Optimum Plant Density Research Articles

The Influence of Seed Rate and Inter-Row Spacing on Seed Yield and Yield Attributes of Black Cumin in Arsi Highlands, Ethiopia

Black cumin is the major and the most important spice in Southeast highlands of Ethiopia. However, the yield of the crop is very low mainly due to lack of optimum plant density. A field experiment was done with the objective to assess the influence of different seed rates and inter-row spacing on yield and yield attributes of black cumin at Kulumsa. This experiment was done in the cropping years of 2017, 2018 and 2019 at Kulumsa Agricultural Research Center, Southeast Ethiopia. Twelve treatment combinations of four seed rates (5 kg ha -1 , 10 kg ha -1 , 15 kg ha -1 and 20 kg ha -1 ) and three inter-row spacing (20 cm, 30 cm and 40 cm) were studied on a black cumin variety – 'Aden', which was laid out in a randomized complete block design (RCBD) with factorial arrangement in three replications. The interaction effect of seed rate and inter-row spacing was not statistically significant (P > 0.05) on all growth and yield parameters. However, the main effect of seed rate was significant (P < 0.05) on most of the parameters studied while inter-row spacing was significant only on days to emergence and plant height. Yield and yield attributing factors such as number of primary branch plant -1 , number of secondary branch plant -1 , number of pods plant -1 and seed yield ha -1 (kg) were significantly influenced by the seed rate. Seed yield increased from 462 kg ha -1 to 634 kg ha -1 as seed rate increased from 5 kg ha -1 to 20 kg ha -1 and showed a decrease in yield from 601 kg ha -1 to 507 kg ha -1 as inter-row spacing increased from 20 cm to 40 cm although it was not significant. Hence, 15 kg ha -1 seed rate and 30 cm inter-row spacing could be recommended for optimum black cumin production in the study area. However, further research needs to be undertaken in different black cumin producing areas of the country on recent varieties to achieve the optimum seed rate and inter-row spacing with information related to cost of production for better recommendation. Keywords: competition, crop management, Nigella sativa , plant density DOI: 10.7176/JBAH/11-1-04 Publication date: January 31 st 2021

Высокобелковый сорт сои Грея

The high-protein soybean cultivar Greya was developed by individual selection from the hybrid population F4 Vilana × Valenta based on a lipid-degrading model of protein accumulation in seeds. According to the results of preliminary and competitive variety testing, the productivity of the high-protein soybean cultivar Greya varied from 1.75 to 2.93 t/ha. The average yield of the new cultivar over four years of variety testing was 2.23 t/ha, which, on average, was 0.71 t/ha higher than the high-protein standard cultivar of the lipid-degrading biotype, and did not significantly differ (-0.09 t/ha) from the high-yielding medium-protein standard cultivar. The height of plants varies from 82 to 98 cm. Under the optimal plant density, the lower pods are located at the height of 15–17 cm from the soil surface. The pubescence is gray. The color of the beans is light brown. The color of the corolla is violet. The seed coat is yellow. The plants of the new cultivar are resistant to lodging and bean shattering. Under optimal cultivation conditions and the presence of mineral or bacterial nitrogen in the soil, up to 46.3 % of protein is accumulated in the seeds of the cultivar Greya. The oil content in the seeds of the cultivar Greya is lower than that of the medium-protein standard, by an average of 2.1 %, which is typical for high-protein cultivars of the lipiddegrading biotype. The growth season of the new cultivar at the latitude of Krasnodar (45°), depending on the meteorological conditions of the year, varied from 108 to 117 days, and on average, for the period of 2017–2020 it was 112 days. Therefore, it can be cultivated as the main crop in soybean-producing farms in the North Caucasus, Lower Volga and Far Eastern regions of the Russian Federation.

Potential impact of climate changes in the field crops production

There is evident stagnation or decline in grain yield, as well as high variability in yields, depending on the environment in many countries in recent years, including Serbia and the Republic of Srpska. The causes of this variation were mainly due to the variation of the climatic factors, the onset of drought and the rise in temperatures. Expected changes and especially negative ones will most likely be reflected in the agriculture of southern Europe, especially the Mediterranean, and yield of main field crops. The most negative effects in the area of the continental climate will be in the Pannonian Region which includes Serbia, Croatia, Hungary, Bulgaria and Romania, R. Srpska as a part of Bosnia and Herzegovina. This area will be affected by more frequent waves of heat and drought, with no greater possibility of avoiding by shift of sowing time or other cropping measures. Based on a detailed analysis of climatic factors in the multy-annual period it can be emphasised that some changes in terms of temperature and precipitation occurred. The causes of drought mainly come from the atmosphere and affect our country and show clearly that the climate is changing in our area. Based on these facts, we must have the right answers in order to mitigate if not to completely eliminate these effects. Agronomic aspect of looking into the problem requires a good knowledge of our crop needs for primary vegetative factors as well as temperature and moisture. Annual air temperatures in the investigated period increased not only at the annual level, but also in the vegetative period of winter wheat and particularly maize. The temperature increase is particularly dangerous in the vegetative period of maize during the three months of June, July and August by almost 2 °C. Precipitations at a monthly level of the vegetative period or a total per year do not provide such a picture. Besides the lack in July, normally the warmest month, by and large, precipitations are somewhat higher than the reference 30-year period 1971-2000. This fact tells us that precipitations are more frequent in other parts of the year, which is more favourable for winter small grain cereals,at least when regarding warmer years (especially in the wet years as it is known in the case of extremely wet 2010 yr when it was vice versa). A man can hardly influence the quantity and distribution of rainfall, therefore his actions to combat drought are mainly of indirect character. This comprises a good knowledge of the problems and prediction. For this, we need a lot of knowledge of agronomy, genetics, ecology, physiology, and relevant technical and economic possibilities. If we start from the assumption that the main goal is to provide sufficient and safe quantities of food for our population, then we need to focus on what we have in our hands and begin with it. In the fight against drought, regular and specific cultivation practices are used along with an adequate assortment of crops with more tolerance to drought. Out of regular practices, soil tillage, particularly conservation tillage, proper fertilization, elimination of all possible mistakes in sowing should be taken into account as for optimal time and plant density. Care treatments are a useful tool which can eliminate the adverse effects and create favourable conditions for the growth and development of cultivated crops, ranging from the usual ones to some special ones that retain moisture and prevent moisture loss by encouraging its more efficient and economical use. Appropriately established crop rotations with greater diversification of crops provide better tolerance of extreme moisture, which is particularly the case of winter wheat. Our research shows inferiority of continuous cropping of both crops compared with different crop rotations. However, when comparing crop rotations with each other then it can be noticed that the proper setting, even under extreme conditions, provides better results. As for maize it is evident that all increases of moisture are suitable for it as it is related to the warmer part of the year, either as direct rainfall during the summer or indirectly if the reserve is provided from a period when there are more precipitations during the autumn, winter and spring. Moisture improves the efficiency of all other cultivation practices. In the case of its extended absence followed by high temperatures it is quite the opposite.

N, P and K use efficiency and maize yield responses to fertilization modes and densities

Optimal planting density and proper fertilization method are important factors to improve maize yield and nutrient utilization. A two-year (2016 and 2017) field experiment was conducted with three plant densities (6.0, 7.5 and 9.0 plants m–2) and three fertilization modes (no fertilizer, 0F; one-off application of slow-released fertilizer, SF; twice application of conventional fertilizer, CF). Results indicated that the grain yields and N, P and K use efficiencies under SF with the optimal planting density (7.5 plants m–2) were the highest among all the treatments in 2016 and 2017. Compared with CF, SF could increase post-silking dry matter accumulation and promote N, P and K uptake at pre- and post-silking stages; this treatment increased grain N, P and K concentrations and resulted in high N, P and K use efficiencies. Nutrient (N, P and K) absorption efficiencies and partial productivity, and nutrient (N and P) recovery efficiency in SF treatment were significantly higher than those in CF treatments under the planting density of 7.5 plants m–2. Under both SF and CF conditions, the grain yield, total N accumulation and nutrient use efficiencies initially increased, peaked at planting density of 7.5 plants m–2, and then decreased with increasing plant density. Based on the yield and nutrient use efficiency in two years, plant density of 7.5 plants m–2 with SF can improve both the grain yield and N, P and K use efficiency of spring maize in Jiangsu Province, China.

Estimating the economic optimal target density of hybrid canola based on data from a western Canadian meta-analysis

Canola production in western Canada has expanded such that in many regions canola area rivals the area seeded to wheat. This change can be mainly attributed to adoption of herbicide resistant hybrid varieties and resulting higher relative profitability. Producers responded to higher seed prices by reducing seeding rates, leading to plant densities that were often lower than industry recommendations. The study objectives were to examine canola yield response to plant density and assess economically optimal density levels relative to industry recommendations and grower practices. A meta-analysis approach was applied to yield response and plant density data with herbicide resistant hybrid canola from multiple studies. Three alternative marginal yield–density functions were estimated and used to calculate economically optimal plant density. Sensitivity of results to key parameters was assessed. Resulting optimal density levels under recent average prices, seed size, and emergence were 62–73 plants·m−2, consistent with industry recommendations for western Canada. Recent field surveys report lower densities than this range, suggesting that producers are seeding at less than optimal rates; however, there is significant uncertainty associated with canola production and interaction of seeding rate with other factors. These would impact optimal plant density, although much of the uncertainty remains until well after seeding. The empirical results represent a foundation for development of more detailed models, highlight the significance of the relationship between plant density and economically optimal yield, and suggest the need to develop decision making tools to support producers in making canola planting decisions.

Review: Winged bean (Psophocarpus tetragonolobus) cropping systems

Abstract. Eagleton GE. 2020. Review: Winged bean (Psophocarpus tetragonolobus) cropping systems. Biodiversitas 21: 5927-5946. Winged bean (Psophocarpus tetragonolobus (L.) DC.) is a rambling, nitrogen-rich, leguminous crop of the Old-World tropics. This review of winged bean (WB) within cropping systems of Southeast Asia and Melanesia revisited four traditional roles that the crop has played: as a minor courtyard vegetable of villages and suburbs throughout the region; as a popular tuber crop in the irrigated plains of Tada-U township in Central Myanmar; as a companion crop in the mixed garden fields of Wamena in Indonesian New Guinea; and as a niche tuber crop in rotation with sweet potato near Goroka in Papua New Guinea (PNG). Drawing upon such traditions, researchers since the 1970s have identified potential new roles for winged bean. In Malaysia, vegetable pod yields up to 35 t ha-1 over a 25-week growing period have been obtained from solidly trellised, branching cultivars. Ratooning the crop through a further two cycles covers the cost of the trellising. Tubers from un-trellised field crops in Myanmar, and of staked, pruned garden crops in highland PNG have been estimated to produce crude protein yields of at least 300 kg ha-1 and 600 kg ha-1, respectively. Synergies between the gene-pools and cultural traditions would be expected to expand the range, raise the yield and stabilize the quality of tuber crop production. Researchers in Sri Lanka intercropped maize with winged bean. At optimal plant densities, they recorded a corn cob yield of 5 t ha-1 together with a cumulative winged bean fresh pod yield of 27 t ha-1. In Kentucky (380N), the combination of maize with winged bean to produce silage resulted in 11-18% greater biomass with 39-67% greater nitrogen per hectare than maize monocrop control plots. Branching winged bean cultivars have significant potential for benign, high-nitrogen cover and forage crops. Promiscuous nodulation and the development of storage root-systems compensate for slow initial top growth which then accelerates to produce a substantial yield of highly digestible leaf protein and vitamins. Hard-seededness and daylength-sensitive phenology are significant, surmountable, barriers to an expanded role for winged beans.

Вплив густоти рослин на ріст і урожайність гібриду помідору індетермінантного типу

Вплив густоти рослин на ріст і урожайність гібриду помідору індетермінантного типу

Intra‐specific competition affects the density tolerance and grain yield of maize hybrids

AbstractIncreasing plant density usually increases the intra‐specific competition of maize plants. This study was conducted to determine whether maize (Zea mays L.) hybrid density tolerance is related to intra‐specific competition. Field experiments were conducted using a split‐plot design, the main plots contained four maize hybrids, and subplots were 12 plant densities varied from 1.5 to 18 × 104 plants ha−1. This study focused on dry matter accumulation, grain yield (GY), competition intensity (CI), and absolute severity of competition (ASC) based on the above treatments. Among all tested hybrids, GY exhibited a curvilinear response to plant density, which was well characterized by the Steinhart–Hart equation. Maize hybrids differed in optimum GY in descending order as follows: Zhongdan909 (ZD909) > Xianyu335 (XY335) = Yedan13 (YD13) > Zhongdan2 (ZD2). The CI and ASC of tested maize hybrids indicated that intra‐specific competition increased with increasing plant density. In most cases, the CI and ASC of older maize hybrids were higher than those of modern maize hybrids when plant density exceeded 9.0 × 104 plants ha−1. The results showed that the slope of the linear regression of ASC and plant density (i.e., the k‐value) could be used to compare the intra‐specific CI of maize hybrids, and there were significant negative correlations of k‐value with optimum plant density and GY. Intra‐specific competition is negatively correlated with the density tolerance of maize hybrids. This relationship may provide new insights for determining future maize breeding targets.

Stone pine (Pinus pinea) growth and cone yield as a function of planting density in Chile

Pinus pinea (stone pine) is an important species for its delicious seeds –the pine nuts–, the most expensive dry fruit worldwide. In native habitats, planting density is a key silvicultural tool in this highly heliophile species due to its impact on growth and cone yield. In Chile, the densities of adult plantations are medium and high. The goal of this study was to assess the impact of density on growth and cone yield in established plantations. Thirty plantations, 15 at high density (1,667 trees ha-1) and 15 at medium density (500 trees ha-1), were matched into 15 pairs of similar plantations regarding age and site characteristics. Planting density had a significant impact on P. pinea growth and cone yield. The medium density was associated with 46 % higher diameter-at-breast-height (DBH) and 2.8 times higher cone yield than those presented by a high-density plantation scheme. However, at 500 trees ha-1, average tree height might turn cone harvesting difficult and expensive. In humid areas (Chilean South macrozone), the medium planting density had a more important effect on cone yield than on growth. Our study confirms previous research in stone pine native habitats and highlights the need to find an optimum planting density to favor cone yield and harvest.

Intensive Technology Before Seeding Treatment And Agrophysical Soil Properties

In the complex of agro-technical measures for the cultivation of cotton and obtaining high yields based on technical progress, the main and pre-sowing soil cultivation, biological characteristics of the variety, the timing and methods of sowing, rational water, nutritional, agrophysical soil regimes, optimal plant density and other agro-technical methods are important. Depending on the climatic, soil and hydrogeological conditions of the region. Before seeding, tillage is one of the most energy-intensive operations in agriculture. It requires a large amount of equipment, oil products, labour resources and time. Also, under conditions of intensification of agriculture, cultivation, along with a positive effect, can have a negative effect on the agrophysical properties of the soil if it is carried out incorrectly.

A Seasonal Change of Active Ingredients and Mineral Elements in Root of Astragalus membranaceus in the Qinghai-Tibet Plateau.

Astragalus membranaceus is an important traditional Chinese herb whose roots have been used for medicinal purposes for more than 2000 years. Because of excessive exploitation, the wild resources are currently almost exhausted, and therefore, artificial planting of Astragalus membranaceus has been increasingly important. But to date, few studies have focused on the active ingredients and mineral element of Astragalus membranaceus in the Qinghai-Tibet Plateau.In this study, five density gradients (M1: 10 cm × 25 cm, M2: 15 cm × 25 cm, M3: 20 cm × 25 cm, M4: 25 cm × 25 cm and M5: 30 cm × 25 cm) were assessed to evaluate the effects of various planting densities on the mineral element and secondary metabolite content of Astragalus membranaceus roots in different months. It was found that the content of calycosin-7-O-β-D-glucoside and astragaloside IV reached its highest in October. Ononin content increased month by month, while formononetin content decreased during months. Calycosin content did not show significant changes during seasons. Taken together, these results suggest that the optimal planting density is 15 cm × 25 cm (D2) and the optimal harvest period is October. According to the results, the Cu content in all samples did not exceed the limit (20 mg/kg). Principal component analysis (PCA) revealed that Na, P, K Al, Ba, Ca, Fe, Li, and Mn were selected as characteristic elements of Astragalus membranaceus. The results also showed a high correlation between elements and active ingredients. Ba and Co had extremely significant associations with astragaloside IV.

Effect of density and directional cultivation on yield, quality and benefit of Nuomi yam

A split-plot experiment was conducted to study the optimum planting density of Nuomi yam in directional groove shallow cultivation. Nuomi yam was the main local cultivar of Dioscorea. The study of this paper may help to give valuable instructions of local production. Three different planting densities and shallow groove diameter were designed in the experiment. The results showed that the fresh weight of aerial part per plant, yield and planting benefit of Nuomi yam tuber were the highest when the planting density was 12 000 plants/hm~2 and the diameter of shallow growth groove was 11.0 cm, while they were the lowest when the planting density was 22 500 plants/hm~2 and the diameter of shallow growth groove was 7.5 cm. Along with the increase of planting density, the fresh weight of aerial part, tuber, fresh yield, benefit and commercial tuber rate of Nuomi yam also decreased. The commercial tuber rate of Nuomi yam of 11.0 cm diameter in shallow growing pot was the highest, while it was the lowest with no shallow growing pot. On the contrary, the content of amylopectin and mucin was the highest when there was no shallow groove, and was the lowest when the diameter of shallow groove was 7.5 cm, although there was no significant difference between the two treatments. Therefore, Nuomi yam with the directional cultivation combination of planting density of 12 000 plants/hm~2 and shallow groove diameter of 11.0 cm showed high yield, good appearance quality, high planting benefit and no obvious adverse effect on internal quality.

АНАЛИЗ ВЛИЯНИЯ ПРИРОДНОЙ ВЛАГООБЕСПЕЧЕННОСТИ НА УРОЖАЙНОСТЬ ПОДСОЛНЕЧНИКА В ЗАСУШЛИВЫХ УСЛОВИЯХ КРЫМСКОГО ПОЛУОСТРОВА

The Crimean Peninsula is located in the dry zone. In the steppe Crimea, which is the driest part of the peninsula, the major limiting factor for crop productivity is the natural moisture supply of plants. The purpose of the research was to establish the relationships between hydrometeorological factors (moisture reserves in the soil before sowing, precipitation amount and Selyaninov hydrothermal coefficient during the growing season) and sunflower yield depending on planting dates (I, II, III decade of April) and plant density (30, 40, 50, 60, 70 thousand units per hectare). The studies were carried out on the trial fields of the Research Institute of Agriculture of Crimea (village of Klepinino) in 2017–2019 using hybrid of ultra-early sunflower ‘Avangard’. The laying of field experiments, accounting, analyzes and statistical processing of data were carried out according to the methods of field research and methodology of field agricultural experiments with oil crops. A strong correlation was observed: 1) between yield and precipitation amount in May (r = 0.977) and moisture reserves before sowing (r = 0.978), planting dates – the first decade of April; 2) between precipitation amount in May (r = 0.932) and moisture reserves before sowing (r = 0.977–0.978), sunflower was sown in the second decade of April; 3) moisture before sowing (r = 0.892), crop planted in the third decade of April. A close positive relationship (r = 0.853–0.972) was observed at the optimal plant density for the region (40 thousand units/ha) between the amount of precipitation in April–May, moisture reserves in the soil before sowing and yield of sunflower. This indicates a high value of moisture availability during this period in the crop yield formation. In denser crops (50–70 thousand units/ha), the closest relationship is observed between the yield and the amount of precipitation in May. This makes the latter primary and decisive in the cultivation of crops with such a density since the competition for moisture increases with an increase in the number of plants per unit area. The closest relationship between the Selyaninov hydrothermal coefficient and sunflower yield was observed in April and May (r = 0.833–0.967) when plants grow more intensively and require sufficient moisture.

Efficiency of <i>Verbascum densiflorum</i> Bertol. bioregulators in stimulation of vegetable growth and development

Relevance. Increasing the resistance of vegetable plants to unfavorable growing conditions with the use of growth regulators that actively affect the seed quality, increase the survival rate of seedlings, stimulate the setting, formation and maturation of the crop is a significant reserve for increasing productivity with the already achieved level of intensification of their production.Material and methods. The effect of verbascosides obtained by exhaustive extraction with 60% aqueous ethyl alcohol from the aboveground part of Verbascum densiflorum Bertol. (Scrophulariaceae) was studied on the germination, growth, development and yield of tomatoes, cucumbers, onions and white cabbage. Before sowing, the seeds were soaked in an aqueous solution of verbascosides for 15-20 minutes, followed by drying to flowability at the rate of 0.5-0.8 liters of solution per 1 kg of seeds.Results. It is shown, that possessing phytoregulatory activity and influencing the metabolic and synthetic reactions of plants, these compounds, applied exogenously, stimulate the seed germination energy and total germination of vegetable crops, provide simultaneous appearance of seedlings and optimal plant density, accelerate the growth dynamics of plants assimilation surface and fruit mass. Reducing the consequences of stresses arising in the process of plant growth and development, they thereby contribute to increasing plant resistance, productivity and improving the commercial quality of the products. The ability of these compounds to improve the production process of vegetable crops, depending on the type and variety of vegetables was established. Their highest stimulating effect was determined on cabbage variants, where the yield exceeded the control by 34.3%. The performed studies and obtained results allow to recommend the pre-sowing seed treatment with a 0.01% solution of biological active substances from Verbascum densiflorum Bertol. as an element in technology of growing vegetable.

The effect of plant density on productivity of the grain sorghum variety ‘Ataman’ in the Lugansk region

Frequently occured dry years and a sharp decrease of productivity and gross harvests of grain crops require scientifically grounded selection of grain crops that stabilize its production. Currently, the drought resistant sorghum varieties can become a good alternative for the main spring grain crops. In the Luhansk region, the average annual amount of precipitation is 475 mm, which confirms the advantage in growing grain sorghum over other spring grain crops. However, plant density of the modern recommended grain sorghum varieties related to specific soil and climatic conditions has not yet been studied enough. The purpose of the current research was to study and highlight the optimal plant density of the grain sorghum variety ‘Ataman' in the conditions of the Luhansk region. The study was carried out on the basis of the Luhansk National Agricultural University in 2018-2019. Sorghum was sown at the rate of 350.000 germinated grains per hectare. In a sprouting phase, plant density was manually formed according to the experimental scheme (from 40 to 340 thousand/ha). The study of the new early-ripening grain sorghum variety ‘Ataman', developed by the FSBSI “Agricultural Research Center “Donskoy”, showed that regardless of the moisture supply and the thermal regime during vegetation, it was advisable to grow this variety with a plant density of 140-220 thousand/ha. In the conditions of the Luhansk region with mineral nutrition N60P40, it was possible to form the productivity of the grain sorghum variety ‘Ataman' at the level of 5.06-5.52 t/ha of grain and more. The vegetation period of the variety ‘Ataman', depending on the plant density and weather/climatic conditions of the year, was 90-102 days, which made it possible to harvest it in the 1st-2nddecade of September without additional drying of the grain. The variety did not lodge or shed its grain, and was also resistant to grain aphids.

Influence of spacing, nutrition and growth regulator on yield and quality enhancement in lavender

A field investigation was carried out at the Horticulture Research Station, Tamil Nadu Agricultural University, Yercaud, Tamil Nadu to standardize the optimum plant density, inorganic fertilizer recommendation and concentration of growth prompting substance for Lavandula angustifolia Mill. The experiment was laid out in a randomized block design with three replications. The treatments consisted of three levels of spacing (40 x 60cm, 45 x 90cm and 60 x 120cm), three graded levels of inorganic fertilizers (100:40:40, 122:400:40 and 150:40:40 kg NPK per hectare) two varying concentration of GA3 (100 and 200 ppm as foliar application). The study revealed that closer spacing of 40x60 cm recorded more plant height (93.28cm) whereas the shortest plant height was observed in the control where GA3 was not sprayed. The earliest flowering (193.43 days), maximum leaf area / plant (9085.62cm2), chlorophyll content (412.63 mg/g), No. of florets/ flower head (22.18), length of flower head (3.75 cm) was observed under the treatment T8. The flower oil yield/plant was maximum in the treatment T14 (29.23mg/plant). The maximum estimated oil yield/ha was registered under the treatment T2 (10.32kg).

Bayesian approach for maize yield response to plant density from both agronomic and economic viewpoints in North America

Targeting the right agronomic optimum plant density (AOPD) for maize (Zea mays L.) is a critical management decision, but even more when the seed cost and grain selling price are accounted for, i.e. economic OPD (EOPD). From the perspective of improving those estimates, past studies have focused on utilizing a Frequentist (classical) approach for obtaining single-point estimates for the yield-density models. Alternative analysis models such as Bayesian computational methods can provide more reliable estimation for AOPD, EOPD and yield at those optimal densities and better quantify the scope of uncertainty and variability that may be in the data. Thus, the aims of this research were to (i) quantify AOPD, EOPD and yield at those plant densities, (ii) obtain and compare clusters of yield-density for different attainable yields and latitudes, and (iii) characterize their influence on EOPD variability under different economic scenarios, i.e. seed cost to corn price ratios. Maize hybrid by seeding rate trials were conducted in 24 US states from 2010 to 2019, in at least one county per state. This study identified common yield-density response curves as well as plant density and yield optimums for 460 site-years. Locations below 40.5 N latitude showed a positive relationship between AOPD and maximum yield, in parallel to the high potential level of productivity. At these latitudes, EOPD depended mostly on the maximum attainable yield. For the northern latitudes, EOPD was not only dependent on the attainable yield but on the cost:price ratio, with high ratios favoring reductions in EOPD at similar yields. A significant contribution from the Bayesian method was realizing that the variability of the estimators for AOPD is sometimes greater than the adjustment accounting for seed cost. Our results point at the differential response across latitudes and commercial relative maturity, as well as the significant uncertainty in the prediction of AOPD, relative to the economic value of the crop and the seed cost adjustments.

Differences in grain yield responses to planting density in twin and narrow row cultivation between early and late maize cultivars

AbstractWe investigated how two planting patterns, twin row (TR) and narrow row (NR), affected maize grain yield compared with conventional row (CR) cultivation at five different planting densities, ranging from 7 to 12 plants/m2, over 2 years using early and late cultivars. For all the planting patterns, the relationship between grain yield and planting density could be fit using the quadratic curve Y = a (X − b)2 + c at the <1% level of significance, where a represents grain yield response to planting density, and c represents the maximum yield. Regardless of the cultivar’s maturation period, the magnitude of a was smaller for TR than for NR and CR. Although the late cultivar had a higher c value than the early cultivar, the a value and annual difference were larger. For the early and late cultivars, TR at 10.8 and 9.9 plants/m2, respectively, easily achieved stable high grain yields. The large magnitude of the grain yield response to planting density for the late cultivar was caused by the large decrease in the number of grains per ear and the harvest index at an above optimum planting density. This large decrease and instability in yield‐related traits resulted from a high maximum leaf area index, the frequent mutual shading of leaf blades and the large differences between the years.

Estimation of Sugarcane Yield Using a Machine Learning Approach Based on UAV-LiDAR Data

Sugarcane is a multifunctional crop mainly used for sugar and renewable bioenergy production. Accurate and timely estimation of the sugarcane yield before harvest plays a particularly important role in the management of agroecosystems. The rapid development of remote sensing technologies, especially Light Detecting and Ranging (LiDAR), significantly enhances aboveground fresh weight (AFW) estimations. In our study, we evaluated the capability of LiDAR mounted on an Unmanned Aerial Vehicle (UAV) in estimating the sugarcane AFW in Fusui county, Chongzuo city of Guangxi province, China. We measured the height and the fresh weight of sugarcane plants in 105 sampling plots, and eight variables were extracted from the field-based measurements. Six regression algorithms were used to build the sugarcane AFW model: multiple linear regression (MLR), stepwise multiple regression (SMR), generalized linear model (GLM), generalized boosted model (GBM), kernel-based regularized least squares (KRLS), and random forest regression (RFR). The results demonstrate that RFR (R2 = 0.96, RMSE = 1.27 kg m−2) performs better than other models in terms of prediction accuracy. The final fitted sugarcane AFW distribution maps exhibited good agreement with the observed values (R2 = 0.97, RMSE = 1.33 kg m−2). Canopy cover, the distance to the road, and tillage methods all have an impact on sugarcane AFW. Our study provides guidance for calculating the optimum planting density, reducing the negative impact of human activities, and selecting suitable tillage methods in actual cultivation and production.

Maize plant density affects yield, growth and source-sink relationship of crops in maize/peanut intercropping

Abstract Maize (Zea mays L.)/peanut (Arachishypogaea L.) intercropping has been widely practiced in semi-arid regions to reduce wind erosion and improve resource (e.g. water and light) use efficiencies. Knowledge on optimal maize plant density is lacking from perspective of dry matter accumulation among organs in this intercropping system. We quantified the effect of maize plant density on relative yield total (RYT), maize and peanut yields, and maize dry matter of organs (ears, leaves, and stems) in maize/peanut intercropping. Field experiments were conducted in a semi-arid area of China in 2015 and 2016. Three maize plant densities (6, 9 and 12 plants m−2) were tested in maize/peanut intercropping (per unit growing area designed for maize) and sole systems, whereas the plant density of intercropped peanut and sole peanut was fixed as 24 plants m-2. The beta and logistic growth functions were used to quantitatively characterize the dynamics of dry matter allocation among organs in maize. Increasing maize plant density significantly increased maize yield gain, but not increased peanut yield loss, in maize/peanut intercropping. The greatest yield advantage (RYTs of 1.21 in 2015 and 1.13 in 2016) occured in maize/peanut intercropping with maize planted at 9 plants m−2. Increasing plant density increased leaf growth rate, but reduced leaf longevity and dry matter allocation to ears for maize grown in both intercropping and sole systems. But, greater increases in leaf growth rate and leaf longevity for intercropped maize compared with sole maize resulted in a greater increase in dry matter accumulation for maize grown at 9 and 12 plants m−2. Greater increases in ear dry matter accumulation and yield were found for maize grown at 9 plants m−2 due to greater dry matter allocation to ears. We conclude that the different responses to plant density of the source capacity (leaves) and sink strength (ears) for maize in intercropping and sole systems could help optimize maize plant density (9 plants m-2) for greater maize yield gain and yield advantage in maize/peanut intercropping.