YANG Xue-le, ZHANG Lu, WANG Su-hua, HE Lu-qiu

Hunan Crops Research Institute , Changsha 410125, PRC

Abstract In order to find the best intercropping pattern of fresh maize and mung bean, five planting patterns, namely fresh maize monocropping, mung bean monocropping, fresh maize and mung bean intercropping at row ratios of 2 ∶4, 3 ∶3 and 4 ∶2 were set up, and the yields and economic benefits of these planting patterns were analyzed. The results showed that the LERs of the three intercropping patterns were all above 1, and the economic benefits of 2 ∶4, 3 ∶3 and 4 ∶2 fresh maize and mung bean intercropping patterns were seen an increase of 2.85%, 17.64% and 14.26% respectively compared with fresh maize monocropping and an increase of 52.06%, 73.92% and 68.93% respectively compared with mung bean monocropping.Among the three intercropping patterns, the intercropping pattern with row ratio 3 ∶3 showed the best effect, which also derived the highest LER with greatest economic benefit.

Key words Fresh Maize; Mung Bean; Intercropping; Economic Benefits

1. Introduction

Intercropping is a traditional agricultural production and cultivation pattern in China. Studies have shown that intercropping could improve crop yields and economic benefits[1-3]by affecting the morphologic formation[4-5], photosynthesis[6-8], dry matter accumulation[9-10], and field microclimate[11-12]. Intercropping can also realize the efficient utilization of nutrient resources and improve the field environment. LI S Met al.[13]found that intercropped maize had obviously higher nitrogen uptake and biological yields than monocropped maize during the whole growth period. TIAN Y Jet al.[14]reported that the number of hunting insects in intercropping field increased significantly, and the attack by maize borer dropped a lot in intercropping field. DANG J Jet al.[15]discovered that legumes had obvious controlling effect against the weeds in intercropping maize fields and had great contribution to maize yields.

Mung beans have a short growth period with high resistance to barren and shade. They have the function of nitrogen fixation and can improve soil fertility, which are usually intercropped with maize or other high-straw crops. Intercropping of maize and mung bean can make full use of the plant height difference to complement the growth space for each other, improve the resource utilization efficiency and achieve the goal of enhancing production efficiency. Previous studies mainly focused on the intercropping between maize and soybean and their effects on the yields and economic benefits, while seldom studied the intercropping between maize and mung bean. Fresh maize has grown to be an important characteristic industry of many regions due to its short growth period and high economic benefits, but there has been a lack of corresponding studies on such highyield and high-benefit intercropping pattern. As such,this study was designed to investigate the effects of different fresh maize and mung bean row ratios of intercropping on the population agronomic traits, yields and economic benefits of maize and mung bean, thus providing theoretical basis for the high-benefit intercropping pattern between fresh maize and mung bean.

2. Materials and Methods

2.1. Test materials

The maize variety was Heinuo 660; the mung bean variety was Zhonglv 5.

2.2. Test site

The tests were carried out in the test field of Hunan Crops Research Institute in the spring of 2020.The test field was winter fallow field; the soil type was sandy loam with moderate fertility; pH value of soil 5.94;total nitrogen 1.90 g/kg; total phosphorus 0.91 g/kg;total potassium 12.2 g/kg; organic matter 39.7 g/kg.

2.3. Test design

The test adopted randomized block design and totally five planting patterns were set up: fresh maize monocropping (YY), mung bean monocropping (DD),fresh maize and mung bean row ratio 2 ∶4 intercropping (YD1), row ratio 3 ∶3 intercropping (YD2) and row ratio 4 ∶2 intercropping (YD3). Both maizes and mung beans adopted strip cropping, each plot with two strips. The size of each plot was 36 m2(3.6 m×10 m), with three repetitions. The maizes were sown in line and the mung beans were sown in hole. The row spacing of maize was 30 cm×60 cm, and the row spacing of mung bean was 30 cm×50 cm (each hole planted 2 seedlings). The planting densities of maize and mung bean were 55 000 and 133 400 plants/hm2,respectively. The maizes and mung beans were sown at the same time on April 15th. Sufficient base fertilizer was applied at one time before hand sowing, and the field management of the test plots was the same as the paddy field.

2.4. Determination items and methods

2.4.1. Yield determination and plant test

Plant tests of maize and mung bean were conducted on July 6thand July 10th, respectively.The yields of maizes and mung beans collected from different plots were determined.

2.4.2. Data processing

Test data were treated by Excel 2010, and data statistics and analyses were performed by SPSS.

2.4.3. Calculation of land equivalent ratio

Land equivalent ratio (LER) = Yiy/Yyy+Yid/Ydd; LER＞1 indicated intercropping was advantageous, and LER＜1 indicated intercropping was disadvantageous; Yiy and Yid were the yields of maize and mung bean respectively under intercropping pattern; Yyy and Ydd were the yields of maize and mung bean respectively under monocropping pattern.

3. Results and Analysis

3.1. Impacts of different planting patterns on the yield and components of maize

As shown in Table 1, the plant heights of maize under different planting patterns in descending order were YY＞YD1＞YD3＞YD2, and YY presented significant difference with YD1, YD2 and YD3; the ear height in descending order were YY＞YD3＞YD1＞YD2, with non-significant difference between YY and YD3, and significant difference between YY and YD1 as well as YD2; the ear length, ear diameter and ear grain number presented no significant difference;the fresh weights in descending order were YY＞YD1＞YD2＞YD3, showing a significant difference between YY and YD2 as well as YD3, and nonsignificant difference between YY and YD1; the hundredgrain weight in descending order were YD2＞YD1＞YD3＞YY, with YD2, YD1 and YD3 increased by 13.37%, 9.92% and 1.91% respectively compared with YY, and YD2 showed significant difference with YY and YD3, while YD2 showed no significant difference with YD1; the yields under different planting patterns in descending order were YY＞YD3＞YD2＞YD1,yields with YD1, YD2 and YD3 decreased by 46.31%,27.20% and 20.12% compared with YY, and the differences between all treatments were all significant.

3.2. Impacts of different planting patterns on the yield and components of mung bean

As shown in Table 2, there was no significant difference between the plant height, branch number and node number on main stem under different treatments; the pods per plant in descending order were DD＞YD1＞YD2＞YD3, with YD1, YD2 and YD3 reduced by 28.87%, 34.20% and 39.59% respectively compared with DD, and with significant difference between the mung bean monocropping (DD) and the intercropping treatments (YD1, YD2 and YD3) and non-significant difference between YD1, YD2 and YD3; the single pod grain numbers in descending order were DD＞YD1＞YD3＞YD2, with YD1, YD2 and YD3 reduced by 0.15%, 9.42% and 2.01%respectively compared with DD; the pod length in descending order were DD＞YD1＞YD3＞YD2, with YD1, YD2 and YD3 reduced by 4.67%, 8.69% and 4.85%; the hundred-grain weight in descending order were YD1＞DD＞YD3＞YD2, with non-significant difference between DD and YD1, while DD and YD1 were obviously higher than the other two treatments;the yields under different planting patterns in descending order were DD＞YD1＞YD2＞YD3, with YD1, YD2 and YD3 reduced by 27.32%, 32.98%and 49.18% respectively compared with DD, and the difference between the mung bean monocropping (DD)and the three intercropping treatments (YD1, YD2 and YD3) were significant.

3.3. Impacts of different planting patterns on economic benefits

According to Table 3, the LERs of different intercropping patterns were all above 1, which showed the obvious advantage of maize and mung bean intercropping, and the land use rates were improved by 26%, 40% and 31% respectively under YD1, YD2 and YD3; with the increase of maize rows, the LER presented a first increasing and then decreasing trend.As shown in Table 4, the economic benefits under different planting patterns in descending order were YD2＞YD3＞YD1＞YY＞DD, and maize's economic benefits under YD1, YD2 and YD3 increased by 2.85%, 18.13% and 14.26% respectively compared with maize monocropping, mung bean's economicbenefits increased by 52.06%, 74.66% and 68.93%respectively compared with mung bean monocropping.

Table 1 Effects of different planting patterns on maize yield and its components

Table 2 Effects of different planting patterns on mung bean yield and its components

Table 3 The yield and LER of different treatments

Table 4 Comparison of economic benefits of different planting patterns

4. Conlusion and Discussion

Appropriate intercropping of maize and mung bean can complement each other in time and space to make full use of photosynthetic resources and eventually achieve the goal of improving total population yields and economic benefits. YANG Fet al.[16]found that both the maize yield and soybean yield under intercropping pattern were lower than monocropping, but the LERs of different intercropping patterns were above 1, which indicated a higher total benefit of intercropping than monocropping; ZHANG X Net al.[17]also concluded that the yield of the crops under different intercropping patterns decreased a certain amount whereas the total yields were higher than monocropping and the LERs were greater than 1;XU Y Het al.[18]reported that the yields of maize and soybean decreased a certain amount under strip compound planting pattern compared with monocropping pattern, but the total economic benefit was higher than the monocropping pattern.

Reasonable intercropping proportion and planting density are the premise of realizing high population yield. WANG H Het al.[19]found that the intercropping of maize and mung bean at row ratio 4∶8 derived the highest yield, which increased by 68.3%compared with maize monocropping and increased by 73.4% compared with mung bean monocropping;MEN H Wet al.[20]reported the highest economic benefits when two rows of maize were planted alternately with two rows of mung bean with the maize planting density of 67 500 plants/hm2and mung bean planting density of 55 500 plants/hm2. The economic benefits under this intercropping pattern increased by 26.9% and 12.3% respectively compared with maize monocropping and mung bean monocropping;CAI L L[21]found that the best intercropping row ratio of mung bean and maize for achieving a highest economic benefit was 2 ∶1; YAN Fet al.[22]also concluded that the highest yield of maize can be achieved when the intercropping row ratio of mung bean and maize was 2 ∶1, while the highest overall economic benefit of the compound population was achieved at the intercropping row ratio of 6 ∶4.The results of this study showed that different patterns could cause a certain decrease of the yield of maize and mung beam, whereas the total output value of the intercropping population was higher than monocropping and the LERs were all above 1. Among the five planting patterns, the row ratio of 3 ∶3 of maize and mung bean exhibited the maximum LER and highest population total output value with the best intercropping effect.