Analysis on Mechanical Grain Harvesting Characteristics of Different New Maize Varieties

Yanlong HAN

Tieling Academy of Agricultural Sciences, Tieling 112616, China

Abstract In order to screen new varieties of suitable mechanical grain harvesting maize, the main agronomic traits, stem traits and harvesting traits of maize in the harvest period were studied through taking 18 main varieties and newly-tested varieties in Liaoning Province as materials. It obtained the following results. Between different maize varieties, there was significant difference in the mechanical grain yield, and the quality difference was also significant. Ten test varieties including Tieyan 818 and Danyu 311 obtained higher yield than the control variety. The moisture content at harvesting was 26.0%-30.4%, the average moisture content was 28.22%, the average breaking rate was 6.52%, the average impurity rate was 1.91%, and the average yield loss rate was 6.33%. Danyu 212, Tieyan 58, Dika 516 and Danyu 801 had higher yield, and the grain moisture content, broken rate, impurity rate and yield loss rate were relatively low, so these varieties are suitable for promoting mechanical harvesting. Among the 8 traits surveyed, the traits positively correlated with yield were the percentage of broken stalks, degree of lodging, moisture content at harvesting, and percentage of kernel weight in ear weight, and traits negatively correlated with the yield included plant height, ear height, percentage of bare plants, and degree of lodging. Therefore, high moisture content is the main problem in the mechanical grain harvesting of maize, it is required to properly select early maturing varieties.

Key words Maize, Mechanical grain harvesting, Broken rate, Impurity rate

1 Introduction

Maize is one of the most widely distributed crops in China and is reputed as the "golden industry" of food crops in the 21st century[1]. With the further development of land circulation, traditional varieties and scattered planting started hindering the development of the maize industry, and the maize production needs expanding the scale. Mechanical harvesting is a key technology to reduce labor and improve economic benefits[2-3], and it is also the bottleneck of China’s maize production scale[4-5]. At present, China’s maize production is mainly based on mechanical harvesting, and mechanical harvesting remains in its infancy, which seriously restricts the mechanization process of maize production in China[6-10]. The high yield and stable yield of maize varieties are the main controlling factors affecting mechanical grain harvesting. Therefore, it is particularly important to screen out the identification indicators of maize mechanical grain harvesting and to promote new varieties suitable for mechanical grain harvesting. Some studies have shown that the stalk rind penetration strength and moisture content are highly correlated with the quality of mechanical grain harvesting[11-12]. With the intensive production of maize, early maturity, tolerance to dense planting, lodging resistance and mechanical grain harvesting become the future maize breeding direction and trend[13-15].

In recent years, some varieties of mature dehydration varieties represented by American Xianyu 335 and Demeiya 1, 2, and 3 have been promoted, and some new breeding varieties have entered the preliminary experimental stage of grain grain harvesting in China. Foreign mechanical grain harvesting technology has been well developed, while there is no mature maize variety in China for mechanical grain harvesting. In view of these, in order to enhance the large-scale maize production in Liaoning Province and give full play to the potential for increasing the yield of cultivars, we analyzed the relationship between the traits of 18 maize varieties and the quality index of mechanical grain harvesting in Liaoning Province. Finally, we screened out the most suitable varieties suitable for harvesting, so as to provide new germplasm resources for mechanical grain harvesting of maize in Liaoning Province.

2 Materials and methods

2.1SamplematerialsThe test materials were main varieties and newly approved maize varieties of Liaoning Province, including Liaodan series of Liaoning Academy of Agricultural Sciences, Danyu series of Dandong Academy of Agricultural Sciences, and Tieyan series of Tieling Academy of Agricultural Sciences. The detailed information is listed in Table 1.

2.2ExperimentdesignThe experiment was carried out in the experimental field of Tieling Academy of Agricultural Sciences in 2018. Previously planted crop was maize, the soil was brown soil, the soil fertility was uniform and medium, the accumulated temperature ≥10℃ was 3 146.1℃, the annual average rainfall was about 600 mm, and the frost-free period was about 150 d.

Randomized block design was conducted, the planting density was 75 000 plants/ha, the plot area was 18 m2, 5 rows per plot; the row length was 6 m, the ridge spacing was 0.6 m, 3 repetitions, the base fertilizer adopted the maize special-purpose fertilizer (N∶P∶K=) 750 kg/ha. In the middle stage, the urea topdressing was conducted, and other management measures were the same as for the field management.

Table1Nameandnumberofmaizevarieties

2.3MeasurementitemsandmethodsAt the maturity stage of maize, 10 plants were randomly selected from each plot to measure the plant height and ear height, and investigate the harvesting period. For each plot, the total number of plants, the number of lodged plants, the number of broken stalks, and the number of bare plants were measured. After threshing, the moisture content was measured using the moisture meter. Collected the falling kernels and ears of each plot, measured their mass, converted into the unit area value, and calculated the yield loss rate.

2.4DataanalysisData processing was performed with the aid of Excel 2010, and data statistics and analysis were performed using with the aid of DPS 7.05 software.

3 Results and analysis

3.1YieldofdifferentmaizevarietiesAccording to the yield results, the control variety Zhengdan 958 was 11 545.5 kg/ha, ranking 10th. The test variety Tieyan 818 had the yield of 12 861 kg/ha, ranking first, increasing by 11.39% compared with the control variety. Danyu 311 and Tieyan 58 ranked second and third, and had the yield of 12 768 and 12 741 kg/ha, increasing by 10.59% and 8.35%, respectively. Other nine varieties including Tieyan 358, Danyu 212, and Liaodan 588 had the yield 9.94%-10.51% higher than the control variety Zhengdan 958. Eight varieties including Liaodan 575 and Danyu 508 had the yield 0.52%-22.26% lower than the control variety Zhengdan 958. According to theLSDmethod, the yield of various maize varieties and the control variety Zhengdan 958 were compared. The nine varieties including Tieyan 818 and Danyu 311 showed significant differences in the yield increase compared with the control variety. The yield decline of Liaodan 575 showed no significant difference, while five varieties including Danyu 508 and Tieyan 388 showed significant difference in the yield decline compared with the control variety, and Liaodan 145 and Tieyan 919 showed extremely significant difference in the yield decline. The yield difference between different maize varieties was significant, indicating that the quantitative heritability between different varieties was large.

Table2Yieldexperimentresultsof18kindsofmechanicalgrainharvestingmaizevarieties

VarietyYieldkg/haYieldincrease/decrease∥%5%Significancelevel1% ExtremesignificancelevelRankTieyan 81812 861.011.39aA1Danyu 31112 768.010.59abA2Tieyan 35812 741.08.35abA3Danyu 21212 693.09.94abA4Liaodan 58812 565.510.13abA5Danyu 33612 487.58.16abA6Tieyan 5812 291.06.46abAB7Dika 51612 181.55.51abAB8Danyu 80111 604.00.51abcABC9Zhengdan 95811 545.50abcABC10Liaodan 57511 485.5-0.52abcABC11Danyu 50811 317.5-1.97bcABC12Tieyan 38811 314.5-2.00bcABC13Liaodan 130110 651.5-7.74cBCD14Liaodan 35210 540.5-8.70cdBCD15Liaodan 121110 390.5-10.00cdeCD16Liaodan 1459 048.0-21.63deD17Tieyan 9198 976.0-22.26eD18

3.2AnalysisonqualityindicatorsofmechanicalgrainharvestingofmaizevarietiesAccording to the analysis results of multiple comparison, there were significant differences in the quality indicators of mechanical grain harvesting between different varieties. The yield loss rate showed the largest change, followed by the broken rate and impurity rate, and the lowest was the moisture content. Among them, Liaodan 565 and Dika 516 were the lowest (1.8%), and Tieyan 818 was the highest (10.4%). According to GB/T 21962-2008 standard, the yield loss rate of Liaodan 565, Dika 516, Danyu 801, Danyu 212, and Tieyan 919 met the national standard (≤5 %), while other 13 varieties (including the control variety) failed to meet the national standard. In terms of the broken rate, Tieyan 358 was the highest (10.48%), Tieyan 58 was the lowest (3.77%). Except Tieyan 358 and Liaodan 145, the rest 16 varieties met the level III grain standard (8%) of the grain drying and collection enterprises (GB/T7890-1999).

In terms of the impurity rate, Liaodan 352 was the highest (2.66%), Tieyan 58 was the lowest, and the impurity rate of all 18 varieties met GB/T21961-2008 national standard (lower than 3%). The moisture content was the highest in Tieyan 818 (30.4%), followed by Liaodan 352 (30.2%), and the lowest was Liaodan 575 (26%). According to the level III grain standard (≤ 5%) of the grain drying and collection enterprises, the moisture content should be controlled within 30%. Except Tieyan 818 and Liaodan 352 slightly higher than the standard, the rest 16 varieties met the national standard. Through summarizing the analysis of the mechanical grain harvesting quality, Liaodan 575, Dika 516, Danyu 801, and Danyu 212 had relatively low impurity rate, broken rate, and yield loss rate, and thus they are suitable for mechanical grain harvesting.

Table3Qualityindicatorsofmechanicalgrainharvestingof18maizevarieties

(%)

3.3AnalysisonthecorrelationbetweenmaizeplanttraitsandqualityindicatorsofmechanicalgrainharvestingAs shown in Table 4, the correlation direction and degree between seven traits and mechanical grain harvesting yield were not consistent. The traits positively correlated with yield were the percentage of broken stalks, degree of lodging, moisture content, and percentage of kernel weight in ear weight, and traits negatively correlated with the yield included plant height, ear height, percentage of bare plants, and degree of lodging. Therefore, it is helpful for obtaining higher mechanical grain harvesting yield through selecting maize varieties with proper ear height, low percentage of bare plants, and low degree of lodging.

Among the surveyed traits, the plant height showed extremely significant correlation with the ear height and degree of lodging, showed significant correlation with the degree of lodging and percentage of kernel weight in ear weight, and had significantly negative correlation with the percentage of bare plants and the moisture content at harvesting. The ear height showed extremely significant correlation with the percentage of kernel weight in ear weight, showed significant correlation with the percentage of broken stalks and the moisture content at harvesting, and had significantly negative correlation with the percentage of bare plants and the degree of lodging. The percentage of bare plants showed extremely significant correlation with the degree of lodging, showed significant correlation with the moisture content at harvesting, and had significantly negative correlation with the percentage of bare plants and the percentage of broken stalks. The degree of lodging showed significant correlation with the ear height and degree of lodging, but showed significantly negative correlation with the moisture content at harvesting and the percentage of kernel weight in ear weight. The percentage of broken stalks was significantly positively correlated with the moisture content at harvesting and the percentage of kernel weight in ear weight. The moisture content at harvesting showed significantly negative correlation with the percentage of kernel weight in ear weight. Therefore, when selecting maize varieties suitable for mechanical harvesting, it is necessary to consider the negative effects of other related trait indicators.

Table4Coefficientofcorrelationbetweenmaizeyieldandagronomictraits

Note: plant height (x1), ear height (x2), percentage of bare plants (x3), degree of lodging (x4), percentage of broken stalks (x5), moisture content at harvesting (x6), and percentage of kernel weight in ear weight (x7).

4 Conclusions and discussions

Apart from the impact of maize varieties, the maize mechanical harvesting quality is also affected by various factors, such as the machinery type, and farming mode[16-18]. Under the mechanical grain harvesting condition, different test varieties obtained different yield. Tieyan 818 ranked first, followed by Danyu 311, Tieyan 58, Tieyan 358, Danyu 212, and Liaodan 588. There were significant difference in the yield increase between these varieties and the control variety. Eight varieties including Liaodan 575 and Danyu 508 had the yield 0.52%-22.26% lower than the control variety. The yield decline of Liaodan 575 showed no significant difference, while five varieties including Danyu 508 and Tieyan 388 showed significant difference in the yield decline variety, and Liaodan 145 and Tieyan 919 showed extremely significant difference in the yield decline.

Indicators for maize mechanical harvesting mainly include the yield loss rate, broken rate, impurity rate, and moisture content. These indicators jointly determine whether a maize variety is suitable for mechanical harvesting. According to the findings of Li Luluetal.[19], the broken rate, the yield loss rate, and impurity rate are correlated with the moisture content, the higher the moisture content, the higher the broken rate and impurity rate, and the lower the yield loss rate. Under conditions of this experiment, there were significant differences between the moisture content, the broken rate, the yield loss rate and the impurity rate. The changes of the yield loss rate and broken rate were large, while the changes of the impurity rate were small.

The relationship between mechanical grain harvesting indicators and the plant traits. The mechanical grain harvesting is also influenced by the plant stalk traits, degree of lodging and percentage of broken stalks, moisture content, and percentage of kernel weight in ear weight.

According to the results of this experiment, among the 7 traits surveyed, the traits positively correlated with yield were the percentage of broken stalks, degree of lodging, moisture content, and percentage of kernel weight in ear weight, and traits negatively correlated with the yield included plant height, ear height, percentage of bare plants, and degree of lodging.

Under the conditions of this experiment, there were significant differences in the mechanical grain harvesting effect between the newly approved 18 maize varieties. The moisture content of the harvested grain was 26%-30.4%, the average moisture content was 28.22%, the average breaking rate was 6.52%, the average impurity rate was 1.91%, and the average yield loss rate was 6.33%. Therefore, high moisture content is the main problem in the mechanical grain harvesting of maize, it is required to properly select early maturing varieties. Danyu 212, Tieyan 58, Dika 516 and Danyu 801 obtained higher yield, and the moisture content, yield loss rate, impurity rate and and broken rate were relatively low, so these varieties are suitable for promoting mechanical harvesting.