Light Interception Rate Research Articles

Quantification of spatial-temporal light interception of crops in different configurations of soybean-maize strip intercropping.

Intercropping can improve light interception and crop yield on limited farmlands. The light interception rate in intercropping is determined by row configuration. Quantifying the spatio-temporal light interception of intercrops is very important for improving crop yields by optimizing the row configuration. A two-year field experiment was conducted at two sites to quantify the responses of the light interception rate of intercrops to five treatments: two rows of maize alternated with three rows of soybean (2M3S), two rows of maize alternated four rows of soybean (2M4S), two rows of maize alternated five rows of soybean (2M5S), sole soybean (SS), and sole maize (SM). We developed a multiple regression model based on the sine of the solar elevation angle (sin(h)) and crop leaf area density (LAD) to quantify the spatio-temporal light interception of intercrops. The predicted light interception rate was positively correlated with the measured values of photosynthetically active radiation (R2 > 0.814) and dry matter (R2 > 0.830). Increasing soybean rows led to an increase in light interception of both soybean and the lower layer of maize. However, this also resulted in a decrease in light interception in the upper layer of maize. At the two sites, compared to 2M3S, the annual average cumulative light interception of soybean in 2M5S increased by 44.73% and 47.18%, that of the lower layer of maize in 2M5S increased by 9.25% and 8.04%, and that of whole canopy of maize decreased by 13.77% and 17.74% respectively. The changes in dry matter and yield of intercrops were consistent with the change in light interception, which further verified the high accuracy of the light interception model. The annual average maize yield of 2M5S was 6.03% and 6.16% lower but the soybean yield was 23.69% and 28.52% higher than that of 2M3S. On the basis of system yield, the best performance was recorded in 2M4S at the two sites. In summary, the newly created light interception model performs well in the quantification of the temporal and spatial changes in crop light interception in strip intercropping and has potential applications in other configurations. Optimizing row configurations across climatic regions to enhance light interception and yield at the system level will become a future target.

Spectrum radiometric approach: a non-destructive method for measuring the canopy light interception rate in crops

Spectrum radiometric approach: a non-destructive method for measuring the canopy light interception rate in crops

Optimizing canopy spacing configuration enhances foxtail millet grain yield and water productivity by improving stalk lodging resistance in the North China Plain

Optimizing canopy spacing configuration can enhance resources utilization, supporting robust growth and dry matter production, while mitigating the risk of lodging and improving crop yield and quality. However, research specifically addressing optimal canopy spacing configurations for foxtail millet remains limited. Over a two-year period, a field experiment in the North China Plain assessed the impacts of four-row spacing configurations (T0: 40 + 40 cm; T1: 30 + 50 cm; T2: 20 + 60 cm; T3: 10 + 70 cm), to investigate the effects of row spacing configuration on lodging resistance, canopy spatial configuration, stem characteristics, yield, and water productivity (WP) of foxtail millet, aiming to elucidate the underlying regulatory mechanisms. Row spacing configurations significantly influenced lodging resistance, yield, and WP. Under T1, improvements were observed in stem morphology and mechanical properties, particularly in the 2nd-6th basal internodes (I2-I6). The light interception rate in T1 at wide rows in the middle canopy (30–90 cm aboveground) increased by 97.89 %, compared to T0. Partial least squares-structural equation modeling revealed that improved light interception in wide rows in the middle canopy contributed to a rise in diameter and dry plumpness of I2. This, in turn, promoted greater breaking resistance of I2 and tensile resistance, ultimately reducing the lodging likelihood. Simultaneously, the decrease in lodging resulted in higher yield and WP at yield level of foxtail millet. Therefore, T1 demonstrated the lowest lodging rate (67.34 %–91.92 % lower than T0), and the highest yield and WP at yield level (4.10 %–8.03 % and 20.79 %–22.46 % higher than T0). Optimizing canopy spacing configuration is essential for cultivating high-yielding and water-efficient foxtail millet populations. The results indicated that the 30 + 50 cm row spacing configuration improves light distribution in the middle canopy, enhancing lodging resistance and consequently increasing both yield and WP. This research offers a theoretical foundation for foxtail millet breeding and agronomic practices to achieve lower lodging rate, higher yields, and enhanced WP in the North China Plain.

Improving cotton productivity and nitrogen use efficiency through late nitrogen fertilization: Evidence from a three-year field experiment in the Xinjiang

ContextPremature senescence is a major concern for crop production especially for high-density cotton in Xinjiang, China, when nitrogen (N) rates are reduced. This study aimed to examine the potential of late N fertilization in mitigating senescence, improving light and N use efficiency, and enhancing cotton productivity under reduced N rate. MethodsA three-year field experiment was conducted from 2019 to 2021, employing a total of 240 kg N ha-1, which was one-third lower than the traditional rate of 360 kg ha-1. Five different N application ratios based on cotton stages were tested, with N064 (0:6:4 ratio at early: middle: late growth stages) representing late N fertilization, and N262 representing traditional ratio in fertilization. The effects of N application timing-based ratios on yield components, N use efficiency, canopy photosynthesis, and root traits were evaluated. ResultsThe results showed that N064 had the highest lint yield 2727–3305 kg ha-1 (2019–2021) among all treatments over the three years. Late N fertilization (N064) resulted in significant increases in boll density (4.6–10.7%), seed cotton yield (5.8–8.1%), and N use efficiency (10.5–14.1%) when compared to traditional N262. During late peak boll-setting to boll opening stages, N064 decreased leaf area index (3.5–6.6%), canopy light interception rate (3.8–11.4%), and boll capacity of root (18.1%) compared to N262, while increasing SPAD (2.3–4.8%), diffuse non-interceptance (3.9–16.6%), canopy apparent photosynthetic rate (13.2–49.4%), root biomass (19.5%), root/shoot ratio (15.0%). N064 also resulted in a higher root surface area density in deep soil than N262. ConclusionsLate N fertigation enhanced post-flowering canopy photosynthetic production by improving the cotton root-shoot relationship and delaying root and canopy senescence, resulting in improved yields and N use efficiency. This N management strategy implemented under reduced N cultivation shows promise for sustainable cotton production in Xinjiang and similar ecological regions.

Ridge-furrow planting with black film mulching increases rainfed summer maize production by improving resources utilization on the Loess Plateau of China

Soil mulching has been widely used to improve crop productivity around the world, but how various mulching practices affect soil hydrothermal conditions, water-temperature-radiation utilization and finally grain yield of rainfed maize has been poorly understood. A two-season field experiment was conducted on rainfed summer maize in 2021 and 2022 on the Loess Plateau of China, with six soil mulching practices: flat planting with non-mulching (FPNM), flat planting with full straw mulching (FPSM), flat planting with full black film mulching (FPBF), flat planting with full transparent film mulching (FPTF), ridge-furrow planting with black film mulching on the ridge (RFBF) and ridge-furrow planting with transparent film mulching on the ridge (RFTF). The results showed that compared with the traditional FPNM, the five mulching treatments (FPSM, FPBF, FPTF, RFBF and RFTF) greatly regulated root-zone soil hydrothermal conditions and resulted in obvious soil drying-wetting alternation, which significantly changed the daytime average root-zone soil temperature in the 0 – 25 cm soil layer (by − 1.1 ℃, − 1.9 ℃, + 2.7 ℃, − 1.6℃ and + 0.8 ℃, respectively) and significantly reduced crop evapotranspiration. The five mulching treatments promoted the root growth, leaf area index and canopy light interception rate due to the improved soil water and/or temperature conditions. The structural equation modeling indicated that soil hydrothermal condition and water-temperature-radiation use efficiency could directly or indirectly explain 98% of the grain yield variation under various soil mulching practices; radiation use efficiency (RUE) determined maize production in the water-sufficient year (2021), whereas maize production was mainly determined by crop water productivity (WP) in the water-limited year (2022). The RFBF increased maize production most, followed by RFTF. Compared with FPNM, RFBF increased leaf area index by 45.4%, canopy light interception rate by 19.1%, aboveground biomass by 68.8%, 1000-grain weight by 15.1%, grain yield by 58.6%, WP by 71.8%, thermal time use efficiency by 64.6% and RUE by 30.5%. In conclusion, RFBF optimized the root-zone soil hydrothermal conditions for root growth, which in turn promoted aboveground growth and water-temperature-radiation use efficiency, and finally improved the gain yield of rainfed summer maize on the Loess Plateau of China. Therefore, RFBF was considered as a promising agricultural practice to improve rain-fed summer maize production and resource utilization efficiency on the Loess Plateau of China.

Leaf shape, planting density, and nitrogen application affect soybean yield by changing direct and diffuse light distribution in the canopy

When attempting to maximize the crop yield from field-grown soybean (Glycine max (L.) Merr.) by means of improving the light conditions for photosynthesis in the canopy, it is crucial to find the optimal planting density and nitrogen application rate. The soybean plants that were the subject of our experiment were cultivated in N-dense mutual pairs, and included two cultivars with different leaf shapes; one cultivar sported ovate leaves (O-type) and the other lanceolate leaves (L-type). We analyzed the results quantitatively to determine the amount of spatial variation in light distribution and photosynthetic efficiency across the canopy, and to gauge the effect of the experimental parameters on the yield as well as the photosynthetic light and nitrogen use efficiency of the crop. Results indicate that the different leaf shapes were responsible for significant disparities between the photosynthetic utilization of direct and diffuse light. As the nitrogen fertilizer rate and the planting density increased, the soybean plants responded by adjusting leaf morphology in order to maximize the canopy apparent photosynthetic light use efficiency, which in turn affected the leaf nitrogen distribution in the canopy. Despite the fact that the light interception rate of the canopy of the L-type cultivar was lower than that of the canopy of the O-type cultivar, we found its canopy apparent photosynthetic nitrogen and light use efficiency were higher. It was interesting to note, however, that the nitrogen and light use efficiency contributions associated with exposure to diffuse light were greater for the latter than for the former.

Optimized N application improves N absorption, population dynamics, and ear fruiting traits of wheat.

Optimizing the N application amount and topdressing ratio can increase crop yield and decrease N loss, but its internal mechanisms have not been well studied, especially from the aspects of population dynamics and structure, ear fruiting traits. Here, field experiments, with three N rates 120 (N1), 180 (N2), and 240 (N3) kg N ha-1 and three N topdressing ratios T1 (7:3), T2 (6:4), and T3 (5:5) were conducted. At the same N level, results showed that the N accumulation amounts in the leaf, grain, and plant in T2 were higher than in T3 and T1, and increasing 60 kg N ha-1 (N3 compared to N2, N2 compared to N1) significantly enhanced N accumulation amounts. The effect of the N topdressing ratio on partial factor productivity of applied N was consistently T2 > T3 > T1, but T1 was more conducive to improving N utilization efficiency for grain and biomass production. After the jointing stage, compared to T1 and T3, T2 was more conducive to increasing the population growth rate of plant height, leaf area index, leaf area growth rate, dry matter weight, dry matter accumulation rate, light interception rate, and spikelets of population, and the above-mentioned indexes of population could be significantly enhanced by increasing 120 kg N ha-1. T2 increased the fruiting spikelets per ear, grains per ear, grain weight per ear, fruiting rate per ear, grain filling rate per ear, and yield but decreased the sterile spikelets at the top and bottom and imperfect grains per ear. Increasing N from 120 kg ha-1 to 180 kg ha-1 or from 180 kg ha-1 to 240 kg ha-1 significantly enhanced yield. The N accumulation amount in the grain, leaf, plant, leaf area growth rate, dry matter accumulation rate, light interception rate, population spikelets, fruiting spikelets per ear, grain filling rate, and yield were significantly positively correlated with each other. This study demonstrates a suitable N application rate with a N topdressing ratio 6:4 would more effectively improve N efficiency, population dynamics, structure, ear fruiting traits, and yield, but the effect of the N topdressing ratio is not as significant as that of increasing 60 kg N ha-1.

Reducing Irrigation and Increasing Plant Density Enhance Both Light Interception and Light Use Efficiency in Cotton under Film Drip Irrigation

High-density planting is an effective technique to optimize yields of mulched cotton. On the other hand, deficit irrigation is an emerging water-saving strategy in cotton cultivation, especially suitable for arid and water-scarce areas. However, the relationships between deficit irrigation, high-density planting, and regulation mechanisms of canopy light radiation and light use efficiency (LUE) in cotton is not yet clear. To clarify the mechanism of light interception (LI) and the LUE of cotton canopies, three irrigation treatments [315 (50% Fc), 405 (75% Fc, farmers’ irrigation practice), and 495 mm (100% Fc), where Fc was the field capacity] with three plant densities [13.5, 18.0 (farmers’ planting practice), and 22.5 plants m2] were applied. The findings of this research revealed that, under deficit irrigation, the above-ground dry matter (ADM) was reduced by 5.05% compared to the farmers’ irrigation practice. Over both years and across all plant densities, LI and LUE under deficit irrigation decreased by 8.36% and 4.79%, respectively, relative to the farmers’ irrigation practices. In contrast, LI and LUE for the highest irrigation level increased by 10.59% and 5.23%, respectively. In the case of the interaction (plant density and irrigation level), the ADM under deficit irrigation and high-density combination increased by 7.69% compared to the control (farmers’ irrigation × sowing practices interaction effects). The LI and LUE also exhibited an increase in 1.63% and 6.34%, respectively. Notably, the LI effect of the middle and upper cotton canopy under film drip irrigation reached 70%. A lower irrigation level resulted in a higher percentage of LI in the lower canopy region. The leaf area index, light interception rate, and extinction coefficient escalated with the increase in plant density. Under deficit irrigation treatment, the LI of the 0–30 cm canopy in high plant density settings increased by 8.6% compared to the control (farmers’ irrigation × sowing practices interaction effects). In conclusion, deficit irrigation and increased plant density improved the interception of LI and LUE of cotton canopy. These findings may help the farmers to optimize their agricultural management strategies in water-deficient areas.

Response Characteristics of Photosynthetic Productivity to the Canopy Spatial Distribution Pattern of Larix kaempferi

The spatial distribution of the forest canopy plays an important role in the transpiration and photosynthetic capacity of trees, ultimately affecting their growth and biomass production. Despite its importance, how canopy photosynthetic productivity enhancement depends on canopy spatial distribution remains unclear. To address this knowledge gap, we conducted a study on Larix kaempferi (Lamb.) Carrière (L. kaempferi) plantations in Gansu, China, investigating the relationship between canopy height, leaf area, seasonal variations in canopy spatial distribution, and photosynthetic parameters. The results showed that the net photosynthetic rate, stomatal conductance, and transpiration rate of L. kaempferi increase with greater canopy height, while photosynthetically active radiation shows the opposite trend. Canopy photosynthetic productivity peaked in April, May, and June when the height in the canopy was 40%, followed by 20%, and then 30% from the perspective of spatiotemporal canopy spatial distribution. Maximum leaf area (10.7 m2) and photosynthesis productivity (919.6 mg·C·h−1) were observed when the height in the canopy ranged from 48%–59%. The changes increased sunlight exposure (75%–88%, 88%–100%) in different canopy areas. Additionally, there was a decrease in the amount of space covered by shade (25%–38%, 50%–63%, and 63%–75%), depending on the specific region within the canopy. By scientifically managing stand density, the canopy spatial distribution can be optimized for photosynthesis, resulting in maximum light interception rates, enhanced photosynthetic capacity, and reduced “non-functional canopy”. These findings offer effective and scientifically informed management strategies for the forestry industry. By optimizing the structure of the canopy, specifically in L. kaempferi, these strategies aim to maximize photosynthetic productivity.

Optimizing nitrogen management enhances stalk lodging resistance and grain yield in dense planting maize by improving canopy light distribution

Enhancing the basal internode mechanical strength by improving the canopy light distribution of dense planting maize to reduce the lodging rate is important for establishing a high-yielding and stable population. A three-year field experiment was carried out at three densities treatments (5.25 × 104, 6.75 × 104 and 8.25 × 104 plants hm−2) × four nitrogen fertilizer treatments (0, 120, 180 and 240 kg hm−2) to study canopy light distribution and stalk lodging resistance characteristics. Results showed that grain yield was increased 3.31–14.68% under 6.75 × 104 plants hm−2 treatment compared to 5.25 × 104 plants hm−2. Meanwhile, plant morphology was altered with the increasing of planting density, light interception rate at lower-middle canopy position (0–150 cm) was decreased 15.10%, thus the mechanical strength of the basal internodes was reduced, and the lodging rate was increased 4.66% points. The formation of maize stalk lodging resistance and grain yield was promoted by the nitrogen fertilizer application. The N180 treatment improved mechanical strength by enhancing canopy light distribution and optimizing internode quality, lodging rate was decreased 6.31–17.22% compared to the N240 treatment while only a 0.54–7.54% reduction in grain yield, finally. Analysis the relationship between characteristic factors and mechanical strength, we found that internode plumpness (explained the 85.6% percentage of variability) was the key factor affecting basal internode mechanical strength. Our results will assist breeders in breeding lodging-resistant hybrids and agronomists improving field management practices for low lodging rate and high yield, and will be equally illuminating for other maize-producing regions.

Mixed cropping increases grain yield and lodging resistance by improving the canopy light environment of wheat populations

The primary technical way to increase wheat yield is to increase planting density. However, the dense planting population has poor stem development quality due to intensified resource competition, ultimately leading to an increased lodging risk. Mixed cropping can take advantage of the genetic diversity of cultivars to solve the contradiction between lodging traits and yield in dense planting wheat populations. Nevertheless, its resistance mechanism to lodging and yield increase still needs to be studied in depth. Here, we conducted a field experiment in the North China Plain using a lodging-resistant cultivar, Shannong 28 (SN28) and a lodging-sensitive cultivar, Shannong 16 (SN16), as test materials to study the effect of mixed cropping on the crop yield by setting 3 planting densities: 225 plants m-2 (D1), 375 plants m-2 (D2), and 525 plants m-2 (D3). We studied the effect of mixed cropping on the resistance of wheat population and yield. The results showed that the mixed sowing treatment (MIX) significantly improved the canopy light interception rate (8.99%) and net photosynthetic efficiency (11.02%) under dense planting conditions (D3). It improved stem quality by increasing the content of carbohydrates (lignin, cellulose and soluble sugar), on the other hand, contributing to yield by increasing grain weight. Meanwhile, the structural equation modeling validated the above results. Compared to SN16 sole cropping (SN16), SN28 sole cropping (SN28) and MEAN (average of the two varieties in sole cropping), MIX yield was significantly higher by 17.39%, 3.86% and 10.21%. These findings revealed that mixed cropping improved yields due to improved wheat denseness tolerance, reduced field lodging rate, and increased grain weight. Our study concluded that this could be a cultivation measure to effectively suppress the occurrence of wheat lodging from the perspective of adaptive changes in stem under dense planting populations, to provide a theoretical basis for wheat lodging resistance and yield increase.

Ray-tracing analysis on the far-red induced light-capturing ability of kale

Far-red (FR, 700–800 nm) light has recently been used to regulate phytochrome-mediated morphological responses in vertical farms. Long-term morphological changes in different FR intensities are well known, but changes in photosynthetic capacity have not been sufficiently investigated. The objectives of this study were to quantitatively analyze the growth, photosynthetic responses, and light interception of kale (Brassica oleracea L. var. acephala) depending on the FR fraction. The plants were cultivated at a photosynthetic photon flux density (PPFD) of 240 μmol m−2 s−1 under red and white LEDs with FR LED (peak at 730 nm) for 16 h. The FR fractions determined as FR/R+FR were FR0.07 (control), FR0.28, FR0.60, and FR0.72. To evaluate the morphological and physiological responses in each FR fraction, the growth, chlorophyll content, chlorophyll fluorescence, P700 absorbance change, and photosynthetic rate were measured. Light interception was quantitatively calculated using 3D-scanned plant models with physiological changes and ray-tracing simulations. The dry weight of shoot and root, total petiole length, and leaf area increased with increasing FR fractions. As a result of ray-tracing analysis, the light interception and canopy photosynthetic rate increased with high FR fraction treatment. As the FR fraction increased, the effective quantum yield of photosystem II [Y(II)], the parameters of the JIP test that is related to quantum yield and efficiency for electron transport in photosystem II and photosystem performance indices decreased. Despite the decreased electron transport efficiency, the canopy photosynthetic rate increased in relation to the FR fraction. In conclusion, the increase in the FR fraction increased the yield of kale because of the synergistic improvement in morphological change and canopy photosynthesis.

Optimal water and nitrogen management increases cotton yield through improving leaf number and canopy light environment

Recently-published information on cotton agronomic and light energy use responses to nitrogen (N) under varying water availability is limited in Xinjiang, northwest China. A two-year field experiment was conducted to evaluate the effects of two irrigation patterns (I 400 , conventional irrigation; I 267 , limited irrigation) and three N fertilizer rates (N 320 , 320; N 272 , 272; N 224 , 224 kg N ha −1 ) on leaf number (LN), mean inclination angle (MIA) of leaves, light interception rate (LIR), dry matter accumulation, and seed cotton yield. Under the I 400 condition, seed cotton yield for N 272 was comparable to that for N 320 , but 9.6% higher than that for N 224 . Compared with N 320 , N 272 plots exhibited a 4.7% reduction in biological yield and 4.9% increase in harvest index. N 272 I 400 slightly reduced the leaf number and increased the MIA of the top-canopy, and improved the LN and LIR in the middle canopy, canopy photosynthetic rate (CAP), and dry matter accumulation. In contrast, under I 267 conditions, N 320 significantly increased leaf area and achieved the better LIR, dry matter accumulation, and yield than N 272 and N 224 . The LIR induced by the variation in leaf number was strongly associated with CAP and dry matter accumulation. The LN of the middle canopy likely represented the strong link in photosynthetic response to N rate and water supply. Leaf number was strongly associated with leaf area and was negatively correlated with MIA. These results suggest that leaf number is a key regulatory factor for regulating canopy leaf inclination and light interception. We suggest that estimates of light energy utilization should be included along with leaf number estimates in future efforts to scale from leaf physiology to canopy construction in cotton. • The leaf number determines the canopy light environment and yield of cotton. • Optimal leaf number of middle canopy promoted light interception, photosynthesis capacity, and dry matter production. • N-induced changes in leaf number are important factors in regulating the leaf angle and light capture. • Nitrogen rate for high-yield cotton should be adjusted based on water availability.

Advancing fruiting season in Annona cv. Arka Sahan through pruning

Annona cultivar ‘Arka Sahan’, an inter-specific hybrid of Annona atemoya × A. squamosacomes to harvest during August-September under mild tropical climate, which coincides with monsoon rains resulting in poor fruit quality and high susceptibility to anthracnose and fruit fly. An attempt was made to advance the fruiting in this hybrid through pruning during 2016- 17 and 2017-18. The effect of three pruning levels (25, 50 and 75% of previous season’s growth) at five different times (60, 75, 90, 105 and 120 days after final harvest of previous crop) on flowering and fruiting were compared. Early sprouting, flowering and fruit harvest were recorded in trees pruned to 75% of the past season’s growth in both the years. Earliest fruits were harvested 271 (3rd week of June) and 268 (2nd week of June) days after pruning in trees pruned during first week of October in 2016-17 and 2017-18 respectively (P<0.05).Bigger fruits with lesser seeds per 100 g of pulp (P<0.05) were harvested from trees pruned to 75% and 25% levels in the first and second year, respectively, irrespective of pruning time. Tree canopy following pruning at 75%level recorded higher light interception and photosynthetic rate (P<0.05). Pruning time and levels significantly influenced the biochemical constituents of leaf and shoot. The fruiting in cultivar ‘Arka Sahan’ could be thus advanced by 8-9 weeks to June from the normal season of August-September with comparable or better fruit quality by pruning 75% of the last season’s growth during October.

OSTRICH-CROPGRO multi-objective optimization methodology for calibration of the growing dynamics of a second-generation transgenic soybean tolerant to high temperatures and dry growing conditions

CONTEXTCurrent estimates show that the impact of climate change on agriculture will result in yield losses in major crops of 8–43%, mainly due to a combination of drought and heat. Second-generation transgenic crops are expected to mitigate these constraints. Soybean HaHB4 is a second-generation transgenic crop tolerant to high temperatures and dry growing conditions created in Argentina carrying the sunflower HaHB4 gene. Soybean HaHB4 has been approved in Argentina, the United States, Brazil, Paraguay, Canada and China. OBJECTIVEThis study presents a robust methodology to calibrate the CROPGRO-soybean model for the growth and development of soybean HaHB4. The approach consists of a holistic treatment of calibration parameters, objective functions, model responses and measured data. Based on the differences between transgenic and controls obtained in field trials, the proposed methodology includes species parameters related to those physiological traits that present the most significant differences, i.e. heat and drought tolerance with no yield penalties, increased light interception and photosynthetic rate, increased crop biomass and crop yield and improved water use efficiency. METHODSWe define multiple objective functions as a way of handling multiple simulated responses in the calibration procedure. For this, we connect CROPGRO with the OSTRICH software toolkit. Adjustments for initial water content in the soil profile, soil root growth factor and root depth progression were made using soft data procedures. The basic procedure for automatic calibration was modified by considering a semi-automated calibration process. The calibration sequence considers phenological development, water balance, biomass and yield parameters. RESULTS AND CONCLUSIONSWe observed good accuracy in the calibrated simulation of soybean HaHB4 development at all phenological stages, with RMSE = 1.62 days. The soil water balance reached RMSE = 27.4 mm. An acceptable biomass simulation at maturity was reached, with RMSE = 34% of average observed values. The grain yield was well predicted, with RMSE = 636 kg/ha. To verify the robustness of the calibrated model we evaluated it for grain yield prediction in fourteen field experiments for different growing seasons, water conditions and locations across the Argentine Pampas. The model accurately simulated grain yield with RMSE = 408 kg/ha, d-index = 0.93 and R2=0.77. SIGNIFICANCEThis study provides a calibration procedure for climate-resilient cultivars that are still missing for long-term studies on climate change impacts. The importance of modelling a climate-resilient crop in the framework of the soil–plant-atmosphere system is a step towards ensuring food security.

Loose and tower-type canopy structure can improve cotton yield in the Yellow River basin of China by increasing light interception

ABSTRACT Determining the optimal plant architecture and canopy structure are important objectives in research on the breeding and cultivation of high-yielding crops. To address this challenge, a field experiment was conducted in Anyang, Henan, China, to assess cotton light interception, boll spatial distribution, leaf area index (LAI), plant height and biomass, lint yield and yield component during 2018–2019. Treatments including 10 cotton cultivars with belong to tower-shaped and tube-type canopy structure. Compared with compact cotton varieties, the loose and tower-shaped cotton varieties intercepted more light (average 28.6%) and had a higher LAI (average 34.2%), resulting in a higher cotton yield (average 14.8%). In addition, polynomial correlation showed that the maximum light interception rate occurred at the flowering and boll-forming stage, when the annual mean plant height (94.6 cm), LAI (3.58) and biomass (15,006 kg ha−1) all reached their peak. Moreover, yield was extremely significantly positively correlated with intercepted photosynthetically active radiation (IPAR) (R = 0.7) and positively correlated with light use efficiency (LUE) (R = 0.36). Overall, the results suggest that cotton cultivars with loose and tower-type canopy structures intercept more light and should be planted to increase cotton yield and LUE in the Yellow River basin of China and areas with similar conditions.

Optimal management of nitrogen fertilizer in the main rice crop and its carrying-over effect on ratoon rice under mechanized cultivation in Southeast China

This study attempted to clarify the carrying-over effect of different nitrogen treatments applied to the main crop on the crop population growth and yield formation of ratoon rice under mechanized cultivation in Southeast China. Based on the constant total nitrogen application amounts (225.00 kg ha−1) in the main crop, an experiment with different ratios of basal and topdressing nitrogen fertilizer (the ratio of basal fertilizer:primary tillering fertilizer:secondary tillering fertilizer:booting fertilizer at 3:1:2:4 (N1), 3:2:1:4 (N2), 3:3:0:4 (N3), and 4:3:0:3 (N4), respectively, and a control without nitrogen treatment (N0)) was set up across two consecutive years in field using hybrid rice variety Yongyou 1540 as the test materials. The results showed that the total tiller number and effective tillering percentage increased in the main crop under the N1 treatment, more nitrogen fertilizer applied in late growth stage of the main crop, and its effective tillering percentage of the main crop was the highest at up to 70.18%, which was 9.15% higher than that of conventional fertilization treatment (N4), more nitrogen fertilizer applied in early growth stage of the main crop. The same tendency was observed in leaf area index (LAI) value of the main crop and its subsequent ratoon rice, which were 16.52 and 29.87% higher, respectively, in the N1 treatment than that in the N4 treatment at the full heading stage. The same was true in the case of the transport rates of stem and sheath dry mater and the canopy light interception rates in both the main and its ratoon crops. The transport rate of stem and sheath in main crop rice under N1 treatment increased by 50.57% compared with N4 treatment. The canopy light interception rate of N1 treatment increased by 5.07% compared with N4 treatment at the full heading stage of the ratoon crop. Therefore, the total actual yield was the highest in the main and its ratoon crops under N1 treatment, averaging 17 351.23 kg ha−1 in two-year trials, which was 23.00% higher than that in the conventional fertilization treatment (N4). The results showed that appropriate nitrogen treatment was able to produce a good crop stand in the main crop, which was essential for producing a good ratoon crop population and high yield especially under mechanized cultivation with low stubble height of the main crop. The study suggested that shifting the proper nitrogen application amounts to the late growth stage of the main crop, such as N1 treatment, not only had a higher productive effect on ensuring the yield of the main crop, but also had a positive effect on the axillary bud sprouts from the stubbles for ratoon rice, resulting in an increased percentage of productive panicles and achieving the goal of one planting with two good harvests under the conditions of our study.

利用叶片荧光参数估算油蒿灌丛群落生态系统生产力

PDF HTML阅读 XML下载 导出引用 引用提醒 利用叶片荧光参数估算油蒿灌丛群落生态系统生产力 DOI: 10.5846/stxb202103210750 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（32071842，31901366，32071843） Estimating ecosystem productivity from leaf chlorophyll fluorescence parameter in Artemisia ordosica shrub community Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:生态系统生产力（GEP）在全球碳循环中具有重要意义，但其准确估算仍然是一个挑战。近年来，叶绿素荧光和冠层GEP的关联成为生态学的研究热点，关系尚不清楚且存在广泛争议。于2015年对宁夏盐池毛乌素沙地荒漠灌木油蒿（Artemisia ordosica）灌丛生态系统碳交换（NEE）特征进行连续观测，使用多通道荧光监测仪对通量贡献区内油蒿叶片的实时荧光（Fs）和光下荧光（Fm'）进行原位连续监测，叶面积指数（LAI）、归一化植被指数（NDVI）以及环境因子同步观测。利用光合有效辐射（PAR）、LAI和实际光化学效率（ΦPSII）等参数构建基于叶绿素荧光的生态系统生产力（GEPChlF）模型，探究叶片和冠层尺度不同参数对环境因子波动的响应，比较分析GEPChlF和基于涡度相关法监测生态系统生产力（GEPEC）相关性及GEPChlF的适用性。研究发现，ΦPSII和NEE日变化规律一致，ΦPSII、GEPChlF和GEPEC由PAR控制，受空气温度（Ta）和饱和水汽压差（VPD）调控，土壤含水量（SWC）和ΦPSII呈显著正相关（P<0.01）。PAR处于400-800 μmol m-2 s-1时，GEPChlF与GEPEC线性关系最优，斜率为0.627（R2=0.67，P<0.01）；弱光下GEPChlF的低估可能是由于冠层实际光能拦截率高造成；强光下GEPChlF显著高于GEPEC，呈非线性关系，可能是GEPEC基于夜间温度敏感性所拟合的生态系统呼吸（Re）无法预测光呼吸部分所导致。GEPChlF具有荧光参数的特性，对环境波动更加敏感，和环境因子相关性优于GEPEC。结果表明，高辐射、极端温度、高蒸腾和干旱是限制叶片和冠层尺度下油蒿光合过程的主要胁迫因素。本研究构建的荒漠生态系统光合过程模型GEPChlF能够替代GEPEC作为一个良好的冠层尺度生态参数，所提出的空间尺度上推方法可为促进区域可持续发展提供数据支撑和决策参考。 Abstract:Accurate estimation of gross ecosystem productivity (GEP) remains a challenge despite its importance in the global carbon cycle. Recently, the relationship between chlorophyll fluorescence and canopy GEP becomes an important scientific concern in plant ecology. However, it remains unclear how they are linked at multiple spatial scales across the growing season. In this study, continuous measurements of net ecosystem CO2 exchange (NEE) were made in a desert shrub (Artemisia ordosica) ecosystem using eddy covariance (EC) technique from May to October 2015 in Mu Us desert. The real-time fluorescence (Fs) and fluorescence under light (Fm') were also measured in situ using the Monitoring-PAM multi-channel fluorometer. Leaf area index (LAI), the normalized difference vegetation index (NDVI), and environmental factors including photosynthetically active radiation (PAR), air temperature (Ta), vapor pressure deficit (VPD), soil water content (SWC) and precipitation (PPT) were measured simultaneously within the range of carbon flux contribution. We developed a chlorophyll fluorescence-based model with input variables of photochemical efficiency (ΦPSII), PAR, and LAI to estimate ecosystem productivity (GEPChlF). We then compared the applicability of GEPChlF with EC-based GEP (GEPEC) and examined the responses of different parameters to environmental factors at leaf and canopy scales. As a result, the diurnal pattern of ΦPSII was similar to that of NEE, being mainly controlled by PAR and modified positively by Ta and VPD (P<0.01). The ΦPSII had a significantly positive correlation with SWC (P<0.01). The GEPChlF agreed well with GEPEC when PAR was 400-800 μmol m-2 s-1, with a slope of 0.627 (R2=0.67, P<0.01). The GEPChlF was likely to be underestimated under low PAR, leading to a high light interception rate of canopy, thus resulting in a low absorbed photosynthetically active radiation (APAR) in the model. The GEPChlF was significantly higher than GEPEC under high PAR and their relationship was nonlinear, which may be due to Artemisia ordosica released excessive sunlight energy for photo-respiration, nitrogen metabolism, Miller reaction and other processes. It was noted that photo-respiration was difficult to predict accurately because the daytime ecosystem respiration (Re) was simulated on the basis of nocturnal temperature sensitivity. Compared with GEPEC, chlorophyll fluorescence-derived GEPChlF was more sensitive to environmental fluctuations and had a better relation with environmental factors. Our results confirmed that the GEPChlF from chlorophyll fluorescence-based model could replace GEPEC as a good ecological parameter at canopy scale in consideration of the plant physiological status. We found that excessive radiation, extreme temperature, high transpiration and drought were the main stress factors limiting the photosynthetic process of Artemisia ordosica at different spatial scales. The study provides a method for estimating ecosystem productivity under the stressed environmental conditions on the basis of monitoring chlorophyll fluorescence in relation to environmental factors. The present results may scientifically support decision-making for promoting regional sustainable development. 参考文献 相似文献 引证文献

Effect of Spatial-Temporal Light Competition on Cotton Yield and Yield Distribution

The photosynthetically active radiation (PAR) of crop canopy is highly related to yield formation, but how it relates to yield and yield distribution is not well understood. The focus of this study was to explore the relationship between light competition under different densities and yield distributions of cotton. The experiment was conducted in 2019 and 2020 at the Cotton Research Institute of the Chinese Academy of Agricultural Sciences in Anyang city, Henan Province, China. A randomized block design was employed, with a total of three repeats. Each repeat had six density treatments: D1: 15,000; D2: 33,000; D3: 51,000; D4: 69,000; D5: 87,000; and D6: 105,000 plants·ha−1. As predicted, the results showed that the canopy light interception, leaf area index, plant height, and biomass of high-density cotton were higher than those of low-density cotton. The aboveground biomass produced by D6 was the highest, and was 12.9, 19.5, 25.4, 46.3, and 69.2% higher in 2019 and 14.3, 19.9, 32.5, 53.7, and 109.9% higher in 2020 than D5, D4, D3, D2, and D1, respectively. Leaf area, plant height, biomass, boll number, and boll weight were significantly correlated with the light interception rate. D5 (87,000 plants·ha−1) had a higher light interception rate and the highest yield. The highest lint yields produced by D5 were 1673.5 and 1375.4 kg·ha−1 in two years, and was 3.2, 4.3, 5.6, 9.7, and 24.7% higher in 2019, and 6.8, 10.6, 13.5, 21.5, and 34.4% higher in 2020 than D6, D4, D3, D2, and D1, respectively. The boll retention of the lower fruit branch under D5 reached 0.51 and 0.57 in two years, respectively. The shedding rate of the upper fruit branch decreased with the increase in cotton density in two years. The boll retention rate and shedding rate in the lower part of cotton plants were most closely related to light interception, with R2 values of 0.91 and 0.96, respectively. Our study shows cotton yield could be improved through higher light interception by optimizing planting density and canopy structure.

Evaluation and estimation of light interception and photosynthetic rate of lettuce plants grown under LEDs using 3D-scanned plant modelling

Evaluation and estimation of light interception and photosynthetic rate of lettuce plants grown under LEDs using 3D-scanned plant modelling