Increasing the maize planting density is considered a potential approach for increasing the grain yield in China, but there is no consensus regarding its yield-increasing effect and the influence of ...specific factors. Thus, we established a database (2721 pairs of data from 187 publications) to quantify the effects of increasing the maize planting density on the phenotypic traits and yield, to determine an appropriate maize planting density for each planting area, and to quantify the effects of environmental factors and agricultural imputs on the outcomes of increasing the planting density. We found that increasing the planting density increased the individual competition among maize plants, with negative effects on their growth, but the grain yield increased by 11.18–13.43 % due to the increased population biomass. Using the database, we found large differences in the optimal density and peak grain yield among maize planting areas, and the factors that caused these differences were analyzed based on subgroup analysis. Field management practices significantly influenced the outcomes of increasing the planting density. In particular, higher agricultural inputs (irrigation amount, and nitrogen and phosphorus application rates) enhanced the positive effect of increasing plant density on the optimal plant density and peak grain yield. In addition, the effects of increasing the planting density were significantly influenced by environmental (climate and soil) factors. When the mean annual temperature was 7–14°C and the mean annual precipitation was 400–800 mm, the yield and maximum peak yield were highest in relatively fertile (high total nitrogen, available nitrogen, and soil organic matter contents) and neutral (pH 6–8) soils. Our results highlight the need to increase the current maize planting density and provide a scientific basis for determining reasonable planting densities for different maize growing areas in China.
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•It is necessary to increase the maize planting density (PD) in China.•Increasing planting density significantly increased maize grain yield.•There were differences in the optimal planting density among maize growing-areas.•The effects of increasing the PD were influenced by environmental factors.
Summary
Improving yield is a primary mission for cotton (Gossypium hirsutum) breeders; development of cultivars with suitable architecture for high planting density (HPDA) can increase yield per unit ...area.
We characterized a natural cotton mutant, AiSheng98 (AS98), which exhibits shorter height, shorter branch length, and more acute branch angle than wild‐type.
A copy number variant at the HPDA locus on Chromosome D12 (HPDA‐D12), encoding a dehydration‐responsive element‐binding (DREB) transcription factor, GhDREB1B, strongly affects plant architecture in the AS98 mutant. We found an association between a tandem duplication of a c. 13.5 kb segment in HPDA‐D12 and elevated GhDREB1B expression resulting in the AS98 mutant phenotype. GhDREB1B overexpression confers a significant decrease in plant height and branch length, and reduced branch angle.
Our results suggest that fine‐tuning GhDREB1B expression may be a viable engineering strategy for modification of plant architecture favorable to high planting density in cotton.
•The grain yield of common buckwheat was significantly correlated with photosynthetic capacity, and agronomic traits.•N fertilizer and planting density had significant effects on the photosynthetic ...capacity, agronomic traits, and yield of common buckwheat.•The combination of N fertilizer of 45 kg ha−1 and 90 plants m−2 is recommended for enhancing the yield of common buckwheat.
Nitrogen fertilizer and planting density are two crucial factors that affect the yield of common buckwheat (Fagopyrum esculentum M.). Youqiao2, a common buckwheat cultivar with high photosynthetic capacity and planted widely in local production was used to investigate the effects of nitrogen fertilizer and planting density on the leaf photosynthetic characteristics, agronomic traits, and grain yield in common buckwheat by a split plot design. The main plots were assigned to three nitrogen fertilizer rates: 0, 45, and 90 kg ha−1, and the subplots were assigned to three planting densities: 60, 90, and 120 plants m−2. Results showed that the grain yield was significantly and positively correlated with net photosynthesis rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), stomatal limitation value (Ls), chlorophyll content (SPAD value), leaf area index (LAI), plant height, stem diameter, branch number, internode number, grain number per plant, and 1000-grain weight, while significantly and negatively correlated with intercellular CO2 concentration (Ci) and water-use efficiency (WUE). The Pn, Gs, Tr, Ls, SPAD, LAI, grain yield, stem diameter, branch number, internode number, grain number per plant, and 1000-grain weight increased and then decreased with the increase of nitrogen fertilizer and planting density, and their maximum values appeared in the nitrogen fertilization of 45 kg ha−1 and planting density of 90 plants m−2 treatment. The Ci and WUE decreased and then increased with the increase of nitrogen fertilizer and planting density, and their minimum values appeared in the nitrogen fertilization of 45 kg ha−1 and planting density of 90 plants m−2 treatment. The plant height increased with the increase of nitrogen fertilizer, while decreased with the increase of planting density. These results suggested that nitrogen fertilizer and planting density had significant effects on the leaf photosynthetic capacity, agronomic traits, and grain yield of common buckwheat, and the combination of nitrogen fertilization of 45 kg ha−1 and planting density of 90 plants m−2 is recommended for common buckwheat planting.
•Moderate to high density increased lint yield under late sowing date.•Moderate density resulted higher reproductive organ nitrogen rates.•Moderate population enhanced cotton leaf net photosynthetic ...capacity.•Moderate density with later or lower density with earlier sowing is an optimal strategy for improving lint yield.
This study assesses the effects of plant population density (PPD) and sowing date (SD) on growth, physiology and lint yield of a cotton crop. Seedling transplanting is one of the most dominant cotton production systems in China. But on the other hand, the net benefit is decreasing because the system is labor intensive. Therefore, a shorter cotton growing season is urgently needed to reduce the production costs through management practices such as adjusting sowing date and PPD. The following hypothesis was tested; would cotton yield and physiology from a late sowing be compensated by plant density? Field experiments were conducted with two sowing dates (S1, May 20; S2, June 04) as the main plot and three PPDs (D1, low; 7.5×104; D2, moderate; 9.0×104 and D3, high; 10.5×104ha−1) as the sub-plot. Early-sown plants produced 23%, 32%, 55%, 77% and 14%, taller stems more nodes, leaves and fruits, respectively, than the late-sown plants. Consequently, S1 produced 26% higher lint yield than S2. This increase in lint yield was mainly attributed to a relatively longer cropping season, which allowed utilization of available resources. Growth and fruit production in S1 plants were further increased by an increased photosynthetic rate (Pn) and N acquisition. Across the plant densities, 13% and 6% more lint yield was achieved under D2 than the D3 and D1, respectively. Moderate PPD increased lint yield by 13% and 6% over high and low, respectively. Nitrogen (N) acquisition was 45%, 33%, higher for S1 sown crop compared with S2, respectively. S1D2 had higher average (3.5VTkgha−1d−1) and maximum (4.5VMkgha−1d−1) rates of N accumulation in reproductive organs at the fastest accumulation point among other treatments. Our data suggest that for both sowing dates moderate PPD is a promising option, which allows light interception and penetration to the lower canopy, efficient N utilization and assimilate distribution to reproductive structures.
•More nitrogen and higher density elevated the radiation use efficiency (RUE).•More nitrogen resulting in elevated whole plant lodging risk.•Increased nitrogen decreased expression of PAL, reducing ...lignin content in the stem.•Higher plant density reduced the lodging angle and lodging index of upper stem.•Higher density induced PAL, CCR1, 4CL expression, increasing stem lignin content.
Using the rapeseed Huayouza 62 as experimental material, yield and lodging related traits were evaluated under various nitrogen applications 120,240 and 360kgha−1 (N1–N3, respectively) and planting densities 15×104, 30×104 and 45×104 plants ha−1 (D1–D3, respectively). Results showed: (1) the increase of nitrogen fertilizer elevated the leaf (and silique) area index (LAI) and light interception rate (LIR), significantly affecting the bud stage. In addition, the radiation use efficiency (RUE) for different growth stages and biomass accumulation were increased, which improved yield by facilitating formation of siliques in both single plants and populations. The increase of planting density significantly elevated the population LAI and LIR in seedlings, and the RUE in various growth stages, increased population biomass accumulation, which may have also improved yield by promoting the formation of siliques in the population. The correlation between LIR/LAI and yield was the highest at the bud stage, while the strongest correlation between RUE and yield was at silique development. (2) More nitrogen increased the lodging angle, base lodging index (LIL) and the upper lodging index (LIU), resulting in elevated whole plant lodging risk. With increases in nitrogen fertilizer, expression of phenylalanine ammonia-lyase (PAL) of lignin biosynthesis decreased in the upper stem, leading to lower lignin content and lodging resistance. However, higher plant density reduced the lodging angle and LIU, but increased LIL. The increase in planting density induced the expression of PAL, cinnamoyl-CoA reductase 1 (CCR1), 4-coumarate: CoA ligase (4CL) in the stem, which showed their highest expression in the N2D3 treatment, leading to higher lignin content and lodging resistance. (3) In this study, N2D3 achieved relative high yield and the lowest lodging index, which will meet the requirements for mechanized harvest.
•Fill the gap in the effect of stand density on microbial compositions.•The effect of stand density on fungi was higher than on bacteria.•Low-density plantations showed higher microbial diversity and ...richness.•Ascomycota and Basidiomycota were key species in response to stand density.
Despite recent improvements in understanding the composition of microbial communities in forest soils, fundamental questions regarding how their dynamics and function vary with forest management strategies, such as stand density, and the factors that affect them are still unclear. In this study, the spectrophotometry and high-throughput sequencing technology were used to determine enzyme activities and microbial community composition in the topsoil (0–20 cm) of 35-year-old Chinese fir plantations with five stand densities. The results showed that stand density had significant effects on soil fungal community composition and diversity and the activity of catalase and sucrase. However, stand density had no significant effects on the bacterial communities, although the diversity of the bacterial communities varied with stand density. Overall, the increase in stand density reduced the activities of catalase, urease and surase and the Chao1 and Shannon diversity of bacterial and fungal communities. We found that positive correlations between enzyme activities and microbial diversity indices were significant. We also found that bacterial community compositions were significantly influenced by pH, alkali available N, available P and available K, and that fungal community composition was significantly influenced by pH, soil moisture, total N, alkali available N, available P and available K. Our results provide important insights into the effect of stand density on soil enzyme activities and microbial community composition, which is certainly significant for developing stand density regulation strategies to mitigate the effects of degradation of soil biological activities.
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