Maize Plant Density Research Articles

Effect of Maize Plant Density, Compost and Sulfur on Productivity of Intercropped Maize and Tomato and some Soil Properties

Two field experiments were carried out at the Experimental Farm, EL- Gemmeiza Agricultural Research Station, El-Gharbia Governorate, ARC, during the two seasons 2019 and 2020 to study the effect of maize plant density (10, 12 and 14 thousand plant fed-1), compost and sulfur on some soil physical and hydro physical properties and productivityof intercropped yellow maize with tomato and net economic return. A split- plot design in randomized complete block design with three replicates was used. The main-plots were assigned to the three plant densities (D1, 100% tomato + 50% maize ; D2, 100% tomato + 60% maize ; D3, 100% tomato + 70% maize) under different intercropping patterns. The sub-plots were allocated for soil conditioners (compost, sulfur and compost + sulfur as well as recommended doses of NPK).The results revealed that the maximum values of the all traits of maize and tomato were obtained when high plant density (D3) with compost + sulfur in both seasons. The lowest soil bulk density and settling percentage values and the highest total porosity ,void ratio and pore size distribution values were recorded with the high plant density (D3) and compost + sulfur in both seasons. Soil hydraulic conductivity and soil moisture characters were increased in all treatments at the two soil depths in both seasons compared with the sole planting of maize or tomato. The high plant density (D3) with compost + sulfur gave the highest values of water use efficiency, LER, ATER, LEC, MAI and Net economic return in both seasons.

Density-dependent maize (Zea mays L.) yield increase in trade-off in reproductive allocation and water use under ridge-furrow plastic-mulching

• Maize yield responses to increasing planting densities were studied in RFM system. • Individual yield declined while population one increased first and then decreased. • This difference resulted from improved soil water availability as affected by RFM. • Optimal density had better trade-off between reproductive and vegetative growth. • Allometric R–V relationship explained density-dependent yield formation under RFM. The law of constant final yield and allometric theory have been seldom used to explore density-dependent yield formation and water use in rainfed farming systems, particularly in ridge-furrow mulching (RFM) system of maize. A two-year RFM field experiment was conducted using maize variety Yuyuan7879 in semiarid Kenya from 2015 to 2016, with four planting densities: 5.2 × 10 4 (D52, conventional density), 6.0 × 10 4 (D60), 6.9 × 10 4 (D69) and 8.5 × 10 4 (D85) plants per hectare. The grain yield and aboveground biomass per plant were significantly decreased with increasing density across two growing seasons. However, the population grain yield significantly was increased from D52 to D60 (from 3395.1–4471.7 kg ha −1 ) but declined significantly from D60 to D69 and D85 (p < 0.05) in 2015 and 2016, respectively. Meanwhile, the population aboveground biomass was significantly promoted from D52 to D60 (p < 0.05) and then remained relatively stable in D69 and D85, achieving a state of constant final yield. Under the improved soil storage, the RFM system raised the rational planting density from conventional D52 to D60 with regard to population yield. Water use efficiency for population yield (WUE G ) was the highest at D52 and D60, followed by D69, and the lowest at D85. However, the WUE for the aboveground biomass (WUE A ) was significantly lower in D52 than D60 and D85. Principal component analysis suggested that the population grain yield and WUE G were significantly positively associated with the reproductive allocation and leaf growth. This result was further affirmed by the allometric relationship between leaf biomass and body size, since the allometric exponent (<1) was raised with density. Allometric relationship between reproductive and vegetative mass demonstrated that the D60 treatment achieved a relatively balanced allocation of photosynthetic products into reproductive organs in comparison with other treatments. The RFM application significantly improved the availability of soil water, and the rational planting density of maize for better yield and WUE G . Thus, this phenomenon mechanically resulted from relatively better trade-offs between reproductive and vegetative growth, together with moderately increased leaf growth.

Reducing maize yield gap by matching plant density and solar radiation

Yield gap exists because the current attained actual grain yield cannot yet achieve the estimated yield potential. Chinese high yield maize belt has a wide span from east to west which results in different solar radiations between different regions and thus different grain yields. We used multi-site experimental data, surveyed farmer yield data, the highest recorded yield data in the literatures, and simulations with Hybrid-Maize Model to assess the yield gap and tried to reduce the yield gap by matching the solar radiation and plant density. The maize belt was divided into five regions from east to west according to distribution of accumulated solar radiation. The results showed that there were more than 5.8 Mg ha–1 yield gaps between surveyed farmer yield and the yield potential in different regions of China from east to west, which just achieved less than 65% of the yield potential. By analyzing the multi-site density experimental data, we found that the accumulated solar radiation was significantly correlated to optimum plant density which is the density with the highest yield in the multi-site density experiment (y=0.09895×–32.49, P<0.01), according to which the optimum plant densities in different regions from east to west were calculated. It showed that the optimum plant density could be increased by 60.0, 55.2, 47.3, 84.8, and 59.6% compared to the actual density, the grain yield could be increased by 20.2, 18.3, 10.9, 18.1, and 15.3% through increasing plant density, which could reduce the yield gaps of 33.7, 23.0, 13.4, 17.3, and 10.4% in R (region)-1, R-2, R-3, R-4, and R-5, respectively. This study indicates that matching maize plant density and solar radiation is an effective approach to reduce yield gaps in different regions of China.

Effects of nitrogen and maize plant density on forage yield and nitrogen uptake in an alfalfa–silage maize relay intercropping system in the North China Plain

Sustainable production of high-yielding and high-quality forages such as alfalfa (Medicago sativa L.) is critically important for fast-growing animal husbandry regions such as the North China Plain (NCP). Alfalfa production in this region is limited during the hot-rainy summer period from July–September, but these conditions may allow the production of intercropped silage maize (Zea mays L.) following spring harvests of alfalfa to boost the overall forage production. In this study, an alfalfa–silage maize (AM) relay intercropping system was evaluated in a field experiment from 2017 to 2019 to assess the impact of maize nitrogen (N) fertilization rates of 0, 60, 120, and 180 kg N ha–1 and maize plant densities of 30,000, 45,000, and 60,000 plants ha–1 on the forage yield and N uptake. The AM system was compared with alfalfa monocropping (AA) and silage maize monocropping (MM) controls. The 3-yr average land equivalent ratio (LER) and land equivalent ratio for nitrogen yield (LERN) of AM ranged from 1.05 to 1.37 relative to AA and MM, indicating that intercropping was advantageous for improving the overall forage production and N utilization. Intercropping reduced the maize yield by 23–30 % and the maize N yield by 26–35 % compared with the monocultured maize across 3 years. Increasing N fertilization and maize plant density often enhanced the maize yield and N uptake in the AM system. The alfalfa stand density in AM was negatively affected by the increased maize plant density and was 30–55 % lower than that in AA. Spring forage production of alfalfa in the AM and AA systems was similar in most cases, but yields in the AM system were reduced in 2018 and 2019 when maize was grown with the highest N rate (180 kg N ha–1) and the highest plant density (60,000 plants ha–1). On the basis of the system yield, N yield, and LER, the AM system with a maize plant density of 45,000 plants ha–1 fertilized at 120 kg N ha–1 was the most advantageous and could be recommended as an alternative cropping system in the NCP to increase forage yields with a relatively low input of N.

Light interception and use efficiency differ with maize plant density in maize-peanut intercropping

<List><ListItem><ItemContent> • Intercropping intercepted more light than sole peanut but less than sole maize. </ItemContent></ListItem><ListItem><ItemContent> • Maize light use efficiency (LUE) increased with plant density in the intercropping. </ItemContent></ListItem><ListItem><ItemContent> • Intercropping did not affect LUE of maize but increased peanut LUE. </ItemContent></ListItem></List> Intercropping increases crop yields by optimizing light interception and/or use efficiency. Although intercropping combinations and metrics have been reported, the effects of plant density on light use are not well documented. Here, we examined the light interception and use efficiency in maize-peanut intercropping with different maize plant densities in two row configurations in semiarid dryland agriculture over a two-year period. The field experiment comprised four cropping systems, i.e. monocropped maize, monocropped peanut, maize-peanut intercropping with two rows of maize and four rows of peanut, intercropping with four rows of maize and four rows of peanut, and three maize plant densities (3.0, 4.5 and 6.0 plants m⁻¹ row) in both monocropped and intercropping maize. The mean total light interception in intercropping across years and densities was 779 MJ·m⁻², 5.5% higher than in monocropped peanut (737 MJ·m⁻²) and 7.6% lower than in monocropped maize (843 MJ·m⁻²). Increasing maize density increased light interception in monocropped maize but did not affect the total light interception in the intercrops. Across years the LUE of maize was 2.9 g·MJ⁻¹ and was not affected by cropping system but increased with maize plant density. The LUE of peanut was enhanced in intercropping, especially in a wetter year. The yield advantage of maize-peanut intercropping resulted mainly from the LUE of peanut. These results will help to optimize agronomic management and system design and provide evidence for system level light use efficiency in intercropping.

The effect of row proportion of maize and soybean intercropping on growth and yield of component crops in sandy soil North Lombok, Indonesia

This study aimed to determine nutrient status, mycorrhiza population, and yields of maize-soybean strip intercropping in sandy soil environments of North Lombok, Indonesia. The experiment designed with Randomized Block Design with three blocks and five treatments, i.e., P1 (2 rows of maize: 2 rows of soybean), P2 (3 rows of maize: 2 rows of soybean), P3 (3 rows of maize : 3 rows of soybean), P4 (4 rows of maize: 2 rows of soybean), P5 (4 rows of maize : 3 rows of soybean). The results show that an increase of one more row from 3 to 4 rows significantly decreases the weight of maize cobs (3.5-folds), pods (2.3-folds), and 1000 seeds (1-folds). One row of maize plant density, which was beginning three rows to 4 rows, causes a decrease in the weight of dry root biomass and shoot of maize and soybean plants. The root weight and dried shoots of maize fell to 3.5 and 4.5 times, and the weight of dried roots of soybeans fell to 1.41 times at the age of 92 days after observing the 4:3 ratio of maize and soybean plants.

Estimates of Maize Plant Density from UAV RGB Images Using Faster-RCNN Detection Model: Impact of the Spatial Resolution.

Early-stage plant density is an essential trait that determines the fate of a genotype under given environmental conditions and management practices. The use of RGB images taken from UAVs may replace the traditional visual counting in fields with improved throughput, accuracy, and access to plant localization. However, high-resolution images are required to detect the small plants present at the early stages. This study explores the impact of image ground sampling distance (GSD) on the performances of maize plant detection at three-to-five leaves stage using Faster-RCNN object detection algorithm. Data collected at high resolution (GSD ≈ 0.3 cm) over six contrasted sites were used for model training. Two additional sites with images acquired both at high and low (GSD ≈ 0.6 cm) resolutions were used to evaluate the model performances. Results show that Faster-RCNN achieved very good plant detection and counting (rRMSE = 0.08) performances when native high-resolution images are used both for training and validation. Similarly, good performances were observed (rRMSE = 0.11) when the model is trained over synthetic low-resolution images obtained by downsampling the native training high-resolution images and applied to the synthetic low-resolution validation images. Conversely, poor performances are obtained when the model is trained on a given spatial resolution and applied to another spatial resolution. Training on a mix of high- and low-resolution images allows to get very good performances on the native high-resolution (rRMSE = 0.06) and synthetic low-resolution (rRMSE = 0.10) images. However, very low performances are still observed over the native low-resolution images (rRMSE = 0.48), mainly due to the poor quality of the native low-resolution images. Finally, an advanced super resolution method based on GAN (generative adversarial network) that introduces additional textural information derived from the native high-resolution images was applied to the native low-resolution validation images. Results show some significant improvement (rRMSE = 0.22) compared to bicubic upsampling approach, while still far below the performances achieved over the native high-resolution images.

Effect of silage maize plant density and plant parts on biogas production and composition

Higher maize plant density represents a possible tool for biomass yield improvement but the effect on biogas production and quality has not been intensively investigated so far. The aim of the study was to compare two different plant densities (90 000 and 130 000 plants ha−1) and their effects on yield and biogas production. Experiments were carried out at two sites in Central Bohemia in 2014 and 2015. Specific biogas yield of maize ears and stover was evaluated in batch tests. In both years, there were significantly higher dry matter yield, volatile solids (VS) degradation, and methane content in biogas from ears in comparison with stover. Stover produced on average 90% of biogas per weight unit (625–719 L kg−1 VS) compared to ears (721–801 L kg−1 VS) depending on locality and year. During the batch tests, ears produced more biogas than stover with the exception of the period from the 4th to 11th day when specific biogas yield of stover was higher. Biogas hectare yield of ears (5039–8962 m3 ha−1) was 1.3–1.8 times higher than biogas hectare yield of stover (3943–4865 m3 ha−1). The influence of plant density on dry matter yield and biogas hectare yield was not significant, but higher plant density supported faster dynamics of specific biogas yield of ears in both years and higher volatile solids degradation of ears in 2014.

A novel plant growth regulator improves the grain yield of high-density maize crops by reducing stalk lodging and promoting a compact plant type

• DHEAP is a novel plant growth regulator. • DHEAP improved maize lodging resistance. • DHEAP shaped a compact maize plant type. • DHEAP is helpful to increases summer maize planting density in NCP. Increasing the planting density (PD) of maize ( Zea mays L.) crops is the most efficient method for enhancing maize grain yield, but supra-optimum PD leads to an increase in lodged maize, which alters the maize canopy structure. In this study, N, N-Diethyl-2-hexanoyl oxygen radicals-ethyl amine (2-ethyl chloride) phosphonic acid salt (DHEAP, a single compound), a novel plant growth regulator, was sprayed at the seven-expanded-leaf stage under two different PDs (75,000, and 90,000 plants ha -1 ) using two maize hybrids, ZD958 (lodging-resistance) and XY335 (lodging-susceptible), to reduce maize lodging rates and improve the maize canopy structure under high PD. After DHEAP treatment, the maize lodging rate of ZD958 and XY335 decreased by 70.87% and 75.22%, respectively, through a change in the morphological structure (i.e., reduced plant and ear heights and increased mean tilt angle) and an improvement in the basal internode quality (i.e., increased diameter, dry weight per unit length, crushing strength, cellulose content, lignin content, and vascular area, and reduced length). In addition, DHEAP treatment significantly reduced gibberellin (GA 3 ) contents in maize basal internodes. Moreover, the increase in the mean tilt angle (MTA) above the maize ear leaf after DHEAP treatment improved the light penetration in the middle leaf strata, which increased the chlorophyll content (SPAD), net photosynthetic rate (P n ), and Rubisco enzyme activities. Finally, DHEAP treatment increased the grain yield of ZD958 and XY335 under 90,000 PD by 22.28% and 43.14%, respectively. Thus, it was concluded that the spraying of DHEAP effectively reduced maize lodging rates and improved the photosynthetic performance of the maize ear leaf, which increased maize grain yield under high PDs.

Correlation between grain yield in maize plant densities

When assessing genotypes in different environments, the result depends on the genotype-environment interac­tion. Among the environmental factors, the spatial arrangement of plants is among the most important manage­ment practices to achieve higher grain yield. This arrangement involves changes in the spacing between rows and between plants. The present study evaluates the correlation between the grain yield of maize genotypes and different plant populations. We conducted the experiments in the 2012/2013 harvest season and in the 2012/13 off-seasons at UNESP - Jaboticabal Campus, in Jaboticabal county, São Paulo State, Brazil, and in the 2013 off-season at Cambuhy Farm, in Matão county, São Paulo State, Brazil. The experimental design was in randomized blocks, with three replicates. For the 0.50 m spacing between rows, the spacing between plants was 0.25 m (80,000 pl ha -1 ), 0.30 m (66,667 pl ha -1 ), and 0.40 m (50,000 pl ha -1 ). For the 0.90 m spacing between rows, the spacing between plants was 0.20 m (55,556 pl ha -1 ). We assessed the treatments for grain yield (six genotypes), analyzing the correlations between grain yield averages and plant population densities for each environment using the Pearson correlation coefficient. The 2012/2013 harvest season in Jaboticabal county provided the highest average yield, regardless of population density. The 2012 off-season in Jaboticabal county provided the lowest average yield. As for population densities, the one that provided the highest yield was 80,000 plants ha -1 . The present study found several types of correlation, which allows us to say that population density recommendations must be specific.

Maize plant density affects yield, growth and source-sink relationship of crops in maize/peanut intercropping

Abstract Maize (Zea mays L.)/peanut (Arachishypogaea L.) intercropping has been widely practiced in semi-arid regions to reduce wind erosion and improve resource (e.g. water and light) use efficiencies. Knowledge on optimal maize plant density is lacking from perspective of dry matter accumulation among organs in this intercropping system. We quantified the effect of maize plant density on relative yield total (RYT), maize and peanut yields, and maize dry matter of organs (ears, leaves, and stems) in maize/peanut intercropping. Field experiments were conducted in a semi-arid area of China in 2015 and 2016. Three maize plant densities (6, 9 and 12 plants m−2) were tested in maize/peanut intercropping (per unit growing area designed for maize) and sole systems, whereas the plant density of intercropped peanut and sole peanut was fixed as 24 plants m-2. The beta and logistic growth functions were used to quantitatively characterize the dynamics of dry matter allocation among organs in maize. Increasing maize plant density significantly increased maize yield gain, but not increased peanut yield loss, in maize/peanut intercropping. The greatest yield advantage (RYTs of 1.21 in 2015 and 1.13 in 2016) occured in maize/peanut intercropping with maize planted at 9 plants m−2. Increasing plant density increased leaf growth rate, but reduced leaf longevity and dry matter allocation to ears for maize grown in both intercropping and sole systems. But, greater increases in leaf growth rate and leaf longevity for intercropped maize compared with sole maize resulted in a greater increase in dry matter accumulation for maize grown at 9 and 12 plants m−2. Greater increases in ear dry matter accumulation and yield were found for maize grown at 9 plants m−2 due to greater dry matter allocation to ears. We conclude that the different responses to plant density of the source capacity (leaves) and sink strength (ears) for maize in intercropping and sole systems could help optimize maize plant density (9 plants m-2) for greater maize yield gain and yield advantage in maize/peanut intercropping.

Maize hybrids response to high plant density in the Guinea savannah of Nigeria

ABSTRACT Several maize (Zea mays L.) hybrids have been developed and commercialized in the Nigeria savannas, but limited informationis available on how they perform at plant densities higher than the recommended density of 53,333 plants ha-1. Therefore, field trials were conducted in northern Nigeria in 2015 and 2016 at two locations with contrasting rainfall amount to evaluate the performance of selected maize hybrids at plant densities of 53,333 and 88,888 plants ha-1. All maize hybrids had higher grain yields, total dry matter, ears m-2, and number of grains m-2 at 88,888 than at 53,333 plants ha-1 at both locations. The magnitude ofincreases in yield when plant density was increased to 88,888 plants ha-1 was, however, higher for the new hybrids than for the old commercial hybrids. In Tudun Wada, five hybrids produced significantly higher mean grain yields than the remaining hybrid sat both plant densities. One of the hybrids (M1227-12) produced the highest grain yield at both planting densities at this location. In Samaru Zaria, the hybrid M1227-12 produced the highest grain yield only at 53,333 plants ha-1 at this location, whereas M0926-8 produced the highest yield at 88,888 plants ha-1. The 500-grain weight was 7-8% lower at 88,888 plants ha-1 than at 53,333 plantsha-1, which was offset by a significant increase in grain number. Our results showed that farmers in the Nigeria savannas can increase planting density of hybrid maize to 88,888 plants ha-1 and significantly increase their yields.

Influence of ridges for planting sweet potato on symbiotic ecological factors, photosynthetic abilities and population yield in relay intercropping system

Sweet potato (Ipomoea batatas L.) relay intercropping with maize exposes sweet potato to weak levels of sunlight due to the shadow maize creates during the symbiotic period. The insufficient light accordingly causes slow growth and development of vines and leaves of sweet potato in its early stage. The planting density and row direction of maize, the width of the intercropping strip, and the lodging type of sweet potato may form various photo conditions that influence sweet potato. The objective of this experiment was to research the effects of different ridging types on sweet potato and to elucidate the mechanisms of ecological conditions, photosynthetic physiology and intercropping benefits. The results indicated that, contrast to the one wide-ridge with planting two rows of sweet potato and two narrow ridges with planting two rows, mound planting was more superior in many aspects. Through mound planting sweet potato showed a larger range of temperature in air and soil, higher net photosynthetic rate, more active enzymes related with photosynthesis, and more benefits of relay intercropping.

Evaluation of maize-soybean intercropping systems and fertilizer rates on maize grain yield using competitive indices

Field trials were conducted in savanna ecologies of Nigeria during the 2015 and 2016 seasons using maize (PVA8) and soybean (TGX 1448-2E) intercropping systems with different fertilizer rates to evaluate the yield of maize and assess the best intercropping system for resource management. Single plant stands and two plants/stand and 2 arrangements of rows (one row on a ridge and two rows on a ridge) were used to impose maize plant densities evaluated in strip inter-crop with soybean. The trial was factorial, laid out in a randomized complete block design and replicated three times. Thus, 8 maize-soybean strip cropping systems and application of 3 NPK rates were evaluated at Saki-Oyo, Ilorin, and Nasarawa (southern Guinea savanna), Kaduna in the northern Guinea savanna, Funtua (Katsina) and Gusau (Zamfara) located within Sudan savanna ecologies of Nigeria. Data on yields and yield components were collected. The intercropping systems were assessed using existing intercropping indices such as Land Equivalent Ratio (LER), Relative Crowding Coefficient (K), Aggressivity (A), Competitive Ratio (CR), Actual Yield Loss (AYL), Intercropping Advantage (IA) and Monetary Advantage Index (MAI). The result showed that Nasarawa and Kaduna were most ideal locations for maize production in the Nigeria savannas. The highest grain yield of 4.04 tons/ha maize and 1.36 tons/ha soybean were obtained from seeding 1 plant/stand in 2-rows per ridge x 4 ridges of maize alternated with 2 rows of soybean with the application of NPK at 100:50:50. The LER was 1.11, AYL (1.10) and MAI (208) gave a profit of ₦312,102.00 (US$990.80) ha-1 with a benefit-cost ratio of 2.38 and production efficiency of 29.56%. The study concluded that, seeding 80% maize and 20% soybean per ha will lead to sustainable maize crop production with limited use of fertilizer. It can be adopted by the farmers in Nigeria savannas as a relatively profitable intercropping system.&#x0D; Keywords: Maize production, Ideal location, Fertilizer rate, Competitive indices, Savanna ecologies, Nigeria

How to increase maize production without extra nitrogen input

Increasing crop yields while reducing environmental impacts are a great challenge to ensuring food security and environmental quality for the world agriculture. Increasing planting density appropriately is one of the most effective strategies for increasing maize (Zea mays L.) yield. In China, overuse of nitrogen (N) fertilization on maize has resulted in excessive N surplus in the soil and environmental impacts. To address this challenge we conducted 212 site-year field experiments at two planting densities of 60000 and 75000 plants per ha with the same inputs of N. Results showed that maize yield could be increased 5.59% across China and 10.5%, 2.7%, 5.2% and 10.3% respectively in Southwest (SW), Huanghuaihai (HM), North (NM) and Northwest (NW) maize regions without extra inputs of N. The Life-cycle assessment showed that reactive N loss intensity and GHG intensity decreased by 2.2% to 10.2% across different regions of China, indicating that yield increase could be achieved without extra N inputs and further negative environmental impacts if planting density was increased by 15000 plants per ha under the current condition of excessive N surplus in China. If farmers in China increase maize planting density by 15000 per ha across the whole country the total maize production from the same planting area of 2017 would be 290 Mt which will be close to the expected demand of 315 Mt by 2030 while reducing the environmental impacts of intensive agriculture.

The optimal plant density of maize for dairy cow forage production

AbstractWhole maize (Zea mays L.) plant (WMP) silage is an important feed for dairy cows. In northern China, yields and feed quality are adjusted by modifying the planting density. This paper is the result of a 2‐yr field study aimed at determining the effects of plant density on maize silage yield and quality. Five planting densities (52,500, 60,000, 67,500, 75,000, and 82,500 plants ha−1) were used. The results showed that plant height and leaf area increased, while stem diameter, chlorophyll, and leaf area per plant decreased with increasing plant density. Both the biomass yield, expressed as the dry matter (DM) per ha, and the utilizable energy yield improved when the density was increased from 67,500 to 75,000 plants ha−1, but increasing the density further reduced these values. The highest observed DM were 17,734 kg ha−1 and 17,055 kg ha−1, and total net energy for lactation (NEL) were 104.1 GJ ha−1 and 97.0 GJ ha−1 in 2017 and 2018, respectively. Feeding quality generally decreased with increasing plant density. The plant density which obtained the highest biomass yield was not the same as the plant density for optimizing feeding production. Compared with the highest predicted DM yields, the highest predicted total NEL yields increased the grading index by 4–9%, which indicated an improvement in forage quality. Total NEL yield is more efficient for the purpose of evaluating the productivity of WMP forage than biomass yield.

Identifying Ways to Narrow Maize Yield Gaps Based on Plant Density Experiments

Exploring the maximum grain yields (GYs) and GY gaps in maize (Zea mays L.) can be beneficial for farmer to identify the GY-limiting factors and take adaptive management practices for a higher GY. The objective of this work was to identify the optimum maize plant density range and the ways to narrow maize GY gaps based on the variation of the GYs, dry matter (DM) accumulation and remobilization with changes in plant density. Field experiments were performed at the 71 Group and Qitai Farm in Xinjiang, China. Two modern cultivars, ZhengDan958 and ZhongDan909, were planted at 12 densities, ranging from 1.5 to 18 plants m−2. With increased plant density, single plant DM decreased exponentially, whereas population-level DM at the pre- (DMBS) and post- (DMAS) silking stages increased, and the amount of DM remobilization (ARDM) increased exponentially. Further analysis showed that plants were divided four density ranges: range I (&lt;6.97 plants m−2), in which no DM remobilization occurred, DMBS and DMAS correlated significantly with GY; range II (6.97–9.54 plants m−2), in which the correlations of DMBS, DMAS, and ARDM with GY were significant; range III (9.54–10.67 plants m−2), in which GY and DMAS were not affected by density, DMBS increased significantly, and only the correlation of DMAS with GY was significant; and range IV (&gt;10.67 plants m−2), in which the correlations of DMBS and ARDM with GY decreased significantly, while that of DMAS increased significantly. Therefore, ranges I and II were considered to be DM-dependent ranges, and a higher GY could be obtained by increasing the population-level DMAS, DMAS, and ARDM. Range III was considered the GY-stable range, increasing population-level DMBS, as well as preventing the loss of harvest index were the best way to enhance maize production. Range IV was interpreted as the GY-loss range, and a higher GY could be obtained by preventing the loss of HI and population-level DMAS.

EFFECT OF PLANT DENSITY AND N-FYM COMBINATION FERTILIZER LEVELS ON TWO YELLOW MAIZE CULTIVARS PRODUCITIVY

Two field experiments were conducted during two consecutive summer seasons of 2014 and 2015 in an administrative field at Diarb Negm District, Sharkia Governorate, under Agronomy Department supervision, Faculty of Agriculture, Zagazig University, Egypt. The aim of this study was to investigate the response of two yellow maize hybrids (Single Cross 176 and Three-way Cross 352) to three plant densities (20000, 24000 and 30000 plants/fad.), and nitrogen-farmyard combination fertilizer levels (60, 80 and100 kg N/fad., without addition of farmyard manure (FYM) and 60 kg N/fad.+20 m3 FYM/fad., 80 kg N/fad.+ 20 m3 FYM/fad., and 100 kg N/fad.+20 m3 FYM/ fad.) under clay soils conditions. The obtained results could be summarized as follows: The tried three maize plant densities had different effects on plant height (cm), ear diameter and length (cm), number of rows/ear, number of kernels/row, 100-kernel weight, kernel weight/ear, and biological yield (ton/fad.) during both seasons and their combined analysis, but the differences among the tried three maize plant densities on aforementioned traits did not reach the level of significance. Results of the first season and the combined analysis detected significant differences among the tried plant densities on ear yield/fad. Where, ear yield/fad., and grain yield/fad., in the first season and combined analysis, harvest index and grain: stover ratio in the two seasons and their combined analysis were significantly increased due to increasing maize density from 20000 or 24000 and up to 30000 plants/fad. Maize SC 173 cultivar appeared to produced taller plants, longer ears and larger number of kernels/row than TWC 352 cultivar. The later produced larger ear diameter, number of rows/ear, 100-kernel weight, kernel weight/ear, ear yield/fad., grain and biological yields/fad., than SC 173 one. No significant differences between two maize cultivars regarding harvest index and grain: stover ratio was observed. The first and the second increments in nitrogen levels up to 100 kg N/fad., with or without addition of farmyard manure was accompanied by a significant increase in ear diameter (cm), ear length (cm), number of rows/ear, number of kernels/row, 100-kernel weight (g), kernel weight/ear (g), ear yield/fad., grain and biological yields (ton/fad.) but harvest index and grain: stover ratio were reduced during both seasons and their combined analysis. These results finally recommend sowing maize cultivar TWC 352 with dense planting of 30000 plants/fad., and raising nitrogen level up to 80 kg N/fad., with addition of farmyard manure to maximize grain yield/fad., under the experimental site and other likely environmental condition.

The Effect of Tillage Methods on the Productivity of Tilled Crops and Soil Fertility

The article presents the results of a long-term research in establishing the share of the effect of various methods and systems of primary soil cultivation on the productivity of maize and sunflower, as well as soil fertility on the territory of the Raduga farm in the Giaginsk district of the Republic of Adygea. The studies were performed according to the following tillage systems: soil plowing to the depth of 25 – 27 cm (continuously (reference)); chisel soil plowing to the depth of 38 – 40 cm (continuously); surface soil tillage to the depth of 10 – 12 cm (continuously); and combined tillage system. The study has established the fact of troubled forming of the optimal maize and sunflower plant density due to the decreased germination with the loose structure of the seed layer. Improper choice of the primary tillage method, deficiency of the required density of seedlings in some years reached 20 % or more. However, after combined tillage, it reduced 1.5 – 2.0 times. During the study, by the methods of primary tillage, the lowest weed infestation of maize and sunflower was noted on the background of plowing to the depth of 25 – 27 cm, and was before harvesting lower by 30 – 80 % than in other tillage variants. The same regularity was observed in counting the number of pests on tilled crops. In the case of continuous surface tillage, an increase in the number of harmful larvae was noted in the variant of plowing to the depth of 25 – 27 cm — within 31 – 96 %. The highest average sunflower yield was achieved in the variant with combined (based on selection) system of soil tillage, where the growth was determined by increased fertilizer rates and ranged from 20 % (in the case of plowing) to 31 % (in the case of combined tillage). The decrease in the yield of grain maize after replacing plowing of compact chernozem with heavy disc harrowing did not exceed 8 %, and in the case of long-delayed sowin, it was at the level of 19 – 28 %.

Post-silking nitrogen accumulation and remobilization are associated with green leaf persistence and plant density in maize

Stay green (SG) maize was found to have higher grain yield and post-silking nitrogen (N) uptake (PostN) compared with a non-stay green (NSG) hybrid. To understand the effects of plant density on grain yield (GY) and N efficiency in modern maize hybrids, we compared two modern hybrids (SG hybrid DY508 and NSG hybrid NH101) with similar maturity ratings at three plant densities (45000, 60000, and 75000 pl ha−1) in 2014 and 2015. GY, leaf senescence, dry matter (DM) accumulation, N accumulation, PostN, and post-silking N remobilization (RemN) were analyzed. DY508 and NH101 had similar GY, but DY508 had higher thousand kernel weight (TKW) and lower kernel number (KN) than NH101. Plant density significantly increased GY in the two hybrids. On average, over the two years, plant density improved GY in DY508 and NH101 by 18.5 and 11.1%, respectively, but there were no differences in total dry matter (TDM) and post-silking DM (PostDM) between the two hybrids. Plant density improved leaf N, stem N, and grain N at the silking and maturity stages in 2014 and 2015. DY508 was lower in harvest index (HI), nitrogen harvest index (NHI), and grain N concentration (GNC) than NH101. Grain N in DY508 was 2.61 kg ha−1 less than in NH101, and this was caused by lower GNC and leaf RemN. On the average, DY508 was 1.62 kg ha−1 less in leaf remobilized N (leaf RemN) than NH101, but was similar in stem remobilized N (stem RemN; 2.47 kg ha−1 vs. 3.41 kg ha−1). Maize hybrid DY508 shows delayed leaf senescence in the upper and bottom canopy layers in the later stages of growth. The present study provides evidence that the NH101, which has rapid leaf senescence at the late grain-filling stage, has gained equivalent GY and higher leaf RemN, and was more efficient in N utilization.