Effects of Different Planting Patterns on Growth and Yield Components of Foxtail Millet

Abstract

Different cultivation measures, including seeding patterns, plastic film mulching, and drip irrigation, significantly affect crop growth and yield. This study conducted a two-year field experiment, involving eight treatments: hole seeding and drill seeding, mulching and bare land, as well as with and without drip irrigation. Analyzed the impact on agronomic traits, photosynthesis, chlorophyll fluorescence parameters, and yield components during the growth period of foxtail millet. The results of two years indicate that the growth trend of foxtail millet was consistent under both hole seeding and drill seeding. The best performance was achieved with drip irrigation treatment for mulching, followed by drip irrigation for bare land, no drip irrigation for mulching, and no drip irrigation for bare land. In 2024, the maximum yield of HFD in hole seeding pattern was 4627.55 kg/ha. The maximum yield of DFD in drill pattern is 4430.22 kg/ha. In summary, based on the comprehensive optimization of two years of data and the effective accumulated temperature in the local area, the best planting method is hole seeding, mulching, and drip irrigation. In cold and cool regions, mulching with film aids in increasing the accumulated temperature of the tillage layer. Hole seeding is conducive to enhancing seedling quality. Performing drip irrigation once during the late heading stage stimulates the growth and fruiting of foxtail millet, thereby increasing yield.

1. Introduction

Foxtail millet [Setaria italic (L.) Beauv] is an annual herb plant. It is the earliest widely cultivated crop in Chinese agricultural civilization [1]. It has characteristics such as drought resistance, poor fertility, storage tolerance, strong stability, and wide applicability [2]. It has a history of over 8700 years [3]. At the same time, the water utilization efficiency is also relatively high, with obvious regional and growth advantages. It is suitable for cultivation in areas with less rainfall, such as Northeast China, North China, Northwest China, and Southwest China. In addition, it has rich nutritional value and is highly favored by consumers, making it an indispensable part of grain crops. It has always been the main grain crop that nurtures the people of northern and southern China, and it is regarded as a distinctive grain crop by people [4]. It has four main functions: tonifying qi and spleen, devouring blood, strengthening tendons and bones, and enhancing body resistance, and it can also increase appetite [5]. Foxtail millet is known as the first of the five grains and is a traditional mixed grain crop domesticated from the wild species of bristlegrass (Setaria viridis) in northern China [6]. So far, the foxtail millet planting area is between 300,000 and 350,000 hectares, and its production has become a key industry in the development plan of Shanxi’s small grain crops and regional characteristic agricultural products. Because the Shanxi area is located in the alpine zone with less rainfall, climate [7], environment, and cultivation measures will have an impact on foxtail millet growth and yield composition [8]. Plastic film covering has multifunctionality in water-saving agriculture [9].

Different planting patterns can directly affect the microenvironment of crop growth and then affect the growth characteristics and yield components of the crops. Row spacing and density have effects on the yield and lodging of spring wheat [10]. Optimizing planting methods effectively improves the environmental conditions for root growth, promotes the development of underground root systems, and enhances the soil’s ability to retain roots [11]. Ridge cultivation enhances root growth, and the stronger its fixation ability, the better the plant’s resistance to lodging [12]. Row spacing and density have an impact on crop yield and lodging resistance [13]. It showed that fertilizer application can increase the water absorption of foxtail millet, and the water use efficiency and grain yield significantly increase with the increase in fertilizer application [14]. The interaction between supplementary irrigation and planting density has a certain promoting effect on winter wheat grain yield [15]. It showed that improving the mechanical strength of the stem base by optimizing canopy spacing organization is the key to reducing lodging risk and forming a high-yield population [16].

Previous studies on the growth characteristics and yield composition of crops such as corn under different planting patterns have been relatively in-depth. The planting method also plays an important role in the population construction and individual development of crops; plant agronomic traits are important indicators for evaluating plant growth. Plant height, stem diameter, and panicle height will not change significantly [17]. Research has shown that different planting densities can affect the accumulation of dry matter per maize plant [18]. Density and row spacing configuration may affect the grain filling process by altering environmental factors, thereby affecting the population quality of crops [19].

The application of agricultural plastic film covering technology is widespread, significantly improving water use efficiency, promoting the growth and development of crop roots, and enhancing crop stress resistance and yield. Plastic film covering can reduce evaporation, improve soil temperature, and thus affect crop yield. In the study of potato cultivation, it has been shown that the use of plastic film furrow and ridge covering technology not only results in denser root systems in the 15 cm soil layer, but also significantly increases soil moisture [20]. The combination of planting patterns and mulching has improved soil moisture content, spring wheat growth, yield, and water use efficiency [21]. Two commonly used patterns of soil moisture preservation and mulching, ridge and furrow mulching and flat mulching, are beneficial for wheat production [22].

The production and accumulation of crop dry matter are prerequisites for crop organ differentiation and the material basis for the formation of economic yield. It showed that deep loosening can improve the root morphology and resistance to environmental stress of maize, which is influenced by the distribution of root structure in the soil [23]. Optimizing the size and structure of the root system plays a crucial role in improving the lodging resistance of crops [24]. It reported that when there is a plant in the well, the concentration of free amino acids in the root sap is higher than when there are two plants in each well [25]. The appropriate planting pattern played a crucial role in the growth of crops.

Therefore, the purpose of this experiment is to find the best planting mode in Shanxi Province, and explore the impact of its seeding pattern, plastic film coverage, and drip irrigation on crop growth and yield. It provides theoretical basis and technical support for the planting of Jingu 21 in different regions.

2. Materials and Methods

The experiment was conducted in Shanyin County (112°86′ E and 39°46′ N), Shuozhou City, Shanxi Province from April to October 2023 and 2024. The altitude was 1002 m, the climate was temperate and continental, the annual average frost-free period was 130 days, and the annual average rainfall was 410 mm. The basic fertility conditions of the experimental soil were shown in

Table 1. Soil basic fertility in 0–20 cm soil layer before seeding in different sites.

Year	Total N (g/kg)	Total P (g/kg)	Total K (g/kg)	Organic Matter (g/kg)	Alkaline- Hydrolytic N (mg/kg)	Available P (mg/kg)	Available K (mg/kg)	PH Value
2023	0.599	0.65	5.9	9.61	47.5	43.6	92	8.67
2024	0.740	0.56	17.8	12.84	59.9	26.3	121.7	8.35

. The average precipitation and temperature of foxtail millet from May to October during the experiment were calculated every 15 days, as shown in Figure 1. The soil moisture is shown in Figure 2.

2.1. Test Materials

The tested foxtail millet variety Jingu 21 was cultivated by the Industrial Crops Institute of Shanxi Agricultural University.

2.2. Experimental Design

The uniform amount of bottom fertilizer applied in the experimental field was 600 kg/ha. The fertilizers used in each community in 2023 and 2024 were compound fertilizers, with a standard content of N-P₂O₅-K₂O (25-10-16), and the total nutrients were more than or equal to 51%. The experiment used the conventional foxtail millet variety Jingu 21 as the experimental material and adopted a split zone experimental design. Four treatments were set up under two seeding patterns: hole seeding and drill seeding, including film mulching with drip irrigation (FD), naked land with no drip irrigation (NN), film mulching with no drip irrigation (FN), and naked land with drip irrigation (ND). Eight planting patterns were shown in

Table 2. Eight planting methods represented.

Planting Pattern	Abbreviation
Hole seeding with film mulching and drip irrigation	HFD
Hole seeding with naked land and no drip irrigation	HNN
Hole seeding with film mulching and no drip irrigation	HFN
Hole seeding with naked land and drip irrigation	HND
Drill seeding with film mulching and drip irrigation	DFD
Drill seeding with naked land and no drip irrigation	DNN
Drill seeding with film mulching and no drip irrigation	DFN
Drill seeding with naked land and drip irrigation	DND

, with the aim of exploring the effects of different factors on the growth of foxtail millet. The area of the community was 180 m², repeated four times. The row spacing of eight planting patterns was 55 cm, and the number of seedlings left in Jingu 21 was 450,000 plants/ha. The plastic film adopted a flat semi covering method, with two rows of planting on top of the film for hole seeding treatment, and two rows of planting under the film for drill seeding treatment. Before sowing, soil preparation, cultivation, and application of cow manure should be carried out. During the growth period of foxtail millet, no fertilization was required. Other field management was the same as that of ordinary fields. The 2023 experimental site was sown on 28 April and harvested on 5 October. The 2024 experimental site was sown on 27 April and harvested on 11 October. Irrigation was carried out in the late stage of heading in 2023 and 2024. The irrigation amount per hectare of land was 150 cubic meters.

2.3. Determination Items and Methods

2.3.1. Plant Height

Select 10 representative plants with consistent growth in each plot during the seedling stage, jointing stage, booting stage, and grain filling stage. After removing the root system from the measurement samples, measure the plant height using a ruler.

2.3.2. Leaf Area

During the seedling stage, jointing stage, booting stage, and grain filling stage of foxtail millet, 10 representative foxtail millet plants with consistent growth were selected from each plot, and the leaf area of the second leaf of each foxtail millet plant was measured. The formula for calculating leaf area is as follows [26]:

Leaf area (cm²) = leaf length (cm) × leaf width (cm) × 0.75

2.3.3. Biomass

Aboveground Fresh Weight

After removing the root system from the measurement sample, use an electronic analytical balance to weigh the fresh weight of the aboveground parts of the plant.

Dry Weight of the Aboveground Parts

Deactivate enzymes at 105 °C for 30 min, adjust the temperature to 80 °C, and dry until a constant weight is obtained. Then weigh the dry weight of the aboveground part of the plant.

2.4. Photosynthetic Physiological Characteristics of Leaves

2.4.1. Blade Gas Exchange Parameters

During the jointing stage, booting stage, and grain filling stage of foxtail millet, choose clear and cloudless weather, and use a portable photosynthesis instrument (CI-340, CID Bio-Science, Inc., Washington, DC, USA) from 9:00 to 11:00 in the morning. Measure the net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and intercellular CO₂ concentration (Ci) of the second leaf of foxtail millet.

2.4.2. Kinetic Parameters of Chlorophyll Fluorescence

During the jointing stage, booting stage, and grain filling stage of foxtail millet, measurements of photosynthesis are conducted simultaneously under natural conditions. The PAM-2500 portable modulated chlorophyll fluorescence analyzer (Walz, Effeltrich, Germany) was used to measure the chlorophyll fluorescence kinetic parameters of the fallen leaves of foxtail millet after 30 min of dark treatment.

2.5. Yield Components

During the mature stage of foxtail millet, unified harvesting, sampling, and yield measurement are conducted. Randomly select a complete 5 m² area from each community and count the effective number of spikes per unit area, repeating 3 times. Randomly select 15 representative plants from each community and conduct indoor seed testing to determine yield components such as panicle length, panicle diameter, panicle weight, and grain weight per panicle. Randomly select 8 m² of actual harvest from each community, air dry naturally, and use a KT-200A (Star Fuse Co., Ltd., Tokyo, Japan) foxtail millet thresher (Bethlehem Instrument Equipment Co., Ltd., Taizhou, Zhejiang, China) to determine the yield of the community after threshing.

2.6. Data Processing

All the experiments were designed by split plot experiment, with 4 replicates. Data processing was performed using Microsoft Excel 2021 (Microsoft, Redmond, WA, USA) and IBM SPSS Statistics 25 software (SPSS Inc., Chicago, IL, USA). Duncan’s new multiple range method was used for the analysis of variance and multiple comparisons (significance was considered at the p < 0.05 level). The statistics were measured by Origin 2021 (Origin Lab, Northampton, MA, USA). Data were presented as mean ± sem.

3. Results

3.1. Effect of Different Planting Patterns on Agronomic Characters of Foxtail Millet

3.1.1. Effects of Different Planting Patterns on Plant Height

As the growth period progresses, the plant height of foxtail millet gradually increased and reached its maximum value during the grain filling stage. Different treatments of hole seeding at different growth stages showed HFD > HND > HFN > HNN for Jingu 21. The performance of Jingu 21 under different treatments of drill seeding was DFD > DND > DFN > DNN. The plant height of HFD was 17.46%, 12.36%, and 5.49% higher than that of HNN, HFN, and HND, respectively, at the filling stage. The plant height of DFD was 20.75%, 18.96%, and 2.17% higher than that of DNN, DFN, and DND (Figure 3).

Compared with 2023, both hole seeding and drill seeding had FD > ND > FN > NN, and the plant height gradually increases with the growth period. The year 2023 had better growth during the booting and filling stages, while 2024 had better growth during the seedling and jointing stages (Figure 4).

3.1.2. Effects of Different Planting Patterns on Leaf Area

With the development of the growth period, the leaf area of the foxtail millet increased gradually and reached the maximum in the filling period. Different treatments of hole seeding at different growth stages showed HFD > HND > HFN > HNN for Jingu 21, while different treatments of drill seeding showed DFD > DND > DFN > DNN for Jingu 21. The leaf area of HFD was 20.60%, 9.12%, and 8.80% higher than that of HNN, HFN, and HND, respectively. The leaf area of DFD was 37.61%, 34.75%, and 33.90% higher than that of DNN, DFN, and DND (

Table 3. Effects of different growth stages on leaf area of foxtail millet (2023).

Planting Pattern	Leaf Area (cm2)
	Seedling Stage	Jointing Stage	Booting Stage	Filling Stage
HFD	23.24 ± 4.03 a	91.62 ± 4.89 a	103.60 ± 7.26 a	126.81 ± 9.16 a
HNN	9.72 ± 0.94 b	58.42 ± 4.31 b	89.78 ± 3.51 a	100.19 ± 2.77 b
HFN	9.48 ± 0.56 b	67.61 ± 9.54 b	101.66 ± 5.24 a	123.10 ± 4.04 a
HND	12.12 ± 1.60 b	87.21 ± 3.43 a	100.10 ± 6.91 a	116.23 ± 3.54 ab
DFD	16.14 ± 0.48 a	88.68 ± 6.85 a	94.67 ± 3.14 a	131.61 ± 6.01 a
DNN	11.98 ± 1.35 b	62.01 ± 2.23 b	69.46 ± 3.11 b	95.64 ± 3.84 b
DFN	14.76 ± 1.38 ab	79.22 ± 5.35 a	84.06 ± 6.81 ab	97.67 ± 4.52 b
DND	16.89 ± 1.56 a	81.86 ± 0.34 a	99.40 ± 9.11 a	98.29 ± 1.23 b

Note: HFD (hole seeding with film mulching and drip irrigation), HNN (hole seeding with naked land and no drip irrigation), HFN (hole seeding with film mulching and no drip irrigation), HND (hole seeding with naked land and drip irrigation), DFD (drill seeding with film mulching and drip irrigation), DNN (drill seeding with naked land and no drip irrigation), DFN (drill seeding with film mulching and no drip irrigation), DND (drill seeding with naked land and drip irrigation) the same applies below. Lowercase letters indicate a significant difference of 5% between different planting methods during the same period, the same applies below.

).

Compared with 2023, both hole seeding and drill seeding had FD > ND > FN > NN. 2023 showed better growth during the booting and grain filling stages, while 2024 showed better growth during the jointing and grain filling stages. In 2024, the booting stage experienced drought (

Table 4. Effects of different growth stages on leaf area of foxtail millet (2024).

Planting Pattern	Leaf Area (cm2)
	Seedling Stage	Jointing Stage	Booting Stage	Filling Stage
HFD	39.20 ± 0.52 a	115.15 ± 0.63 a	96.39 ± 0.69 a	111.38 ± 0.87 a
HNN	27.06 ± 0.70 d	72.39 ± 0.73 d	79.31 ± 0.56 d	91.59 ± 1.51 d
HFN	30.71 ± 0.46 c	100.06 ± 0.83 c	85.63 ± 0.53 c	95.02 ± 0.92 c
HND	34.40 ± 0.38 b	108.28 ± 0.66 b	88.95 ± 0.66 b	104.83 ± 1.03 b
DFD	32.34 ± 0.53 a	113.97 ± 0.99 a	99.74 ± 0.81 a	114.87 ± 0.96 a
DNN	20.35 ± 0.30 d	75.98 ± 0.74 d	78.49 ± 0.90 d	81.58 ± 0.78 d
DFN	23.70 ± 0.36 c	82.88 ± 0.87 c	85.44 ± 0.80 c	88.95 ± 0.48 c
DND	28.56 ± 0.68 b	89.90 ± 0.64 b	93.21 ± 0.66 b	97.99 ± 0.59 b

).

3.1.3. Effects of Different Planting Patterns on Aboveground Biomass

As the growth period progresses, the aboveground fresh weight of foxtail millet gradually increased and reached its maximum value during the grain filling period. Different treatments of hole seeding for Jingu 21 showed HFD > HND > HFN > HNN, and different treatments of drill seeding for Jingu 21 showed DFD > DND > DFN > DNN. The fresh weight of the shoot of HFD was 56.20%, 46.16%, and 17.88% higher than that of HNN, HFN, and HND, respectively. The fresh weight of the shoot of DFD was 51.71%, 45.95%, and 11.16% higher than that of DNN, DFN, and DND (

Table 5. Effects of different growth stages on fresh weight of aboveground parts of foxtail millet (2023).

Planting Pattern	Fresh Weight of Aboveground Parts (g)
	Seedling Stage	Jointing Stage	Booting Stage	Filling Stage
HFD	2.31 ± 0.49 a	32.09 ± 1.42 a	67.82 ± 2.98 a	126.69 ± 1.93 a
HNN	0.82 ± 0.14 b	10.89 ± 0.82 c	43.40 ± 1.43 c	81.11 ± 2.11 c
HFN	0.88 ± 0.16 b	14.55 ± 1.08 b	59.03 ± 2.29 b	86.68 ± 3.24 c
HND	1.18 ± 0.12 b	16.36 ± 1.01 b	58.41 ± 1.53 b	107.47 ± 2.50 b
DFD	1.56 ± 0.17 a	30.38 ± 0.76 a	64.00 ± 2.20 a	108.97 ± 1.81 a
DNN	1.10 ± 0.24 a	13.78 ± 0.52 c	31.40 ± 1.55 d	71.83 ± 1.41 c
DFN	1.41 ± 0.16 a	22.85 ± 0.97 b	56.17 ± 2.14 c	74.66 ± 1.37 c
DND	1.69 ± 0.25 a	24.99 ± 0.81 b	76.67 ± 2.20 b	98.03 ± 2.10 b

).

Compared with 2023, the fresh weight of the aboveground parts of foxtail millet in 2024 showed a gradually increasing trend, with FD > ND > FN > NN. The highest fresh weight was observed during the grain filling period. In 2024, the fresh weight of aboveground parts under drill seeding with mulching and drip irrigation was the best. The fresh weight of aboveground parts under drill seeding with mulching and drip irrigation in 2024 was 9.15% higher than that under hole seeding with mulching and drip irrigation (

Table 6. Effects of different growth stages on the fresh weight of the aboveground parts of foxtail millet (2024).

Planting Pattern	Fresh Weight of Aboveground Parts (g)
	Seedling Stage	Jointing Stage	Booting Stage	Filling Stage
HFD	3.34 ± 0.06 a	42.89 ± 1.03 a	64.35 ± 0.74 a	119.51 ± 0.79 a
HNN	2.23 ± 0.03 d	28.83 ± 0.70 d	48.49 ± 0.45 d	95.17 ± 0.92 d
HFN	2.45 ± 0.07 c	33.46 ± 0.58 c	51.73 ± 0.69 c	102.45 ± 1.30 c
HND	3.00 ± 0.07 b	37.11 ± 0.49 b	55.58 ± 0.61 b	112.75 ± 1.06 b
DFD	3.02 ± 0.05 a	34.01 ± 0.97 a	63.43 ± 0.60 a	130.45 ± 1.12 a
DNN	2.26 ± 0.05 d	23.26 ± 0.69 d	42.14 ± 0.64 d	106.26 ± 0.95 d
DFN	2.45 ± 0.04 c	26.92 ± 0.73 c	45.42 ± 0.48 c	113.19 ± 0.60 c
DND	2.76 ± 0.03 b	29.49 ± 0.59 b	58.21 ± 0.56 b	118.19 ± 0.81 b

).

With the development of the growth period, the dry weight of the foxtail millet increased gradually and reached the maximum in the filling period. Different treatments of hole seeding for Jingu 21 showed HFD > HND > HFN > HNN, and the different treatments of drill seeding for Jingu 21 showed DFD > DND > DFN > DNN. The dry weight of the shoot of HFD was 70.74%, 51.27%, and 33.00% higher than that of HNN, HFN, and HND, respectively. The dry weight of the shoot of DFD was 30.92%, 29.73%, and 7.94% higher than that of DNN, DFN, and DND (

Table 7. Effects of different growth stages on shoot dry weight of foxtail millet (2023).

Planting Pattern	Shoot Dry Weight (g)
	Seedling Stage	Jointing Stage	Booting Stage	Filling Stage
HFD	0.60 ± 0.12 a	6.52 ± 0.76 a	15.56 ± 1.04 a	44.05 ± 1.28 a
HNN	0.22 ± 0.02 b	3.83 ± 0.88 b	9.21 ± 0.89 b	25.80 ± 0.64 c
HFN	0.24 ± 0.02 b	5.04 ± 0.48 ab	12.06 ± 1.13 b	29.12 ± 1.84 c
HND	0.31 ± 0.05 b	4.45 ± 0.79 ab	11.24 ± 1.05 b	33.12 ± 1.11 b
DFD	0.39 ± 0.03 a	6.48 ± 0.43 a	13.11 ± 0.71 a	35.91 ± 0.99 a
DNN	0.28 ± 0.06 a	3.11 ± 0.19 c	5.59 ± 0.79 c	27.43 ± 1.03 b
DFN	0.29 ± 0.02 a	5.24 ± 0.41 b	12.74 ± 1.09 b	27.68 ± 1.11 b
DND	0.38 ± 0.04 a	5.38 ± 0.24 b	15.53 ± 0.73 ab	33.27 ± 0.78 a

).

Compared with 2023, the aboveground dry weight of foxtail millet in 2024 showed a gradually increasing trend, with FD > ND > FN > NN; the highest during the grain filling period. During the grain filling period in 2024, the fresh weight of aboveground parts under drill seeding with mulching and drip irrigation was the best. In 2024, the fresh weight of the aboveground parts under drill seeding with mulching and drip irrigation was 3.36% higher than that under hole seeding with mulching and drip irrigation (

Table 8. Effects of different growth stages on shoot dry weight of foxtail millet (2024).

Planting Pattern	Shoot Dry Weight (g)
	Seedling Stage	Jointing Stage	Booting Stage	Filling Stage
HFD	0.60 ± 0.03 a	9.95 ± 1.05 a	16.15 ± 0.49 a	43.47 ± 0.64 a
HNN	0.40 ± 0.03 c	6.58 ± 0.37 c	10.65 ± 0.49 d	31.24 ± 0.65 d
HFN	0.44 ± 0.02 bc	7.59 ± 0.46 bc	12.10 ± 0.22 c	36.11 ± 0.58 c
HND	0.51 ± 0.02 b	9.11 ± 0.31 ab	14.25 ± 0.43 b	39.39 ± 0.39 b
DFD	0.58 ± 0.04 a	9.37 ± 0.16 a	17.77 ± 0.33 a	44.93 ± 0.43 a
DNN	0.34 ± 0.05 c	5.31 ± 0.41 d	10.75 ± 0.14 d	29.14 ± 0.40 d
DFN	0.42 ± 0.05 b c	6.44 ± 0.30 c	11.64 ± 0.21 c	33.01 ± 0.48 c
DND	0.49 ± 0.02 ab	7.53 ± 0.12 b	14.15 ± 0.13 b	36.36 ± 1.00 b

).

3.2. Effects of Different Planting Patterns on Light and Characteristics of Foxtail Millet Leaves

3.2.1. Effects of Different Planting Patterns on the Net Photosynthetic Rate (Pn)

As the growth period progresses, Pn of foxtail millet showed a trend of first increasing and then decreasing, and it reached its maximum value at booting stage. Different treatments of hole seeding show HFD > HND > HFN > HNN for Jingu 21, while different treatments of drill seeding showed DFD > DND > DFN > DNN for Jingu 21. Pn of HFD was 42.02%, 20.72%, and 12.88% higher than that of HNN, HFN, and HND at the booting stage. Pn of DFD was 67.82%, 33.18%, and 25.07% higher than that of DNN, DFN, and DND at the booting stage (

Table 9. Effects of different planning patterns on Pn of foxtail millet leaves (2023).

Planting Pattern	Pn (μmol·m−2·s−1)
	Jointing Stage	Booting Stage	Filling Stage
HFD	27.30 ± 0.44 a	28.49 ± 0.53 a	21.87 ± 1.27 a
HNN	11.55 ± 1.19 d	20.06 ± 0.64 d	8.64 ± 0.37 c
HFN	18.55 ± 0.77 c	23.60 ± 0.46 c	11.04 ± 0.34 b
HND	22.55 ± 0.86 b	25.24 ± 0.25 b	12.62 ± 0.45 b
DFD	25.83 ± 0.73 a	32.07 ± 1.49 a	16.05 ± 1.21 a
DNN	15.13 ± 0.91 d	19.11 ± 1.65 c	10.10 ± 0.56 c
DFN	19.34 ± 0.48 c	24.08 ± 0.63 b	11.51 ± 0.14 bc
DND	21.59 ± 0.62 b	25.64 ± 0.19 b	12.98 ± 0.41 b

).

Compared with 2023, the planting patterns of hole seeding and drill seeding showed FD > ND > FN > NN in 2024. Pn of Jingu 21 performed well during the jointing and filling stages, but poorly during the booting stage, which differs from the experiment in 2023. This is due to the extreme drought in Shanxi Province during the booting stage in 2024 (

Table 10. Effects of different planning patterns on Pn of foxtail millet leaves (2024).

Planting Pattern	Pn (μmol·m−2·s−1)
	Jointing Stage	Booting Stage	Filling Stage
HFD	35.40 ± 0.41 a	27.56 ± 0.43 a	31.25 ± 0.42 a
HNN	27.87 ± 0.48 d	22.03 ± 0.51 d	18.99 ± 0.32 d
HFN	29.84 ± 0.34 c	23.53 ± 0.33 c	23.41 ± 0.35 c
HND	31.66 ± 0.53 b	24.83 ± 0.38 b	25.63 ± 0.46 b
DFD	32.26 ± 1.21 a	26.93 ± 0.39 a	37.42 ± 0.39 a
DNN	19.30 ± 1.32 d	17.25 ± 0.99 d	19.56 ± 0.43 d
DFN	24.87 ± 0.81 c	21.68 ± 0.69 c	27.01 ± 0.56 c
DND	28.63 ± 1.06 b	24.08 ± 0.65 b	29.11 ± 0.33 b

).

3.2.2. Effects of Different Planting Patterns on the Transpiration Rate (Tr)

As the growth period progresses, Tr of foxtail millet showed a trend of first increasing and then decreasing, reaching its maximum value at the booting stage. Different treatments of hole seeding show HFD > HND > HFN > HNN for Jingu 21, while different treatments of drill seeding show DFD > DND > DFN > DNN for Jingu 21. At the booting stage, Tr of HFD was 39.61%, 22.72%, and 10.44% higher than that of HNN, HFN, and HND, respectively. Tr of DFD was 54.67%, 24.37%, and 16.67% higher than that of DNN, DFN, and DND at the booting stage (

Table 11. Effects of different planting patterns on Tr of foxtail millet leaves (2023).

Planting Pattern	Tr (mmol·m−2·s−1)
	Jointing Stage	Booting Stage	Filling Stage
HFD	5.74 ± 0.20 a	4.97 ± 0.16 a	4.13 ± 0.38 a
HNN	2.31 ± 0.23 d	3.56 ± 0.18 d	2.23 ± 0.08 c
HFN	4.26 ± 0.28 c	4.05 ± 0.10 c	2.60 ± 0.07 bc
HND	5.07 ± 0.13 b	4.50 ± 0.10 b	2.89 ± 0.08 b
DFD	5.07 ± 0.28 a	5.46 ± 0.26 a	3.34 ± 0.23 a
DNN	2.22 ± 0.16 c	3.53 ± 0.23 c	2.14 ± 0.05 c
DFN	3.27 ± 0.12 b	4.39 ± 0.08 c	2.54 ± 0.10 bc
DND	3.76 ± 0.11 b	4.68 ± 0.13 b	2.65 ± 0.11 b

).

Compared with 2023, the planting patterns of hole seeding and drill seeding showed FD > ND > FN > NN in 2024. Under the hole seeding planting method, Tr of Jingu 21 was better in the jointing and filling stages, but not in the booting stage. Under the drill seeding planting method, Tr of Jingu 21 showed a gradually increasing trend with the advancement of the growth period, which performs the best during the grain filling period. The difference from the experiment in 2023 is due to the extreme drought in the Shanxi region during the booting stage in 2024 (

Table 12. Effects of different planting patterns on Tr of foxtail millet leaves (2024).

Planting Pattern	Tr (mmol·m−2·s−1)
	Jointing Stage	Booting Stage	Filling Stage
HFD	5.62 ± 0.11 a	4.79 ± 0.05 a	5.32 ± 0.03 a
HNN	4.19 ± 0.06 d	3.89 ± 0.02 d	4.36 ± 0.03 d
HFN	4.66 ± 0.05 c	4.04 ± 0.06 c	4.56 ± 0.08 c
HND	5.14 ± 0.04 b	4.30 ± 0.01 b	4.81 ± 0.07 b
DFD	4.11 ± 0.08 a	4.21 ± 0.08 a	6.78 ± 0.04 a
DNN	2.64 ± 0.07 d	3.13 ± 0.06 d	3.86 ± 0.05 d
DFN	3.28 ± 0.04 c	3.39 ± 0.06 c	5.09 ± 0.03 c
DND	3.65 ± 0.06 b	3.79 ± 0.04 b	5.60 ± 0.04 b

).

3.2.3. Effects of Different Planting Patterns on Stomatal Conductance (Gs)

The Gs of foxtail millet leaves increased at first and then decreased with the advance of the growth period, and it reached the maximum at the booting stage. Different treatments of hole seeding for Jingu 21 were HFD > HND > HFN > HNN, and different treatments of drill seeding for Jingu 21 were DFD > DND > DFN > DNN. During the booting stage of hole seeding, the Gs of HFD leaves was 59.30%, 28.32%, and 12.60% higher than that of HNN, HFN, and HND, respectively. During the booting stage of drill seeding, the Gs of DFD leaves was 60.36%, 51.39%, and 24.34% higher than that of DNN, DFN, and DND (

Table 13. Effects of different planting patterns on Gs of foxtail millet leaves (2023).

Planting Pattern	Gs (mmol·m−2·s−1)
	Jointing Stage	Booting Stage	Filling Stage
HFD	116.32 ± 1.25 a	184.64 ± 1.15 a	83.53 ± 1.63 a
HNN	63.41 ± 1.08 d	115.91 ± 1.50 d	49.06 ± 1.56 d
HFN	77.21 ± 1.12 c	143.89 ± 1.16 c	58.77 ± 1.42 c
HND	92.34 ± 1.28 b	163.98 ± 1.60 b	64.77 ± 1.65 b
DFD	114.58 ± 1.74 a	225.95 ± 1.36 a	70.42 ± 1.90 a
DNN	63.91 ± 1.17 d	140.90 ± 1.39 d	41.69 ± 0.92 d
DFN	82.86 ± 1.07 c	149.25 ± 1.65 c	48.11 ± 0.58 c
DND	99.85 ± 1.74 b	181.72 ± 1.18 b	55.48 ± 1.64 b

).

Compared with 2023, the planting patterns of hole seeding and drill seeding showed FD > ND > FN > NN in 2024. Under the planting method of hole seeding, the Gs of the leaves of Jingu 21 gradually decreases with the advancement of the growth period, showing the best performance in the jointing and filling stages, and the worst performance in the filling stage. Under the drill seeding planting method, the Gs of the leaves of Jingu 21 performs well during the jointing and filling stages, but performs the worst during the booting stage. The difference from the experiment in 2023 is due to the extreme drought during the booting stage in 2024, where hole seeding and drill seeding have a significant impact on the Gs of leaves under different weather conditions (

Table 14. Effects of different planting patterns on Gs of foxtail millet leaves (2024).

Planting Pattern	Gs (mmol·m−2·s−1)
	Jointing Stage	Booting Stage	Filling Stage
HFD	189.10 ± 3.24 a	143.51 ± 1.09 a	128.77 ± 1.86 a
HNN	136.93 ± 1.16 d	102.56 ± 0.81 d	82.68 ± 3.31 d
HFN	154.82 ± 2.86 c	113.59 ± 1.32 c	94.19 ± 0.82 c
HND	164.52 ± 1.43 b	136.36 ± 1.70 b	107.37 ± 1.23 b
DFD	157.43 ± 3.78 a	134.23 ± 1.16 a	195.11 ± 2.89 a
DNN	75.72 ± 1.33 d	84.24 ± 0.53 d	105.94 ± 1.25 d
DFN	105.98 ± 0.88 c	96.81 ± 1.75 c	120.15 ± 0.89 c
DND	124.65 ± 2.18 b	104.20 ± 1.96 b	138.32 ± 2.73 b

).

3.2.4. Effects of Different Planting Patterns on Intercellular Carbon Dioxide Concentration (Ci)

As the growth period progressed, the Ci in the leaves of foxtail millet showed a gradually increasing trend and reached its maximum value during grain filling. The different treatments of hole seeding for Jingu 21 showed HNN > HFN > HND > HFD, while the different treatments of drill seeding showed DNN > DFN > DND > DFD. The Ci in HNN were 4.98%, 0.87%, and 1.44% higher than those in HFD, HFN, and HND, respectively. At the booting stage, the Ci of DNN leaves were 2.19%, 0.51%, and 1.05% higher than that of DFD, DFN, and DND (

Table 15. Effects of different planting patterns on Ci of foxtail millet leaves (2023).

Planting Pattern	Ci (μmol·m−2·s−1)
	Jointing Stage	Booting Stage	Filling Stage
HFD	234.67 ± 0.42 d	219.17 ± 0.50 d	255.04 ± 1.22 c
HNN	249.79 ± 1.14 a	227.27 ± 0.61 a	267.73 ± 0.35 a
HFN	243.07 ± 0.74 b	223.87 ± 0.44 b	265.43 ± 0.32 b
HND	239.23 ± 0.82 c	222.29 ± 0.24 c	263.92 ± 0.43 b
DFD	236.08 ± 0.70 d	215.74 ± 1.43 c	260.62 ± 1.16 c
DNN	246.35 ± 0.88 a	228.18 ± 1.59 a	266.33 ± 0.53 a
DFN	242.31 ± 0.46 b	223.41 ± 0.61 b	264.98 ± 0.13 ab
DND	240.16 ± 0.60 c	221.91 ± 0.19 b	263.57 ± 0.39 b

).

Compared with 2023, the planting patterns of hole seeding and drill seeding showed NN > FN > ND > FD in 2024. The Ci in the leaves of Jingu 21 gradually increased with the growth period, and the best performance was observed during the grain filling period (

Table 16. Effects of different planting patterns on Ci of foxtail millet leaves (2024).

Planting Pattern	Ci (μmol·m−2·s−1)
	Jointing Stage	Booting Stage	Filling Stage
HFD	249.37 ± 0.11 d	254.99 ± 0.71 d	274.14 ± 0.61 d
HNN	255.83 ± 0.66 a	263.28 ± 0.57 a	280.63 ± 0.89 a
HFN	253.12 ± 0.30 b	260.02 ± 0.56 b	278.04 ± 0.24 b
HND	251.36 ± 0.20 c	257.69 ± 0.48 c	276.23 ± 0.35 c
DFD	252.83 ± 0.67 c	257.00 ± 0.20 d	270.15 ± 0.70 d
DNN	258.70 ± 0.89 a	266.47 ± 0.54 a	280.93 ± 0.51 a
DFN	256.44 ± 0.38 b	263.13 ± 0.80 b	276.82 ± 0.36 b
DND	254.45 ± 0.55 bc	259.95 ± 0.38 c	274.09 ± 0.32 c

).

3.3. Effects of Different Planting Patterns on Chlorophyll Fluorescence Parameters

The Fv/Fm, Y (II), NPQ, and qP of foxtail millet increased at first and then decreased. The overall trend of Fv/Fm of Jingu 21 under hole seeding and drill seeding was the same, HFD > HND > HFN > HNN for hole seeding, DFD > DND > DFN > DNN for drill seeding. Fv/Fm and Y (II) reached the maximum at booting stage, and the NPQ and qP reached the maximum at grain filling stage (Figure 5).

Compared with 2023, the Fv/Fm and Y (II) of foxtail millet in 2024 showed a gradual decrease trend, while the NPQ showed an initial increase followed by a decrease trend, and the qP showed a gradual increase trend. Under all planting patterns in 2024 and 2023, mulching with drip irrigation was the best, while bare land without drip irrigation was the worst, that is, FD > ND > FN > NN (Figure 6).

3.4. Effects of Different Planting Patterns on Yield Components

Under the condition of hole seeding, the highest yield of HFD was 3565.74 kg/ha and the lowest yield of HNN was 1359.32 kg/ha. The panicle length, panicle diameter, panicle weight, and grain weight per panicle of HFD were 15.14%, 38.14%, 43.67%, and 77.00% higher than that of HNN, respectively. Under the condition of drill seeding, the highest yield of DFD was 3444.71 kg/ha and the lowest yield of DNN was 953.18 kg/ha. The panicle length, panicle diameter, panicle weight, and grain weight per panicle of DFD were 21.28%, 34.75%, 101.08%, and 163.04% higher than that of DNN, respectively (

Table 17. Comparison of yield composition under different planting patterns (2023).

Planting Pattern	Panicle Length (cm)	Panicle Diameter (cm)	Panicle Weight (g)	Grain Weight Per Panicle (g)	Yield (kg/ha)
HFD	25.70 ± 0.43 a	3.26 ± 0.06 a	24.41 ± 0.65 a	19.47 ± 0.74 a	3565.74 ± 78.93 a
HNN	22.32 ± 0.22 d	2.36 ± 0.08 d	16.99 ± 0.33 d	11.00 ± 0.49 d	1359.32 ± 50.95 c
HFN	23.22 ± 0.11 c	2.66 ± 0.05 c	19.65 ± 0.60 c	14.39 ± 0.59 c	1508.42 ± 99.90 c
HND	24.28 ± 0.12 b	2.96 ± 0.04 b	22.17 ± 0.54 b	16.61 ± 0.41 b	2129.66 ± 94.74 b
DFD	25.76 ± 0.45 a	3.18 ± 0.09 a	26.14 ± 0.64 a	20.78 ± 0.56 a	3444.71 ± 92.62 a
DNN	21.24 ± 0.40 d	2.36 ± 0.04 c	13.00 ± 0.26 c	7.90 ± 0.47 c	953.18 ± 26.97 d
DFN	22.88 ± 0.26 c	2.60 ± 0.03 b	13.99 ± 0.56 c	9.52 ± 0.62 c	1122.26 ± 49.96 c
DND	24.22 ± 0.20 b	2.78 ± 0.07 b	22.94 ± 0.52 b	16.92 ± 0.59 b	2290.08 ± 55.60 b

).

The panicle length, panicle diameter, panicle weight, grain weight per panicle, and yield of foxtail millet are different under different planting patterns. The yield of HFD was the highest under hole seeding, which was 4627.55 kg/ha, and the panicle length, panicle diameter, panicle weight, and grain weight per panicle of HFD were the highest. The yield of DFD under drill seeding was the highest, which was 4430.22 kg/ha, and the panicle length, panicle diameter, panicle weight, and grain weight per panicle of DFD were the highest (

Table 18. Comparison of yield composition under different planting patterns (2024).

Planting Pattern	Panicle Length (cm)	Panicle Diameter (cm)	Panicle Weight (g)	Grain Weight Per Panicle (g)	Yield (kg/ha)
HFD	25.48 ± 0.30 a	3.32 ± 0.08 a	29.03 ± 0.56 a	23.28 ± 0.50 a	4627.55 ± 59.24 a
HNN	20.32 ± 0.23 d	2.44 ± 0.09 d	21.17 ± 0.37 d	16.47 ± 0.43 d	3401.62 ± 32.33 d
HFN	21.90 ± 0.26 c	2.72 ± 0.07 c	24.65 ± 0.47 c	19.52 ± 0.67 c	4030.31 ± 45.70 c
HND	23.08 ± 0.24 b	3.02 ± 0.06 b	26.37 ± 0.65 b	21.31 ± 0.40 b	4240.25 ± 32.99 b
DFD	25.46 ± 0.17 a	3.14 ± 0.05 a	26.48 ± 0.69 a	21.12 ± 0.38 a	4430.22 ± 47.37 a
DNN	20.94 ± 0.16 d	2.50 ± 0.05 d	19.97 ± 0.46 d	15.95 ± 0.30 d	3263.25 ± 42.00 d
DFN	22.22 ± 0.29 c	2.72 ± 0.02 c	21.60 ± 0.40 c	17.53 ± 0.32 c	3648.83 ± 66.77 c
DND	23.32 ± 0.42 b	2.92 ± 0.07 b	24.00 ± 0.58 b	19.54 ± 0.30 b	4195.26 ± 24.46 b

).

Compared with 2023, HFD has the highest production in 2024 at 4627.55 kg/ha, followed by DFD at 4430.55 kg/ha and DNN with the worst production at 3263.25 kg/ha. The overall production in 2024 was higher than that in 2023.

4. Discussion

4.1. Effects of Different Planting Patterns on Agronomic Characters of Foxtail Millet

Constructing a reasonable group structure has a positive effect on increasing crop yield. The plastic film mulching cultivation technology is also an effective cultivation measure, which can affect the individual development and crop population structure of plants by regulating the growth and development of their aboveground and underground parts, thereby affecting crop yield [27]. Cultivation measures can significantly affect and regulate the composition and content of corn kernels in crops [28]. Plant height and leaf area are important indicators reflecting high-quality populations [29]. This study found that the plant height of Jingu 21 with plastic mulching and drip irrigation treatment at various growth stages was significantly higher than that of bare land without drip irrigation treatment, and the plant height of plastic mulching and hole seeding showed the maximum value. The plant height showed the highest performance during the grain filling period in 2023, at 172.53 cm. This may be due to the fact that plastic mulching treatment provides a good water temperature environment for plants. The plastic film covering technology has the effect of increasing yield and efficiency [30], and the effect of improving cultivation patterns on canopy light radiation and yield of spring soybean population [31]. Ridge cultivation significantly improves the leaf area index and yield of maize throughout its entire growth period compared to traditional flat cultivation [32]. Plastic film mulching significantly increases crop dry matter accumulation compared to bare land planting [33]. Research showed that the non-porous film covering planting mode is suitable for foxtail millet in sandy soil [34]. Covering is an effective irrigation method to improve corn yield and water use efficiency [35]. Adequate soil moisture can induce plant roots to penetrate deep into the soil, allowing deep soil moisture to be absorbed and utilized, thus laying the foundation for high yields [36]. Leaves, as the site of photosynthesis in plants, play an important role in intercepting light energy and maintaining a high leaf area, which is an important characteristic of high-yield crop populations.

4.2. Effects of Different Planting Patterns on Photosynthetic Physiological Characteristics of Foxtail Millet

Appropriate planting mode is an important measure to improve crop photosynthetic characteristics. Most of the dry matter in the shoot of crops comes from photosynthesis, so one of the keys to improving the yield is to improve the light energy utilization rate of crops [37], it showed that photosynthesis in maize has a significant impact on yield [38]. Research has shown that light has a certain impact on the yield and quality of winter wheat [39]. The experimental results of this study indicate that with the progress of the growth period, the Pn, Tr, and Gs of Jingu 21 reach their maximum during the booting stage. At the same time, the photosynthetic parameters of mulching with drip irrigation treatment are significantly higher than those of bare land without drip irrigation treatment. Chlorophyll fluorescence parameters play a unique role in determining the absorption, conversion, dissipation, and distribution of light energy in crop photosystems [40]. This study also indicates that different planting patterns have varying effects on the photosynthetic efficiency of foxtail millet flag leaves. Under the hole sowing planting method, the photosynthetic parameters of HFD showed the best performance during the booting stage in 2023 and the jointing stage in 2024. Pn were 28.49 and 35.40, Tr were 5.74 and 5.62, Gs were 184.64 and 189.10, and Ci were 219.17 and 249.37. Under the drill seeding pattern, the photosynthetic parameters of DFD showed the best performance during the booting stage in 2023 and the grain filling stage in 2024. Pn were 32.07 and 37.42, Tr were 5.46 and 6.78, Gs were 225.95 and 195.11, Ci were 215.74 and 252.83. Research has shown that there is only a rare correlation between chlorophyll fluorescence and ear parameters [41]. Chlorophyll fluorescence is closely related to plant photosynthesis and is an effective probe for studying plant photosynthesis [42]. A higher Y (II) value can accumulate more energy required for photosynthetic carbon assimilation in dark reactions, promoting efficient operation of carbon assimilation and organic matter accumulation [43]. Through mulching treatment, the photochemical quenching coefficient of foxtail millet leaves increased while the nonphotochemical quenching coefficient decreased, indicating that mulching treatment can convert the absorbed light energy of leaves into chemical energy, improve the photosynthetic assimilation ability and light energy utilization efficiency of Jingu 21, and reduce the heat dissipation of light energy.

4.3. Effects of Different Planting Patterns on Foxtail Millet Yield and Yield Components

Reasonable planting patterns can optimize the population structure of crops, enhance their adaptability to the environment, and thereby increase crop yields. This experimental study showed that compared to naked land treatment, mulching treatment helped to increase the accumulated temperature in the tillage layer and significantly improved the yield of Jingu 21. Under the planting pattern of hole seeding, the yield of plastic mulching without drip irrigation treatment in 2024 was 18.48% higher than that of naked land without drip irrigation treatment. Under the drill planting pattern, the yield of plastic mulching without drip irrigation in 2024 was 11.82% higher than that of naked land without drip irrigation. Drip irrigation treatment is more beneficial for the growth of foxtail millet than no drip irrigation treatment, and it could significantly increase the yield of Jingu 21. Under the hole seeding planting pattern, the yield of naked land with drip irrigation treatment in 2024 was 24.65% higher than that naked land without drip irrigation treatment. Under the drill planting pattern, the yield of naked land with drip irrigation in 2024 was 28.56% higher than that naked land without drip irrigation. This indicates that different planting methods have a significant regulatory effect on the formation of millet yield, and reasonable planting methods can promote the increase in millet yield.

5. Conclusions

The experimental comparison of different planting patterns on the growth and yield composition of foxtail millet showed that both hole seeding and drill seeding had the best growth under mulching with drip irrigation, and the worst growth under bare land without drip irrigation. This indicated that mulching and drip irrigation could significantly improve the agronomic traits, photosynthetic parameters, chlorophyll fluorescence parameters, and yield of Jingu 21. The best growth is achieved under drip irrigation for hole seeding with mulching.