Radiation Use Efficiency Research Articles

Quantifying physiological contributions to yield loss in response to planting date in short-season cotton under a cotton[sbnd]wheat double-cropping system

Crop yield is primarily determined by physiological parameters, including light interception by the canopy (IPAR), radiation use efficiency (RUE), and harvest index (HI). However, little information is available about how these physiological parameters are impacted by planting date and what their contributions are to cotton yield loss. To evaluate the relative contribution of each physiological parameter to planting date-associated yield loss in cotton, an experiment was conducted during the 2019 to 2021 growing seasons at a field site in Anyang, Henan, China. Two contemporary cotton cultivars were grown in the field with four different planting dates (PDMAY10, PDMAY20, PDMAY30 and PDJUN10) for the growing seasons from 2019 to 2021. The measurements included climatic parameters, seed cotton yield, yield components, HI and biweekly leaf area index, light interception and biomass. First, seed cotton yield was significantly affected by the planting dates, with yields ranging from 1984 to 3388 kg ha−1, averaged across cultivars and years, while a significant difference between the first three planting dates was observed only in 2021. Second, the planting date significantly impacted the total light interception during the growing season (IPARtotal) and HI, while IPARtotal and HI decreased with the delayed planting date in all the years of the study. Compared to PDMAY10, IPARtotal was 0.34%, 13.2%, and 19.9% lower for PDMAY20, PDMAY30 and PDJUN10, respectively. Averaged across cultivars and years, PDMAY10 resulted in the highest HI value (0.28). The RUE gradually decreased as the planting date was delayed, but a significant difference in RUE between planting dates was observed only in 2021. Overall, among the three physiological yield-driving parameters, IPARtotal was a stronger contributor (46.9–47.0%) to the yield loss for PDJUN10 than PDMAY10 and PDMAY20. However, when compared to PDMAY30, HI was the greatest contributor, accounting for approximately 72.5% of the seed cotton yield loss for PDJUN10, followed by IPAR. We found that when cotton sowing in the Yellow River basin was postponed until June 10, the cotton yield was significantly reduced, and IPAR and HI were the main factors responsible for PDJUN10 yield loss on average. This study identified the most important functional traits for seed cotton yield response to planting date and has important reference value for stable cotton production.

Contrasting leaf-scale photosynthetic low-light response and its temperature dependency are key to differences in crop-scale radiation use efficiency.

Radiation use efficiency (RUE) is a key crop adaptation trait that quantifies the potential amount of aboveground biomass produced by the crop per unit of solar energy intercepted. But it is unclear why elite maize and grain sorghum hybrids differ in their RUE at the crop level. Here, we used a non-traditional top-down approach via canopy photosynthesis modelling to identify leaf-level photosynthetic traits that are key to differences in crop-level RUE. A novel photosynthetic response measurement was developed and coupled with use of a Bayesian model fitting procedure, incorporating a C4 leaf photosynthesis model, to infer cohesive sets of photosynthetic parameters by simultaneously fitting responses to CO2 , light, and temperature. Statistically significant differences between leaf photosynthetic parameters of elite maize and grain sorghum hybrids were found across a range of leaf temperatures, in particular for effects on the quantum yield of photosynthesis, but also for the maximum enzymatic activity of Rubisco and PEPc. Simulation of diurnal canopy photosynthesis predicted that the leaf-level photosynthetic low-light response and its temperature dependency are key drivers of the performance of crop-level RUE, generating testable hypotheses for further physiological analysis and bioengineering applications.

Optimization of N Fertilizer Type and Ridge–Furrow Ratio to Improve Resource Use Efficiency and Grain Yield of Rain-Fed Winter Wheat in Loess Plateau, China

Ridge and furrow plastic mulch (RFPM) and nitrogen (N) application are effective strategies for improving crop productivity in China’s Loess Plain. However, it is not clear how the ridge–furrow ratio and nitrogen fertilizer type (NT) affect the use of water, nitrogen, heat, and radiation resources for the enhancement of rain-fed wheat production. Two nitrogen fertilizer types (traditional urea (TU) and controlled-release urea (CRU)) and four planting patterns (conventional flat planting (F) and the RFPM system of 20 cm ridges with 40 cm furrows (R2F4), 40 cm ridges with 40 cm furrows (R4F4), and 60 cm ridges with 40 cm furrows (R6F4)) were tested from September 2018 to June 2021 during the winter wheat growing season. It was found that the RFPM system can increase soil thermal time (TTsoil) from 41.0 to 152.1 °C d compared to the F. RFPM system thermal effect, which reduced the vegetative growth period and prolonged the reproductive growth period for 2 to 7 days, which promoted an increase in the leaf area index (LAI) and final dry matter (DM) accumulation. These significantly increased the grain yield (GY) in the RFPM system by 51.6–115.2% and enhanced the thermal time use efficiency (TUE) by 48–99.5%, water productivity (WP) by 37.4–76.3%, radiation use efficiency (RUE) by 16.3–34.4%, and partial factor productivity of nitrogen (PFPN) by 51.6–115.2% compared to F. Although a high ridge and furrow ratio in combination with CRU increased the GY and resource use efficiency, it also exacerbated the soil water depletion, especially in the soil layer between 40 and 140 cm. Overall, CRU combined with the 40 cm ridge and 40 cm furrow RFPM system maximized resource efficiency and increased wheat production on China’s Loess Plateau.

Maximizing the Radiation Use Efficiency by Matching the Leaf Area and Leaf Nitrogen Vertical Distributions in a Maize Canopy: A Simulation Study.

The radiation use efficiency (RUE) is one of the most important functional traits determining crop productivity. The coordination of the vertical distribution of light and leaf nitrogen has been proven to be effective in boosting the RUE from both experimental and computational evidence. However, previous simulation studies have primarily assumed that the leaf area is uniformly distributed along the canopy depth, rarely considering the optimization of the leaf area distribution, especially for C4 crops. The present study hypothesizes that the RUE may be maximized by matching the leaf area and leaf nitrogen vertical distributions in the canopy. To test this hypothesis, various virtual maize canopies were generated by combining the leaf inclination angle, vertical leaf area distribution, and vertical leaf nitrogen distribution and were further evaluated by an improved multilayer canopy photosynthesis model. We found that a greater fraction of leaf nitrogen is preferentially allocated to canopy layers with greater leaf areas to maximize the RUE. The coordination of light and nitrogen emerged as a property from the simulations to maximize the RUE in most scenarios, particularly in dense canopies. This study not only facilitates explicit and precise profiling of ideotypes for maximizing the RUE but also represents a primary step toward high-throughput phenotyping and screening of the RUE for massive numbers of inbred lines and cultivars.

Effect of red and blue light versus white light on fruit biomass radiation-use efficiency in dwarf tomatoes.

The effect of the ratio of red and blue light on fruit biomass radiation-use efficiency (FBRUE) in dwarf tomatoes has not been well studied. Additionally, whether white light offers a greater advantage in improving radiation-use efficiency (RUE) and FBRUE over red and blue light under LED light remains unknown. In this study, two dwarf tomato cultivars ('Micro-Tom' and 'Rejina') were cultivated in three red-blue light treatments (monochromatic red light, red/blue light ratio = 9, and red/blue light ratio = 3) and a white light treatment at the same photosynthetic photon flux density of 300 μmol m-2 s-1. The results evidently demonstrated that the red and blue light had an effect on FBRUE by affecting RUE rather than the fraction of dry mass partitioned into fruits (Ffruits). The monochromatic red light increased specific leaf area, reflectance, and transmittance of leaves but decreased the absorptance and photosynthetic rate, ultimately resulting in the lowest RUE, which induced the lowest FBRUE among all treatments. A higher proportion of blue light (up to 25%) led to a higher photosynthetic rate, resulting in a higher RUE and FBRUE in the three red-blue light treatments. Compared with red and blue light, white light increased RUE by 0.09-0.38 g mol-1 and FBRUE by 0.14-0.25 g mol-1. Moreover, white light improved the Ffruits in 'Rejina' and Brix of fruits in 'Micro-Tom' and both effects were cultivar-specific. In conclusion, white light may have greater potential than mixed red and blue light for enhancing the dwarf tomato FBRUE during their reproductive growth stage.

Delayed Leaf Senescence Improves Radiation Use Efficiency and Explains Yield Advantage of Large Panicle-Type Hybrid Rice

Super hybrid rice with predominantly large panicle types has achieved remarkable success in enhancing crop yield. However, when compared with multi-panicle-type varieties, the yield stability of large panicle-type varieties remains a challenge, and limited information is available on the comparative advantages of multi-panicle types. Consequently, a two-year experiment was conducted to evaluate the grain yield, biomass production, leaf area index (LAI), and radiation use efficiency (RUE) of large panicle-type hybrid rice (Y-liangyou 900, YLY900) and multi-panicle-type hybrid rice (C-liangyouhuazhan, CLYHZ) under three nitrogen (N) treatments (0, 180, 270 kg N ha−1). The effects of increased N fertilization were more pronounced in the large panicle-type varieties. YLY900 outperformed CLYHZ in terms of average yield (6% higher), and its yield advantage was attributed to higher spikelets per panicle (28%). Due to YLY900’s RUE being 9% higher than CLYHZ, it results in a 12% greater accumulation of dry matter than CLYHZ. Furthermore, YLY900 exhibited significant improvements of 16%, 4%, and 14% in specific leaf weight, effective leaf area ratio, and LAI at 20 days after the heading stage (20DAH), respectively, compared with CLYHZ. YLY900 also demonstrated a stronger correlation between rice yield and intercepted photosynthetically active radiation (IPAR) compared with CLYHZ, with R2 values of 0.80 and 0.66, respectively. These findings highlight the superior performance of YLY900, resulting from higher light interception percentage (IP) and IPAR values, which consequently led to enhanced RUE and grain yield. Our research reveals that delayed leaf senescence by increasing LAI at the post-heading stage for large panicle-type hybrid rice, thereby contributing to greater RUE, led to higher biomass production and grain yield.

Matching light and nitrogen distributions in the maize canopy to achieve high yield and high radiation use efficiency

Light and nitrogen distribution within a plant's canopy reflect growth adaptation of crop to the environment and are conducive to improving the carbon assimilation ability. So is it possible to rationalize regulation in crop production to maximize yield by improving light and nitrogen distribution without adding additional inputs? In this study, the effects of different nitrogen application rates and planting densities on canopy light and nitrogen distribution of two high-yielding maize cultivars (i.e., XY335 and DH618) and the regulation of canopy physiological characteristics on radiation use efficiency (RUE) and yield were studied based on high yield field experiments in Qitai, China, during 2019 and 2020. The results showed that the distribution of photosynthetically active photon flux density (PPFD) in the maize canopy has been decreasing from top to bottom, while the vertical distribution of specific leaf nitrogen (SLN) initially increased and then decreased from top to bottom in the canopy. When SLN began to decrease, the PPDF of XY335 and DH618 were 0.5 and 0.3, corresponding to 40.6 and 49.3% of the total leaf area index (LAI). The KN/KL in the middle and lower canopy of the XY335 (0.32) was 0.08 higher than that of DH618 (0.24). Yield and RUE of the XY335 (17.2 t ha-1, 1.8 g MJ-1) were 7.0% (1.1 t ha-1) and 13.7% (0.2 g MJ-1) higher than that of DH618 (16.1 t ha-1, 1.6 g MJ-1). Therefore, better light conditions (the proportion of LAI in the upper and middle canopy is small) improved the light distribution when SLN started to decrease, thus helping to mobilize nitrogen distribution and maintain a high nitrogen extinction coefficient (KN) and KN/light extinction coefficient (KL). And KN/KL was a key parameter for yield improvement when maize nutrient requirements were met at 360 kg ha-1. At this time, an appropriately optimized high planting density could promote nitrogen utilization and produce higher yield and higher efficiency. This study will be important for maize high yield and high efficiency cultivation and breeding in the future.

Use of intercropping and mulch to improve the water and natural resources use efficiencies of forage cactus and millet production in a semiarid region

1. CONTEXT - Improving the use of natural resources (e.g., water, nutrients, and radiation) within production systems under different technologies (mulch and intercropping) is fundamental to intensifying sustainable agriculture. 2. OBJECTIVE - The objective was to quantify the parameters of water consumption and the efficiency of using natural resources of forage cactus and millet under different technologies of crops in a semiarid environment. 3. METHODS - The forage cactus (clone Orelha de Elefante Mexicana) and millet (cv. IPA Bulk-1-BF) were evaluated to six cropping arrangements: single cactus with mulch (CWM), single cactus with no mulch (CNM), single millet with mulch (MWM), single millet with no mulch (MNM), a cactus-millet intercropping system with mulch (CMWM), and cactus-millet intercropping system with no mulch (CMNM). Data on crop growth, crop production, and soil moisture were collected, and the following were determined: crop evapotranspiration (ETc), crop transpiration (T), soil water evaporation (E), single crop coefficient (Kc), dual crop coefficient (Kcb and Ke), water use efficiency (WUE), nutrient use efficiency (NUE) and radiation use efficiency (RUE). Biological efficiency and competitive ability indicators were calculated for the intercropped systems. 4. RESULTS AND CONCLUSIONS - The ETc (mm day −1) was higher under MWM (4.69), MNM (3.60), and CMWM (3.81). There was little variation in the values of ETc, T, or E between CNM and CWM, unlike between MNM and MWM. Intercropping reduced E compared to the single crops of cactus (8%) and millet (58%). On average, Kc was higher under MWM (0.98), CWM (0.69), and CMWM, (0.88), compared to MNM (0.75), CNM (0.63), and CMNM (0.48). The intercrops were more efficient for WUE (44%) and RUE (2.28 g MJ −1), with no difference for NUE. It can be concluded that the cactus-millet intercropping system is a good alternative for more-resilient agriculture in semi-arid environments, especially when the use of mulch. 5. SIGNIFICANCE - The results of this study are significant for the management of water resources in the semi-arid region, as they favour knowledge of the water needs of these crops in different production systems, and how the adoption of technologies such as intercropping and mulching can improve efficiency in the use of available natural resources, compared to exclusive planting.

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.

Assessing the yield difference of double-cropping rice in South China driven by radiation use efficiency

Double-cropping rice in South China continues to break the total yield record, but the yield potential of single-cropping rice is not being realized. Radiation use efficiency (RUE) has been singled out as an important determinant of grain yield in many cereal species. However, there is no information on whether the yield gaps in double-cropping rice involve differences in RUE. Field experiments were performed over two years to evaluate the effects of intercepted radiation (IP) and RUE on the above-ground biomass production, crop growth rate (CGR), and harvest index (HI), in four representative rice varieties, i.e., Xiangyaxiangzhan (XYXZ), Meixiangzhan 2 (MXZ2), Nanjingxiangzhan (NJXZ), and Ruanhuayoujinsi (RHYJS), during the early and late seasons of rice cultivation in South China. The results revealed that grain yield in the early season was 8.2% higher than in the late season. The yield advantage in the early season was primarily due to higher spikelets per panicle and above-ground biomass resulting from a higher RUE. The spikelets per panicle in the early season were 6.5, 8.3, 6.9, and 8.5% higher in XYXZ, MXZ2, NJXZ, and RHYJS, respectively, than in the late season. The higher early season grain yield was more closely related to RUE in the middle tillering stage (R2=0.34), panicle initiation (R2=0.16), and maturation stage (R2=0.28), and the intercepted photosynthetically active radiation (IPAR) in the maturation stage (R2=0.28), while the late season grain yield was more dependent on IPAR in the middle tillering stage (R2=0.31) and IPAR at panicle initiation (R2=0.23). The results of this study conclusively show that higher RUE contributes to the yield progress of early season rice, while the yield improvement of late season rice is attributed to higher radiation during the early reproductive stage. Rationally allocating the RUE of double-cropping rice with high RUE varieties or adjustments of the sowing period merits further study.

Light interception and radiation use efficiency (RUE) in maize (Zea mays. L) intercropping with greengram (Vigna radiata L.)

Intercropping is growing two or more crop species simultaneously, different canopy architectures by row configuration, changing light interception, radiation utilisation, and increased yield. The present study aimed to evaluate different intercropping systems affected light interception per cent and radiation use efficiency in maize (Zea mays L.) intercropping with greengram (Vigna radiata L.) different ratios. Field experiments were conducted for Kharif 2022 and Rabi 2022-2023 seasons, which were laid out in a split-plot design and replicated three times. Three Nitrogen levels viz., N1 - 75 % RDN (Recommended dose of Nitrogen), N2 – 100% RDN, N3-125% RDN had taken as the main plot and three intercropping treatments were taken as subplot viz., M2G2- replacement series (two row of maize and two row of Greengram), M4G2- replacement series (four rows of maize and two row of Greengram), M2G3-paired row system (two rows of maize and three rows of Greengram), and sole maize. Both light interception and radiation use efficiency were significantly affected by intercropping systems. Light interception per cent of the main crop (maize) was significantly higher (69.0, 75.5 and 71.0 % during Kharif and 60.1, 78.1 and 76.6 during rabi) at vegetative, flowering and maturity phases, respectively. The Kharif 2022 and Rabi 2022-2023 maximum Radiation Use Efficiency (RUE) of Maize intercropping with green gram (maize + greengram) was higher in T12 (M2G3 paired row with 125 % Recommended Dose of Nitrogen) recorded as 2.46 (Kharif) and 1.43 (rabi). The outcome might be utilised to optimise the row configuration of intercropping design, explain the mechanism of intercropping on light utilisation, and improve radiation use efficiency.

Estimating yield-contributing physiological parameters of cotton using UAV-based imagery.

Lint yield in cotton is governed by light intercepted by the canopy (IPAR), radiation use efficiency (RUE), and harvest index (HI). However, the conventional methods of measuring these yield-governing physiological parameters are labor-intensive, time-consuming and requires destructive sampling. This study aimed to explore the use of low-cost and high-resolution UAV-based RGB and multispectral imagery 1) to estimate fraction of IPAR (IPARf), RUE, and biomass throughout the season, 2) to estimate lint yield using the cotton fiber index (CFI), and 3) to determine the potential use of biomass and lint yield models for estimating cotton HI. An experiment was conducted during the 2021 and 2022 growing seasons in Tifton, Georgia, USA in randomized complete block design with five different nitrogen treatments. Different nitrogen treatments were applied to generate substantial variability in canopy development and yield. UAV imagery was collected bi-weekly along with light interception and biomass measurements throughout the season, and 20 different vegetation indices (VIs) were computed from the imagery. Generalized linear regression was performed to develop models using VIs and growing degree days (GDDs). The IPARf models had R2 values ranging from 0.66 to 0.90, and models based on RVI and RECI explained the highest variation (93%) in IPARf during cross-validation. Similarly, cotton above-ground biomass was best estimated by models from MSAVI and OSAVI. Estimation of RUE using actual biomass measurement and RVI-based IPARf model was able to explain 84% of variation in RUE. CFI from UAV-based RGB imagery had strong relationship (R2 = 0.69) with machine harvested lint yield. The estimated HI from CFI-based lint yield and MSAVI-based biomass models was able to explain 40 to 49% of variation in measured HI for the 2022 growing season. The models developed to estimate the yield-contributing physiological parameters in cotton showed low to strong performance, with IPARf and above-ground biomass having greater prediction accuracy. Future studies on accurate estimation of lint yield is suggested for precise cotton HI prediction. This study is the first attempt of its kind and the results can be used to expand and improve research on predicting functional yield drivers of cotton.

Using crop intercepted solar radiation and vegetation index to estimate dry matter yield of Choy Sum.

An accurate assessment of vegetable yield is essential for agricultural production and management. One approach to estimate yield with remote sensing is via vegetation indices, which are selected in a statistical and empirical approach, rather than a mechanistic way. This study aimed to estimate the dry matter of Choy Sum by both a causality-guided intercepted radiation-based model and a spectral reflectance-based model and compare their performance. Moreover, the effect of nitrogen (N) rates on the radiation use efficiency (RUE) of Choy Sum was also evaluated. A 2-year field experiment was conducted with different N rate treatments (0 kg/ha, 25 kg/ha, 50 kg/ha, 100 kg/ha, 150 kg/ha, and 200 kg/ha). At different growth stages, canopy spectra, photosynthetic active radiation, and canopy coverage were measured by RapidScan CS-45, light quantum sensor, and camera, respectively. The results reveal that exponential models best match the connection between dry matter and vegetation indices, with coefficients of determination (R2) all below 0.80 for normalized difference red edge (NDRE), normalized difference vegetation index (NDVI), red edge ratio vegetation index (RERVI), and ratio vegetation index (RVI). In contrast, accumulated intercepted photosynthetic active radiation (Aipar) showed a significant linear correlation with the dry matter of Choy Sum, with root mean square error (RMSE) of 9.4 and R2 values of 0.82, implying that the Aipar-based estimation model performed better than that of spectral-based ones. Moreover, the RUE of Choy Sum was significantly affected by the N rate, with 100 kg N/ha, 150 kg N/ha, and 200 kg N/ha having the highest RUE values. The study demonstrated the potential of Aipar-based models for precisely estimating the dry matter yield of vegetable crops and understanding the effect of N application on dry matter accumulation of Choy Sum.

Physiological contributors to yield in advanced cotton breeding lines

AbstractCotton (Gossypium hirsutum L.) yield can be expressed as the product of intercepted photosynthetically active radiation (IPAR), radiation use efficiency (RUE), and harvest index (HI). Studies comparing genetic diversity in functional yield drivers for the progeny of elite breeding lines are limited or non‐existent. A field study was conducted during the 2020 and 2021 growing seasons to characterize crop development and to evaluate yield and underlying yield drivers in 16 advanced breeding lines (F7 generation). Significant breeding line differences existed for lint yield, cutout date, reproductive, vegetative, and total biomass, RUE, and HI but not for IPAR. The lint yield for the lowest yielding lines was 24% lower than the highest yielding line with a lint yield of 1706 kg ha−1. Differences in RUE were not associated with single‐leaf photosynthetic rates. HI positively contributed to lint yield gain for most lines evaluated, whereas RUE was negatively correlated with lint yield for the majority of breeding lines evaluated. However, in the two highest‐yielding lines, two different strategies of yield maximization were identified. One line exhibited the earliest cutout date, reduced biomass production, low RUE, and the highest HI values, whereas the other line had the latest cutout date and produced the highest total biomass, highest RUE, and a low to intermediate HI. Breeding lines used in the current study achieved high yields by differentially manipulating underlying physiological components such as RUE, biomass accumulation, or dry matter allocation to fiber. Our work provides future direction for efforts aimed at maximizing yield through the selection for functional yield drivers.

Planting time and stand density effect on radiation interception and use efficiency of maize and sunn hemp intercropping in semi-arid South Africa

Solar radiation must be efficiently utilised to enhance dry matter accumulation and carbon sequestration capacity within dryland agroecosystems. The study evaluated the effects of sunn hemp (Crotalaria juncea L.) intercropping time and stand density on radiation interception and radiation use efficiency (RUE) in a maize-based system. Field experiments were conducted under the in-field rainwater harvesting (IRWH) technique for two consecutive growing seasons, 2019/20 and 2020/21. Radiation interception and productivity were measured and calculated for maize and sunn hemp, sole and intercrops. The intercrops were identified by the sunn hemp intercropping times [simultaneous with maize planting (P1), at V15 maize growth stage (P2), at R1 maize growth stage (P3)] and stand densities [16 plants m–2 (D1-low), 32 plants m–2 (D2-medium), 48 plants m–2 (D3-high)]. Total radiation interception was calculated using a row-crop radiation transmission (RCRT) model from strip width of component crops, extinction coefficient (k), plant height, and leaf area index (LAI) measurements taken throughout the growing season. The results showed that the LAI of sunn hemp was high when intercrop was planted simultaneous with maize planting and at 48 plants m–2. The overall k for the sole sunn hemp (SSH) cropping system was 0.37. The correlations (r2) between the modelled and measured fractions of photosynthetic active radiation (PAR) in simultaneous maize planting, V15 maize growth stage, and R1 maize growth stage intercropping treatments were 0.87, 0.97 and 0.93, respectively. Simultaneous planting of sunn hemp intercrop with maize captured the most growing season PAR of 798.70 MJ m–2 and had the highest RUE of 1.42 g MJ−1. These results suggest that intercropped sunn hemp planted simultaneously with maize would help to increase production through the more efficient use of solar radiation. Optimising planting time and density can help plan the planting time to increase radiation utilisation in maize/sunn hemp intercropping systems.

Leaf Area Duration and Crop Radiation Use Efficiency Determine Biomass Yield of Lignocellulosic Perennial Grasses under Different Soil Water Content

The aim of the present work was to assess the leaf area duration (LAD) and the radiation use efficiency (RUE) of six warm-season perennial biomass grasses (PBGs) in a two-year field trial in the semiarid Mediterranean climate under different soil water availability. Two ecotypes of giant reed (Arundo donax L., ARCT and ARMO), one ecotype of African fodder cane (Saccharum spontaneum L. subsp. aegyptiacum (Willd.) Hack., SAC) and three hybrids of Miscanthus (the commercial M. × giganteus J.M. Greef, Deuter ex Hodk., Renvoize, M × G, and two new seed-based hybrids, GNT9 and GNT10) were compared under three levels of soil water availability: rainfed, 50% and 100% of maximum crop evapotranspiration (ETm) restoration. The determination of RUE of perennial plants is controversial and has led to contrasting results in past studies. In the present work, LAD and RUE differed among crops and irrigation regimes, being positively affected by supplemental water inputs. SAC, ARCT and ARMO showed both high LAD and RUE, which determined the high biomass yield than both the commercial M × G and the improved Miscanthus hybrids GNT9 and GNT10. RUE was particularly high and less affected by soil water availability during the mid-season, while the effect of irrigation and the differences among the genotypes were larger during the late season. Adequate biomass yield can be achieved by sub-optimal soil water availability, thus reducing the water footprint and increasing the sustainability of these biomass perennial grasses selected for the Mediterranean climate.

Performance evaluation of vertical bifacial and single-axis tracked agrivoltaic systems on arable land

This study evaluates and compares two types of interspersed bifacial agrivoltaic systems in Belgium: a fixed vertical system and a dynamic single-axis tracker, focusing on sugarbeet cultivation. Additionally, the impact of different tracking algorithms on crop yield and quality is investigated. The main approach involves developing an empirical crop model based on radiation use efficiency (RUE) and utilizing a radiation tool to simulate crop yield and quality. Field measurements of electricity and crop output are conducted over a span of two years, 2021 and 2022. The findings reveal that the dynamic solar tracker outperforms the fixed vertical bifacial setup in both years. The smart-tracking algorithm, applied under optimal watering conditions in the 2021 season, leads to a significant increase in energy yield (＋30%) and land use efficiency (＋20%) at a lower cost, while maintaining comparable crop yields to the vertical setup. However, limitations are observed in the empirical crop growth model’s ability to account for climatic variability in the dry 2022 year, reducing its usefulness during the design phase. Notably, the practical implementation of the systems highlights challenges during construction and exploitation, emphasizing the significance of considering these practical factors together with climate, structure and crop choice assessing the effectiveness and to de-risk investments.

In-Field Rainwater Harvesting Tillage in Semi-Arid Ecosystems: II Maize-Bean Intercrop Water and Radiation Use Efficiency.

The purpose of this study was to evaluate alternative management practices such as in-field rainwater harvesting (IRWH) and intercropping techniques through conducting on-farm demonstrations. Seven homestead gardens in Thaba Nchu rural communities in the central part of South Africa were selected as demonstration trials. Two tillage systems, conventional (CON) and IRWH, as the main plot, and three cropping systems as sub-plot (sole maize and beans and intercropping) were used to measure water use and radiation use parameters. The water productivity (WP) of various treatments was positively related to the radiation use efficiency (RUE), and the degree of associations varied for different tillage systems. The water use in IRWH was higher by 15.1%, 8.3%, and 10.1% over the CON for sole maize and beans and intercropping, respectively. Similarly, the intercropping system showed water use advantages over the solely growing crops by 5% and 8% for maize and by 16% and 12% for beans under IRWH and CON tillage, respectively. Maximum RUE was found for sole maize and beans under IRWH, higher by 13% and 55% compared to the CON tillage, respectively. The RUE under IRWH tillage was estimated to be 0.65 and 0.39 g DM MJ-1 in sole maize and intercropping, respectively. However, in sole and intercropped beans, the RUE showed higher values of 1.02 g DM MJ-1 and 0.73 g DM MJ-1, respectively. WP and RUE were associated with water deficits and proportional to lower radiation use. This relationship indicates that the intercepted radiation by plants for photosynthesis is directly related to the transpiration rate until radiation saturation occurs. Therefore, the higher water deficit and lesser efficiency in using the radiation available during the season can be improved by practicing IRWH techniques. Furthermore, in semi-arid areas, to enhance the efficiency of water and radiation usage in intercropping management, it is crucial to adjust plant population and sowing dates based on water availability and the onset of rainfall.

Optimizing Grain Yield and Radiation Use Efficiency through Synergistic Applications of Nitrogen and Potassium Fertilizers in Super Hybrid Rice.

The remarkable yield performance of super hybrid rice has played a crucial role in ensuring global food security. However, there is a scarcity of studies investigating the contribution of radiation use efficiency (RUE) to hybrid rice yields under different nitrogen and potassium treatments. In this three-year field experiment, we aimed to evaluate the impact of two hybrid rice varieties (Y-liangyou 900: YLY900 and Quanyouhuazhan: QYHZ) under varying nitrogen regimes (N90: 90 kg N ha-1, N120: 120 kg N ha-1, N180: 180 kg N ha-1) and potassium regimes (K120: 120 kg K2O ha-1, K160: 160 kg K2O ha-1, K210: 210 kg K2O ha-1) on grain yield and its physiological determinants, including RUE, intercepted photosynthetically active radiation (IPAR), aboveground biomass production, and harvest index (HI). Our results revealed that both rice varieties exhibited significantly higher yields when coupled with nitrogen and potassium fertilization. Compared to the N90 × K120 treatment, the N120 × K160 and N180 × K210 combinations resulted in substantial increases in grain yield (12.0% and 21.1%, respectively) and RUE (11.9% and 21.4%, respectively). The YLY900 variety showed notable yield improvement due to enhanced aboveground biomass production resulting from increased IPAR and RUE. In contrast, the QYHZ variety's aboveground biomass accumulation was primarily influenced by RUE rather than IPAR, resulting in higher RUE and grain yields of 9.2% and 5.3%, respectively, compared to YLY900. Importantly, fertilization led to significant increases in yield, biomass, and RUE, while HI remained relatively constant. Both varieties demonstrated a positive relationship between grain yield and IPAR and RUE. Multiple regression analysis indicated that increasing RUE was the primary driver of yield improvement in hybrid rice varieties. By promoting sustainable agriculture and enhancing fertilizer management, elevating nitrogen and potassium levels from a low base would synergistically enhance rice yield and RUE, emphasizing the critical importance of RUE in hybrid rice productivity compared to HI.

Quantifying physiological contributions to nitrogen-induced yield variation in field-grown cotton

The effect of nitrogen (N) application rate on lint yield and yield components have been studied extensively in cotton. However, reports quantifying contributions to N-induced yield loss and the response of intra-boll yield components to N deficiency are far less common. The objectives of this study were to 1) determine the effect of N application rate on lint yield biomass and fiber quality in cotton, 2) assess the contributions of intercepted photosynthetically active radiation (IPAR), radiation use efficiency (RUE), and harvest index (HI) to N-induced yield loss in cotton, and 3) characterize the effect of N application rate on yield component responses in cotton. An experiment was conducted at a field site near Tifton, Georgia, USA during the 2021 and 2022 growing seasons. The experiment was arranged as a randomized complete block design with five replications and five nitrogen application rates (0, 44, 89, 134, and 179 kg N ha−1). The studied parameters were lint yield, IPAR, RUE, HI, fiber quality, yield components, and yield loss contributions. Lint yield was significantly affected by N application rate, with yields ranging from 1452 to 1848 kg ha−1. Similarly, total IPAR was 23% lower for the 0 kg N ha−1 treatment than the 134 kg N ha−1 treatment, and IPAR contributed significantly to yield loss, with a 427 kg ha−1 loss attributable to IPAR under N deficiency. RUE was 37% higher for the 179 kg N ha−1 treatment than the 0 kg N ha−1 treatment and contributed positively to yield in the highest N rates (179 kg N ha−1). However, yield improvements due to RUE were mitigated by low HI values in the highest N application rate. Boll density was the most strongly and positively associated yield component parameter with N-induced variability in lint yield, whereas lint percent and lint production per seed were negatively associated with lint yield. Among the three physiological yield-driving parameters, light interception by the canopy was the primary contributor to N-induced yield loss. Boll density was the primary yield component governing N-induced variation in lint yield. Increased N application rate promotes greater dry matter partitioning to seeds than fiber, resulting in more seeds per boll and lower lint percent, lint weight per seed, and individual fiber weight. The results contained here identify the most important functional traits for determining lint yield response to N application rate.