Tree establishment on post-mining waste soils: species, density, and mixture effects

Tree establishment to restore degraded boreal post-mining lands is challenged by low soil productivity, a harsh microclimate, and potentially high contaminant levels. Use of mixed vegetation can facilitate microclimate but increase competition for soil resources. A statistical accounting of plant-plant interactions and adaptation to multi-species conditions is hard to achieve in field experiments; trials under controlled conditions can distinguish effects of planting density and species interactions in the early stages of plant establishment. A greenhouse trial was established in containers (‘mesocosms’) with waste rock or fine tailings from gold mines. Pre-germinated (one-week-old) seedlings (Alnus viridis subsp. crispa, Picea glauca, Populus tremuloides, Salix arbusculoides) were planted using a Nelder density gradient design, modified for species combinations. A Relative Competition Effect (RCE) was estimated as a competitiveness index for each species combination, calculated as ratio of α coefficients in the Holliday growth equation. The Specific Leaf Area (SLA) was measured to indicate plant water stress adaptation. All species grew better in monoculture on fine tailings, while only P. tremuloides grew better in all mixtures on waste rock. Although net positive effects of density on SLA increment during early growth suggested microclimate improvement on fine tailings, no mixture provided advantages for both species in paired combinations.

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Growth responses of Leymus chinensis (Trin.) Tzvelev to sheep saliva after defoliation

The Rangeland Journal ◽

10.1071/rj09061 ◽

2010 ◽

Vol 32 (4) ◽

pp. 419 ◽

Cited By ~ 5

Author(s):

Xing Teng ◽

Lei Ba ◽

Deli Wang ◽

Ling Wang ◽

Jushan Liu

Keyword(s):

Plant Growth ◽

Aboveground Biomass ◽

Field Experiments ◽

Perennial Grass ◽

Leaf Length ◽

Leymus Chinensis ◽

Growth Responses ◽

Time Duration ◽

Positive Effects ◽

Leaf Weight

Many studies indicated that saliva from herbivores might be involved in plant growth responses when plants have been grazed. However, there is currently no general agreement on whether saliva can affect plant growth. Our aims were to determine the growth response of plants to sheep saliva after defoliation under diverse environmental conditions (different sward structures), and whether the effect of saliva is influenced by time (duration) after its application. We conducted field experiments with clipping treatments and the application of sheep saliva to the damaged parts of tillers to simulate sheep grazing on the perennial grass Leymus chinensis (Trin.) Tzvelev during the early growing seasons. Results demonstrated that clipping with saliva application significantly increased tiller numbers 8 weeks after treatments in comparison with clipping alone. A key finding is that the effect of sheep saliva on plant growth was short-lived. Clipping with saliva application increased leaf weight in the second week, while clipping alone had no effect. Moreover, clipping with saliva application promoted the elongation of new leaves (not the old ones) in the first week whereas clipping alone was ineffective. Results also showed that there were no differences between clipping with saliva application and clipping alone for relative height growth rate and aboveground biomass. Therefore, we concluded that saliva application to clipping treatment would produce an additional effect compared to clipping alone for the plant and the positive effects are time dependent. The additional effects primarily embodied in the individual level of plant, such as the changes of leaf weight and leaf length. Beyond the level, the effects of saliva only produced many more tiller numbers rather than the accumulation of aboveground biomass.

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The effect of a crown shape on the activity of the processes of growth and the complexity of apple tree (Borkh) pruning in the conditions of the Piedmont zone of Crimea

Magarach. Vinogradstvo i Vinodelie ◽

10.35547/im.2020.22.3.012 ◽

2020 ◽

pp. 242-245

Author(s):

Виктория Сергеевна Кириченко ◽

Нина Александровна Бабинцева ◽

Надежда Александровна Тихомирова

Keyword(s):

Field Experiments ◽

Structural Parameters ◽

High Growth ◽

Fruit Trees ◽

Labor Cost ◽

Planting Density ◽

Fruit Crops ◽

High Productivity ◽

Crown Shape ◽

Dense Distribution

Основным направлением повышения продуктивности насаждений плодовых культур будет смена технологических подходов по эксплуатации садовых экосистем, основой которых является загущенное размещение плодовых деревьев, изменение формы кроны с ограничением их размеров, подбор сортов, подвоев, отвечающих требованиям плотного размещения деревьев с высокой продуктивностью, хорошим качеством плодов. Цель исследований - изучение влияния формы кроны на структурные параметры, степень облиственности и трудоемкость затрат труда при обрезке для создания интенсивных садов на слаборослых подвоях. Были проведены трехлетние полевые опыты по схеме: 1 вариант - стройное веретено (контроль); 2 вариант - безлидерная уплощенная крона; 3 вариант - трёхлидерная крона; 4 вариант - французская ось при плотности посадки 2500 дер./га (4 х 1 м). Объектом исследований являлись сорта яблони Бреберн, Джалита, Ренет Симиренко на подвое ЕМ IX в саду с капельным поливом. Работа проводилась по методикам полевых опытов с плодовыми культурами. Установлено, что высокая ростовая активность наблюдалась у сорта Ренет Симиренко независимо от формы кроны, где параметры варьировали от 0,71 м до 1,06 м. Структура плодообразующей древесины дерева зависит от биологических особенностей сорта и формы кроны. На третий год после посадки сада в кронах деревьев свободного веретена и французской оси сформировано наибольшее количество генеративных образований от 20,3 и 24,7% (Джалита, Бреберн) до 23,3 и 25,6% (Ренет Симиренко). Трудоемкость обрезки зависит от сорта, формы кроны и структуры обрастающей древесины. Максимальные затраты труда применяет один человек на обрезку деревьев сорта Джалита с трехлидерной кроной (25,6 чел.-час./га) и безлидерной уплощенной кроной (22,9 чел.-час./га). На обрезку сада деревьев с кроной по типу французской оси требуется 1,0 и 1,4 дня одному человеку или 7,2 (Джалита) и 9,5чел.- час./га (Ренет Симиренко), что в 1,9 и 2,2 раза меньше, чем на обрезку деревьев по типу стройного веретена (контроль). Область применения - садоводческие с.-х. предприятия всех форм собственности, садоводы - любители, специалисты The main direction of improving the productivity of plantations of fruit crops will be a change of technological approaches to the use of garden ecosystems, based on dense placement of fruit trees, changing the shape of the crown cap size, selection of varieties, rootstocks, meeting the requirements of a dense distribution of trees with high productivity, good fruit quality. The purpose of the research was to study the effect of crown shape on structural parameters, the degree of foliage and labor coefficient of pruning for the creation of intensive gardens on dwarf rootstocks. We carried out three-year field experiments according to the scheme: option 1 - slender spindle (control); option 2 - leaderless flattened crown; option 3 - triple leaders crown; option 4 - French axe, when planting density was 2500 trees/ha (4 х 1 м). The varieties ‘Braeburn’, ‘Dzhalita’, ‘Renet Simirenko’ on the rootstock EM IX in the garden with drip irrigation were the object of research. The study was performed according to the techniques of field experiments with fruit crops. It was found that high growth activity was observed for the variety ‘Renet Simirenko’, regardless the form of the crown, with parameters ranged from 0.71 m to 1,06 м. The structure of carpogenous wood depended on the biological characteristics of variety and crown shape. In the third year after planting the garden in the trees of control and French axe the greatest number of generative formations from 20.3 and 24.7% (‘Dzhalita’, ‘Braeburn’) to 23.3 and 25.6% (‘Renet Simirenko’) were developed. The complexity of pruning depended on the variety, the crown shape and the structure of the overgrown wood. Maximum labor cost one person spends for pruning the variety ‘Dzhalita’ with triple leader crown (25.6 man-hour/ha) and leaderless flattened crown (22.9 man-hour/ha). Pruning trees with French axe type of crown required 1.0 and 1.4 days per one person or 7.2 (‘Dzhalita’) and 9.5 man-hour/ha (‘Renet Simirenko’), which was 1.9 and 2.2 times less than the pruning according to the control. The scopes of the research are horticultural agricultural enterprises of all forms of ownership, gardener amateurs and experts.

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Solar Radiation Effects on Dry Matter Accumulations and Transfer in Maize

Frontiers in Plant Science ◽

10.3389/fpls.2021.727134 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yunshan Yang ◽

Xiaoxia Guo ◽

Guangzhou Liu ◽

Wanmao Liu ◽

Jun Xue ◽

...

Keyword(s):

Solar Radiation ◽

Radiation Effects ◽

Dry Matter ◽

Field Experiments ◽

Maize Yield ◽

Planting Density ◽

Stay Green ◽

Vegetative Organs ◽

Maize Hybrids ◽

Weak Light

Solar radiation is the energy source for crop growth, as well as for the processes of accumulation, distribution, and transfer of photosynthetic products that determine maize yield. Therefore, learning the effects of different solar radiation amounts on maize growth is especially important. The present study focused on the quantitative relationships between solar radiation amounts and dry matter accumulations and transfers in maize. Over two continuous years (2017 and 2018) of field experiments, maize hybrids XY335 and ZD958 were grown at densities of 4.5 × 104 (D1), 7.5 × 104 (D2), 9 × 104 (D3), 10.5 × 104 (D4), and 12 × 104 (D5) plants/ha at Qitai Farm (89°34′E, 44°12′N), Xinjiang, China. Shading levels were 15% (S1), 30% (S2), and 50% (S3) of natural light and no shading (CK). The results showed that the yields of the commonly planted cultivars XY335 and ZD958 at S1, S2, and S3 (increasing shade treatments) were 7.3, 21.2, and 57.6% and 11.7, 31.0, and 61.8% lower than the control yields, respectively. Also, vegetative organ dry matter translocation (DMT) and its contribution to grain increased as shading levels increased under different densities. The dry matter assimilation amount after silking (AADMAS) increased as solar radiation and planting density increased. When solar radiation was <580.9 and 663.6 MJ/m2, for XY335 and ZD958, respectively, the increase in the AADMAS was primarily related to solar radiation amounts; and when solar radiation was higher than those amounts for those hybrids, an increase in the AADMAS was primarily related to planting density. Photosynthate accumulation is a key determinant of maize yield, and the contributions of the vegetative organs to the grain did not compensate for the reduced yield caused by insufficient light. Between the two cultivars, XY335 showed a better resistance to weak light than ZD958 did. To help guarantee a high maize yield under weak light conditions, it is imperative to select cultivars that have great stay-green and photosynthetic efficiency characteristics.

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Leaf Removal Affects Maize Morphology and Grain Yield

Agronomy ◽

10.3390/agronomy10020269 ◽

2020 ◽

Vol 10 (2) ◽

pp. 269 ◽

Cited By ~ 1

Author(s):

Guangzhou Liu ◽

Yunshan Yang ◽

Wanmao Liu ◽

Xiaoxia Guo ◽

Jun Xue ◽

...

Keyword(s):

Grain Yield ◽

Leaf Area ◽

Field Experiments ◽

Photosynthetic Capacity ◽

Maize Yield ◽

Light Distribution ◽

Planting Density ◽

Leaf Removal ◽

Area Index ◽

Source Sink

Increasing planting density is an important practice associated with increases in maize yield, but densely planted maize can suffer from poor light conditions. In our two-year field experiments, two morphologically different cultivars, ZD958 (less compact) and DH618 (more compact), were planted at 120,000 plants ha−1 and 135,000 plants ha−1, respectively. We established different leaf area index (LAI) treatments by removing leaves three days after silking: (1) control, no leaves removed (D0); (2) the two uppermost leaves removed (D1); (3) the four uppermost leaves removed (D2); (4) the leaves below the third leaf below the ear removed (D3); (5) the leaves of D1 and D3 removed (D4); (6) the leaves of D2 and D3 removed (D5). Optimal leaf removal improved light distribution, increased photosynthetic capacity and the post-silking source-sink ratio, and thus the grain yield, with an average LAI of 5.9 (5.6 and 6.2 for ZD958 and DH618, respectively) for the highest yields in each year. Therefore, less-compact cultivars should have smaller or fewer topmost leaves or leaves below the ear that quickly senesce post-silking, so as to decrease leaf area and thus improve light distribution and photosynthetic capacity in the canopy under dense planting conditions. However, for more compact cultivars, leaves below the ear should senesce quickly after silking to reduce leaf respiration and improve the photosynthetic capacity of the remaining top residual leaves. In future maize cultivation, compact cultivars with optimal post-silking LAI should be adopted when planting densely.

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Estimation of Peanut Leaf Area Index from Unmanned Aerial Vehicle Multispectral Images

Sensors ◽

10.3390/s20236732 ◽

2020 ◽

Vol 20 (23) ◽

pp. 6732

Author(s):

Haixia Qi ◽

Bingyu Zhu ◽

Zeyu Wu ◽

Yu Liang ◽

Jianwen Li ◽

...

Keyword(s):

Leaf Area Index ◽

Leaf Area ◽

Vegetation Index ◽

Field Experiments ◽

Predictive Accuracy ◽

Vegetation Indices ◽

Planting Density ◽

Coefficient Of Determination ◽

Multispectral Images ◽

Area Index

Leaf area index (LAI) is used to predict crop yield, and unmanned aerial vehicles (UAVs) provide new ways to monitor LAI. In this study, we used a fixed-wing UAV with multispectral cameras for remote sensing monitoring. We conducted field experiments with two peanut varieties at different planting densities to estimate LAI from multispectral images and establish a high-precision LAI prediction model. We used eight vegetation indices (VIs) and developed simple regression and artificial neural network (BPN) models for LAI and spectral VIs. The empirical model was calibrated to estimate peanut LAI, and the best model was selected from the coefficient of determination and root mean square error. The red (660 nm) and near-infrared (790 nm) bands effectively predicted peanut LAI, and LAI increased with planting density. The predictive accuracy of the multiple regression model was higher than that of the single linear regression models, and the correlations between Modified Red-Edge Simple Ratio Index (MSR), Ratio Vegetation Index (RVI), Normalized Difference Vegetation Index (NDVI), and LAI were higher than the other indices. The combined VI BPN model was more accurate than the single VI BPN model, and the BPN model accuracy was higher. Planting density affects peanut LAI, and reflectance-based vegetation indices can help predict LAI.

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Design and Evaluation of Uniform LED Illumination Based on Double Linear Fresnel Lenses

Applied Sciences ◽

10.3390/app10093257 ◽

2020 ◽

Vol 10 (9) ◽

pp. 3257

Author(s):

Hoang Vu ◽

Ngoc Minh Kieu ◽

Do Thi Gam ◽

Seoyong Shin ◽

Tran Quoc Tien ◽

...

Keyword(s):

High Speed ◽

Field Experiments ◽

Numerical Control ◽

Free Form ◽

Light Sources ◽

Cnc Machine ◽

Led Lighting ◽

Positive Effects ◽

Fresnel Lenses ◽

Linear Fresnel Lenses

Redistribution of LED radiation in lighting is necessary in many applications. In this article, we propose a new optical component design for LED lighting to achieve a higher performance. The design consists of a commercial collimator and two linear Fresnel lenses. The LED radiation is collimated by a collimator and redistributed by double linear Fresnel lenses to create a square-shaped, uniform distribution. The linear Fresnel lenses design is based on Snell’s law and the “edge-ray principle”. The optical devices are made from poly methyl methacrylate (PMMA) using a high-speed computer numerical control (CNC) machine. The LED prototypes with complementary optics were measured, and the optical intensity distribution was evaluated. The numerical results showed we obtained a free-form lens that produced an illumination uniformity of 78% with an efficiency of 77%. We used the developed LED light sources for field experiments in agricultural lighting. The figures of these tests showed positive effects with control flowering criteria and advantages of harvested products in comparison with the conventional LED sources. This allows our approach in this paper to be considered as an alternative candidate for highly efficient and energy-saving LED lighting applications.

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Using Goals to Motivate College Students: Theory and Evidence From Field Experiments

Review of Economics and Statistics ◽

10.1162/rest_a_00864 ◽

2020 ◽

Vol 102 (4) ◽

pp. 648-663 ◽

Cited By ~ 3

Author(s):

Damon Clark ◽

David Gill ◽

Victoria Prowse ◽

Mark Rush

Keyword(s):

College Students ◽

Loss Aversion ◽

Field Experiments ◽

Theoretical Framework ◽

The Other ◽

Task Completion ◽

Course Performance ◽

Positive Effects ◽

Present Bias

Will college students who set goals work harder and perform better? We report two field experiments that involved four thousand college students. One experiment asked treated students to set goals for performance in the course; the other asked treated students to set goals for a particular task (completing online practice exams). Task-based goals had robust positive effects on the level of task completion and marginally significant positive effects on course performance. Performance-based goals had positive but small and statistically insignificant effects on course performance. A theoretical framework that builds on present bias and loss aversion helps to interpret our results.

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Planting Density Induced Changes in Cotton Biomass Yield, Fiber Quality, and Phosphorus Distribution under Beta Growth Model

Agronomy ◽

10.3390/agronomy9090500 ◽

2019 ◽

Vol 9 (9) ◽

pp. 500 ◽

Cited By ~ 5

Author(s):

Aziz Khan ◽

Xiangjun Kong ◽

Ullah Najeeb ◽

Jie Zheng ◽

Daniel Kean Yuen Tan ◽

...

Keyword(s):

Field Experiments ◽

Biomass Yield ◽

Accumulation Rate ◽

Fiber Quality ◽

Phosphorus Uptake ◽

Biomass Accumulation ◽

Planting Density ◽

Maximum Height ◽

Low Density ◽

Moderate Density

High input costs combined with multiple management and material inputs have threatened cotton productivity. We hypothesize that this problem can be addressed by a single fertilization at flowering with late sowing in a moderately populated plant stand. Field experiments were conducted to evaluate the cotton biomass accumulation, phosphorus dynamics, and fiber quality under three planting densities (low, 3 × 104; moderate, 6 × 104; and dense, 9 × 104 ha−1) and two cultivars (Zhongmian-16 and J-4B). High planting density had 6.2 and 12.6% larger stems and fruiting nodes m−2, while low density produced a 37.5 and 59.4% maximum height node ratio. Moderate density produced 26.4–15.5%, 24.7–12.6%, and 10.5–13.6% higher biomass accumulation rate at the peak bloom, boll set, and plant removal stages over low and high density in both years, respectively. J-4B produced a higher reproductive organs biomass yield when compared with Zhongmian-16 in both years. This higher biomass formation was due to both the higher average (0.8 VT kg·ha−1·d−1) and maximum (1.0 VM kg·ha−1·d−1) reproductive organ phosphorus uptake, respectively. Plants with low density had 5.3–18.5%, 9.5–15%, and 7.8–12.8% greater length, strength, and micronaire values over moderate and dense plants, respectively. Conclusively, moderate density with J-4B is a promising option for improved biomass, phosphorus acquisition, and fiber quality under a short season.

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IMPROVED EARLY SEASON MANAGEMENT OF SUB1 RICE VARIETIES ENHANCES POST-SUBMERGENCE RECOVERY AND YIELD

Experimental Agriculture ◽

10.1017/s0014479717000588 ◽

2018 ◽

Vol 55 (1) ◽

pp. 105-116 ◽

Cited By ~ 4

Author(s):

NINO P. M. BANAYO ◽

RANEE C. MABESA-TELOSA ◽

SUDHANSHU SINGH ◽

YOICHIRO KATO

Keyword(s):

Management Practices ◽

Field Experiments ◽

Transition Period ◽

Management Practice ◽

Recovery Period ◽

Planting Density ◽

Shoot Biomass ◽

Seeding Rate ◽

Rice Varieties ◽

Conventional Practice

SUMMARYMore than 10 Sub1 rice varieties carrying the submergence-tolerance gene have been released for flood-prone environments in tropical Asia. Improved management practices have been shown to enhance yields of these varieties. The objective of this study was to dissect the growth response of IR64-Sub1 to integrated crop management in a flash flood at the late vegetative stage. Field experiments were conducted at the International Rice Research Institute, Philippines in the dry and wet seasons of 2013. Complete submergence was imposed for 14 days starting at 37 days after transplanting. Integrated management practice (IMP) consisting of: (i) application of fertilizer (compared with no fertilizer use in conventional practice), (ii) use of lower seeding rate (400 vs. 800 kg ha−1) in the nursery bed, (iii) use of slightly older seedling for transplanting (30 vs. 18 day-old), and (iv) higher planting density (33.3 vs. 25.0 hills m−2) gave yields higher by 8–87% compared with the conventional practice (1.3–2.4 t ha−1) in both seasons. This was attributable to higher shoot biomass after water recession, more tillers m−2, greater leaf area expansion and shoot biomass accumulation during the recovery period, and higher filled-grain percentage at maturity. The improved management had no positive effect on panicle formation, spikelets panicle−1, and harvest index since stress was imposed at the transition period between vegetative and reproductive phases. Our results suggest the appropriate nursery management, for submergence-resilient seedlings to further alleviate damage caused by flash floods and increase the yield of Sub1 varieties in flood-prone rainfed lowlands.

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