Early Sowing Dates Research Articles

Formation of the leaf surface and grain yield of winter rye (Secale L.) with the use of mineral fertilizers in irrigated soils of Uzbekistan

One of the most important, useful and promising grain crops is winter rye. The advantage of winter rust is: resistance to winter and cold, adaptation to a stress factor, high content of minerals and vitamins in grain. The rye grain contains 13% protein, as well as a large amount of minerals such as: manganese, boron, aluminum, iodine, bromine, fluorine, cobalt, molybdenum, strontium, cesium, copper and also vitamins A1, B1, B2, E3, threonine and tyrosine other substances. Therefore, rye bread is considered the main dietary bread. In recent years, the need for rye bread has been increasing. This research intends to analyze formation of the leaf surface and grain yield of winter rye while using different type of mineral fertilizers. The results showed that at earlier sowing dates, the use of foliar feeding and the Baikal biostimulant had a positive effect on the formation of winter rye fruit elements. Accordingly, the highest indicator in terms of grain weight per 1 ear of 1.37 grams was noted at early sowing dates using foliar feeding, an increase from the control was 0.47 grams.

К юбилею ФНЦ «ВИК им. В. Р. Вильямса»: об отделе защиты растений

The main directions of research on chemical means of protecting fodder crops from diseases, pests and weeds in the field fodder production of the All-Russian Fodder Research Institute are given. Studies on toxicological assessment of feed and soil are given. Plant Protection Department included three laboratories: the Herbicide Laboratory, the Plant Protection Laboratory and the Feed Toxicological Evaluation Laboratory. The Laboratory of Herbicides was established in 1967 to conduct research on the chemical method of controlling weeds on fodder crops, hayfields and pastures. Research on the study of pests of fodder crops was started in 1939 in the newly created laboratory for the protection of fodder crops from pests and diseases. The Feed Toxicology Assessment Laboratory was established in 1980 to assess pesticide residues in crop and soil. As a result of the studies, a system of measures for clover from pests has been developed; alfalfa diseases and pests and measures to combat them in the Non-Chernozem zone were studied. Pests and pathogens of corn, root crops, peas, lupine and other fodder crops were identified; their biology, ecology and harmfulness have been studied. A set of protective measures has been developed to combat the main pests and diseases of fodder crops, including soil cultivation techniques, early sowing dates, the use of resistant varieties, micro- and macrofertilizers, pre-sowing treatment of seeds with combined preparations, etc. Plant Protection Department carried out work with herbicides. As a result of research begun in 1950, a method was developed to clean the meadows from weedy herbaceous vegetation with the help of preparations 2,4-D and 2M-4X. A chemical method for the destruction of woody and shrubby vegetation with the help of the same preparations in the Non-Chernozem zone of the European part of the USSR has been developed. Methods of using herbicides on crops of almost all fodder crops have been developed: perennial and annual legumes and cereal grasses for green mass and seeds, corn, fodder beets, rapeseed, etc. The theoretical issues of the mutual influence of fodder crops and weeds are studied, the substantiation of the effectiveness of the use of herbicides on different types of soils is given.

Modeling future climate change impacts on sorghum (Sorghum bicolor) production with best management options in Amhara Region, Ethiopia

Sorghum is one of the most important cereal crops well adapted in arid and semi-arid areas of Ethiopia but yield is low as compared to its potential. The crop has been adversely affected by climate change and climate variability accompanied by low soil fertility, insects and weeds. Thus, assessment of impact of projected climate change is important for developing suitable management strategies. The present study was conducted with the objectives (1) to calibrate and evaluate the CERES-sorghum model in DSSAT (2) to assess impact of projected climate change on sorghum production in 2030s (2020–2049) and 2050s (2040–2069) under RCP4.5 and RCP8.5 scenarios and (3) to identify best crop management strategies that can sustain sorghum production. The CERES-sorghum model was calibrated and evaluated using field experimental data of anthesis, physiological maturity, grain yield and aboveground biomass yield. In the simulation, the initial weather and CO2 were modified by future climates under the two climatic change scenarios (RCP4.5 and RCP8.5). Historical daily weather data (1981–2010) of rainfall, maximum temperature, minimum temperature, and solar radiation were obtained from the nearest weather stations at Sirinka and Kombolcha while future climate date for 2030s and 2050s were downloaded from the ensemble of 17 CMIP5 GCM outputs run under RCP4.5 and RCP8.5 downscaled to the study sites using MarkSim. Different sowing dates, nitrogen rates, and supplemental irrigation were evaluated for their effectiveness to increase sorghum yield under the present and future climate conditions of the study area. The result of model calibration showed that the RMSE for anthesis, physiological maturity, grain yield, and above-ground biomass yield were 2 days, 2 days, 478 kg ha−1, and 912 kg ha−1, respectively with normalized nRMSE values of 2.74%, 1.6%, 13.42%, and 5.91%, respectively. During the model evaluation the R2 values were 78% for anthesis, 99% for physiological maturity, 98% for aboveground biomass yield, and 94% for grain yield. The d-statistics values were 0.87, 0.91, 0.67, and 0.98 while the nRMSE values were 2.6%, 2.7%, 23.4%, and 4.1% for the respective parameters. The result of statistical analysis for both model calibration and evaluation revealed that there existed strong fit between the simulated and observed values that indicated the model can be used for different application to improve sorghum productivity in the region. The result of impact analysis showed that sorghum grain yield may decrease by 2030s and 2050s under both RCPs scenarios. However, the result of management scenarios showed that sorghum yield may be substantially increased through use of optimum nitrogen fertilizer, application of supplemental irrigation and by using early sowing dates individually or in combination. In conclusion, projected climate change could adversely affect sorghum production in the semi-arid areas of Ethiopia in the present and future climate conditions but impact could be reduced by using suitable crop management strategies.

Augmentation of maize yield by strategic adaptation to cope with climate change for a future period in Eastern India

The changing climate may adversely affect crop production unless appropriate adaptation strategies are used. The appropriate level of fertilization and sowing dates are some of the simple and most economic but effective strategies which can be developed and applied for specific climatic regions. Keeping the aforesaid fact in mind, varying sowing dates were analyzed as a strategic adaptation to cope with the climate change for maize yield in Eastern India under rainfed and irrigated conditions. Evaluation of sowing dates was performed by the CERES-maize model for estimating the maize yield for the projected time periods 2021–2050 (2050s), and 2051–2080 (2080s) by using different Representative Concentration Pathways (RCP) 2.6, 4.5, 6.0, and 8.5 W m-2 respectively from the 17 Global circulation models (GCM) of CMIP5 (Coupled Model Intercomparison Project Phase 5) climate projection scenarios, and the results projected were compared with the baseline scenario of 1982–2012. The results indicated that the effect of late sowing dates (30 June and 10 July) was more in RCPs 6.0, and 8.5 for both the time periods 2050s and 2080s as during the tasseling stage the intensity of solar radiation decreased, while for the recommended (20 June), and earlier sowing (30 May and 10 June) dates reduced grain yield was recorded for the rainfed condition due to higher temperature stress. In irrigated conditions, the recommended sowing date (15 January) was suitable for time slice 2050s in all the RCP scenarios, while the earlier sowing date (25 December) was found to be suitable in the time slice period of 2080s with RCP 8.5. Thus, shifting sowing dates can be an effective management strategy to cope with climate change with less waste and efficient use of resources.

ВЛИЯНИЕ НОРМ ВЫСЕВА И СРОКОВ ПОСЕВА НА ПРОДУКТИВНОСТЬ ЯРОВОГО РАПСА В УСЛОВИЯХ ЛЕСОСТЕПНОЙ ЗОНЫ РСО – АЛАНИЯ

One of the main factors in the growth of feed production is the cultivation of the most productive varieties of forage crops. Annual grasses are cultivated to obtain green mass, silage haylage. They are characterized by a different growing season. Using these biological features and sowing crops at a certain time, it is possible to obtain a feed mass for a long period. The article presents the results of research on the influence of seeding rates and sowing dates on the productivity of spring rapeseed. The use of spring rapeseed in mowing and crop crops is considered as an environmentally friendly and effective way to increase the yield of green mass. Biological survival of plants with an increase in seeding rates from 1.2 to 3.6 million. germination of seeds decreased and averaged 77.4 – 71.9%. The seeding rate is 2.0 million. germinating seeds per hectare provided optimal density of herbage in all terms of sowing. The specified norms provided the actual density before harvesting – 1.4 million/ha. Biological characteristics of plants - leaf area, foliage and plant height were the best at a seeding rate of 2.0 million vsx. seeds per hectare. The analysis of crop data has shown the exceptional importance for the formation of high yields of spring rapeseed - early sowing dates. The optimal sowing period for spring rapeseed should be considered July 20 to August 20. It is better to harvest rapeseed for green fodder in the budding phase – the beginning of flowering, since during this period the feedability and feed value are much higher than in the later phases of the growing season.

ОСОБЕННОСТИВОЗДЕЛЫВАНИЯ И ИСПОЛЬЗОВАНИЯ НЕТРАДИЦИОННЫХЛЕКАРСТВЕННЫХ КУЛЬТУР

The article presents an assessment of various types of agricultural raw materials according to technological indicators. Three groups of medicinal plants were taken for study, distinguishing among themselves by type of use. The sowing dates affecting the gross harvest of medicinal plant raw materials were studied. It has been established that early sowing dates allow increasing the yield of medicinal plant raw materials from 10.0 to 25%. The use of the studied range of medicinal herbs, which differ by type of use, will allow farms to increase the profitability of production up to 75%.The conducted pharmaceutical analysis of the obtained medicinal raw materials, in the control and analytical laboratory of Ulyanovsk, showed that the obtained material corresponds in its indicators to the quality of medicinal raw materials used by pharmaceutical enterprises.

Sunflower Yield and Quality Under the Influence of Sowing Date, Plant Population and the Hybrid

Sunflower yield and quality can be significantly increased by optimizing agricultural practices and in corroboration with plant characteristics and environment. Sowing time and plant population are two important factors which affects vegetation and sunflower production. The paper focuses on the influence of these factors in conjunction with other technological elements and the climatic evolution on the final production and its quality in the southern part of the country. The researches were performed during the 2019-2021, in the experimental field of NARDI Fundulea and the aim of this study was to evaluate the effect of sowing date, plant population and climatic conditions on the yield and quality of sunflower. Experimental treatment comprised three different sowing dates (I - April 1, II - April 15 and III - May 1), using three sunflower hybrids (FD15E27, FD19E42 and Performer) and three plant populations (30,000, 50,000 and 70,000 plants/hectare). Rainfall was uneven during the growing season, from year to year, and maximum sunflower production and quality was maximized from medium plant density and earlier sowing dates, depending on hybrid and technology. The oil content varied widely between 44.2-50.0% depending on the hybrid and plant density and sowing date. The early sowing date led to increase of oil content, which was depending on climatic conditions and plant populations. The primary source of variation was the sowing date, the difference between oil content in early and late sowing dates was influenced by plant population, hybrid and year varying from 0.7% to 5.8%. The seeds yield and quality of the sunflower were significantly influenced by the climatic conditions of the agricultural year, the sowing date, the plant population and used hybrids, as well as the interaction between these factors.

Formation of Sorghum vulgare and Sorghum orysoidum productivity as affected by sowing dates in the conditions of the eastern part of the Forest-Steppe of Ukraine

Purpose. To investigate the influence of varietal characteristics and terms of sowing seeds on the productivity of Sorghum vulgare and Sorghum orysoidum in the conditions of the Eastern Forest-Steppe of Ukraine.
 Methods. The following methods were used in the research: field – study of biological, ecological features of growth and development of productivity and quality of the crop; mathematical and statistical – used to process experimental data.
 Results. On average, over the years of research, the highest field germination of Sorghum vulgare and Sorghum orysoidum seeds was observed at the optimal sowing dates, i.e. early to middle May: and in ‘Dniprovskyi 39’ variety of Sorghum vulgare it was 88.1 and 87.3%, while in Sorghum orysoidum variety ‘Samaran 6’ 87.6 and 87.1%. In the early sowing dares, the field germination of seeds was lower on average in the experiment by 11.0–12.3%. Tillering of the plants depended on the studied varieties and averaged 1.1–1.2 shoots/plant in ‘Dniprovskyi 39’ and 1.0–1.3 shoots/plant in ‘Samaran 6’. The height of plants in the experiment was 118.2–122.3 cm in ‘Dniprovskyi 39’ and 112.8–116.2 cm in ‘Samaran 6’. The diameter of the stem of sorghum plants on average in the experiment ranged from 1.5 to 1.6 cm. The leaf area during the stages throwing of panicle – flowering reached a maximum for sowing seeds in the early and middle May and amounted to 37.4 and 36.7 thousand m2/ha in ‘Dniprovskyi 39’ and 36.8 and 35.9 thousand m2/ha in ‘Samaran 6’. Optimal sowing of sorghum seeds contributed to the formation of high crop productivity: in ‘Dniprovskyi 39’, grain yield was 7.1 and 6.8 t/ha, biomass yield 37.4 and 35.6 t/ha; in ‘Samaran 6’, grain yield was 6.4 and 6.1 t/ha, biomass yield 35.9 and 33.6 t/ha.
 Conclusions. It was found that the field germination of seeds mostly depends on weather conditions in the research years (32.1%) and sowing dates 23.4%. Varietal characteristics influenced much less, with the share of influence of 8.4%. Early sowing dates (late April), in comparison with the optimal terms (early to middle May) reduced the grain yield of ‘Dniprovskyi 39’ by 4.2–12.6% and ‘Samaran 6’ by 4.7–9.4%; biomass yield by 4.8–9.6% and 6.4–10.6%, respectively. Biometric indicators of plant growth and development were also higher. As a result of correlation-regression analysis, a close relationship was found between grain yield and leaf area. The correlation coefficient was R = 0.9454 ± 0.163 and 0.997 ± 0.037, and the coefficient of determination was R² = 0.8939 and 0.9946. According to Student criteria, tf = 5.81 > t0.05 = 2.78 and tf = 27.14 > t0.05 = 2.78. A strong correlation was observed between grain yield and plant height with a coefficient of determination R2 = 0.842 and a correlation coefficient R = 0.918 ± 0.199 and between biomass yield and plant height, respectively R2 = 0.7065 and R = 0.841 ± 0.271. According to Student criteria, tf = 3.10 > t0.05 = 2.78 and tf = 4.62 > t0.05 = 2.78.

Combining multi-environmental trials and crop simulation to understand soybean response to early sowings under contrasting water conditions

Anticipating sowing date in spring-sown crops is an agronomic strategy often suggested in Europe to escape water and heat stresses during the most susceptible growth periods occurring in early summer. This strategy was evaluated experimentally in soybean (Glycine max (L.) Merrill) by comparing early and conventional sowing dates for a range of cultivars grown in 18 “site x year” environments from southern France between 2010 and 2018. Conventional sowing often resulted in higher grain yields than early sowing, the latter being more favorable to grain size and protein concentration. STICS crop growth model was used to calculate dynamic abiotic (radiation, water, high and low temperatures, nitrogen) stress factors influencing the main crop physiological processes. Ecoclimatic and STICS-based agrophysiological indicators were used in a PLS (Partial Least Squares) regression as explanatory variables of grain yield (r² = 0.33). The key indicators were radiation interception from emergence to maturity, severe stomatal water stress during all the reproductive phase and high temperature since the beginning of grain filling. STICS crop model was used to characterize the 157 “cultivar x site x year x sowing date x irrigation” environments, according to water, heat and cold stresses importance in different phenophases. Then 5 profiles of abiotic stresses emerged from a clustering analysis in two steps by hierarchical ascending classification and K-means. STICS-based environmental characterization was used to explain the relative success or failure of early sowing dates and early-maturing cultivars.

Interplay of irrigation strategies and sowing dates on sunflower yield in semi-arid Mediterranean areas

Sunflower (Helianthus annuus L.) is one of the most cultivated oil crops in the world. Given its high dependence on water availability, its cultivation in the Mediterranean area is severely threatened by climate change: very hot and dry weather conditions currently occurring in the Mediterranean area have a negative impact on sunflower yield. Many studies have pointed to earlier sowing dates as a promising strategy to prevent summer drought stress causing sunflower yield losses, but the literature on winter sowing dates is scarce. The aim of this research was to quantify the interplay between sowing date (winter time included) and water regime to sustain sunflower cultivation in the Mediterranean area. A field experiment and a modeling study were carried out to evaluate the effects of different sowing dates (00SD: ‘conventional sowing date’ in March/April and ‘earlier sowing dates’ in December-January-February, depending on years) under two different water regimes (irrigated vs. rainfed) on quantitative traits of high oleic cultivars of sunflower. Field experiments revealed that sowing in late February - mid March was the most effective strategy in terms of achene productivity. Achene production by sunflower was also simulated using EPIC under a baseline climatic scenario and for 4 hypothetical sowing dates (D1: 10th January, D2: 10th February, D3: 10th March, D4: 10th April) and different irrigation strategies. The most effective sowing date was D3 under rainfed conditions, confirming the results of the field study. Irrigation from 20 days before anthesis up to flowering significantly improved achene yield for the early sowing dates (D1 and D2), which almost reached their respective yield potentials. This confirms that an earlier sowing date could be a viable management strategy in Mediterranean areas with little water availability.

Formation of productivity of naked oat varieties under different cultivation conditions

The results of studying naked oat yield indicators depending on different sowing dates and seeding rates are presented. The study was carried out in 2016-2020 in a field experiment in Western Siberia. Samples of different groups of the crop ripeness were studied: mid-early variety Gavrosh and mid-ripening variety Ofenya. The duration of the growing season of naked oats was influenced by meteorological factors. There was a tendency observed for a decrease in the duration of interphase periods and the growing season as a whole from an early sowing date to a later one by 4-10 days for the Gavrosh variety and by 8-10 days for the Ofenya variety. The yield of the Gavrosh variety at an early sowing period significantly exceeded the same indicator at a mid-period by 17.6% and at a late period - by 19.0%, of the Ofenya variety - by 10.9% and 16.2%, respectively. The increase in the yield for the early sowing period of the mid-early variety Gavrosh relative to the middle and late sowing dates was determined by a larger grain size (r = 0.6929 ... 0.9535 at R = 0.5140). For the midripening variety Ofenya, the number of productive stems per unit area (r = 0.7444 ... 0.9054 with R = 0.5140) and the weight of 1000 grains (r = 0.5350 ... 0.8297 at R = 0.5140) were of more importance in the years of research on all variants. The most optimal seeding rate for naked oat varieties is 5.0-6.0 million germinating grains/ha. At this rate, it was not the maximum manifestation of individual indicators of the yield structural elements, but a combination of their average values was noted.

Using a gene-based phenology model to identify optimal flowering periods of spring wheat in irrigated mega-environments.

To maximize the grain yield of spring wheat, flowering needs to coincide with the optimal flowering period (OFP) by minimizing frost and heat stress on reproductive development. This global study conducted a comprehensive modelling analysis of genotype, environment, and management to identify the OFPs for sites in irrigated mega-environments of spring wheat where the crop matures during a period of increasing temperatures. We used a gene-based phenology model to conduct long-term simulation analysis with parameterized genotypes to identify OFPs and optimal sowing dates for sites in irrigated mega-environments, considering the impacts of frost and heat stress on yield. The validation results showed that the gene-based model accurately predicted wheat heading dates across global wheat environments. The long-term simulations indicated that frost and heat stress significantly advanced or delayed OFPs and shrank the durations of OFPs in irrigated mega-environments when compared with OFPs where the model excluded frost and heat stress impacts. The simulation results (incorporating frost and heat penalties on yield) also showed that earlier flowering generally resulted in higher yields, and early sowing dates and/or early flowering genotypes were suggested to achieve early flowering. These results provided an interpretation of the regulation of wheat flowering to the OFP by the selection of sowing date and cultivar to achieve higher yields in irrigated mega-environments.

Kanolada (Brassica napus L.) Farklı Ekim Zamanı, Çeşit ve Tohumluk Miktarının Verim ve Kalite Özelliklerine Etkisi

This study was carried out to determine the effect of different sowing dates and seeding rate on seed yield, oil and protein contents of seed in two rapeseed cultivars in the field of experiment and application of Aydin Adnan Menderes University Faculty of Agriculture during 2014/2015 and 2015/2016. The experiment was the split-split-plot design with 4 replications. The sowing dates, cultivars and seeding rates were arranged to main, sub and sub-sub plots, respectively. This experiment was conducted applying two sowing dates (early and late), two winter type cultivars (NK Petrol and NK Caravel) and five seeding rates (3, 5, 7, 9 and 11 kg ha-1). The early sowing date and 7.0 kg ha-1 seeding rate given the highest seed yield for both cultivars based on two-year results. The interaction between sowing dates and cultivars for crude oil rate was significant, and the highest crude oil rate was recorded in NK Petrol cultivar (43.34 - 43.54%) at the first sowing date in both years. Non-significant protein content for all factors and interactions varied from 19.10% to 23.72%. Finally, it was recommended the earliest possible sowing with 7.0 kg ha-1 seeding rate for seed yield and quality in winter rapeseed growing. Moreover, it was recommended that NK Petrol for early sowing dates and NK Caravel for late sowing dates should be used as a cultivar.

Evaluation of Genotype, Environment, and Management Interactions on Fava Beans under Mediterranean Field Conditions

Faba beans (Vicia faba L.), also known as fava beans, like other crops, are influenced by several factors: their genotype, environment, and management, as well as the interaction between these, have an important impact on seed yielding and seed quality traits. This study was conducted at three locations in South Italy between 2017 and 2019 to evaluate the sowing date effect on yield and yield components of three Vicia faba L., originating from cool climates. The results showed that seed yield (SY) and yield components declined with sowing delay. The crop’s environment (year × site) and management (sowing date) were found to explain 34.01% and 42.95% of the total seed yield variation, respectively. The data showed that the tested genotypes were positively influenced by the environment with sandy loam soil and early winter sowing date, resulting in either a greater number of SY and THS than in the other environment. The three faba bean genotypes showed tolerance to winter frost conditions in the two growing seasons.

Genetic and Management Effects on Barley Yield and Phenology in the Mediterranean Basin.

Heading time in barley is considered a key developmental stage controlling adaptation to the environment and it affects grain yield; with the combination of agronomy (planting dates) and genetics being some of the determinants of adaptation to environmental conditions in order to escape late frost, heat, and terminal drought stresses. The objectives of this study are (i) to apply a gene-based characterization of 118 barley doubled haploid recombinants for vernalization, photoperiod, and earliness per se; (ii) use such information to quantify the optimal combination of genotype/sowing date that escapes extreme weather events; and (iii) how water and nitrogen management impact on grain yield. The doubled haploid barley genotypes with different allelic combinations for vernalization, photoperiod, and earliness per se were grown in eight locations across the Mediterranean basin. This information was linked with the crop growth model parameters. The photoperiod and earliness per se alleles modify the length of the phenological cycle, and this is more evident in combination with the recessive allele of the vernalization gene VRN-H2. In hot environments such as Algeria, Syria, and Jordan, early sowing dates (October 30 and December15) would be chosen to minimize the risk of exposing barley to heat stress. To maintain higher yields in the Mediterranean basin, barley breeding activities should focus on allelic combinations that have recessive VRN-H2 and EPS2 genes, since the risk of cold stress is much lower than the one represented by heat stress.

Divergent climate feedbacks on winter wheat growing and dormancy periods as affected by sowing date in the North China Plain

Abstract. Crop phenology exerts measurable impacts on soil surface properties, biophysical processes and climate feedbacks, particularly at local or regional scales. Nevertheless, the response of surface biophysical processes to climate feedbacks as affected by sowing date in winter wheat croplands has been overlooked, especially during winter dormancy. The dynamics of leaf area index (LAI), surface energy balance and canopy temperature (Tc) were simulated by a modified SiBcrop (Simple Biosphere) model under two sowing date scenarios (early sowing, EP; late sowing, LP) at 10 stations in the North China Plain. The results showed that the SiBcrop model with a modified crop phenology scheme well simulated the seasonal dynamic of LAI, Tc, phenology and surface heat fluxes. An earlier sowing date had a higher LAI with earlier development than a later sowing date. But the response of Tc to the sowing date exhibited opposite patterns during the dormancy and active-growth periods: EP led to higher Tc (0.05 K) than LP in the dormancy period and lower Tc (−0.2 K) in the growth period. The highest difference (0.6 K) between EP and LP happened at the time when wheat was sown in EP but was not in LP. The higher LAI captured more net radiation with a warming effect but partitioned more energy into latent heat flux with cooling. The climate feedback of the sowing date, which was more obvious in winter in the northern areas and in the growing period in the southern areas, was determined by the relative contributions of the albedo radiative process and partitioning non-radiative process. The study highlights the surface biophysical process of land management in modulating climate.

Optimization of timing of next-generation emergence in Amaranthus hybridus is determined via modulation of seed dormancy by the maternal environment.

The timing of emergence of weed species has critical ecological and agronomical implications. In several species, emergence patterns largely depend on the level of dormancy of the seedbank, which is modulated by specific environmental factors. In addition, environmental conditions during seed maturation on the mother plant can have marked effects on the dormancy level at the time of seed dispersal. Hence, the maternal environment has been suggested to affect seedbank dormancy dynamics and subsequent emergence; however, this modulation has not been adequately examined under field conditions, and the mechanisms involved are only partly understood. Combining laboratory and field experiments with population-based models, we investigated how dormancy level and emergence in the field are affected by the sowing date and photoperiod experienced by the mother plant in Amaranthus hybridus, a troublesome weed worldwide. The results showed that an earlier sowing date and a longer photoperiod enhanced the level of dormancy by increasing the dormancy imposed by both the embryo and the seed coat. However, this did not affect the timing and extent of emergence in the field; on the contrary, the variations in dormancy level contributed to synchronizing the emergence of the next generation of plants with the time period that maximized population fitness. Our results largely correspond with effects previously observed in other species such as Polygonum aviculare and Arabidopsis, suggesting a common effect exists within different species.

Effective Seed Yield and Flowering Synchrony of Parents of CIMMYT Three-Way-Cross Tropical Maize Hybrids

Genotype, environmental temperature, and agronomic management of parents influence seed yield in three-way cross hybrid maize seed production. The objective of this research was to generate information on the seed production of six three-way cross hybrids and their progenitors, adapted to tropical lowlands. Data on days to—and duration of—flowering, distance to spike and stigmas, and seed yield of five female single crosses and five male inbred lines were recorded for different combinations of four planting densities and four sowing dates in Mexico. The effect of planting density was not significant. The male inbred line T10 was the earliest and highest seed yield and T31 the latest, occupying second place in yield. The single crosses T32/T10 and T13/T14 were the earliest and had the highest effective seed yield. At the earliest sowing date, the females were later in their flowering, accumulated fewer growing degree days (GDD), and obtained higher yields since the grain-filling period coincided with hot days and cool nights. To achieve greater floral synchronization and therefore greater production of hybrid seed, differential planting dates for parents are recommended based on information from the accumulated GDD of each parent. The three-way cross hybrids were classified according to the expected seed yield of the females and the complexity in the synchronization of flowering of their parents.

Impact of early and normal sowing dates on seed cotton yield and fiber quality traits of elite cotton lines (Gossypium hirsutum L.)

Impact of early and normal sowing dates on seed cotton yield and fiber quality traits of elite cotton lines (Gossypium hirsutum L.)

Early-Stage Phenotyping of Root Traits Provides Insights into the Drought Tolerance Level of Soybean Cultivars

Soybean (Glycine max (L.) Merr.) may contribute to the agro-ecological transition of cropping systems in Europe, but its productivity is severely affected by summer drought. New drought-avoidance cropping strategies, such as early sowing, require cultivars with high early plant growth under suboptimal conditions. This study aims at phenotyping early-stage root and shoot traits of 10 cultivars commonly grown in Europe. Cultivars were grown in minirhizotrons under two soil moisture status in controlled conditions. Root and shoot traits were evaluated at 10 days after sowing. Field early growth of two cultivars was also analyzed under early and conventional sowing dates. A significant intraspecific variability (p < 0.05) was found for most investigated shoot and root morpho-physiological traits regardless of the soil moisture status under controlled conditions. However, no significant difference among cultivars (p > 0.05) was found in terms of root architectural traits that were mainly affected by water stress. Total root length was positively correlated with shoot length and shoot dry matter (p < 0.05). Under field conditions, the differences between cultivars were expressed by the canopy cover at emergence, which determines the subsequent canopy cover dynamics. The significant early growth difference among cultivars was not related to the maturity group. Cultivars characterized by high root depth and length, high root density and narrow root angle could be considered as good candidates to cope with water stress via better soil exploration. New agronomic strategies mobilizing the diversity of cultivars could thus be tested to improve soybean water use efficiency in response to climate change.