Effect Of Different Distance Between Maize Strips On Light Energy Utilization Of Strip Intercropped Maize

In order to investigate the effect of different distance between maize strips on light energy utilization of strip intercropped maize under the same growth environment(same plant spacing,row spacing,and fertilizer application),this experiment was conducted in2021-2022 using a one-way randomized group design with five different distance between maize strips of 1 m(1M1S: 1 row of maize:1 row of soybeans),1.2 m(2M1S: 2 rows of maize:1 row of soybeans),1.6 m(2M2S: 2 rows of maize:2 rows of soybeans),2 m(2M3S:2 rows of maize:3 rows of soybeans),2.4 m(2M4S: 2 rows of maize:4 rows of soybeans),and two other monocultures of maize were set as controls with row spacing of 80 cm(M80)and 40 cm(M40),respectively.the effects of the differences in light environment caused by different distance between maize strips on strip intercropped maize were investigated by examining the photosynthetic effective radiation,leaf area,leaf angle,dry matter accumulation,light energy utilization,net photosynthetic rate,photosynthetic physiology,and yield of maize canopy.1.Characteristics of light distribution under different distance between maize stripsAs the distance between maize strips increased,the light transmittance of both the maize ears position layer(100 cm)and the lower middle part(0-100 cm)became larger,and the distance between maize strips was linearly and positively correlated with the light transmittance of strips intercropped maize.the light transmission in the maize ears position layer showed M80(0.75)> 2M4S(0.67)> 2M3S(0.57)> 2M2S(0.53)> 1M1S(0.52)>2M1S(0.37)> M40(0.23).The lower and middle transmittance showed 2M4S(0.38)> 2M3S(0.34)> 2M2S(0.32)>1M1S(0.27)> M80(0.23)> 2M1S(0.21)> M40(0.12).2.Effects of different distance between maize strips of light environment on maize form and dry matter accumulationAs the distance between strips increased,maize plant height and leaf area per plant showed a tendency to increase and leaf pinch angle showed a tendency to decrease.The distance between strip distance did not significantly affect plant height and leaf pinch angle,but significantly affected maize single leaf area.Compared with the two monocrop treatments(M80 and M40),the intercrop 2M4 S treatment had the largest plant leaf area,which was 14.43% and 29.34% greater than the M80 and M40 treatments,respectively.compared with 1M1 S treatment,2M2 S,2M3S and 2M4 S treatments increased leaf area per plant at the nodulation,spatulation and filling stages by 2.71%,7.40%and 16.17%.Dry matter accumulation increased with increasing distance between maize strip.with 2M4 S reaching 124.84 g/plant,significantly higher than the single maize M80 and M40 treatments by 8.12% and 73.32%,and 19.00%,13.00%,and 7.00% higher than the 1M1 S,2M1S,and2M1 S treatments.3.Effects of different distance between maize strips of light environment on light interception and light energy utilization of maizeThe light energy interception rate of maize per unit land area decreases gradually with increasing distance between maize strips,and distance between maize strips had a significant effect on light energy interception rate,which was 1M1S>2M1S>2M2S> 2M3S>2M4S.The light energy interception rate of intercropped 2M4 S treatment was significantly lower than that of M80 and M40 treatments by 44.72% and 53.54%,respectively.Strip intercropping improved the light energy utilization of maize,which was 21.72%,19.95%,48.22%,90.88% and 114.80% higher in intercropping 1M1 S,2M1S,2M2 S,2M3S and 2M4 S treatments,respectively,than in M80 treatment alone,and 117.74%,109.65%,117.74%,109.65% and 271.37% higher than in M40 treatment alone.152.21%,222.31%and 271.37% higher than the M40 treatment alone.As the distance between maize strips increase.The light energy utilization of the intercropping treatments showed2M4S>2M3S>2M2S>1M1S>2M1S.Compared with the 1M1 S treatment,the light energy utilization of the 2M4 S treatment increased by 33.67%,38.26%and 48.02% at the nodulation,spatulation and filling stages.4.Effect of different distance between maize strips of light environment on photosyn thetic characteristics and photosynthetic physiological propertiesDistance between maize strips had a significant effect on net photosynthetic rate,chlorophyll content and activities of photosynthetic key enzymes(Rubisco and PEPC)in wide row ears of maize leaves,which increased with increasing distance between maize strips.Strip intercropping increased net photosynthetic rate,chlorophyll content,Rubisco and PEPC enzyme activities in wide rows,and the distance between maize strips was linearly and positively correlated with its.net photosynthetic rate in wide rows was significantly higher in 2M4 S treatment than in the two monocultures(M80,M40),1M1 S treatment by11.24% to 15.85%,37.45% to 62.57%,and 19.76%-47.31%;chlorophyll content of 2M4 S treatment was 17.51% and 27.30% higher than the two monocultures M80 and M40 treatments,and 2M4 S treatment was significantly higher than 1M1 S and 2M1 S treatments;Rubisco and PEPC enzyme activities in the broad rows of 2M4 S treatment were significantly higher than the two monocultures M80 and M40 treatments by 8.33%,118.70% and 34.16%,76.97%.Net photosynthesis rate,chlorophyll content and Photosynthetic key enzyme activity(Rubisco and PEPC)in narrow row ears of leaves differed among treatments,with intercropped narrow rows being lower than mono cropped maize.Compared to the monocrop M80 and M40 treatments,the net photosynthetic rate was 6.79%and 26.76%lower in the 2M4 S treatment;chlorophyll content was 8.32% and 22.19% lower;Rubisco and PEPC enzyme activities were significantly lower than the two monocrops.Distance between maize strips had a significant effect on net photosynthetic rate,chlorophyll content and photosynthetic key enzymes(Rubisco and PEPC)in narrow row spikes.2M4 S treatment reduced net photosynthetic rate by 19.66% compare to 1M1 S treatment and increased it by39.27% and 5.30%.Compared to 2M1 S and 2M2 S treatments.2M4 S treatment reduced chlorophyll content by 2.72% compared to 1M1 S treatment Rubisco and PEPC activities were 103.08%,128.09%,68.39% and 31.23%,20.26%,19.51% higher in the 2M4 S treatment than in the 2M1 S,2M2S and 2M3 S treatments,respectively.5.Effect of different distance between maize strips of light environment on yieldStrip intercropping increased the yield of maize per plant,compared to M80 treatment,with 3.76%,10.47% and 13.43% increase in intercropping 2M2 S,2M3S and 2M4 S treatments,respectively.Intercropping 1M1 S,2M1S,2M2 S,2M3S,and 2M4 S treatments increased 38.63%,46.96%,50.05%,57.08%,and 61.31%,respectively,compared to the M40 treatment alone.The distance between maize strips had a significant effect on the yield of intercropped maize plants,which increased with increasing distance between maize strips.2M4 S treatment had the highest yield of 117.56 g/plant.The 2M4 S treatment significantly increased by 20.62% and 10.22% compared to the 1M1 S and 2M1 S treatments.The above results showed that there were large differences in light energy utilization of maize caused by different distance between maize strips under the same growth environment of maize monocultures.As the distance between maize bands increased,the light transmission rate in the lower and middle parts of maize increased,leaf area,dry matter accumulation,light energy utilization and yield showed an increasing trend,leaves maintained a high net photosynthetic rate and enzyme activity,and the light energy interception rate per unit land area decreased with the distance between maize strips.