Research On The Technical Combination Of Agronomy And Machinery For Potato/Maize Relay Cropping System And The Photosynthetic Performance Of Potatoes

Intercropping system is widely used in southwest of China and the pattern of potato/maize is one of the most important modes. It is an important mean and research direction for increasing this system?s agriculture output persistently of exploring the combination measures of agricultural machinery and agronomy for relay-cropping potatoes adapting to small and medium agricultural producers and its high photosynthetic efficiency. Herewith, the field experiment in this paper used L16(45) orthogonal design by row-ratios, plant spacing, fertilizer amount, inter-cropping spacing and maize density and simulated mechanization production mode from sowing to harvest to study the influences of different combinations on the potatoes? photosynthetic physiology rule, d ry matter accumulation and yield formation in order to obtain the optimal distribution for relay-cropping potatoes.The main conclusions were as follows:1.Effects of different agrotechnologies on dry matter accumulation above ground of potatoIn the whole growth period, the dry weight above ground changed as a single peak curve and the maximums of different factors and different levels all appeared at the tuber expansion stage. Row-ratio, plant spacing, fertilizer amount and inter-cropping spacing had very significantly effects on dry weight, however maize density was insignificant. With potato rows and fertilizer amount increased, the dry weight above ground increased and with plant spacing increased, it reduced. As for plant spacing, 22.5cm and 25.5cm had no significant difference.2.Effects of different agrotechnologies on LAI and chlorophyll of potatoIn the whole growth period, LAI changed as a single peak curve and the maximums of different measures and different levels appeared at different time. Row-ratio, plant spacing, fertilizer amount and inter-cropping spacing had very significantly effects on LAI. With potato rows and fertilizer amount increased, LAI increased and with plant spacing and inter-cropping spacing increased, it reduced. There were no significant differences between plant spacing 22.5cm and 25.5cm, fertilizer amount 100kg/667m~2 and 125kg/667m~2, inter-cropping spacing 62.5cm, 67.5cm and 72.5cm. Row-ratio, plant spacing, fertilizer amount and inter-cropping spacing had very significantly effects on Chla+Chlb. With potato rows and fertilizer amount increased, Chla+Chlb increased but with plant spacing and inter-cropping spacing increased, it increased and then decreased. There were no significant differences between plant spacing 22.5cm and 25.5cm, inter-cropping spacing 72.5cm and 72.5cm. As for fertilizer amount, 100kg/667m~2 and 125kg/667m~2 had no significant difference at tuber expansion period but had significant difference at starch accumulation period.3.Effects of different agrotechnologies on photosynthetic parameters of potatoRow-ratio, fertilizer amount and inter-cropping spacing had significant or very significant effects on Pn, Gs, Tr and Ci. Significant positive correlations were found between Pn, Tr and Gs and they all significantly negatively correlated with Ci.With potato rows, fertilizer amount and inter-cropping spacing increased, Pn, Gs, Tr increased and Ci decreased. With the growth process moving forward, Pn, Gs, Tr decreased and Ci increased.4.Effects of different agrotechnologies on chlorophyll fluorescence parameters of potatoRow-ratio, plant spacing, fertilizer amount and inter-cropping spacing had significant or very significant effects on Y(II), ETR, q P and NPQ. Significant positive correlations were found between Y(II), ETR and q P and they all significantly negatively correlated with NPQ. With potato rows, plant spacing, fertilizer amount and inter-cropping spacing increased, Y(II), ETR, q P increased and NPQ decreased within limits. With the growth process moving forward, Y(II), ETR, q P decreased and NPQ increased.5.Effects of different agrotechnologies on the key photosynthetic enzymes of potato Row-ratio, fertilizer amount and inter-cropping spacing had very significant effects on Ru BPCase activity. Plant spacing and maize density were insignificant. With potato rows, fertilizer amount and inter-cropping spacing increased, Ru BPCase activity increased, however there were no significant differences between row-ratio 4:2 and 4:3, inter-cropping spacing 67.5cm, 72.5cm and 77.5cm. With the growth process moving forward, Ru BPCase activity decreased. Row-ratio, plant spacing, fertilizer amount and inter-cropping spacing had significant or very significant effects on SPS activity. With potato rows and fertilizer amount increased, SPS activity increased and with plant spacing and inter-cropping spacing increased, it decreased. There were no significant differences between plant spacing 22.5cm and 25.5cm, fertilizer amount 75kg/667m~2, 100kg/667m~2 and 125kg/667m~2, inter-cropping spacing 62.5cm, 67.5cm and 72.5cm.6. Correlations between potato yield and the other indicators The yield of potato had significant or very significant correlations with LAI, Chla+Chlb, Pn, Gs, Tr, Y(II), ETR, q P, activities of Ru BPCase and SPS and had significantly negative correlation with Ci and NPQ, respectively.7. Effects of different agrotechnologies on tuber quality of potato and population yieldFertilizer amount had very significant effect on marketable tuber percentage and it increased with fertilizer amount increased, however there were no significant differences between fertilizer amount 75kg/667m~2, 100kg/667m~2 and 125kg/667m~2. Row-ratio, plant spacing and fertilizer amount had very significant effects on the soluble sugar content. With potato rows and fertilizer amount increased, the content increased and with plant spacing increased, it decreased. There were no significant differences between plant spacing 22.5cm and 25.5cm, fertilizer amount 100kg/667m~2 and 125kg/667m~2. Row-ratio, plant spacing and fertilizer amount and inter-cropping spacing had very significant effects on starch content. With potato rows and fertilizer amount increased, the content increased, with plant spacing increased, it decreased and with inter-cropping spacing increased, it changed like a parabola going downwards.Row-ratio, plant spacing, fertilizer amount and inter-cropping spacing had significant or very significant effects on potato yield but maize density was insignificant. Potato yield increased with potato rows and fertilizer amount increased and decreased with inter-cropping spacing increased. There were no significant differences between plant spacing 22.5cm and 25.5cm, fertilizer amount 100kg/667m~2 and 125kg/667m~2, inter-cropping spacing 62.5cm, 67.5cm and 72.5cm. Therefore, the optimal configuration for potato is row-ratio 4:2+plant spacing 22.5/25.5cm+fertilizer amount 100 or 125kg/667m~2, inter-cropping spacing 62.5, 67.5 or 72.5cm. And this formula was identical with Treatment 10, in which potato density was 4269plant/667m~2 and the yield reached 2171.48 kg/667m~2. Only maize density had significant effect on maize yield and the yield increased and then decreased with the density increased and reached the maximum at 2800 plant/667m~2.8.The optimal configuration fitting for different harvestersIn consideration of yield, operation and practice, combining the trial test and the experiment, we suggest hand harvester(the fuselage dimension≦100cm) could use the configuration of row-ratios 4:2+plant spacing 25.5cm+ fertilizer(NPK15-15-15)amount 100kg/667m~2+ intercropping spacing 72.5cm +maize density 2800plant/667m~2;the harvesters driving by tractor( wheel base≦120cm) could use the configuration of row-ratio 4:2+plant spacing 25.5cm+fertilizer(NPK15-15-15)amount 100kg/667m~2+ intercropping spacing 72.5cm+maize density 2800 plant/667m~2.