Increasing photosynthetic performance and post-silking N uptake by moderate decreasing leaf source of maize under high planting density

Yang

Food and Energy Security

et al. 2022

Improved canopy structure was instrumental in setting maize yield records, and yet it has rarely been examined in China. At Qitai Farm in Xinjiang, we conducted a 4‐year field experiment using China's six highest‐yielding maize hybrids sorted into three yield level groups that were grown at similar growth durations and at optimum densities. The average yield of high‐yield level (HL, 22.3 Mg ha−1) was 7.2% and 24.6% higher than that of medium‐yield level (ML) and low‐yield level (LL), respectively. For each yield level, we measured morphological traits that influence canopy structure and yield. They included plant height, ear height, ear ratio, internode length, leaf numbers, leaf angle, LOV, leaf area, and spatial density of leaf area. Among the preceding morphological traits of the three yield levels, HL’s best optimized the canopy structure, as shown by improved light distribution (19.0% light transmission at the ear) and increased light interception per unit leaf area per day (LIPA, 51.7 MJ m−2 day−1) in the canopy. In comparison, light transmission was 12.2% and 15.9% at the ear and the total LIPAs were 37.2 and 29.0 MJ m−2 day−1 at silking for ML and LL, respectively. HL had significantly longer leaf area duration and a higher photosynthetic rate, especially at the grain filling stage, and its total accumulated biomass at maturity was significantly better (by 13.9%) than LL’s. HL’s harvest index (0.54) was significantly higher than that of ML (0.52) and LL (0.48). HL’s radiation and heat use efficiencies were 2.61% and 1.37 g °C−1 day−1 m−2, both significantly greater than those of ML and LL. Therefore, optimum maize plant types can significantly improve canopy structure and increase resource use efficiency and grain yield.

Section: Introductionmentioning

confidence: 99%

Optimized canopy structure improves maize grain yield and resource use efficiency

Yang

Food and Energy Security

et al. 2022

“…showed that shading would reduce dry matter accumulation after silking and eventually lead to yield loss. However, moderately decreasing leaf source at high planting density could enhance canopy photosynthesis 62 and increase dry matter accumulation and grain yield after silking 63,64 . In SEM, the negative effect of LAI at silking stage on HKW also reflects the productivity decrease.…”

Section: Discussionmentioning

confidence: 98%

“…However, moderately decreasing leaf source at high planting density could enhance canopy photosynthesis 62 and increase dry matter accumulation and grain yield after silking. 63,64 In SEM, the negative effect of LAI at silking stage on HKW also reflects the productivity decrease. In addition, our study also found that the linear rapid growth period of maize ended earlier at high planting densities and the leaf area decreased more at maturity compared with low densities, which may be caused by shade-induced senescence at high densities.…”

Section: Source-sink Relationships and Limiting Factors Of Yieldmentioning

confidence: 99%

Combination of suitable planting density and nitrogen rate for high yield maize and their source–sink relationship in Northwest China

Tong

Kang

et al. 2023

J Sci Food Agric

BACKGROUND Increasing crop yield per unit area by increasing planting density is essential to ensure food security. However, the optimal combination of planting density and nitrogen (N) application for high‐yielding maize and its source–sink characteristics need to be more clearly understood. RESULTS A 2‐year field experiment was conducted combining three planting densities (D1: 70 000 plants ha−1; D2: 100 000 plants ha−1; D3: 130 000 plants ha−1) and three nitrogen rates (N1: 150 kg hm−2; N2: 350 kg hm−2; N3: 450 kg hm−2). The results showed that increasing planting density significantly increased leaf area index and grain yield but negatively affected ear traits. The Richards model was used to fit the dynamic changes of dry matter accumulation of maize under different treatments, and the fitting results were good. Increasing planting density increased population yield while limiting the development of individual plants, bringing the period of rapid dry matter accumulation to an early end and accelerating leaf senescence. An appropriate nitrogen rate could prolong the period of rapid accumulation of dry matter in maize, and increase the 100‐kernel weight. Increasing planting density enhanced post‐silking dry matter accumulation to a lesser extent, and the source–sink relationship of the maize population gradually developed from sink limitation to source limitation with increasing planting density. CONCLUSION The decrease in yield due to the insufficient source strength to meet the sink demand at too high densities was the reason that limited further improvement of the optimal planting density. An appropriate nitrogen rate facilitated the realization of yield potential at high density. © 2023 Society of Chemical Industry.

“…The crop density affects the habitat and the assimilation surface of individual plants. A high sowing density shades the crop canopy, reduces the light transmittance within a population and accelerates leaf senescence, all of which affect photosynthesis of maize and both the accumulation and the distribution of substances and limit the grain development [36][37][38]. Considering the above stated, it should not be forgotten that the D × E interaction was significant.…”

Section: Descriptive Statistics and Mean Differences Of Studied Factors And Defoliation Treatmentsmentioning

confidence: 99%

Direct and Joint Effects of Genotype, Defoliation and Crop Density on the Yield of Three Inbred Maize Lines

Ranković¹,

Todorović

Tabaković

et al. 2021

Agriculture

The aim of this study was to observe direct and joint effects of three factors (genotypes, ecological environmental conditions and the applied crop density) on the level of defoliation intensity and yield. Three inbred lines (G) of maize (G1–L217RfC, G2–L335/99 and G3–L76B004) were used in the study. The trials were performed in two years (Y) (Y1 = 2016 and Y2 = 2017) and in two locations (L) (L1 and L2) under four ecological conditions of the year–location interaction (E1–E4) and in two densities (D1 and D2) (50,000 and 65,000 plants ha−1). Prior to tasselling, the following five treatments of detasseling and defoliation (T) were applied: T1—control, no leaf removal only detasseling, T2–T5—removal of tassels and top leaves (from one to four top leaves). The defoliation treatments had the most pronounced effect on the yield reduction in G1 (T1–Tn+1… T5), p < 0.05. The ecological conditions on yield variability were expressed under poor weather conditions (E3 and E4), while lower densities were less favorable for the application of defoliation treatments. The result of joint effects of factors was the lowest grain yield (896 kg/ha) in G3 in the variant E3D1 for T2 and the highest grain yield (11,389 kg/ha) in G3 in the variant E2D2 for T1. The smallest effect of the defoliation treatment was on the kernel row number (KRN).