Optimum Plant Density Research Articles

Grazing and Cutting under Different Nitrogen Rates, Application Methods and Planting Density Strongly Influence Qualitative Traits and Yield of Canola Crop

Canola crop has the potential for both seeds and grazing. Optimal planting density, time of nitrogen (N) fertilizer application and rates are the major aspects for successful qualitative traits and canola yield formation. In this content, optimization of planting density, N levels and its time of application in dual purpose canola are needed. This study was carried out in RCB design with split pot arrangement having three repeats during winter 2012–2013 and 2013–2014. The study evaluated N levels (120 and 80 kg N ha−1), cutting treatment, N application timings and planting density (20 and 40 plants m−2) effects on qualitative traits and yield of canola. No-cut treatment had 7.02%, 2.46%, and 4.26% higher, glucosinolates, oil, and protein content with 31.3% and 30.5% higher biological and grain yield respectively, compared with grazed canola. Compared with no-cut canola, grazed canola resulted in 7.74% of higher erucic acid. Further, application of N at 120 kg N ha−1 had 8.81%, 5.52%, and 6.06% higher glucosinolates, percent protein, and seed yield, respectively than 80 kg N ha−1. In-addition, the application of N into two splits was most beneficial than the rest application timings. Cutting had 15% reduction in grain yield of canola and fetched additional income of 143.6 USD compared with no-cut. Grazing resulted in a 23% reduction in grain yield while had additional income of 117.7 USD from fodder yield. Conclusively, the application of N in two splits at 120 kg N ha−1 combined with 20 plants m−2 is a promising strategy to achieve good qualitative attributes and canola yield under dual purpose system.

The optimal plant density of maize for dairy cow forage production

AbstractWhole maize (Zea mays L.) plant (WMP) silage is an important feed for dairy cows. In northern China, yields and feed quality are adjusted by modifying the planting density. This paper is the result of a 2‐yr field study aimed at determining the effects of plant density on maize silage yield and quality. Five planting densities (52,500, 60,000, 67,500, 75,000, and 82,500 plants ha−1) were used. The results showed that plant height and leaf area increased, while stem diameter, chlorophyll, and leaf area per plant decreased with increasing plant density. Both the biomass yield, expressed as the dry matter (DM) per ha, and the utilizable energy yield improved when the density was increased from 67,500 to 75,000 plants ha−1, but increasing the density further reduced these values. The highest observed DM were 17,734 kg ha−1 and 17,055 kg ha−1, and total net energy for lactation (NEL) were 104.1 GJ ha−1 and 97.0 GJ ha−1 in 2017 and 2018, respectively. Feeding quality generally decreased with increasing plant density. The plant density which obtained the highest biomass yield was not the same as the plant density for optimizing feeding production. Compared with the highest predicted DM yields, the highest predicted total NEL yields increased the grading index by 4–9%, which indicated an improvement in forage quality. Total NEL yield is more efficient for the purpose of evaluating the productivity of WMP forage than biomass yield.

An overview on problems and prospects of transplanted maize with special reference to India

Transplanting is the technique of moving of a plant from one location to another. This strategy is commonly practiced to establish crops when conditions are less favourable for direct seeding. Birds and squirrels damage to seedlings of maize is a serious problem resulting in poor crop stand and low yield. Delayed germination and plant growth receives a major setback due to late sowing of maize which reduces grain yield; however, reduction of yield can be compensated by transplantation technique. Transplanting of maize is a strategy that can be used to achieve optimum plant densities, better crop stand and obviously to get optimum yield. It reduces the nutrient requirement and also shortens the growth period of crop that helps farmers to harvest a third crop in intensive cropping system. Transplanted crop produces about 15.44% higher grain yield and can be harvested 10-12 days earlier that of direct seeding crop, so, late maturity high yielding cultivars can be fitted in to available growing season. Though, there are several advantages of transplanted maize, it is not popular in India due to lack of awareness, lacking in proper rational scientific technology and very little information about age of seedling and optimum dose of nutrient. Farmers can be benefitted if proper technology regarding age of seedling, process of transplanting and other cultivation techniques of raising transplanted maize is supplied to them.

Winter Wheat Yield Response to Plant Density as a Function of Yield Environment and Tillering Potential: A Review and Field Studies

Wheat (Triticum aestivum L.) grain yield response to plant density is inconsistent, and the mechanisms driving this response are unclear. A better understanding of the factors governing this relationship could improve plant density recommendations according to specific environmental and genetics characteristics. Therefore, the aims of this paper were to: i) execute a synthesis-analysis of existing literature related to yield-plant density relationship to provide an indication of the need for different agronomic optimum plant density (AOPD) in different yield environments (YEs), and ii) explore a data set of field research studies conducted in Kansas (USA) on yield response to plant density to determine the AOPD at different YEs, evaluate the effect of tillering potential (TP) on the AOPD, and explain changes in AOPD via variations in wheat yield components. Major findings of this study are: i) the synthesis-analysis portrayed new insights of differences in AOPD at varying YEs, reducing the AOPD as the attainable yield increases (with AOPD moving from 397 pl m-2 for the low YE to 191 pl m-2 for the high YE); ii) the field dataset confirmed the trend observed in the synthesis-analysis but expanded on the physiological mechanisms underpinning the yield response to plant density for wheat, mainly highlighting the following points: a) high TP reduces the AOPD mainly in high and low YEs, b) at canopy-scale, both final number of heads and kernels per square meter were the main factors improving yield response to plant density under high TP, c) under varying YEs, at per-plant-scale, a compensation between heads per plant and kernels per head was the main factor contributing to yield with different TP.

Economically Optimal Plant Density for Machine-harvested Edamame

Consumer demand for edamame [Glycine max (L.) Merr.], the vegetable version of soybean (Glycine max), has grown during the past decade in North America. Domestic production of edamame is on the rise; however, research to guide fundamental crop production practices, including knowledge useful for developing appropriate recommendations for crop seeding rate, is lacking. Field experiments near Urbana, IL, were used to quantify edamame response to plant density and determine the economically optimal plant density (EOPD) of machine-harvested edamame. Crop growth and yield responses to a range of plant densities (24,700 to 395,100 plants/ha) were quantified in four edamame cultivars (AGS 292, BeSweet 292, Gardensoy 42, and Midori Giant) across 2 years. Plots were harvested with the Oxbo BH100, a fresh market bean harvester. In general, as plant density increased, branch number and the ratio of pod mass to vegetative mass decreased, while plant height and leaf area index increased. Recovery, the percent of marketable pods in the machine-harvested sample, varied among cultivars from 86% to 95%. Results identified the EOPD for machine-harvested edamame ranged from 87,000 to 120,000 plants/ha. When considering the effect of plant density on plant morphology, as well as seeding cost, harvester efficiency, recovery, and marketable pod yield, edamame EOPDs are considerably lower than seeding rates of up to 344,200 seeds/ha recommended in recent publications.

Optimum plant stand and nutrient doses for summer groundnut under check basin irrigation and drip fertigation in light black soils of peninsular Western India

A field experiment was conducted at Research Farm of ICAR-Directorate of Groundnut Research, Junagadh for consecutive three summer seasons of 2013, 2014, and 2015 with the objectives of identifying optimum plant density and nutrient doses under check basin irrigation and drip fertigation for higher productivity and net returns. The treatments were; three plant densities viz., 3,33,333 plants/ha (100% of recommended plant density; P1); 4,16,666 plants/ha (125% of recommended plant density; P2), and 4,99,999 plants/ha (150% of recommended plant density;P3) in main plots, and three nutrient doses viz., 18.75–37.5–22.5 NPK kg ha−1 (75% of recommended nutrient dose; F1), 25-50-30 NPK kg ha−1 (100% of recommended nutrient dose; F2), and 31.25–62.5–37.5 NPK kg ha−1 (125% of recommended nutrient dose; F3) in sub-plots, and replicated thrice. The same sets of treatments were tested under both check basin irrigation and drip fertigation. The data were analyzed using split plot design. Pod yield, haulm yield, and net returns were significantly higher with P3 as compared to P1 under check basin irrigation but only haulm yield was found significantly higher with P3 under drip fertigation. Under check basin irrigation, NH4–N, NO3–N, and available P and K in soil were found in the order P1 > P2 > P3 (p < 0.05) while in case of drip fertigation, differences were significant only for available K which was significantly higher in P1 over both P2 and P3. Under check basin irrigation, F2 i.e., application of 100 percent of recommended nutrient doses, being at par with F3, significantly improved pod yield, haulm yield and net returns over that with F1 however, differences were not significant under drip fertigation. NH4–N, NO3–N and available P and K in soil under both the irrigation systems were in the order F3 > F2 > F1 (p < 0.05).

Some biological features of erva wooly seeds

Some morphological features and quality of Erva woolly seeds were revealed. The sizes of the seeds of the NBG’s reproduction in 2018 varied within 0.6-0.8 mm, with a mass of 1000 seeds being 0.083-0.086 g. Seeds obtained under the conditions of the Southern Coast of the Crimea are characterized by a long germination period of 22-29 days. Laboratory germination at variable temperatures amounted to 64.3%, field under the condition of surface seeding with rolling 46.7%. Seeds are half-burned according to the I.V. Borisova classification of types of seed germination belong to the second type, a subtype with slow germination and a maximum of germinated seeds in the middle of the germination period. It was established that for the germination of Erva woolly seeds, an air temperature above 20°C is necessary. The lowest seed germination rate was obtained when they were germinated at a constant temperature of 20°C. Dry heating of seeds during the day before sowing had no effect. Seeding of seeds cleared of pericarp to a depth of not more than 1.0 cm results in sparse seedlings in comparison with surface sowing. Sowing seeds with pericarp can provide optimal plant density, both in the conditions of surface sowing and with the incorporation of seeds into the soil.

Identifying Ways to Narrow Maize Yield Gaps Based on Plant Density Experiments

Exploring the maximum grain yields (GYs) and GY gaps in maize (Zea mays L.) can be beneficial for farmer to identify the GY-limiting factors and take adaptive management practices for a higher GY. The objective of this work was to identify the optimum maize plant density range and the ways to narrow maize GY gaps based on the variation of the GYs, dry matter (DM) accumulation and remobilization with changes in plant density. Field experiments were performed at the 71 Group and Qitai Farm in Xinjiang, China. Two modern cultivars, ZhengDan958 and ZhongDan909, were planted at 12 densities, ranging from 1.5 to 18 plants m−2. With increased plant density, single plant DM decreased exponentially, whereas population-level DM at the pre- (DMBS) and post- (DMAS) silking stages increased, and the amount of DM remobilization (ARDM) increased exponentially. Further analysis showed that plants were divided four density ranges: range I (&lt;6.97 plants m−2), in which no DM remobilization occurred, DMBS and DMAS correlated significantly with GY; range II (6.97–9.54 plants m−2), in which the correlations of DMBS, DMAS, and ARDM with GY were significant; range III (9.54–10.67 plants m−2), in which GY and DMAS were not affected by density, DMBS increased significantly, and only the correlation of DMAS with GY was significant; and range IV (&gt;10.67 plants m−2), in which the correlations of DMBS and ARDM with GY decreased significantly, while that of DMAS increased significantly. Therefore, ranges I and II were considered to be DM-dependent ranges, and a higher GY could be obtained by increasing the population-level DMAS, DMAS, and ARDM. Range III was considered the GY-stable range, increasing population-level DMBS, as well as preventing the loss of harvest index were the best way to enhance maize production. Range IV was interpreted as the GY-loss range, and a higher GY could be obtained by preventing the loss of HI and population-level DMAS.

Understanding variability in optimum plant density and recommendation domains for crowding stress tolerant processing sweet corn.

Recent research shows significant economic benefit if the processing sweet corn [Zea mays L. var. rugosa (or saccharata)] industry grew crowding stress tolerant (CST) hybrids at their optimum plant densities, which may exceed current plant densities by up to 14,500 plants ha-1. However, optimum plant density of individual fields varies over years and across the Upper Midwest (Illinois, Minnesota and Wisconsin), where processing sweet corn is concentrated. The objectives of this study were to: (1) determine the extent to which environmental and management practices affect optimum plant density and, (2) identify the most appropriate recommendation domain for making decisions on plant density. To capture spatial and temporal variability in optimum plant density, on-farm experiments were conducted at thirty fields across the states of Illinois, Minnesota and Wisconsin, from 2013 to 2017. Exploratory factor analysis of twelve environmental and management variables revealed two factors, one related to growing period and the other defining soil type, which explained the maximum variability observed across all the fields. These factors were then used to quantify the strength of associations with optimum plant density. Pearson’s partial correlation coefficients of ‘growing period’ and ‘soil type’ with optimum plant density were low (ρ1 = -0.14 and ρ2 = -0.09, respectively) and non-significant (P = 0.47 and 0.65, respectively). To address the second objective, six candidate recommendation domain models (RDM) were developed and tested. Linear mixed effects models describing crop response to plant density were fit to each level of each candidate RDM. The difference in profitability observed at the current plant density for a field and the optimum plant density under RDM level represented the additional processor profit ($ ha-1) from a field. The RDM built around ‘Production Area’ (RDMPA) appears most suitable, because plant density recommendations based on RDMPA maximized processor profits as well grower returns better than other RDMs. Compared to current plant density, processor profits and grower returns increased by $448 ha-1 and $82 ha-1, respectively at plant densities under RDMPA.

Boron fertilization affects the physiological quality of soybean seeds, conventional and transgenic

High physiological quality soybean seeds are essential for a successful production, because they promote optimal plant density in the field. The objective of this work was to evaluate the effect of boron doses applied at different phenological stages of two soybean varieties on the physiological quality of the seeds. Two field experiments were carried out, one with each variety of soybean, conventional and transgenic. Five doses for boron were applied to the soil as boric acid (17%): 0, 1.0, 2.0, 3.0 and 4.0 kg ha-1, at three phenological stages (V6, V9 e R1). In R8 stage the seeds are harvested and then tested for physiological quality, through the tests of Germination, germination first count, germination speed index, accelerated aging and electrical conductivity. For the conventional variety, the boron doses promoted a quadratic effect on variables when the boron was applied near the reproductive stages. For the transgenic variety, the first-degree polynomial model presented the best fit, meaning that the higher the boron dose the better the physiological quality. The optimal boron application stage for producing high vigor seeds was R1 for both varieties. Four (4.0) kg ha-1 of boric acid is recommended for both varieties to produce high quality seeds.

Effects of Plant Density and Planting Pattern on Growth and Seed Yield of Groundnuts [Arachis hypogaea (l.)] in the Wet Middleveld of Eswatini

The most appropriate plant density and planting pattern to use for optimum growth and yield of groundnuts (Arachis hypogaea L.) in Eswatini among those currently used is not known, as the patterns are highly influenced by environmental conditions in specific regions. A field trial was conducted with the objective of determining the optimum plant density and planting pattern for groundnut in the Wet Middleveld of Eswatini. The experiment was conducted at the University of Eswatini, Luyengo Campus during the 2018/2019 cropping. The treatments consisted of three planting densities (i.e. 88,889 plants/ha, 44,444 plants/ha, and 29,630 plants/ha) and two planting patterns (i.e. Ridges and Raisedbeds) in a split plot arrangement. Results showed that all the measured parameters including seed yield were not significantly different in all treatments. However, the highest seed yield was obtained at low plant density which was 71.4 kg/ha followed by 568 kg/ha at medium and the least was 434 kg/ha at high plant density. The high plant density (88889 plants/ha) obtained the highest value of dry biomass (13018 kg/ha) at ridges which was higher than 3859 kg/ha obtained at the low plant density (29630 plants/ha) at raised beds at R6 growth stage. The ridges at the intermediate plant density (44444 plants per hectare) obtained the highest shelling percentage of 59.67% while the lowest (56%) shelling percentage was obtained at raised beds at 88889 plants per hectare. It is concluded that groundnuts at raised beds with low plant density yielded higher than those at ridges with high plant density. It is therefore, recommended that groundnuts be planted at raised beds with low plant density to increase groundnut production and for ease of harvesting.

Response of cotton fruit growth, intraspecific competition and yield to plant density

Abstract Increasing plant density has been an effective way for cotton yield improvements. The density of plants in a community also determines competition intensity and the efficiency to exploit available resources. However, the competition response as well as optimal density for yields and the mechanisms of which in terms of fruit growth rate are poorly known. A field experiment was conducted on cotton (Gossypium hirsutum L. SCRC 28) at a wide range of plant densities from 1.5–10.5 plants m−2. The results indicated that intraspecific competition between cotton plants increased nonlinearly with increasing plant density. Seedcotton yield per unit ground area declined precipitously at plant densities below the 4.0 plants m−2 threshold and yield did not further increase above this threshold, which is interpreted as the minimum plant density at which yield should be maximized. Moreover, maximum fruit production and fruit growth rate were also recorded at the same density threshold, above which there was no significant response. Cotton yield was positively correlated with fruit production and fruit growth rate. We thus conclude that high fruit production and fruit growth rate are responsible for maximum yield under optimal plant density in cotton.

Seedling Raising Nursery Business for Sustainable Mechanical Rice Transplanting in the Southern Delta of Bangladesh

Mechanical rice transplanting needs special seedling raising. The Appropriate Scale Mechanization Innovation Hub (ASMIH)-Bangladesh project trained farmers on raising rice seedling. Extensive field trials were conducted during 2017 to 2019 by the ASMIH-Bangladesh and farmers’ groups are now confident to establish seedling nursery on commercial basis. It will solve the seedling raising problem for mechanical transplanting and also increase their income. The main advantages of mechanical transplanting are transplanting of seedlings at the age of 12-30 days with uniform spacing and optimum plant density; higher productivity compared to traditional transplanting where plant spacing and density are not always be consistent; less transplanting shock, early seedling vigor and uniform crop establishment; less time, labor, drudgery and health risks for farm laborers. FAO developed a rural invest software named “RuralInvest” to access the sustainability of rural projects such as mechanization, development projects, entrepreneurial opportunities, investment projects etc. In this study, the RuralInvest software was used to evaluate the seedling raising nursery business. The total time duration of the project was estimated for 5 years with farmer’s own investment where the direct beneficiaries were 08 farmers and indirect beneficiaries were 45 farmers. Two types of seedling raising techniques were evaluated with the RuralInvest software, one for mat-type and another for economy plastic tray-type seedling raising. The IRR, NPV, payback period and Investment per direct beneficiaries were found 29.10%, BDT 2056, 2.46 year, BDT 348.75 and 22.52%, BDT 3834, 2.84 years, BDT 911.25 for mat-type and plastic tray-type seedling raising, respectively. To establish the sustainable mechanization of rice transplanting and meet the challenges of labor crisis during rice transplanting season, seedling raising nursery business would generate sustainable entrepreneurship through income generation and raising seedlings for mechanical rice transplanting in the Southern delta of Bangladesh.

Response of Chickpea (&amp;lt;i&amp;gt;Cicer aeritinum&amp;lt;/i&amp;gt; L.) Genotype to Intra and Inter Row Spacing at Huletegna Choroko, Southern Ethiopia

Chickpea has a major role in the daily diet of the rural community and urban population as a good source of energy, protein, minerals, vitamins, fiber and its straw is used for animal feed, and it also improves soil fertility by fixing the atmospheric nitrogen. Optimum plant density and appropriate genotypes for a given agro ecology influences plant size, yield components and ultimately the seed yield. Hence, a field experiment was carried out to determine the effect of intra and inter-row spacing on growth, yield and yield component of chickpea (Cicer aeritinum L.) Genotypes under rain fed condition in Huletegna Choroko, Southern Ethiopia in 2016 cropping season. A split-split plot design with three replications was used with two chickpea genotypes: Genotypes Habru and Mastewal were arranged in main plot and intra-row spacing of 5, 10 and 15 cm in sub-plot and inter-row spacing’s of 30, 40 and 50 cm in sub-sub plot. Days to flowering and hundred seed weight were significantly different between the two genotypes. Intra-row spacing had significantly affected physiological maturity, nodule dry weight plant-1, plant height, primary branch plant-1, pods plant-1, seeds pod-1, above ground biomass and seed yield. Inter row spacing also significantly affected days to flowering, days to physiological maturity, nodule number plant-1, nodule dry weight, plant height, primary branch, pod plant-1, seed number pod-1, above ground dry matter and seed yield. Mastewal genotype obtained the maximum (2.91 t ha-1) grain yield at the combination of 15 cm intra row and 30 cm inter row spacing while Habru genotype obtained (2.57 t ha-1) at the same intra and inter-row spacing. Finally it could be concluded that intra row spacing of 15 cm and inter row spacing of 30 cm were found to be the optimum for maximum grain yield of chickpea using genotype Mastewal and Habru at Halaba, Huletegna choroko.

Biotechnology of Australian red-claw crayfish (Cherax quadricarinatus) juvenile ongrowing in recirculating aquaculture system

As a result of the work done, the biotechnology of growing Australian red claw crayfish (Cherax quadricarinatus) juvenile in recirculating aquaculture system facilities was developed. The research work was carried out in the laboratory of advanced technologies in aquaculture on the basis of the business incubator the Federal State-Funded Educational Institution of Higher Education “Kuban State University”. The composition of the material base necessary for the implementation of biotechnology is determined, growth rates are determined, an optimal diet is formed and optimal planting densities are determined. For the working process two recirculating aquaculture system units were used. As food we used: minced fish, sturgeon food, artemia nauplii, oatmeal, frozen bloodworm, dried gammarus. During 80 days, decades-long survival varied from 83.6 to 91.8%. The average weight of individuals had changed from 0.03 to 5.10 g. The coefficient of variation of this feature was in the permissible range and increased from 9.1 to 22.6%. The total feed coefficient at a cost of 3387.3 g of feed per increase of 1347.7 g of biomass composed 2.5 units. Using the data obtained, it is possible to make primary calculations when organizing the cultivation of ARCC juveniles.

Response of maize (Zea mays L.) to nitrogen and planting density in Jabitahinan district, Western Amhara region

The optimum nitrogen (N) level and planting density (PD) have not been studied for the newly introduced BH-QPM-545 maize variety in the Jabitahinan district agroecology. To determine the optimum N ...

РАЗРАБОТКА ОПТИМАЛЬНЫХ СХЕМ ЛЕСОПОСАДКИ МЕТОДОМ ИМИТАЦИОННОГО МОДЕЛИРОВАНИЯ

One way to increase the productivity of artificial forestation is to control the density and relative position of trees. In this regard, there are tasks of finding the optimal planting schemes to obtain the maximum wood stock of a given diameter. Based on the developed simulation model, a comparative analysis of the productivity of spruce stands with different planting schemes was carried out. The optimal forest planting schemes for spruce stands, which provide the maximum stock of small, medium and large wood, are determined. It is shown that in order to maximize the stock of wood of different size classes, different initial planting densities are required. The higher the size classes of the grown wood, the lower the optimal planting density.

Estimación de máximas densidades para mitigar el impacto de la enfermedad HLB en plantaciones de naranja Valencia

Objectives: This work was carried out to estimate the optimal plant density for 4 Valencia orange varieties and to determine the highest yield potential as a strategic to overlap the yield reduction by citrus HLB disease. Methodology: Tree growth data of nine years [(height, diameter and canopy volume (CV); area of soil covered by canopy (ASC)] and yield in kg/tree (Y) of four varieties were analyzed first by correlation analysis and then submitted to a lineal and multiple regression analysis. Contribution: Correlation values of 0.8 and 0.85 were observed for ASC and CV with Y, respectively. Based on these variables the optimal calculated tree densities by regression for “Pineapple”, “Queen”, “Cutter” and “Campbell” varieties were 900-1000 trees/ha, which can yield 30 to 60 ton/ha/year, from 4th to 9th year.

Effects of planting density on potato growth, yield, and water use efficiency during years with variable rainfall on the Loess Plateau, China

A 3-yr field study was conducted in semiarid areas of the Loess Plateau to investigate the effects of different planting densities on the soil water, potato growth, yield, and WUE during the normal year (2015), relatively dry year (2016), and relatively wet year (2017). The five potato planting densities were 3.75 × 104 (A, traditional local planting density as a control), 4.50 × 104 (B), 5.25 × 104 (C), 6.00 × 104 (D), and 6.75 × 104 plants ha–1 (E). During the three years, the differences in soil water storage among the five planting densities were significant in the early and middle potato growth stages, when the soil water storage levels in treatments B and C were 8.8 % and 10.8 % higher (P < 0.05) than those in A. Treatments B and C significantly (P < 0.05) increased the potato emergence rate by 12.5 % and 7.5 % to promote growth in the early and middle stages. The planting density had a decreasing parabolic relationship with the potato yield. After fitting a function to the three years of data, the highest tuber potato yield varied with the amount of rainfall and the optimum level was 5.12–5.58 × 104 plants ha−1. The WUE and rainwater use efficiency (RWUE) were significantly higher under B and C compared with A in the normal and relatively dry years. WUE and RWUE were significantly higher in B, C, and D compared with A in the relatively wet year. The optimum planting density with treatments B and C obtained higher net profits. Thus, the recommended optimum planting density should be 4.50–5.12 × 104 plants ha−1 in relatively dry years and 5.13–5.58 × 104 plants ha−1 in normal and relatively wet years to increase dryland potato production and water use efficiency in the semiarid regions of the Loess Plateau, China.

Plant Density Influences Reproductive Growth, Lint Yield and Boll Spatial Distribution of Cotton

The number of cotton plants grown per unit of ground area has gained attention due to the high prices of inputs and lower production. Cotton yield per unit of area in Henan province has been stagnant in the last few years. The objectives of this study were to investigate cotton growth, yield, boll spatial distribution and biomass accumulation using different plant densities at cultivation and to find out the optimal plant density. A 2-year field experiment was conducted in a randomized complete block design under six plant densities (D1, 15,000; D2, 33,000; D3, 51,000; D4, 69,000; D5, 87,000 and D6, 105,000 ha−1). Cotton grown at lower plant density produced taller plants and high number of leaves per plant while greater number of branches, fruiting nodes and high number of bolls per unit of ground area were produced under high plant density. Boll retention rate decreased as plant population increased and at nodes 1–8 the rate decreased slowly and then increased dramatically. The highest seed cotton yield (4546 kg ha−1) and lint yield (1682 kg ha−1) was produced by D5. The seed cotton and lint yield produced by D5 were 51–55%, 40–37%, 22–26%, 11–15%, 12–15%, 28–30%, 21–24%, 15–20%, 7–13% and 13–17% higher than D1, D2, D3, D4 and D6 during both years of experimentation, respectively. The increase in seed yield was due to higher biomass accumulation in reproductive organs under D5 plant density. The highest average (110.4 VA kg ha−1 d−1) and maximum (126 VM kg ha−1 d−1) rate of reproductive organs biomass was also accumulated by D5 as compared to other plant densities. The results suggest that D5 is the optimal plant density for high reproductive biomass accumulation and high yield for the area of Henan province.