Yield Of Cultivars Research Articles

Effects of Different Harvesting Practices on Forage Yield and Quality Characteristics in some Sweet Sorghum Cultivars

Effects of Different Harvesting Practices on Forage Yield and Quality Characteristics in some Sweet Sorghum Cultivars

Effect of dates of transplanting on bulb yield and quality of kharif onion cultivars

Effect of dates of transplanting on bulb yield and quality of kharif onion cultivars

CROPGRO-soybean model – Validation and application for the southern Amazon, Brazil

Agricultural models are useful tools for predicting phenology, biomass, and crop yield under different environmental conditions during the growth period. Notwithstanding their use in the Southern Cone of Rondônia (southern Amazon, Brazil) is still limited. Thus, the objective in this work was to calibrate and validate the CROPGRO-Soybean model with soybean data collected in harvests of 2017 to 2019, being the data from the first growing period devoted to model calibration, and crop data from 2018/2019 to model validation. Six soybean cultivars were planted at the municipality of Vilhena, State of Rondônia, Brazil. The model was parameterized using climatic, hydric and physical soil properties, and growth data of the evaluated soybean cultivars. To evaluate the accuracy of model prediction we used the coefficient of determination (r2), percentage difference (Pd), root mean square error (RMSE), and Willmott’s index of agreement (d-value). The model accurately simulates the vegetative and reproductive stages, and the yields of the soybean cultivars under the climatic conditions of the Southern Cone of Rondônia. However, the CROPGRO-Soybean model tended to overestimate soil moisture content especially in upper soil layer (0.0–0.1 m depth). Taking the observed data, as the baseline, the model predicted the time to flowering, first pod, seeding, and physiological maturity, with a discrepancy of just one to seven days. In most of the soybean cultivars (five of the six cultivar evaluated), the differences between observed and simulated yields (growing cycle of 2018/2019 – validation harvest) ranged from –6 % to (underestimation) to 27 % (overestimation).

Assessing the Performance of Chickpea Cultivars in Mandi District of Himachal Pradesh, India

This study assessed the yield gaps of chickpea (Cicer arietinum L.) in Mandi district of Himachal Pradesh where a total of 240 trials on improved chickpea cultivars viz. GNG 1581, GPF 2 and Himachal Chana 2 along with best practices were conducted by KVK in Mandi for three consecutive years under the Cluster Front Line Demonstration (CFLDs) program during Rabi 2015-16 to Rabi 2017-18. The study revealed that the demonstration yield of chickpea cultivars viz. GNG 1581, GPF 2 and Himachal Chana 2 were significantly better than the farmer's practice. Overall, a seed yield of 616 kg ha-1 was achieved in the three years of data collected in the demonstration plot, which was 40.32 percent higher than the farmer's practice. The technology and extension gap in the data collected under the three-year CFLDs program were 1546.5 kg ha–1 and 177 kg ha–1 respectively. The improved technology package not only improved water use efficiency, chickpea profitability in terms of gross and net returns, but also improved the benefit-cost ratio (BC). The overall technology index of 71.51 percent revealed a satisfactory performance of technology interventions, which can be further strengthened in the region by bridging the gaps through more effective research and extension services.

SUITABLE SUBSTRATE VOLUMES AND CULTIVARS FOR ENHANCING GROWTH AND IN-CREASING YIELD OF YARD-LONG BEAN IN URBAN ECOSYSTEMS

Yard-long bean, a favored vegetable known for its taste and nutritional value, holds economic importance. Its climbing nature and environmental resilience make it ideal for urban cultivation in pots and climbing frames. This study, conducted in a limited urban space, aimed to determine optimal pot size and cultivars for yard-long bean cultivation, emphasizing growth and yield. Two pot sizes were used: a larger one (30 cm diameter x 37 cm height, M1) and a smaller one (30 cm diameter x 30 cm height, M2), alongside three commercial cultivars: Kanton Tavi (V1), Camellia (V2), and Arafi (V3). Results indicated that a larger pot size increased pod number and total pod weight per plant, facilitating root development, vine growth, and enhanced yield. The larger substrate volume retained moisture and boosted plant biomass. Cultivar treatment affected branch length and flowering time, with Camellia exhibiting the longest harvest period (14 harvests). Hence, for Camellia varieties, cultivation using larger pots (30 cm diameter x 37 cm height) is recommended.

Impact of different levels of foamed sulfur and Nitrogen fertilizer (Urea) on soil reaction (pH) and yield of wheat (Triticum aestivum L.) cultivar (IBAA 99)

An experiment was conducted in one of the agricultural lands of Al-Muthanna Governorate for the agricultural season 2018_2019, to find out the effect of adding one of the soil conditioners represented by foamed sulfure by three levels (0, 1000 and 2000) kg S ha-1 , addition of nitrogen fertilizer (Urea) CO(NH2)2 at three levels (200, 400 and 600) kg N ha-1 to the soil in the degree of soil reaction (pH) and the yield of wheat cultivar (IPAA 99). The treatments within the experimental units were arranged according to the Randomized Complete Block Design (RCBD) with four replicates, so the total experimental units were 36 experimental units, where the level of addition of 2000 kg N ha-1 of foamed sulfur and the level of 600 kg N ha-1 of nitrogen fertilizer (Urea) were significantly higher, to give them the lowest averages for the soil reaction (pH) of 7.13 and 7.38 at germination and 7.19 and 7.29 at the flowering stage for each of the sulfur and nitrogen fertilizers, respectively, compared to the comparison treatment. Both levels were significantly superior in giving them the highest averages for some growth characteristics, and the yield amounted to(343 and 304 spikes m-2 , 65 and 62 grains of spike-2 , 43.58 and 42.20 gm, and 4.88 and 478 tons ha-1 and 25.60 and 24.32%, for the characteristics spikes numbers, the grains spike number, 1000 grain weights, grains yield and the protein content percentage in grains, respectively, for both levels. Keywords: foamed sulfur, Nitrogen fertilizer (Urea), soil reaction (pH), yield, wheat (Triticum aestivum L.), IBAA 99cultivar.

Nitrogen fertilization application strategies improve yield of the rice cultivars with different yield types by regulating phytohormones

Rice (Oryza sativa L.) is the most important food crop worldwide, and its sustainable development is essential to ensure global food security. Panicle morphological and physiological characteristics plays an important role in rice yield formation. However, under different nitrogen (N) fertilization strategies, it is not clear whether the morphological and physiological state of panicles at panicle development stage affects the formation of yield. To understand how the panicle differentiation and development, and grain yield are affected by the N fertilization strategies, and clarify the relationship between related traits and yield in the process of panicle development in different cultivars. In this study consisted of no N fertilizer and four N fertilization strategies, a panicle weight type (PWT) rice cultivar, Dongfu 114 (DF114) and a panicle number type (PNT) rice cultivar, Longdao 11 (LD11) were grown in the field. The results showed that N fertilization strategies could improve the nitrogen use efficiency and yield of rice, but the response of different rice varieties to N fertilizer strategies was different. Different from the DF114, the further increase of panicle N fertilizer ratio could not further improve the yield of LD11, and the highest grain yield of DF114 and LD11 was obtained under N4 and N3 conditions, respectively. In addition, this study found that N fertilizer strategies can affect the content of phytohormones in rice at the panicle differentiation stage, and then regulate the differentiation and development of rice panicles to affect yield. It is of great significance to optimize the application mode of N fertilizer according to the characteristics of varieties to improve rice yield and ensure food security.

Seed productivity of switchgrass depending on varietal characteristics

Purpose. To establish the features of yield formation and seed quality of switchgrass depending on varietal characteristics. Methods. Laboratory, field, measuring and weighing, mathematical and statistical. Results. It was established that the productivity of switchgrass varietis depends on the ripeness group. A significantly higher seed yield was provided by the mid-late cultivar ‘Cave-in-Rock’, 0.137 t/ha, early-ripening ‘Forestbur’, 0.128 t/ha, and mid-early ‘Nebraska’, 0.124 t/ha, while the yield of other cultivars was significantly lower. The lowest seed yield was provided by the very early variety ‘Dakota’ and late ‘Carthage’ and very late ‘Kanlow’. The highest indicators of seed quality – germination energy and germination – were found in very early ‘Dakota’ variety, 50 and 52%, respectively, and in mid-early ‘Samburst’, 50 and 53%, respectively. Germination energy and seed germination of the early-ripening variety ‘Forestbur’, mid-early ‘Nebraska’, and mid-late ‘Cave-in-Rock’ were 30–34 and 32–35%, respectively, depending on the varietal characteristics, and no significant difference was found. Much lower seed quality was obtained in mid-late varieties, and the lowest – in very late varieties. Analyzing seed quality over the years of research, it was found that its germination depended on the sum of effective temperatures during the growing season. The highest germination of all varieties, 47% was in 2018, which is caused by the sum of effective temperatures over 3539 °С. The 2019 and 2020 growing seasons were less favourable than 2018, but significantly better than 2021. Conclusions. Productivity of switchgrass, seed yield, its germination energy and germination depended on maturity group and growing weather conditions, i.e., the sum of effective temperatures. It was found that the higher the sum of effective temperatures, the higher the seed germination. The highest germination of all varieties, 47%, was obtained for the sum of effective temperatures above 3539 °C. A strong correlation was found between seed germination and the sum of effective temperatures (r = 0.96).

Deficit Irrigation on Fruit Yield and Quality of Sweet Pepper

Background: Deficit irrigation is an approach to use less water in crop growth in places where water resources are the limiting factor for agricultural production, to maximize the production per unit of volume of water available. Objective: The study aimed to evaluate the effect of four levels of irrigation applied to replenish soil moisture depletion on the growth and yield of two sweet pepper cultivars. Methods: The experiment was performed on field conditions from January to June 2020 in a randomized block experimental design with three repetitions arranged in divided plots, the main plot was the four irrigation depths, and the sub-plots were the two cultivars (Tres Filos and Pepón) for a total of eight treatments. The irrigation depths applied corresponded to 60%, 80%, 100%, and 120% of the crop evapotranspiration. Results: The ANOVA (analysis of variance) of the main factors indicates that for the irrigation treatment factor, the number of fruits per plant for the two varieties is statistically equal when irrigation is applied at 120, 100 and 80% of the crop evapotranspiration (ETc) and greater than the one obtained with irrigation at 60% of ETc. For the cultivars factor, the number of fruits per plant and the fruit yield (g plant-1) in the different irrigation treatments was higher in the cv Tres Filo, but the weight of the fruit was higher in the cv Pepón. Conclusion: The application of irrigation at 60% of the ETc represents a saving of 40% of the volume of water compared to the application at 100% of ETc. The reduction in the number of fruits per plant, fruit weight, and average yield (g plant-1) of both cultivars was only 4.21%, 7.47%, and 11.95%, respectively. Therefore, if the limiting factor for agricultural production is water availability, it is advisable to irrigate at 60% of the ETc and increase the surface for irrigation to increase total production.

Response of yield, root traits and plasticity of nitrogen-efficient cultivars of drip-irrigated rice to a nitrogen environment

The response of drip-irrigated rice physiological traits to water and fertilisers has been widely studied. However, the responses of yield, root traits and their plasticity to the nitrogen environment in different nitrogen-efficient cultivars are not fully understood. An experiment was conducted from 2020-2022 with high nitrogen efficient (high-NUE) cultivars (T-43) and low-NUE cultivars (LX-3), and four nitrogen levels (0, 150, 300, and 450 kg ha-1) under drip irrigation in large fields were used. The aim was to study the relationship between root morphology, conformation, biomass, and endogenous hormone content and yield and nitrogen use efficiency. The results showed the following: 1) Under the same N application rate, compared with LX-3, T-43’s yield, N partial factor productivity (PFP), fine root length density (FRLD), shoot dry weight (SDW), root indole-3-acetic acid (IAA), and root zeatin and zeatin riboside (Z+ZR) were significantly increased by 11.4-18.9%, 11.3-13.5%, 11.6-15.7%, 9.9-31.1%, 6.1-48.1%, and 22.8-73.6%, respectively, while the root-shoot ratio (RSR) and root abscisic acid (ABA) were significantly decreased (P<0.05). 2) Nitrogen significantly increased rice root morphological indexes and endogenous hormone contents (P<0.05). Compared to N0, yield, root length density (RLD), surface area density (SAD), Root volume density (RVD), and root endogenous hormones (IAA, Z+ZR) were significantly increased in the 2 cultivars under N2 by 61.6-71.6%, 64.2-74.0%, 69.9-105.6%, 6.67-9.91%, 54.0-67.8%, and 51.4-58.9%, respectively. Compared with N3, the PFP and N agronomic efficiency (NAE) of nitrogen fertiliser under N2 increased by 52.3-62.4% and 39.2-63.0%, respectively. 3) The response of root trait plasticity to the N environment significantly differed (P<0.05). Compared with LX-3, T-43 showed a longer root length and larger specific surface area, which is a strategy for adapting to changes in the nutrient environment. For rice cultivars with high-NUE, the root-shoot ratio was optimised by increasing the FRLD, root distribution in upper soil layers, and root endogenous hormones (IAA, Z+ZR) under suitable nitrogen conditions (N2). An efficient nutrient acquisition strategy can occur through root plasticity, leading to increased yield and NUE.

Effect of Combinations of Chemical, Nano-Fertilizer and Bio-Fertilizer NPK on Yield and Quality Traits of some Bread Wheat Cultivars Triticum aestivum L.

A field experiment was conducted during the agricultural season 2022-2023 in the fields of the College of Agriculture - Al-Qasim Green University, located at latitude 32.33 north and longitude 42.45 east, in soil with a mixture of clay textures in order to study the effect of chemical and nano fertilizer NPK and bio-fertilizer on yield and quality traits of wheat cultivars. the bread. The experiment was applied according to split-plots arrangement using randomized complete block design (RCBD) with three replicates. Three cultivars of bread wheat occupied IPA-99, Bahouth-22 and Baghdad, and were given the symbols V1, V2, and V3 on the main plots, while fertilizer combinations occupied the sub plots, which are fully recommended compound fertilizer and fully recommended compound fertilizer + biofertilizer and compost. Full compound recommendation + nano fertilizer and 50% compound fertilizer only and 50% compound fertilizer + 50% biofertilizer and 50% compound fertilizer + 50% nanofertilizer and 50% complex fertilizer + 50% biofertilizer + 50% nanofertilizer and the codes were given F1 and F2 and F3, F4, F5, F6, and F7, respectively. The results of the study showed the superiority of cultivar IBA-99 over the other two cultivars by giving the highest average percentage of protein in grains and the ratio of wet and dry gluten, which amounted to 12.73%, 36.13% and 13.54%, respectively. Baghdad cultivar achieved a significantly excelled by giving the highest average of grain yield, biological yield and harvest index, which amounted to 4.60 tons ha-1 and 13.55 tons ha-1 and 33.04%, respectively. The plants treated with the fertilizer combination 50% compound fertilizer + 50% bio-fertilizer + 50% nano-fertilizer excelled in most of the studied traits (grain yield, biological yield, harvest index, protein percentage in grains, carbohydrates in grains, and the ratio of wet and dry gluten), which amounted to 5.15 tons ha-1 and 15.89 ton ha-1, 35.70%, 13.87%, 60.46%, 38.24%, and 14.71%, respectively.

Response of Growth and Forage Yield of some Oat (Avena sativa L.) Cultivars to Nitrogen Spraying and Cutting Time

This study was conducted during winter season of 2021-2022 at the Field Crops research station - College of Agriculture - University of Anbar to study the response of growth characteristics and forage yield for some oats cultivars under the influence of nitrogen spraying and cutting times. A split-split plots arrangement according to randomized complete block design at three replications was used. The results showed that the nitrogen spraying had a significant effect on all studied traits, as the spraying of nitrogen at a concentration of 6 g N L-1 recorded the highest means of plant height (63.03 cm), stem diameter, number of leaves per plant and green forage yield (64.43 ton ha-1). The mowing dates had a significant effect on the studied traits, as the mowing date after 60 days of planting achieved the highest means of plant height (74.34 cm) and green forage yield (73.87 ton ha-1). The cultivars was significantly differed in the studied traits, as the Carlop cultivar gave a highest green forage yield (58.11 tons ha-1). The di-interactions and tri-interaction between studied factors had a significant effect on the most studied traits.

Assessment of phenotypic and genotypic stability for seed and lint cotton yields of some cotton cultivars

Assessment of phenotypic and genotypic stability for seed and lint cotton yields of some cotton cultivars

Effect of Spraying Nano Fertilizer NPK and Nano Fertilizer Microelements on the Growth Characteristics of Maize Plants (Zea May L.)

To find out the effect of spraying nano fertilizer NPK and nano-microelements and the interaction between them on the growth and yield of yellow corn cultivar (Al Maha), a factorial experiment was carried out during the spring season in 2021. The first factor (Nano NPK) included the addition of nano-fertilizer NPK 20:20:20 with four concentrations, F0, the comparison treatment (spraying with water only), the first concentration (F1) 1.0 gm L−1, the second concentration (F2) 2.0 gm L−1, concentration third (F3) 2.5 g L−1. While the second factor included the addition of nano micro elements fertilizer (IQ COMBI) containing (8% Fe, 1.5% Zn, and 1.5% Mn) with four concentrations, namely (M0), the comparison treatment (spraying with water only), the first concentration (M1) 1.0 gm L−1 The second concentration (M2) 2.0 gm L−1, the third concentration (M3) 2.5 gm L−1, the experiment included (16) experimental units for the workers and they were distributed randomly with three replications for each treatment to become (48) experimental units, as the least difference test was used Significant Least Significant Difference (LSD) in comparison of means at a probability level of 0.05. The interaction between the two factors of the study, which are NPK nano fertilizer and nano fertilizer of microelements, it gave the same significant superiority to the F3M2 treatment for all vegetative growth indicators, which included plant height with the highest rate of (218.00 cm), leaf area (61.60 cm2 plant−1), dry weight (270.26 gm), chlorophyll (56.32 SPAD).

Response of some Yield and Quality Indicators of Different Cultivars of Bread Wheat to Spraying with Nano-Potassium Fertilizer

A field experiment was conducted in plot numbered 95 affiliated to Al-Mahaweel district, north of Babylon, during the seasons 2020-2021 and 2021-2022. In order to know the response of three bread wheat cultivars to the stages and concentrations of nano-spraying potassium. A randomized complete block design (RCBD) was used in a split-split plot with three replicates, where the cultivars(Abu Ghraib, Hawler, Aras) occupied the main plot, and the spraying stages (tilleting, elongation, booting) occupied the sub plot, while potassium nano-fertilizer concentrations occupied (2,1,0 g/L) for sub-sub-plot. The results showed that the cultivar had excelled in the highest values for the characteristics of weight of 1000 grains, total protein yield, and grain yield for both seasons, with averages of (38.01 g and 38.59 g), (0.498 tons.ha-1, 0.520 tons.ha-1) and (4.629 tons.ha-1). 1 and 4.777 tons.ha-1) respectively. The spraying treatment excelled in the booting stage of the nano potassium at a concentration of 2 g L-1, and recorded the highest values in the trait of the number of grains per spike and the percentage of gluten in the grains in%, as it recorded (44.43 grains and 44.88 grains), (16.59% and 16.71%), respectively, and the weight of 1000 grains for both seasons were (35.77 and 36.63 g) respectively.

The yields of industrial cultivars of primocane raspberry in the Central region of Russia

Industrial raspberry plantations in Russia occupy just over 10 % of all plantings and do not fully meet the needs of the population and the berry processing industry. One of the ways to increase the production efficiency of this crop is the use of high-yielding cultivars for planting new plantations. The aim of the researches was to evaluate the industrial assortment of primocane raspberry type in the conditions of the Central region of the Russian Federation in terms of productivity components and to isolate the most productive ones of them. The work was carried out in 2019-2022 on the basis of the genetic collection of berry crops of the Kokino base station of the FSBSI FRC of Horticulture. 8 cultivars of the primocane raspberry type of domestic selection, included in the register of breeding achievements and meeting the requirements for the industrial cultivar: Atlant, Zhar-ptista, Caramel’ka, Medvezhonok, Pingvin, Podarok Kashiny, Poklon Kazakovy, Salyut served as researches objects. It was established that the largest fruits were formed by the cultivars Salyut (4.6 g), Poklon Kazakovy (4.8 g), Medvezhonok (5.0 g), Podarok Kashiny (5.1 g). The multi-fruited cultivars Medvezhonok, Zhar-ptista and Podarok Kashiny were among the best in terms of stem loading by generative organs (194-216 pcs.). The cultivars Zhar-ptista, Poklon Kazakovy, Atlant, Salyute, Medvezhonok and Podarok Kashiny were distinguished by high yields (15.0-20.0 t/ha). The ripening degree of their harvest on average over the years of researches was 75.4-100 %.

Varietal Differences in the Root Systems of Rice (Oryza sativa L.) under Drip Irrigation with Plastic Film Mulch

With the escalating water scarcity in agriculture, a novel water-saving technique has emerged: drip irrigation with plastic film mulch (DI). Root function is crucial for sustaining rice production, and understanding its response to DI is essential. However, few studies have evaluated root systems in rice varietals and examined which kind of root system contributes to improving rice grain yield and water productivity in DI. If varietal differences of root reactions for water regimes were made clear, it might be more effective to find suitable varieties for DI and to improve grain yield in the DI system. To fill this knowledge gap, we conducted a two-year field experiment comparing two irrigation systems: continuous flooding (CF) and DI. We analyzed their effectiveness with four rice cultivars, including upland, F1 lowland, animal feed lowland, and lowland cultivars. Vertical root distribution, root bleeding rate, photosynthetic-associated parameters, water productivity, and yield performance were analyzed. In our study, the average grain yield of cultivars in the DI system (6.4 t/ha) was equivalent to those in the CF system (6.6 t/ha). The average water productivity under DI (0.34–0.75 kg m−3) demonstrated significant water-saving potential, saving approximately 35% of the total water supplied, resulting in higher water productivity compared to CF (0.27–0.51 kg m−3). Among the cultivars, the deep root weight of the upland cultivar significantly increased by 51% under DI compared to CF. The deep root ratio was positively correlated with the transpiration rate, grain yield, and water productivity, suggesting its contribution to high transpiration, thus maintaining a high carbon assimilation rate that results in high yield and water productivity. Therefore, deep roots are a notable trait corresponding to high yield under DI, and should be considered for the development of rice growth models for DI and the breeding of aerobic-adapted cultivars.

Biochar Regulates 2-Acetyl-1-Pyrroline, Grain Yield and Quality in Fragrant Rice Cropping Systems in Southern China

With the existing model of chemical fertilizer application faces, improving grain yield and quality is challenging. Fragrant rice is known for its distinctive aroma and flavor, but it generally produces less grain than non-fragrant rice varieties. Limited research has been conducted on the potential of biochar as a solution for increasing the grain yield of fragrant rice. In a two-year field trial conducted in 2022 and 2023, two fragrant rice cultivars, Meixiangzhan2 (MXZ2) and Xiangyaxiangzhan (XYXZ), were selected as the experimental materials. These rice cultivars were subjected to four different rates of biochar application: no biochar treatment(T1); biochar with 0.375 t ha−1 (T2); biochar with 0.75 t ha−1 (T3); and biochar with 1.50 t ha−1 (T4). The results showed that the grain yield of both cultivars increased to an extent in both 2022 and 2023 (an 8.57–33.77% increase for MXZ2; a 6.00–21.59% increase for XYXZ). Furthermore, under the T2, T3, and T4 treatments, there was an increase in the number of effective panicles, seed setting rate, 1000-grain weight, biomass accumulation, net photosynthetic rate, and intercellular CO2 concentration. However, the transpiration rate and stomatal conductance decreased. The content of 2-acetyl-1-pyrroline (2-AP) increased with an increased rate of biochar application, and the highest content was observed under the T4 treatment (153.54–178.32 µg kg−1 in 2022; 163.93–180.28 µg kg−1 in 2023). The activities of proline dehydrogenase (PDH) and 1-pyrrolin-5-carboxylic acid synthase (P5CS), as well as the contents of proline (PRO), 1-pyrrolin-5-carboxylic acid (P5C), ∆1-pyrroline, and methylglyoxal, were improved under the T2, T3, and T4 treatments compared to the T1 treatment. Moreover, under the T2, T3, and T4 treatments, the brown rice rate, milled rice rate, and head rice rate increased, while the chalkiness degree and chalk rice rate decreased. Our correlation analysis showed that grain yield was positively correlated with total biomass accumulation, the number of grains per panicle, and the seed setting rate. Additionally, the content of 2-AP showed positive correlations with PRO, P5C, ∆1-pyrroline and methylglyoxal, and the activities of PDH and P5CS. In conclusion, applying biochar at a rate of 1.5 t ha−1 can be more effective in increasing the grain yield and 2-AP content of fragrant rice.

Higher yields of modern maize cultivars are not associated with coordinated light and N distribution within the canopy

ContextCanopy architecture and associated light distribution, nitrogen distribution, and leaf physiological characteristics drive canopy photosynthesis, and ultimately determine grain yields. Breeding has increased those yields during the past decades of breeding history but it is not clear if this also improved efficiency in nitrogen allocation for optimal light use. Research questionsTo what extent has selection for yields affected maize canopy architecture and the vertical distribution of light and nitrogen? MethodsA 2-year field experiment was conducted in Jilin province, Northeast China, involving six maize cultivars released between 1950 and 2004. The canopy architecture, the vertical distribution patterns of light and nitrogen, and grain yields of these cultivars were quantified and analysed. ResultsThe genetic gain in grain yield through breeding was 109 kg ha−1 year−1, and the concomitant increase in aboveground biomass was 16.1 g m−2 ground year −1 at maturity stage. Modern cultivars had more erect leaves compared to older cultivars, especially the leaves above the ear leaf, showing a decrease of 0.31° year−1. The changes in leaf area index (LAI) and leaf angle contributed to the improved light distribution within the canopy over generations of selection, as the light extinction coefficient KL decreased significantly by 0.67% year−1. The canopy nitrogen content increased by 0.09 g N m−2 ground year−1, but the average canopy specific leaf nitrogen (canopy N/LAI) tended to decrease. The relationship between light and nitrogen distribution within the canopy differed among cultivars but did not relate to year of release(YOR), indicating that breeding of maize cultivars from the 1950–2004 primarily led to changes in canopy N and canopy architecture and did not improve the coordination between light and nitrogen in maize canopy. ConclusionYield gain through breeding history from 1950 to 2004 was strongly associated with increases in canopy N and LAI linked to increasing erectness of leaves, which improved light distribution under these conditions. In contrast, the coordination of light and nitrogen distribution was not changed much. We conclude that the higher yields that are obtained with modern cultivars do not appear to rely on a coordinated light and N distribution within the canopy.

The enhancement of photosynthetic performance, water use efficiency and potato yield under elevated CO2 is cultivar dependent.

As a fourth major food crop, potato could fulfill the nutritional demand of the growing population. Understanding how potato plants respond to predicted increase in atmospheric CO2 at the physiological, biochemical and molecular level is therefore important to improve potato productivity. Thus, the main objectives of the present study are to investigate the effects of elevated CO2 on the photosynthetic performance, water use efficiency and tuber yield of various commercial potato cultivars combined with biochemical and molecular analyses. We grew five potato cultivars (AC Novachip, Atlantic, Kennebec, Russet Burbank and Shepody) at either ambient CO2 (400 μmol CO2 mol-1) or elevated (750 μmol CO2 mol-1) CO2. Compared to ambient CO2-grown counterparts, elevated CO2-grown Russet Burbank and Shepody exhibited a significant increase in tuber yield of 107% and 49% respectively, whereas AC Novachip, Atlantic and Kennebec exhibited a 16%, 6% and 44% increment respectively. These differences in CO2-enhancement of tuber yield across the cultivars were mainly associated with the differences in CO2-stimulation of rates of photosynthesis. For instance, elevated CO2 significantly stimulated the rates of gross photosynthesis for AC Novachip (30%), Russet Burbank (41%) and Shepody (28%) but had minimal effects for Atlantic and Kennebec when measured at growth light. Elevated CO2 significantly increased the total tuber number for Atlantic (40%) and Shepody (83%) but had insignificant effects for other cultivars. Average tuber size increased for AC Novachip (16%), Kennebec (30%) and Russet Burbank (80%), but decreased for Atlantic (25%) and Shepody (19%) under elevated versus ambient CO2 conditions. Although elevated CO2 minimally decreased stomatal conductance (6-22%) and transpiration rates (2-36%), instantaneous water use efficiency increased by up to 79% in all cultivars suggesting that enhanced water use efficiency was mainly associated with increased photosynthesis at elevated CO2. The effects of elevated CO2 on electron transport rates, non-photochemical quenching, excitation pressure, and leaf chlorophyll and protein content varied across the cultivars. We did not observe any significant differences in plant growth and morphology in elevated versus ambient CO2-grown plants. Taken all together, we conclude that the CO2-stimulation of photosynthetic performance, water use efficiency and tuber yield of potatoes is cultivar dependent.