Effects Of Plant And Row Allocation On Population Quality And Microclimate Of Wheat And Corn Relay Intercropping System

Using two plant-type wheat cultivars(Chuannong27of the compact-short type and Mianmai367of the intermediate type) and one corn cultivar(Chuandan418), the major cultivar in local production, a two-year field experiment was carried out in Sichuan Province from November2010to August2012. Under fixed strip width (2m) and planting density (wheat150×104ha-1and corn5.25×104ha-1), seven planting patterns were compared, which changing number and interspace of wheat planting rows and the distance between the edge row of wheat and corn. The traditional double-three-zero strip planting pattern(CK), indicated planting five rows wheat with row spacing of20cm+20cm+20cm+20cm, and40cm distance between the edge row of wheat and corn. F3-1, F3-2and F3-3indicated planting three rows wheat with row spacing of30cm+30cm,35cm+35cm and40cm+40cm, respectively, and50cm,45cm and40cm distance between the edge row of wheat and corn, respectively. F4-1, F4-2and F4-3indicated planting four rows wheat with row spacing of20cm+20cm+20cm,20cm+30cm+20cm and20cm+40cm+20cm, respectively, and50cm,45cm and40cm distance between the edge row of wheat and corn, respectively. The effect of plant and row allocation on wheat population growing, lodging resistance, border advantage, corn seedling quality, field microclimate, and yield were investigated in hilly region in Sichuan province under relay intercropping condition, and the correlation of population quality, border advantage, and yield with field microclimate was analyzed. The objective of this study was to screen the optimum plant and row allocation pattern for wheat and corn relay intercropping system in hilly regions in Sichuan province. The result could provide theory and technique basis for production. The main results showed as follows:1. As far as population quality and yield of wheat, population and individual quality significantly increased with the increase of row spacing after reducing number of planting rows from5to4or3and widening row spacing, but those of edge row remained unchanged. the related quality index of inner row showed that, spike setting rate and effective spike number increased, furthermore, the decline rate of leaf area greatly decreased from booting to milky stage, and the accumulation of dry weight increased. Besides, The related lodging resistance index of inner row indicated that plant height and height of gravity centre decreased, and the second basal culm internode became shorter and thicker, meanwhile, dry weight per stem, wall-thickness, mechanical strength, culm dry density, culm filling degree, the cellulose and lignin content increased, while lodging index decreased. Moreover, the border advantage was cut down, and expression of lodging resistance showed well in field test. Finally, grain per spike, spike weight and yield increased. The edge row of CK had the best quality quality and the strongest lodging resistance, but population quality of inner row showed serious deterioration, especial for the middle row. What’s more, CK demonstrated the strongest border advantage and the highest lodging odds in field test. In addition, the yield of CK was lower than that of F3-3and F4-3, and was equivalent to that of F3-2and F4-2, however, populaiton quality of inner rows were better than those of CK, and expression of lodging resistance showed well in field test.2. As far as seedling quality and yield of corn, seedling quality and yield of corn increased with the increase of the distance between wheat and corn. After reducing number of planting rows from5to4or3and widening row spacing of wheat, the distance between wheat and corn was cut down from50cm to40cm, therefore, plant height, width of basal stem, leaf area per plant, dry weight per plant, and chlorophyll content decreased, and seedling quality became weak, finally, grain number per spike, thousand-grain weight, and yield decreased. Seedling quality and yield among the treatments with the same diatance between wheat and corn, for example, F3-1with F4-1, F3-2with F4-2, and F3-3, F4-3with CK, demonstrated that little difference exited between F3-1and F4-1or between F3-2and F4-2, but great difference exited among F3-3, F4-3, and CK, meanwhile, that of CK was higher than F3-3and F4-3.3. As far as field microclimate of wheat and corn relay intercropping system, the results indicated that reduction of row number per strip and increase of row spacing resulted in higher light transmission rate at the top and basal parts of wheat population at booting stage, and the circulation of air reinforced, meanwhile, temperature and CO2concentration inner population increased. F3-3or F4-3had the best microclimate, F3-2or F4-3the second, and that of all above treatments were better than that of CK. In addition, after reducing number of wheat planting rows from5to4or3, widening row spacing of wheat meant the reduction of distance between wheat and corn. Therefore, the shading of wheat for corn reinforced during symbiosis period, and the canopy light transmission at20-60cm signifancantly decreased, besides, the shorter corn plant, the less shading stress. The canopy light transmission decreased with the reduction of distance between wheat and corn, and the canopy light transmission of F3-1or F4-1was highest, F3-2or F4-2was the second, F3-3, F4-3or CK was the lowest, however, CK was higher than F3-3and F4-3, and the shorter corn plant, the higher difference.4. The correlation analysis of population quality, border advantage, and yield with field microclimate showed as follows:wheat population quality of edge row was slightly correlated to microclimate, but that of inner row was highly positively or positively correlated with microclimate. Border advantage of wheat was highly negatively correlated to microclimate, whereas yield was positively correlated with microclimate. Seedling quality and yield of corn were highly positively correlated with canopy light transmission.5. As far as the total yield of wheat-corn interplanting system, the yield of wheat and corn limited each other. Because of coordinated yield of wheat and corn, F4-2and F3-2obtained the highest total yield.In conclusion, the allocation pattern, planting three rows wheat with row spacing of35cm+35cm and45cm distance between the edge row of wheat and corn, or planting four rows wheat with row spacing of20cm+30cm+20cm and45cm distance between the edge row of wheat and corn, is the optimum plant and row allocation pattern for wheat-corn interplanting system in hilly regions in Sichuan. For wheat, that allocation pattern have improved microclimate, better population quality, stronger lodging resistance, lower border advantage, and well-balanced population. Meanwhile, for corn, the shading stress become weak during wheat and corn symbiosis period, and seedling quality increase. So the development of wheat and corn keep coordinated, and that allocation pattern obtained highest production.