Optimum Plant Density Research Articles

Effects of Inter and Intra Row Spacing on Growth and Yield Components of Hot Pepper (Capsicum Annum L.) Var Halaba

A field experiment was carried out during 2014 and 2015 growing seasons at Galato research farm located in Halaba, southern Ethiopia to identify optimum plant density (row x plant spacing) that maximize growth and pod yield components of hot pepper. Four row spacing (40, 50, 60 and 70cm) and four plant spacing (20, 30, 40 and 50 cm) were arranged in 4 x 4 factorial combination in Randomized Complete Block Design (RCBD) with three replications. Results indicated that year x row spacing produced more significant (P<0.05) interaction compared to year x plant spacing, row x plant spacing or year x row x plant spacing. Row x plant spacing of 70 cm x 30 cm (47,619 plants/ha), 60 cm x 30 cm (55,555 plants/ha), 50 cm x 30 cm (66,666 plants/ha), 40 cm x 40 cm (62,500 plants/ha) and 40 cm x 50 cm (50,000 plants/ha) produced statistically similar HI results to that of 50 cm x 20 cm row x plant spacing (100,000 plants/ha). Lowest HI was measured due to 40 cm x 20 cm row x plant spacing (125,000 plants/ha). The maximum of 29.3 qt/ha of dry pod yield of hot pepper was measured due to 60 cm wide rows in 2014 (good year) where as the lowest pod yield of 15.4 qt/ha was obtained due to 40 cm wide rows in 2015 (bad year). Dry biomass yield of hot pepper was significantly higher (P<0.05) due to 50 cm wide rows in 2014 where as the lowest dry biomass yield was recorded due to 70 cm wide rows in 2015. Fruit yield/plant showed positive significant correlation with plant height (r=0.572) and pod numbers (r=0.641). Significant negative association was observed between HI (harvest index) and plant height (r=-0.429), and HI and branch number (r=-0.512). Results indicated that significantly higher (P<0.01) dry pod yield in 2014 was obtained due to 60 cm x 20 cm row x plant spacing (83,333plants/ha). However, 50 cm x 30 cm (66,666plants/ha) spacing produced statistically similar dry pod yield to that of 60 cm x 20 cm row x plant spacing. In 2015, dry pod yield was significantly higher (P<0.01) due to 70 cm x 30 cm row x plant spacing (47,617 plants/ha) compared to other row x plant spacing combinations. 60 cm x 30 cm row x plant spacing produced intermediary results in 2015. Thus, hot pepper requires wider row x plant spacing in drier times and narrower row x plant spacing in rainy times under field conditions of Halaba.

Effect of Moisture Conservation Methods and Plant Density on the Productivity of Two Maize (<i>Zea mays</i> L.) Varieties under Semi-Arid Tropics of Hamelmalo, Eritrea

The productivity of maize in Eritrea in general and under semi-arid tropics of Hamelmalo in particular is low because of moisture stress. The low moisture content is ascribed to the low and erratic distribution of rainfall, high temperature, lack of suitable varieties, and competition by weeds and low soil fertility. To overcome some of these problems, a field experiment was carried out to assess the effect of moisture conservation methods (MCM) and plant density on the productivity of two maize (Zea mays L.) varieties under semi-arid tropics of Hamelmalo, Eritrea. The experiment was conducted in split-split plot design with three MCM viz tied ridge, ridge and furrow and flat-bed in main plots; two maize varieties viz early local and 04sadve hybrid in sub plots and three plant densities by manipulating the plant to plant distance viz 35 cm, 25 cm and 15 cm at a fixed 75 cm row spacing in sub-sub plots, each replicated thrice. The experiment was focused in addressing the effective moisture conservation techniques, optimum plant density to each variety thus to improve productivity. The crop experienced 10°C to 34.8°C minimum and maximum temperature, respectively and received 429.1 mm total rainfall. The results of the experiment indicated that among all the combinations, 04sadve hybrid variety sown at 75 cm × 25 cm spacing in ridge and furrow method or at 75 cm × 15 cm spacing in tied ridge or flat-bed method and early local variety sown at 75 cm × 15 cm spacing in flat-bed being statistically at par resulted in significantly higher moisture conservation and consequently higher grain yield (4509 kg·ha-1) and higher water use efficiency. It is, therefore, recommended that tied ridge or flat-bed of moisture conservation method at 15 cm plant spacing and 04sadve is preferable to optimize productivity in Hamelmalo area, Eritrea.

Effect of plant population dynamics and different weed free regimes on growth, yield and quality of peanut (Arachis hypogaea L.)

Productivity of groundnut ( Arachis hypogaea L.) in Bangladesh is very low, due to many limiting factors beset in its cultivation. Plant density and weed competition in crop constitute the main limiting factors. In order to combat the problems, the optimum plant density and most appropriate weeding period for good production in groundnut has been investigated at Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, Bangladesh. Two plant density viz. 200,000 and 400,000 plants ha -1 , and seven weed competition periods from 0, 25, 40, 55, 70, 85 DAS and up to harvesting time were studied. Nineteen species of weeds representing 10 families were found to grow and population density was 150 plants m -2 . The major infesting species of weeds were Cyperus rotundus L. (Mutha), Chenopodium album L. (Bathua), Physalis heterophylla L. (Foska begun), Gnaphalium luteo-album L. (Shwetomuli) and Paspalum disticum L. (Knot grass) which constituted about 84.66% of the total weed population. Cyperus rotundus alone shared the maximum relative density (57%) having 85.5 plants m -2 area of total weed vegetation and also shared the maximum intensity of infestation (2.85). Intensity of weed infestation was always higher at lower plant density. Weed dry matter production was higher at a density of 200000 plants compared to 400000 plants ha -1 . In contrast, weed dry weight was progressively increased with increasing weed competition period and it was the highest in unweeded plot and critical period of weed competition appeared at 40 DAS. Weed competition period from zero to 40 DAS and thereafter weed free up to crop harvest with a density of 400000 plants ha -1 gave the highest pod yield The pod yield was found to have a significant negative correlation with weed dry matter production i.e. an increase in the dry matter production will lead to a decrease in the yield of pods.

Yield and economic benefits of late planted short-season cotton versus full-season cotton relayed with garlic

Relay intercropping of garlic with full-season cotton is currently one of the dominant cropping systems in China, but the net benefit is decreasing because the system is labor-intensive. Direct planting of short-season cotton after garlic harvest may increase net revenue through reducing labor and material input. Three field experiments were consecutively conducted in Jinxiang County of China, to determine the effects of plant density and soil fertility on yield, yield components, boll load and leaf senescence in the 1st and 2nd experiments. In the third experiment, we compared the economic benefits of the two cropping systems. Data from the 1st experiment showed that plant density affected yield and yield components, with the optimum plant density being 3.0plantsm−2 for full-season cotton and 9.0plantsm−2 for short-season cotton. In the 2nd experiment, the seedcotton yield of full-season cotton was 9.1% higher under high than medium soil fertility, but there was no yield difference between the two soil fertility levels for short-season cotton. Full-season cotton exhibited larger boll load, earlier leaf senescence and lower boll weight under medium than high fertility. Results of the third experiment showed that seedcotton yield or output value of short-season cotton was 14.5% lower than that of full-season cotton, but the gross return for short-season cotton was 69.2% higher than that for full-season cotton because the short-season cotton required 27.3% less labor and material inputs. The overall results showed that late planted short-season cotton after garlic harvest can be a promising alternative for enhancing the benefits of garlic-cotton production in China.

Morphological, Physiological and Proteomic Analyses Provide Insights into the Improvement of Castor Bean Productivity of a Dwarf Variety in Comparing with a High-Stalk Variety.

Ricinus communis displays a broad range of phenotypic diversity in size, with dwarf, common, and large-sized varieties. To better understand the differences in plant productivity between a high-stalk variety and a dwarf variety under normal growth conditions, we carried out a comparative proteomic study between Zhebi 100 (a high stalk variety) and Zhebi 26 (a dwarf variety) combined with agronomic and physiological analyses. Over 1000 proteins were detected, 38 of which differed significantly between the two varieties and were identified by mass spectrometry. Compared with Zhebi 100, we found that photosynthesis, energy, and protein biosynthesis related proteins decreased in abundance in Zhebi 26. The lower yield of the dwarf castor is likely related to its lower photosynthetic rate, therefore we hypothesize that the lower yield of the dwarf castor, in comparing to high stalk castor, could be increased by increasing planting density. Consequently, we demonstrated that at the higher planting density in Zhebi 26 (36,000 seedlings/hm2) can achieve a higher yield than that of Zhebi 100 (12,000 seedlings/hm2). Proteomic and physiological studies showed that for developing dwarf R. communis cultivar that is suitable for large scale-production (i.e., mechanical harvesting), it is imperative to identify the optimum planting density that will contribute to higher leaf area index, higher photosynthesis, and eventually higher productivity.

Yield Responses to Planting Density for US Modern Corn Hybrids: A Synthesis‐Analysis

Identifying an optimal plant density is a critical management decision for corn (Zea maysL.) production. The main objectives of this study were to: (i) investigate the grain yield responses to plant density (yield–density relationship), (ii) identify best fitted yield–density response curves, and (iii) explore genotype (G) × environment (E) interaction effect on yield–density response models. Analysis was conducted on meta‐data (124,374 observations) gathered from 22 US states and 2 Canadian provinces, diverse sites (E), for years from 2000–2014 on multiple hybrids (G). Yield data were further grouped into four yield environments (low [LY], <7 Mg ha−1; medium [MY], 7–10 Mg ha−1; high [HY], 10–13 Mg ha−1; and very high [VHY], >13 Mg ha−1yielding groups). Primary outcomes from this analysis were: (1) strong G × E interaction; (2) a quadratic model best fitted yield–density relationship; (3) four contrasting yield–density responses identified as dominant in each yield productivity environment, i.e., a declining, a constant, an increasing, and ever‐increasing type; (4) the yield productivity environment varied for the different corn comparative relative maturity (CRM) groups, i.e., the LY environment for long‐maturing hybrids matched with a MY or HY environment for short maturing hybrids; and (5) maximum yielding plant density (MYPD) was lower but maximum yield was greater for long‐ versus short‐maturing hybrids. In summary, optimal plant density should be decided based on detailed G × E analysis of production conditions that include factors such as CRM, yield productivity environment (weather–soil × management practices), and site information.

Determination of optimum plant density for faba bean (Vicia faba L.) on vertisols at Haramaya, Eastern Ethiopia

A field experiment was carried out to identify the optimum plant density, inter and intra-row spacing for the maximum agronomic performance of Gachena (a recently released faba bean variety). A thr...

Yield potential and yield stability of Argentine maize hybrids over 45 years of breeding

Maize (Zea Mays L.) grain yield have increased during the last decades and there is an ample range of rates of grain yield increments reported in the literature. Maize hybrids comparison at their optimum plant density might contribute to elucidate the yield potential increments during the last decades. In addition, high plant density testing and multi-location trials in modern breeding programs might have contributed to greater stress tolerance in modern hybrids. Then, a close relationship between tolerance to high plant density and yield stability in hybrids released in different decades is expected. The objectives of this study were (i) to determine the optimum plant density and the gain in yield potential and its components, and (ii) to test the hypothesis that tolerance to high plant densities and yield stability are strongly associated, for Argentinean maize hybrids released between 1965 and 2010. One set of experiments was conducted at Balcarce, Argentina during five growing seasons (Exps. 1–5), each experiment included a combination of plant densities (1.5–20plants m−2) and hybrids released in different years (1965–2010). Data from these experiments were used to estimate optimum plant density, gains in yield potential and tolerance to high plant density. Another experiment (Exp. 6) included 18 trials conducted in a wide range of environments and data from these trials were used to estimate yield stability. The optimum density to attain the maximum yield ranged from 9.7 to 16.4plm−2 and it did not present a clear trend with the year of hybrid release. Yield potential increased at a rate of 0.83% or 107kgha−1year−1 (p<0.001) and yield increments were attributed mainly to gains in kernel number per unit area and to biomass production steady increments during the 1965–2010 period. Harvest index contributions to yield increments were important for the period 1980–1993, but HI remained stable during the last two decades. Yield stability increased with the year of hybrid release, in accordance with higher mean yields and lower CV (coefficient of variation) across environments of modern compared with older hybrids. Tolerance to high plant densities increased during the last 45 years and it was direct and significantly associated with yield stability, providing strong bases for the use of high plant densities as a method to attain gains in yield stability.

Plant and soil fertility characteristics of different winter wheat fields in the Huang-huai-hai plain of China

ABSTRACTHigh-profile nutrient accumulation has caused low nutrient use efficiency and environmental pollution. A total of 140 points in farmers’ wheat fields were investigated and sampled under a typical winter wheat and summer maize rotation system in the Huang-huai-hai Plain of China (HPC). The average wheat yield in the high-yield field is more than 10% relative to the mid-low-yield areas based on historical data. The results showed in the high-yield wheat field the effective spike number was the main yield component, followed by 1000-grain weight. Uptake contents and ratios of N, P2O5 and K2O in the whole wheat plant were also examined. Along the soil depth, organic matter (OM), alkali-hydrolyzable N (AN), available P (AP) and available K (AK) concentration gradually decreased. Soil critical values of AN, AP and AK in the 0–20 cm depth needed to achieve the maximum grain yield were 85.9, 17.7 and 114.2 mg kg−1 calculated by the significant linear-plus-plateau model between wheat grain yield and soil nutrient concentration at harvest, respectively. These results indicated that the rational application of fertilizer based on the soil nutrient supply capacity and residual nutrients in root zone and optimum planting density are key determinants of grain production in the HPC.

Comprehensive analysis of soil nitrogen removal by catch crops based on growth and water use

Abstract A new methodology for comprehensive analysis of the characteristics of nitrogen (N) removal from greenhouse soil by catch crop was proposed in relation to its growth and water use. The N removal is expressed as the product of five parameters: net assimilation rate, specific leaf area, shoot dry weight, water use efficiency for N removal, and water requirement for growth. This methodology was applied to the data of a greenhouse experiment where corn was cultivated under three plant densities. We analyzed the effect of plant density and examined the effectiveness of the methodology. Higher plant densities are advantageous not only for total N removal but also for water use efficiency in N removal and growth because of the large specific leaf area, shoot dry weight, and decreased soil evaporation. On the other hand, significant positive or negative linear relationships were found between all five parameters and N removal. This should improve the understanding of the N removal mechanisms and the interactions among its components. We show the effectiveness of our analytical methodology, which can contribute to identifying the optimum plant density according to the field situations (available water amount, soil N quantity to be removed) for practical catch crop cultivation.

Genotype × Environment Interaction for Plant Density Response in Maize (Zea mays L.)

Increased adaptation to high plant density has been an important factor in improvements in grain yield in maize (Zea mays L.). Despite extensive public literature on variation and improvement in plant density response among maize varieties, much less public information is available on effects of environment and genotype × environment interactions (G × E) on plant density response for grain yield in maize. The present study was conducted to quantify environment effects and G × E effects on plant density response for maize grain yield. A set of 57 synthetic populations, synthetic × inbred line crosses, and synthetic × synthetic population crosses were evaluated across a five year period including 17 individual location–years. The data in this study were an unbalanced combination of multiple experiments that included 370 pedigree‐environment combinations with each containing at least four planting densities and two replications per environment in most cases. G × E accounted for 26% of total genetic variance (genetic variance plus G × E variance) in linear regression coefficients and 39% of variance in quadratic regression coefficients in the regression of grain yield on observed plant density. Variance in G × E for linear and quadratic regression coefficients resulted in variation in optimal densities among varieties being highly specific to individual environments. Average plant density responses varied widely among environments with average optimal plant densities ranging from 5.6 to 9.1 plants m–2.

Optimizing plant density and weed control techniques in yield enhancement of mungbean

Field experiment was carried out at the Agronomy farm, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh to investigate the effect of plant density and weed control techniques on yield enhancement of mungbean. The experiment consisted of two factors viz. plant densities and weed control. Plant densities were 30 cm×continuous (D1), 30 cm×5 cm (D2), 30 cm×10 cm (D3) and 30 cm×15 cm (D4) arranged in the main plot. Weed control techniques were no weeding (W0), two hand weeding at 15 and 30 DAS (W1), Topstar 80 WP @ 75 g ha-1 as pre-emergence at 3 DAS (W2) and Whip Super 9 EC @ 750 ml ha-1 at 15 and 30 DAS as post-emergence herbicide (W3) arranged in the sub plot in a split plot design. Results showed that both plant density and weed control techniques significantly influenced most of the parameters studied. It was observed that application of pre and post emergence herbicide controlled weeds effectively compared to other weed control techniques whereas weed population and weed biomass were less in 30 cmx10 cm plant density. Considering yields, combination of 30 cm×10 cm plant density with application of Topstar 80 WP (D3W2) attributed to highest seed yield (1.47 t ha-1), stover yield (1.94 t ha-1) and biological yield (3.41 t ha-1) of mungbean.J. Asiat. Soc. Bangladesh, Sci. 42(1): 107-114, June 2016

ИНТРОДУКЦИЯ ПРОСОВИДНЫХ КУЛЬТУР

Each particular crop has a number of features that lead to changes in the use of new substances and also impact productivity and product quality. From this point of view, panicoid grass crops deserve much attention, especially when introduced in the mountain and foothill regions of the Republic of North Ossetia - Alania where poultry husbandry is well developed. Setaria italica subsp. moharicum Alef., Echinochloa frumentacea Link, Setaria italica subsp. maxima Alef. have been introduced at the North Caucasus Research Institute of Mountain and Foothill Agriculture as new crops for the republic. The goal was to improve their biological potential by applying innovative technologies. To achieve this, the sowing time and methods, as well as reproductive features of these crops were studied. Sowing and harvesting dates have been varied, and peculiarities of developmental biology taken into account. During the years of research, Echinochloa frumentacea Link has been found resistant to abiotic stresses in the foothill areas of the republic. Also, the optimal sowing time, seeding rate, plant density and survival rate, as well as 1000 seeds weight have been determined.

Response of grain yield to plant density and nitrogen rate in spring maize hybrids released from 1970 to 2010 in Northeast China

The objective of this study was to identify the response of grain yield to plant density and nitrogen rate in spring maize hybrids released from 1970 to 2010 and grown extensively in Northeast China. Twenty-one hybrids were grown for 2years in Northeast China at densities of 30,000, 52,500, 75,000, and 97,500plantsha−1 and N application levels of 0, 150, 300, and 450kgNha−1. Irrespective of density or nitrogen application rate, grain yields both per plant and per unit area were significantly higher for newer than older hybrids. As plant density increased from 30,000 to 97,500plantha−1, yield per plant of 1970s, 1980s, 1990s, and 2000s hybrids decreased by 50%, 45%, 46%, and 52%, respectively. The response of grain yield per unit area to plant density was curvilinear. The estimated optimum plant densities were about 58,000, 49,000, 65,000, and 65,000plantsha−1 for hybrids released in the 1970s, 1980s, 1990s, and 2000s, respectively. The theoretical optimum densities for the hybrids released from the 1970s to the 2000s increased by 1750plantsha−1 decade−1. Nitrogen fertilization significantly increased grain yields per plant and per unit area for all hybrids. The theoretical optimum N application rates for high yield for hybrids released in the 1970s and 1980s were about 280 and 360kgha−1, and the hybrids from the 1990s and 2000s showed highest yield at 330kgha−1N. No significant difference in the grain yields of 2000s hybrids between the N levels of 150 to 450kgha−1 was found. Significant yield gains per plant and per unit area were found, with average increases of 17.9g plant−1 decade−1 and 936kgha−1 decade−1 over the period 1970–2010, respectively. Yield gains were attributed mainly to increased yield per plant, contributed by increases in kernel number per ear and 1000-kernel weight. The rates of lodging and barren plants of newer hybrids were significantly lower than those of older ones, especially at high plant density.

Density responses and spatial distribution of cotton yield and yield components in jujube (Zizyphus jujube)/cotton (Gossypium hirsutum) agroforestry

Abstract Trees are the dominant species in agroforestry systems, profoundly affecting the performance of understory crops. Proximity to trees is a key factor in crop performance, but rather little information is available on the spatial distribution of yield and yield components of crop species under the influence of trees in agroforestry systems. Also, little information is available on how crop density may be exploited to optimize the yield in such systems. Here we studied the performance of cotton in jujube/cotton agroforestry. Field experiments were conducted in 2012 and 2013 in Hetian, Xinjiang, China. Cotton was grown at a row distance of 60 cm in three densities, 13.5, 18.0 and 22.5 plants m−2 in six m wide paths between tree lines in a jujube plantation. Plant density affected both cotton aboveground dry matter and yield significantly. The highest yield was attained at the intermediate density of 18.0 plants m−2 (20.0 plants m−2 corresponding in sole cotton), lower than the optimal density in sole cotton (25.0 plants m−2). Yield at the lower density was constrained by the low number of bolls per m2 as a direct consequence of the low density, whereas at the high plant density yield was constrained by a lower allocation of assimilates to cotton seed and lint, as a consequence of intraspecific and interspecific competitions. There were strong gradients in yield and yield components in relation to the distance from the tree rows. Leaf area and total dry matter of cotton in rows close to the tree lines were reduced, especially in the rows next to the trees. Moreover, biomass allocation to cotton fruits was reduced in these rows. Competitive influences from the trees on cotton performance extended two rows deep in a six-year old jujube stand, and even three rows deep in a seven-year old stand. Shading effects on cotton yield were compensated by increasing plant density as a result of greater boll numbers per unit ground area. Data from this study help guide the design of optimal plant density of cotton in jujube plantations and give insight in the spatial distribution and dynamics of competitive effects in agroforestry systems in general.

Assessing the contribution of weather and management to the annual yield variation of summer maize using APSIM in the North China Plain

Long-term field experimental data provides a good opportunity to evaluate the effects of different management practices and weather factors on maize yield. An 11-year field experiment (2003–2013) with the same maize cultivar and two short-term experiments including different sowing dates and plant densities were conducted at Luancheng Agro-ecological Experimental Station in the North China Plain (NCP). The measured pheonological development, biomass and grain yield were used to calibrate and validate the APSIM-maize model. The results showed that APSIM-maize model could capture the biomass and grain yield of summer maize under the various management practices and weather conditions. After calibration and validation, five scenarios were simulated using the APSIM model. The simulated results showed that weather factors including sunshine hours and the diurnal temperature range during the grain fill stage had the positive effects on maize yield. For different management practices, plant density was the most important factor which affected the maize yield. The optimal plant density was approximate 8.6plants/m2. Maize yield would be decreased with the sowing dates delayed after the middle of June. Meanwhile, earlier sowing before the end of May also reduced the grain production. The optimized sowing date and plant density could reduce the seasonal yield variation of maize caused by the weather factors. The findings of this study suggest that the maize plant density should be properly increased and sowing time should be optimized according to the harvesting of its previous crop.

Assessment of Yield and Yield Components of Cassava (Manihot esculenta Crantz) as Influenced by Population Density and Varieties in Anyigba, Kogi State.

The study was conducted at the Teaching and Research Farm of the Faculty of Agriculture, Kogi State University during the 2014 cropping season to determine the optimum planting density that would enhance the optimum growth and yield potential of two cassava genotypes. The experiment was conducted using a split-plot in a Randomized Complete Block Design (RCBD) replicated four times. The main plot treatment consisted of two improved cassava varieties; TMS 30572 and TME 419; while the sub-plot treatment consisted of four different planting spacing of 70, 80, 90 and 100 cm. The parameters measured in the study were plant height at harvest, plant girth, stem weight, leaf weight, tuber length, tuber diameter and tuber yield. The yield and yield components of cassava were significantly reduced at plant spacing of 70cm. The results revealed that TME 419 and TMS 30572 tuber yields were highest when planted at intra spacing of 90 and 100 cm. The yields were 5.83 and 5.33kg/plant translating to tuber yields of 58300 and 65798kg/ha for TMS 30572 at plant spacing of 100 and 90 cm respectively. On the other hand, tuber yields in respect of TME 419 were 7.60 and 7.99kg/plant translating to 76000 and 96636kg/ha at 100 and 90cm intra spacing. When planted at the spacing of 70cm, the cassava tuber yield was 3.59kg for TMS 30572 and 4.46kg/plant for TME 419. The results also showed that population density had no significant effect on the leaf weight of the two cassava varieties investigated. At the planting spacing of 100 and 90cm, leaf weight in TMS 30572 was 0.17kg. Across the planting spaces studied, leaf weights were higher in TME 419 in comparison to that of TMS 30572.

Ecological intensification management of maize in northeast China: Agronomic and environmental response

Optimum field management practices need to be developed and improved to solve the challenge of increasing food production while retaining the ecological integrity of farming system underlying the goal of sustainable agriculture. In our study, the concept of ecological intensification (EI) was applied to a spring maize cropping system in Jilin province, China during 2009–2013. Results indicated that the average grain yield was 11.8tha−1 in the EI treatment; while the farmers’ practice (FP) treatment had an average of 11.4tha−1 grain yield across five seasons. The Hybrid Maize Model was used to simulate the potential yield under water-limited condition, and the results showed that grain yield with 92.6% of the average potential yield (14.3tha−1) in EI treatment was closer to the yield potential than FP treatment. Adjusted nitrogen (N) fertilizer rate, split-application of N at the right time and suitable recommended hybrid maize plant density were used for improving N use efficiency and decreasing the negative effects to the environment. Consequently, a total of 180kgNha−1 was enough for maize growth and resulted in equal plant N uptake as the 251kgNha−1 applied in FP. Higher agronomic efficiency of N (AEN), recovery efficiency of N (REN) and partial factor productivity of N (PFPN) in EI treatment (39.7kgkg−1, 66.1% and 66.2kgkg−1, respectively) were observed relative to those in FP treatments (26.9kgkg−1, 42.5% and 50.4kgkg−1, respectively). Improved N use efficiency contributed significantly less N loss to the environment. Our results showed that calculated residual Nmin, the apparent N loss and total GHG emission was 37.5%, 34.3% and 29.8% lower in EI treatment when compared to FP treatment. This study helps quantify and understand the concept and practices of EI. Adoption of 4R Nutrient Stewardship (fertilizer right source, right rate, time and placement) and supporting agronomic practices (optimizing plant density and plant hybrid selection) in our study optimized crop production and minimized potential environmental impact.

Modeling the effects of plant density on maize productivity and water balance in the Loess Plateau of China

Loess Plateau of China is an area with serious soil evaporation and large inter-annual rainfall variations. Water stress is the major limiting factor for crop production in local area. Optimizing plant density is one crucial management in semi-arid dry land areas where crop growth is constrained by precipitation and a high evaporative demand. The Agricultural Production System Simulator (APSIM) was parameterized and tested with two years datasets, and then used to investigate long-term rainfed maize productivity and water balance with the historical weather records. Model application showed that water use and yield were varied because of the plant density and the inter-annual variability of precipitation. Plant density presented no influence on the evapotranspiration (ET) in extremely dry years, dry years and mild wet years but a significantly (P<0.05) influence in normal and extremely wet years. In extremely dry years, the grain yield and (WUE) were all significantly (P<0.05) decreased when plant density increased. The grain yield and WUE showed a parabolic relation with the plant density except extremely dry years. On average, the maximum yield and WUE were 6715kgha−1 and 1.81kgm−3 at 52500 plants ha−1 (D2) in dry years, 7857kgha−1 and 1.92kgm−3 at 67500 plants ha−1 (D3) in normal years, 8937kgha−1 and 2.19kgm−3 at 67500 plants ha−1 (D3) in mild wet years，and 9713kgha−1 at 82500 plants ha−1 (D4) and 2.25kgm−3 at 67500 plants ha−1 (D3) in extremely wet years, respectively. However, no significant difference was obtained for average yield or WUE when compared traditional density of 52500 plants ha−1 (D2) with higher plant density. Compared with the traditional plant density of 52500 plants ha−1 (D2), the increase of plant density significantly (P<0.05) reduced soil evaporation, only with the exception of extremely dry years. In order to get long term average benefits in the study area and similar agro-ecological zones, plant populations should not exceed 32500 plants ha−1 (D1) in extremely dry years, indeed, lower may be better. A plant density of 52500 plants ha−1 (D2) in dry years and 67500 plants ha−1 (D3) in normal years, mild wet years and extremely wet years are recommended as the optimum value, respectively.

ВЛИЯНИЕ ЗАСОРЕННОСТИ ПОСЕВОВ НА ПОКАЗАТЕЛИ УРОЖАЙНОСТИ ЗЕРНА ПШЕНИЦЫ В ЛЕСОСТЕПИ САМАРСКОЙ ОБЛАСТИ

Research objective is improving the grain yield of wheat by reducing of winter and spring wheat cropsweedines. The studies were carried out on experimental fields of the Povolzsje Science Research Institute of selection and seeds production of P. N. Konstantinov. Volga region Scientifical-research Institute of Selection and Seed growing named after P. N. Konstantinov in 2012-2014. The main purpose of researches was to study influence of weeds for grain yield components in winter and spring wheat. The evaluation of the abundance of weeds was performed by the method of Drude. Under the influence of weed, productivity of land winter wheat decreased by 3-26%, spring wheat decreased by 17-33%. The most harmful for winter wheat turned out creeping-rooted weeds: Cirsium arvense, Convolvulus arvensis, of young weeds dominated Cánnabis ruderális, and wintering weed: Lactuca serriola, Thlaspi arvense. In the spring wheat was dominated weeds of creeping-rooted form: Convolvulus arvensis, Cirsium arvense, Sónchus arvénsis and Euphorbia virgata. Winter wheat is less exposed to weeds than spring wheat. Yield depression was mainly due to decrease the number of productive stems and dry wheat mass. Also on the harmfulness of weeds is influenced by the weather conditions of the year. For winter wheat during the wet and warm autumn dominated wintering weed: Thlaspi arvense, Lactuca serriola. In years with dry weather conditions creeping-rooted weeds prevail For spring wheat during the wet spring it is dominated the spring weeds in dry years the most harmful creeping-rooted weeds. For the harmfulness of weeds the density of the crop also affect. When sparse crops of weeds more harmful than at the optimum plant density. Infestation weeds adversely for the yield of both winter wheat and spring wheat.