Decrease In Plant Density Research Articles

The effects of water stress and plant density on vegetative and reproductive characteristics of safflower in the semi-arid region

The limited availability of water for irrigation in semi-arid areas necessitates the use of deficit irrigation techniques. Deficit irrigation is an irrigation practice whereby water supply is reduced below maximum levels and a mild water-deficit stress affect the crop yield. Current field experiment was aimed to investigate different densities of safflower (Carthamus tinctorius L.) (33, 40, 50, 66 plants m2 abbreviated as P33, P40, P50, and P66, respectively) under different soil moisture content (irrigation up to 100%, 70%, and 50% field capacity showed as FC100, FC70, and FC50, respectively) on the growth characteristics of safflower in a semi-arid region in the northwest of Iran. Number of days to maturity decreased significantly under deficit irrigation (FC70 and FC50). The longest growth period was recorded for plants grown under P66-FC100 conditions which was 7% higher than P50-FC100. The decrease in plant density caused an increase in chlorophyll content and this trend was more evident under Fc100. Increasing the density under FC100 conditions increased the plant height. However, this trend was not observed under deficit irrigation conditions. Decreasing the plant density per unit area induced the lateral growth, and increased the number of capitula per plant, the weight of capitulum, the number of achenes per capitulum and the 1000-achenes weight. This trend was more prominent under FC100 conditions. Mild deficit-irrigation (irrigation up to FC70) resulted approximately 20% reduction in achene yield. Thus, water management is very important to certify a conservational water supply in semi-arid regions. Irrigation up to FC70 under the studied area is a reasonable and good management method to save irrigation water.

Dynamic plant spacing in tomato results in high yields while mitigating the reduction in fruit quality associated with high planting densities.

High planting densities achieve high light interception and harvestable yield per area but at the expense of product quality. This study aimed to maintain high light interception without negative impacts on fruit quality. Dwarf tomato was grown at four densities in a climate-controlled room-at two constant densities (high and low) and two dynamic spacing treatments (maintaining 90% and 75% ground coverage by decreasing planting density in 3-4 steps)-resulting in ~100, 19, 54, and 41 plants/m2 averaged over 100 days of cultivation, respectively. Constant high density resulted in the highest light use efficiency (LUE; 7.7 g fruit fresh weight per mol photons incident on the canopy) and the highest harvestable fruit yield (11.1 kg/m2) but the lowest fruit size and quality. Constant low density resulted in the lowest LUE and yield (2.3 g/mol and 3.2 kg/m2, respectively), but higher fruit size and quality than high density. Compared to low density, maintaining 90% ground coverage increased yield (9.1 kg/m2) and LUE (6.4 g/mol). Maintaining 75% ground coverage resulted in a 7.2 kg/m2 yield and 5.1 g/mol LUE. Both dynamic spacing treatments attained the same or slightly reduced fruit quality compared to low density. Total plant weight per m2 increased with planting density and saturated at a constant high density. Assimilate shortage at the plant level and flower abortion lowered harvestable fruit yield per plant, sweetness, and acidity under constant high density. Harvestable fruit yield per plant was the highest under dynamic spacing and low density. Under constant high density, morphological responses to lower light availability per plant-i.e., higher specific leaf area, internode elongation, and increased slenderness-coincided with the improved whole-plant LUE (g plant dry weight per mol photons). We conclude that a constant high planting density results in the highest harvestable fruit yield per area, but with reduced fruit quality. Dynamic spacing during cultivation produces the same fruit quality as constant low density, but with more than double the harvestable yield per area.

Drought intensity and post-drought precipitation determine vegetation recovery in a desert steppe in Inner Mongolia, China

Extreme drought events are expected to increase in frequency and severity, posing significant threats to ecosystems worldwide. While considerable research has been concentrated on the effects of climate extremes on the stability of grasslands, the process by which grassland productivity may recover after extreme drought events are still not well understood. Here, we conducted a four-year (2019–2022) recovery investigation after four-year's (2015–2018) extreme drought treatments of different intensities (control, press and pulse) to explore the vegetation recovery of desert-grassland ecosystems Inner Mongolia, China. Press drought involved a 66 % reduction in natural precipitation from May to August, while pulse drought reduced it by 100 % during June and July. We found that both press and pulse droughts led to a sharp decrease in aboveground net primary productivity (ANPP) after four years, primarily due to reduced growth, density, and productivity of annual and perennial plants. However, ANPP under pulse drought could recover fully after four years of stopping of drought treatment, and it could not under press drought. Additionally, community structure (i.e., species richness, plant density, and height) fully recovered within 1 year after the end of the two extreme drought treatments. Both plant density and height contributed to the ANPP recovery after press and pulse droughts. Structural equation modeling (SEM) results further revealed that the reduction in ANPP during the extreme drought was primarily due to a decrease in plant density caused by reduced soil water content. The recovery of ANPP in pulse drought was directly caused by increased soil water content in the post-extreme drought. These results suggest that drought intensity and precipitation determine ANPP recovery in a degraded desert steppe. Our findings are crucial for deepening understanding of the processes and mechanisms of ecosystem recovery after extreme drought, as well as for the successful management and protection of grassland ecosystems.

Biometric parameters and yield of maize hybrids in dependence on agricultural technology elements

Modern innovative corn hybrids of the intensive type have a significant individual response of morphometric and photosynthetic indicators to the density of the coenosis. Establishing correlations of these indicators with the level of grain yield of different genotypes of corn hybrids and determining the optimal parameters for the manifestation of these characteristics allows technological measures to ensure the realization of productive potential. The purpose of the research was to establish the peculiarities of the formation of biometric and photosynthetic indicators of innovative corn hybrids depending on the genotype, and the density of the coenosis, and to determine the correlationregression dependence of these characteristics. Field experiments were conducted during 2019-2021 in the agroecological zone of the Central Forest Steppe. The soil of the experimental site is typical chernozem, the precursor is soybean. With the help of field, morphometric, laboratory, and statistical (dispersion and correlation analysis) it was established that the height of the plant, the height of attachment of the upper (productive) cob, the area of the assimilation surface of one plant, and the photosynthetic potential depended on the studied factors – the genotype of the hybrid and the density of the coenosis. A medium and strong positive correlation was established between productivity and these characteristics, which indicates the need to technologically ensure optimal plant growth and development at various stages of the development of corn plants of all hybrids. The mid-ripe hybrid Zedan 32 (FAO 320) showed maximum productivity at a density of 80,000 plants/ha and sharply reduced productivity at a density of up to 100,000 plants/ha. Mid-early hybrids showed maximum yield at a density of 90,000 plants/ha, while an increase or decrease in plant density from the optimum led to a decrease in grain yield. Therefore, each hybrid has its optimal coenosis density for obtaining the maximum grain yield, and increasing the photosynthetic potential of crops by agrotechnical measures does not always guarantee a parallel increase in the grain yield of corn hybrids

Changes in yield and its structure elements of winter bread wheat depending on the conditions of a moisture supply and a genotype

Relevance. In this regard, it is of great relevance to study influence of individual arid situations on the yield and its structure elements for winter bread wheat varieties; to identify more reliable selection criteria in breeding for drought resistance; to determine differences in the drought conditions’ response among genotypes with contrasting length of a vegetation period.Methods. The study was carried out in 2017–2021 on the fields of the research crop rotation of the FSBSI «ARC “Donskoy”», according to a green manure fallow due to the methods of SVT and a field trial. The objects of the research were 25 modern varieties and promising breeding lines of our own breeding.Results. There have been considered the types of droughts and their influence on the yield and its structural elements through the years of research in comparison with the control year 2017, which was favorable in precipitation and temperature conditions in all vegetation and development periods of winter wheat with HThC = 0.92–1.46. The yield decrease amounted to 39.4% in 2019 vs. 2017 and was due to a decrease in the number of sprouted plants and productive heads on 50.5% and 37.2%. In 2020, the productivity reduced on 10.7% due to head and plant productivity decrease on 31.8% and 12.1% and a grain size on 21.0%. In 2021, the yield decreased on 18.6% due to a decrease in plant density and productive head stand on 41.7% and 18.6%, and 1000-grain weight on 15.0%. Based on the correlation analysis, there have been identified the structural elements which could make the main contribution to productivity formation depending on the type of drought, namely plant density (r = 0.78), productive head (r = 0.70), grain size of a head and a plant (r = 0.60 and r = 0.79), plant height (r = 0.70).

Effect of Initial Planting Density on the Moisture Content and Chemical Composition of the Triploid Chinese White Poplar (Populus× tomentosa Carrière) Plantation

The triploid Chinese white poplar (Populus × tomentosa Carrière) features desirable growth traits and wood properties, making it the preferred species in the pulp and paper industries and the sawn timber industry. In this study, we characterized the effects of initial planting densities on the moisture content (MC) and four chemical components (benzene-alcohol (BA), holocellulose (HC), alpha-cellulose (AC), and klason lignin (KL)) of the triploid Chinese white poplar. In this study, 11-year-old Chinese white poplars with three triploid clones (S86, B331, and B301) and one diploid clone (1316) that were planted using seven levels of planting densities (2490, 1665, 1110, 832, 624, 499 and 416 trees/hm2) were examined in the Huabei Great Plain in China. The MC was observed to initially decrease and then subsequently increase with decreasing planting density, and exhibited significant differences under different initial planting densities (0.001 < p < 0.01). In terms of the chemical composition, the BA content of the triploid hybrid clones presented with much higher phenotypic variation (CVp = 17.11%–32.45%) at each planting density compared to either the MC (CVp = 3.73%–11.21%) or the other three chemical composition variations (CVp = 1.16%–11.46%). Substantial differences were observed in the chemical composition of the triploid hybrid clones (p < 0.05), while no differences were found in the chemical composition within the initial planting density categories. The correlation between the chemical composition of wood (BA, HC, AC, and KL) and growth traits was generally weak. These results demonstrate that compared with the MC, the chemical composition of the triploid Chinese white poplar was primarily controlled by its own genetic background and was almost unaffected by the initial planting density. Thus, it is important to select a suitable clone and initial planting density to ensure the full growth of these trees and to improve the quality of pulping in the construction of pulp timber forests.

Planting Arrangement and Effects of Planting Density on Tropical Fruit Crops—A Review

With the growing importance of fruits as valuable food resources, attention has been paid in recent years to enhance productivity and quality. Increasing productivity per unit area through agronomic management is one of the important strategies to increase the production of fruit crops. Keeping this view, this review was undertaken to improve understanding of the planting arrangement and the effect of planting density on productivity and quality of fruit crops. This review will thus provide updated and in-depth information about the influence of planting density on yield and fruit quality, which will also be useful for the growers, consumers, exporters, and processing industry. In fruit crops, the effect of plant density and planting arrangement is well documented. From the review, it is understood that yield per unit area is the product of fruit yield plant−1 and the number of plants per unit area. Fruit size increases with a decreasing planting density, while total yield increases with an increasing density at a certain level. However, fruit quality decreases with an increasing planting density.

Evaluation of imazapic and flumioxazin carryover risk for Carinata (Brassica carinata) establishment

AbstractCarinata (Brassica carinata A. Braun) is a potential crop for biofuel production, but the risk of injury resulting from carryover of soil herbicides used in rotational crops is of concern. The present study evaluated the carryover risk of imazapic and flumioxazin for carinata. Label rates of imazapic (70 g ai ha−1) and flumioxazin (107 g ai ha−1) were applied 24, 18, 12, 6, and 3 mo before carinata planting (MBP). The same herbicides were applied preemergence right after carinata planting at 1X, 0.5X, 0.25X, 0.125X, 0.063X, and 0X the label rate. When either herbicide was applied earlier than 3 MBP, there was no difference in plant density compared with the nontreated control. Carinata damage was <25% when flumioxazin or imazapic was applied at least 6 MBP in Clayton, NC (sandy loam soil), while in Jackson Springs, NC (coarser-textured soil and higher precipitation), at least 12 MPB were needed to lower plant damage to <25%. Preemergence application of 0.063X each herbicide decreased plant density by 40%, with damage reaching >25%. Quantification of herbicide residues in both soils showed that imazapic moved deeper in the soil profile than flumioxazin. This was more evident in Jackson Springs, where 0.68, 3.52, and 7.77 ng of imazapic g−1 soil were detected (15- to 20-cm depth) when the herbicide was applied at 12, 6 and 3 MBP, respectively, while no flumioxazin residues were detected at the same soil depths and times. When residues were 7.78 and 6.90 ng herbicide g−1 soil in the top 10 cm of soil for imazapic and flumioxazin, respectively, carinata exhibited at least 25% damage. Rotational intervals to avoid imazapic and flumioxazin damage to carinata should be between 6 and 12 MBP depending on soil type and environmental conditions, with longer intervals for the former than the latter.

YIELD OF SUNFLOWER SEEDS DEPENDING ON THE USE OFMINERAL FERTILIZERS AND BIOLOGICAL PRODUCTS

The results of the influence of nitrogen-phosphorus fertilizers in combination with Vitavax 200 FF, Helafit Seeds and Helafit Combi on the yield of sunflower in the ForestSteppe of western Ukraine for 2018-2020 are presented. It was found that pre-sowing treatment of seeds with the chemical pesticide Vitavax 200 FF caused a decrease in plant density by 2.2 thousand/ha (4.1%), and the complex biological product Helafit Seeds, on the contrary, to some extent stimulated plant growth and development.Sunflower plants formed a powerful leaf surface, which reached its maximum value in the flowering phase. This indicator gradually increased from 30.9 thousand m2/ha on the control without fertilizers to 40.0 thousand m2/ha on the background of N30P45 + Helafit Combi and to 44.2 thousand m2/ha on the background of N60P90 + Helafit Combi.The combined use of nitrogen-phosphorus fertilizers and the drug Helafit Combi caused a prolongation of the photosynthetic activity of the leaves for 6-8 days and provided an increase in the photosynthetic potential of sunflower plants by 64.7-95.8%. Under these conditions, the highest yield of dry biomass was achieved – 8.2-8.8 t/ha and the highest seed yield – 3.03-3.11 t/ha. Analysis of crop structure elements showed that the increase in seed productivity was due to an increase in the number of seeds in the flower head (34.1%) and the weight of seeds from one flower head (41.3%). The best economic indicators were provided by the joint use of N30P45 and the drug Helafit Combi: the profit was UAH 19,120 / ha, the cost of 1 ton of seeds – UAH 4,690, the level of profitability – 134%. Increasing the rate of fertilizer to N60P90 negatively affected the economy of sunflower cultivation.

The influence of weather and climatic conditions on the phenological indicators and productivity of winter wheat cultivated by direct seeding technology in the arid zone of the Stavropol Territory

The studies were conducted in the arid zone of Stavropol region to determine the productivity of winter wheat cultivated by direct seeding technology, based on phenological observations and NDVI. The work was carried out on the basis of the agro-enterprise JSC "Agrohleboprodukt" for 2018-2020. The predecessors are sunflower, chickpeas, winter wheat varieties (Zustrich (St.), Bagheera and Bagrat). Plant samples were selected according to the generally accepted method. Satellite mapping data of vegetation cover is obtained on the basis of the service "VEGA-Science". It was found that the growth, development and productivity of winter wheat depended on the prevailing weather and climatic conditions. Studies of the dynamics of the average annual indicators showed that precipitation tended to decrease (37.6-14.4 mm), and the temperature and vegetation index NDVI-to increase (9.6-12.3 °C and 0.456-0.491, respectively). The analysis showed the absence of a reliable level of significance of the combined application of these factors for predicting the productivity of winter wheat. The terms of sowing the crop were determined by external conditions and shifted to a later period. The largest average linear deviation of the indicator was revealed in 2020 (6.4444). On average, the variation of seedlings for different varieties and predecessors was 9 % (the lowest for chickpeas – 7.5 %). Seedlings of grain crops appeared 19-20 days after sowing. The coefficient of variation showed a high heterogeneity of the phenological index for all phases, except for tillering (8.6-9.0 %). The average density of plant seedlings was 379 pcs./m2. The coefficient of variation of the indicator is uniform for all varieties and precursors (3.65 %). A decrease in plant density was observed from the germination phase to earing and for all the predecessors (the largest for the Zustrich variety – 7.3 % and 10.2 % for sunflower and chickpeas, respectively). From 2018 to 2020, the yield of winter wheat when sowing for sunflower was 301-450 t/ha, for chickpeas – 326-468 t/ha.

Long-term effects of stand density management and genotype on wood properties of loblolly pine (Pinus taeda L.) in the mid-South USA

Changes in ownership and forest product use patterns have incentivized growing loblolly pine (Pinus taeda L.) for chip-and-saw and sawtimber in shorter rotations in the southeastern United States. These management objectives can be accomplished by relatively low stand densities and moving fast-growing genotypes from the Atlantic Coastal Plain to other regions of the loblolly pine range, but wood quality concerns accompany these silvicultural options. In three trials in the Western Gulf region of the mid-South United States, effects of stand density management options on key wood properties (specific gravity, corewood (juvenile wood) diameter, corewood proportion, latewood proportion, corewood:outerwood (juvenile wood:mature wood) transition age as determined using specific gravity) were tested. At one site, clearwood modulus of elasticity (MOE) and modulus of rupture (MOR) were measured. Genotypes of Atlantic Coastal Plain and Western Gulf origin were also tested at two sites. In a trial in which stand density was managed at diverse levels through sequential thinning, beginning at precommercial size, only a regime that was commercially thinned to half its density two times from 297 TPH at age 7 to 62 TPH by age 41 had significant reductions in MOE, MOR, and specific gravity. Corewood diameter increased with decreasing planting density at two sites at the northwestern edge of the loblolly pine range, but corewood proportion declined with decreasing planting density due to greater diameter growth and earlier transition from corewood to outerwood. Specific gravity differences among planting densities was site-specific, with no differences at the more well-drained site. Latewood proportion, which was greater at higher planting densities, was more strongly correlated with specific gravity differences among planting densities. A planting density between 1075 and 1680 TPH would likely be optimum for these site conditions for balancing tree volume growth with minimizing reductions in specific gravity associated with reduced latewood proportion and larger corewood size. The Atlantic Coastal Plain genotype retained its tendencies to transition to outerwood earlier and have greater latewood proportions relative to a local genotype when planted at these Western Gulf sites, and its specific gravity was similar to that of the local genotype. Together these trials suggest that forest managers have flexibility in managing loblolly pine stand density without altering wood properties. Furthermore, these results provide some evidence that moving genotypes may not carry a risk of reduced wood specific gravity.

Effects of Mechanically Transplanting Methods and Planting Densities on Yield and Quality of Nanjing 2728 under Rice-Crayfish Continuous Production System

Rice–crayfish continuous production system offers high economic and ecology benefits, which developed rapidly in China. To investigate the effects of different mechanical transplanting methods and planting densities on rice yield and quality, Nanjing 2728 was used to determine rice growth performance under mechanically transplanted carpet seedling (MTCS) with equal row spacing (30 cm) at five spacings and mechanically transplanted pot seedling (MTPS) with wide and narrow rows (23 + 33 cm) at five spacings. The results showed that MTPS presented significantly higher rice yields than MTCS as more spikelets per panicle. Rice yields of both mechanical transplanting methods first increased and then reduced with decreasing planting density, and its highest value was obtained at 77.9 × 104 seedlings ha−1. Compared with MTCS at the same stage, rice tiller dynamics of MTPS first increased and then decreased. Additionally, its dry matter accumulation per stem at jointing, heading, and maturity stages, leaf area index, photosynthetic potential, crop growth rate, and net assimilation rate were all significantly higher relative to MTCS. For each mechanical transplanting method, dry matter accumulation per panicle, leaf area index, photosynthetic potential, crop growth rate, and net assimilation rate from the sowing to jointing stages declined with decreasing planting density, while dry matter accumulation per stem and net assimilation rate from the heading to maturity stages increased. Compared with MTCS, MTPS significantly improved rice milling and appearance quality, decreasing density was also beneficial to rice milling and appearance quality, while grain content of amylose and protein were not sensitive to both transplanting method and planting density. Consequently, MTPS with 13.8 cm plant spacing is a suitable mechanical transplanting method for Nanjing 2728 to obtain better yield and quality under rice–crayfish continuous production system.

Effects of grazing exclusion on spring and autumn pastures in arid regions of China: Insights from field surveys and landsat images

Overgrazing has caused serious grassland degradation, and grazing exclusion (GE) has been considered an effective and economic approach for restoring vegetation and soils in degraded grassland. In this study, we evaluated the ecosystem restoration of two types of degraded spring and autumn pasture in arid regions of northwest China, based on field surveys (community structure characteristics, soil C and N) and Landsat images (greenness and wetness). In temperate typical steppe (TS), our findings indicated that GE significantly increased plant height, coverage, biomass, soil C and N, as well as greenness and wetness values from Landsat images, however GE decreased plant density and species diversity. Restoration on greenness and wetness peaked in the fourth and fifth years, respectively, following GE. The restoration of greenness and wetness showed bimodal curves during growing season. In temperate desert (TD), results revealed that community structure characteristics, greenness, and wetness improved after GE, and the restoration of greenness and wetness increased with duration of GE. Soil C and N however, did not recover significantly after six years of GE. The restoration of greenness and wetness remained stable during growing-season months. Our findings suggest that longer GE might be considered in the restoration of TD, whereas short-term (not more than 4–5 years) GE, reduction in the livestock load or mowing regularly may be more appropriate for TS. Decision to adopt measures of GE and the duration of GE should be reasonably determined according to the specific grassland type. This research can provide guidance for the restoration of degraded grassland ecosystems in arid and semi-arid regions all over the world.

Production of baby corn influenced by Nitrogen application and crop geometry: A review

Baby corn is a short-term crop, with an unfertilized maize ear which is harvested within 2-3 days of silk emergence of the plant. It is a newly introduced crop in India and being a high-value and short-span crop (50-60 days) it has a good perspective in improving the financial status of the farmers. Advancement and standardization of agronomic practices are required before familiarizing the crop among farmers. Among different agro-techniques, crop geometry and Nitrogen application are considered as one of the most important factors to the production yield of crop. Nitrogen deficiency is a broad phenomenon its proper management is mandatory from a financial and environmental view. It is concluded in studies that the yield of crop increase with an increase in N rates but the optimum dose is dependent upon plant density. However response of the N application was different for quality and yield attributes. Plant density is another major aspect of the performance of baby corn. It is reported that quality attributes were much better in wider spacing due to a decrease in plant density. It is also reported that narrow spacing and increase in N application concurrently increase the yield attributes. More research studies are needed on the combined approach (Plant geometry and N application) in the baby corn can intensify yield and quality in baby corn. Optimization of both attributes is depended on location and season. However, economically effective and user’s friendly precision tools may be a feasible option for getting the real farm situation.

Interpretation and Evaluation of Electrical Lighting in Plant Factories with Ray-Tracing Simulation and 3D Plant Modeling

In plant factories, light is fully controllable for crop production but involves a cost. For efficient lighting, light use efficiency (LUE) should be considered as part of light environment design. The objectives of this study were to evaluate and interpret the light interception, photosynthetic rate, and LUE of lettuces under electrical lights using ray-tracing simulation. The crop architecture model was constructed by 3D scanning, and ray-tracing simulation was used to interpret light interception and photosynthesis. For evaluation of simulation reliability, measured light intensities and photosynthetic rates in a growth chamber were compared with those obtained by simulation at different planting densities. Under several scenarios modeling various factors affecting light environments, changes in light interception and LUE were interpreted. The light intensities and photosynthetic rates obtained by simulation showed good agreement with the measured values, with R2 > 0.86. With decreasing planting density, the light interception of the central plant increased by approximately 18.7%, but that of neighboring plants decreased by approximately 5.5%. Under the various scenarios, shorter lighting distances induced more heterogenetic light distribution on plants and caused lower light interception. Under a homogenous light distribution, the light intensity was optimal at approximately 360 μmol m−2 s−1 with an LUE of 6.5 g MJ−1. The results of this study can provide conceptual insights into the design of light environments in plant factories.

Response of Soybean (Glycine max (L.) Merrill) to Mineral Nitrogen Fertilization and Bradyrhizobium japonicum Seed Inoculation

A growing interest in soybean cultivation in Poland has been observed in the recent years, however it faces a lot of difficulties resulting from a poorly understood effectiveness of plant nitrogen fertilization and from the introduction of Bradyrhizobium japonicum to the environment. The aim of the study was to evaluate the consistency of response of two soybean cultivars to three different rates of mineral N fertilization and two seed inoculation treatments with B. japonicum in field conditions over four years regardless of previous B. japonicum presence in the soil. A highly-diversified-over-years rainfall and temperature in the growing season do not allow for a definite statement of the differences resulting from seed inoculation and mineral N fertilization applied separately or jointly in soybean. A high sensitivity of the nodulation process to rainfall deficits was noted, which resulted in a decreased amount of B. japonicum DNA measured in qPCR and dry matter of nodules. ‘Annushka’ demonstrated a higher yield of seeds and protein, higher plants and the 1st pod setting. ‘Aldana’, due to a significant decrease in plant density, produced a higher number of pods, seeds per pod and the 1000 seed weight per plant. Both cultivars responded with an increase in the seed yield after seed inoculation with HiStick, also with an application of 30 and 60 kg N, as well as with Nitragina with 60 kg N.

Comparison of Aeroponics and Conventional Potato Mini Tuber Production Systems at Different Plant Densities

Mini tubers are the starting materials of a disease-free seed potato production scheme. Low multiplication rates as well as non-homogenous tuber size distribution are considered the main constraints of a conventional mini tuber production system. In recent years, an aeroponics production system has been developed to overcome the aforementioned problems. It has previously been observed that this system allows multiple harvests with an average yield of 20–50 mini tubers per plant. Several factors, such as cultivar, planting density, nutrient composition of the mist solution, spraying interval and duration and lighting also affect both tuber number and tuber size. However, less attention has been paid to the association of these factors with the aeroponics system. This paper highlights the importance of planting density effect on conventional and aeroponics system. The mini tuber production performances of three potato cultivars (Hermes, Marabel and Sante) were compared at four different planting densities (25, 50, 100 and 200 plants/m2) under both conventional and aeroponics systems in two production cycles. The number of tubers per plant increased with decreasing planting density, being highest at 25 plants/m2 and lowest at 200 plants/m2 for both cycles. Mean tuber number in the aeroponic system was 19.85 tubers per plant at 25 plants/m2 and 13.20 tubers per plant at 200 plants/m2. As the number of tubers per plant decreased, so did their size. As planting density increased, tuber yield per plant both in aeroponics and conventional system decreased, but in general, tuber yield per plant was higher in aeroponics than in the conventional system. In the 1st cycle, the number of tubers per m2 for Hermes, Sante and Marabel was 290, 364 and 334, respectively, in the conventional system and 787, 1021 and 1168, respectively, in the aeroponics system. Similar numbers were recorded in the 2nd cycle. The average tuber weight was higher in the conventional than in the aeroponics system. Tuber yield/m2 in this study varied from 5.9 to 9.3 kg/m2 in the aeroponics system, about twice as high as in the conventional system.

Effect of integrated agronomic managements on leaf growth and endogenous hormone content of summer maize

<p indent=0mm>The leaves are the main place of photosynthesis directly related to the nutritional status, dry matter accumulation and yield formation of maize plants. The experiment was conducted using summer maize hybrid Zhengdan 958 with treatments of T1: local conventional cultivation practices; T2: based on T1, increasing planting density, delaying harvesting time, decreasing fertilizer application, and changing fertilization time; T3: based on T2, further increasing planting density, and further increasing fertilizer rate; T4: based on T3, decreasing planting density and the amount of fertilizer; and nitrogen treatments of N0, N1, N2, and N3, with 0, 129.0, 184.5, and <sc>300.0 kg N</sc> hm^-2, respectively. The contents of IAA, ZR, and GA₃ decreased and the content of ABA increased, resulting in the decreases of SPAD, leaf area index (LAI) and specific leaf mass, when nitrogen application was not enough. And the contents of IAA, ZR, and GA₃ increased, and ABA content decreased, and LAI, SPAD and dry matter accumulation per plant increased significantly with increasing nitrogen application. Integrated agronomic management practices could regulate the content of endogenous hormones in leaves. In T4 treatment, IAA, ZR, and GA₃ contents increased by 23.1%, 9.8%, and 14.7%, the ABA content decreased by 12.4%, resulting in a suitable LAI; SPAD and final dry matter accumulation per plant were by 4.2% and 12.6% higher, respectively, than those in T1 treatment. Integrated agronomic managements could coordinate endogenous hormone contents, increase leaf SPAD and specific leaf mass, and be beneficial to dry matter accumulation per plant under the condition of reducing nitrogen application combining with optimal agronomic managements, which might be one of the important reasons for increasing summer maize yield.

First Report of Gaeumannomyces graminicola Causing Bermudagrass Decline of Ultradwarf Bermudagrass Putting Greens in North Carolina

HomePlant DiseaseVol. 104, No. 5First Report of Gaeumannomyces graminicola Causing Bermudagrass Decline of Ultradwarf Bermudagrass Putting Greens in North Carolina PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Gaeumannomyces graminicola Causing Bermudagrass Decline of Ultradwarf Bermudagrass Putting Greens in North CarolinaCameron M. Stephens and James P. KernsCameron M. Stephens†Corresponding author: C. M. Stephens; E-mail Address: cmsteph2@ncsu.eduhttp://orcid.org/0000-0002-4708-9669Varsity Research Building, Raleigh, NC 27695Search for more papers by this author and James P. KernsVarsity Research Building, Raleigh, NC 27695Search for more papers by this authorAffiliationsAuthors and Affiliations Cameron M. Stephens † James P. Kerns Varsity Research Building, Raleigh, NC 27695 Published Online:23 Feb 2020https://doi.org/10.1094/PDIS-10-19-2147-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Bermudagrass decline is a detrimental disease of ultradwarf hybrid bermudagrass maintained at <5 mm for golf course putting greens. Stand symptoms include off-color to white, irregular patches, chlorosis of older leaf tissue, basal necrosis at plant crowns, and a decrease in stand density. Gaeumannomyces graminis is reported to be the causal agent of this disease (Elliott 1991); however, multiple closely related fungi within the Magnaporthaceae have recently been associated with take-all root rot and bermudagrass decline (Vines et al. 2015). When bermudagrass decline stand symptoms are present, darkly pigmented ectotrophic runner hyphae and lobed hyphopodia are ubiquitous on necrotic roots, the stoloniferous matrix, and the plant crown under severe disease pressure. Symptomatic turf samples from a golf course in Greensboro, NC, were collected using a golf course cup cutter (10.8-cm diameter) in October 2018. Pure cultures of Gaeumannomyces sp. were obtained through isolation from symptomatic root and stolon tissue. Symptomatic roots and stolons were surface disinfested for 1 min in 0.5% sodium hypochlorite solution, rinsed in three consecutive sterile water baths for 30 s, and air dried on sterile filter paper. Once dry, surface-disinfested samples were set on antibiotic-amended water agar containing 0.5 g/liter of streptomycin sulfate and penicillin-G potassium for 5 to 8 days and then subcultured onto potato dextrose agar. Gaeumannomyces sp. was successfully isolated from 80% of the symptomatic tissue evaluated following the aforementioned protocol. Colony morphology was consistent with Gaeumannomyces graminicola M. Hern.-Restr. & Crous sp. nov. (Hernández-Restrepo et al. 2016; Lin et al. 2019). The internal transcribed spacer (ITS) region was sequenced because this marker has the ability to distinguish between the majority of the species within the Gaeumannomyces genus (Hernández-Restrepo et al. 2016). The ITS region of Gaeumannomyces sp. isolates 31282-1A to 1D (accession nos. MN559724, MN559725, MN559726, and MN559727) had 506/507, 503/504, 495/495, and 502/504 similar nucleotides (99.6 to 100% homology) when compared with a known G. graminicola isolate, CPC 26025 (accession no. KX306495), originally isolated from Stenotaphrum secundatum (Walt.) Kuntze (Hernández-Restrepo et al. 2016). Koch’s postulates were performed on healthy ‘Champion’ ultradwarf hybrid bermudagrass plugs (4.4-cm diameter) that were processed by removing the root system and washing the remaining below-ground material with water. G. graminicola was grown on sterile oats for 3 weeks at 25 ± 2°C, and infested oats (n = 10) were placed in the center of 10-cm pots filled with 250 cm3 of sterile sand. A processed bermudagrass plug free of ectotrophic root-infecting fungi was placed directly on the inoculum and lightly top dressed (∼20 cm3 of sterile sand). Experimental units were maintained in the greenhouse at 28 ± 2°C and watered once daily. Basal necrosis, a decrease in plant density and turfgrass quality, and lobed hyphopodia (16.5 to 24 × 15.5 to 23.5 μm) were observed 4 weeks after inoculation. Symptoms were not present on noninoculated and noninfested oat inoculated control plants. G. graminicola was reisolated from symptomatic root and stolon material of inoculated plants and confirmed with ITS sequencing. To our knowledge, this is the first report of G. graminicola causing bermudagrass decline of ultradwarf hybrid bermudagrass in North Carolina, which may influence management of this important disease.The author(s) declare no conflict of interest.

Optimizing Dryland Crop Management to Regional Climate via Simulation. Part I: U.S. Southern High Plains Cotton Production

Over semi-arid agricultural regions such as the U.S. Southern High Plains (SHP) producers of dryland crops need to know which management practices increase yields and decrease production risk. Here, a modelling approach is used to explore management options (MO) that increase dryland cotton yields and estimate those practice’s yield risk effects under current SHP climate conditions. To simulate current dryland yield variability, dense distributions of lint yield outcomes were generated using the CROPGRO-Cotton crop model driven by weather inputs from 21 SHP weather stations during 2005-2016. Management effects were explored by repeating simulations over 32 MOs defined by 4 planting dates, 4 planting densities, and applying or not applying nitrogen. Both earlier planting date and decreased plant density increased median simulated yields, with earlier planting having the greatest positive yield effects. The MO that produced the highest median lint yields planted on the earliest planting date (May 15), at the lowest density (3 plants m-1), and applied no nitrogen. Recent SHP field studies generally confirm the earlier planting date effect, but suggest insignificant yield effects for different seeding rates. Even so, negligible yield effects and lower input costs favor lower seeding densities from a profit standpoint. These crop simulations demonstrate a modelling-based method for climate-related agricultural risk management, and suggest mid-May planting dates and low plant densities as part of management practices that increase yields and profits in dryland SHP cotton production.