize/soybean N and P accumulation,soil available N and P, yield and its component; but for sole maize and soybean N and Paccumulation, there was no difference between the interactions of above-and/orbelow-ground. Interactions of above-and below-ground promoted N and P distributing toseed, enhanced distribution quantity and ratio to seed.3. There were the same trends among Pn, Tr, Fo, Fm, Fv, Fv/Fm, Fv/Fo of intercroppingand sole maize, intercropping and sole soybean and yield and its component of intercroppingand sole maize, intercropping soybean.There were the same trends between Pn, Tr, and Gs, Ci of intercropping maize andsoybean, Gs of sole maize and soybean, except for Ci of sole maize and soybean. Interactions of above-and below-ground, below-ground enhanced obviously the SPADvalue of intercropping and sole maize (decreased obviously the SPAD value of intercroppingsoybean, but enhanced obviously the SPAD value of sole soybean).4. Interactions of above-and/or below-ground effected soil moisture in intercropping andsole system significantly: above-and below-ground> below-ground> above-ground> above-or below-ground. The RLD and RMD in intercropping changed in three times with takingroots.5. Two kinds of results showed that interactions of above-and/or below-ground had thesame effect tendency on the respective maize/soybean intercropping yield advantage, nutrientabsorption, intercropping system yield advantage, land equivalent ratio, relative tointerspecific competition ability: the largest contribution from interactions of above-andbelow-ground, which had the extremely significant intercropping advantage, and a greatercontribution to intercropping advantages from below-ground interactions than above-groundinteractions, with the interactions between the two. Nutrition of maize/soybean intercroppingsystem of competitive ratio: two kinds of results showed that in the symbiotic period of twocrops, maize N and P competition ability was stronger than soybean, and more uptake thansole maize. But soybean had the disadvantage competition ability, and fewer uptakes than solesoybean.In summary, the below-ground part plays a dominant role in the maize/soybeanintercropping system, maize had stronger resources competitive advantage than those ofsoybean, maize used soil moisture and nutrient resources of soybean line to increase maizephotosynthesis efficiency, and to perform the interactive effect of above-and below-groundpart, which can promote the growth of maize, and inhibit soybean. The promotion effect wasstronger than inhibition effect, which displays the intercropping advantage. |
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