Stereoscopic Planting in Ridge and Furrow Increases Grain Yield of Maize (Zea mays L.) by Reducing the Plant’s Competition for Water and Light Resources

Increasing planting density is an important ways to increase maize yield. A hot topic of conversation in the current research is how to improve crop light efficiency and yield potential by optimizing the cultivation mode under high density planting is a hot topic in current research. Thus, in this study, a field experiment was conducted to explore the effects of stereo-planting patterns on water and the utilization light resource and maize yields. Planting patterns included the conventional flat planting pattern (as the control, CK) and the stereo-planting in ridge and furrow (T). Each planting pattern had three planting densities, i.e., 60,000 plants ha−1 (D1), 75,000 plants ha−1 (D2) and 90,000 plants ha−1 (D3). The results showed that stereo-planting affected the physiological characteristics of plants by changing the spatial distribution of soil moisture. At the silking stage (R1), photosynthetic rate (Pn) of plants on the ridge was similar to CK, and transpiration rate (Tr) was significantly lower than that of CK. Pn of maize in the furrow was significantly higher than that of CK, and Tr was similar to CK. Stereoscopic planting had different effects on intraspecific competition intensity in maize population in different growing stages. In the six-leaf stage (V6), stereo-planting increased competition intensity of maize on the ridge, but lowered that of maize in the furrow by affecting the spatial distribution of soil moisture. During the R1 stage, stereo-planting increased the light transmittance rate within the canopy and eased the plant’s competition for light by reducing plant height and leaf area of maize under three density conditions. Stereo-planting had no effect on grain yield and dry matter accumulation of ridge-planted maize in the later growing stage, but it did increased the dry matter accumulation and grain yield of furrow-planted maize due to the improvement of the light environment and photosynthetic characteristics of the population. In two test years, stereo-planting increased 5.0–11.0% average yield of maize compared to CK under three density conditions. These results indicate that stereo-planting can reduce the plant’s competition for light and water resources and improve its physiological traits of plant by optimizing its spatial distribution of soil moisture and canopy structure, thus further increasing grain yield of maize under high-density planting conditions.

Automatic calibration of a functional-structural wheat model using an adaptive design and a metamodelling approach

- Background and Aims Functional-structural plant models are increasingly being used by plant scientists to address a wide variety of questions. However, the calibration of these complex models is often challenging, mainly because of their high computational cost. In this paper, we applied an automatic method to the calibration of WALTer: a functional-structural wheat model that simulates the plasticity of tillering in response to competition for light. - Methods We used a Bayesian calibration method to estimate the values of 5 parameters of the WALTer model by fitting the model outputs to tillering dynamics data. The method presented in this paper is based on the Efficient Global Optimisation algorithm. It involves the use of Gaussian process metamodels to generate fast approximations of the model outputs. To account for the uncertainty associated with the metamodels approximations, an adaptive design was used. The efficacy of the method was first assessed using simulated data. The calibration was then applied to experimental data. - Key Results The method presented here performed well on both simulated and experimental data. In particular, the use of an adaptive design proved to be a very efficient method to improve the quality of the metamodels predictions, especially by reducing the uncertainty in areas of the parameter space that were of interest for the fitting. Moreover, we showed the necessity to have a diversity of field data in order to be able to calibrate the parameters. - Conclusions The method presented in this paper, based on an adaptive design and Gaussian process metamodels, is an efficient approach for the calibration of WALTer and could be of interest for the calibration of other functional-structural plant models .

Post-harvesting natural regeneration of Theobroma subincanum Mart. (Cupuí) (Malvaceae) inside and around logging gaps

The natural regeneration dynamics of Theobroma subincanum Mart. (Malvaceae) around canopy gaps created by tree felling due to selective logging was assessed. For that, an experiment located in the Experimental Field of Embrapa Eastern Amazon in Moju municipality, PA, Brazil was carried out. Nine logging gaps were selected, and four strips of 10 m x 50 m were installed in each of these gaps following the cardinal directions. These plots were split in five 10 m x 10 m plots numbered from 1 to 5 from the gap’s border toward the forest. In plots 1, 3, and 5 and in the gap’s center 2 m x 2 m plots were installed to monitor individuals ≥ 10 cm in height and < 5 cm in DBH. In most of the variation factors analized, Theobroma subincanum presented higher recruitment rate in period 1 (1998-2000), since the competition for light were less intense. In period 2 (2000-2010), under a possible lower luminosity and higher competition, RR was lower for all factors analyzed. In relation to gap size, T. subincanum presented the best results in RR around medium size gaps. The distance of 20 m in relation to the gap center, with intermediary sunlight condititions, T. subincanum presented higher RR. The population of T. subincanum had better performance under intermediate light conditions.

Land-use history impacts spatial patterns and composition of woody plant species across a 35-hectare temperate forest plot

Land-use history is the template upon which contemporary plant and tree populations establish and interact with one another and exerts a legacy on the structure and dynamics of species assemblages and ecosystems. We use the first census (2010-2014) of a 35-ha forest-dynamics plot at the Harvard Forest in central Massachusetts to explore such legacies. The plot includes 108,632 live stems ≥ 1 cm in diameter (2215 individuals/ha) and 7,595 dead stems ≥ 5 cm in diameter. Fifty-one woody plant species were recorded in the plot, but two tree species - Tsuga canadensis (eastern hemlock) and Acer rubrum (red maple) - and one shrub - Ilex verticillata (winterberry) -comprised 56% of all stems. Live tree basal area averaged 42.25 m2/ha, of which 84% was represented by T. canadensis (14.0 m2/ha), Quercus rubra (northern red oak; 9.6 m2/ha), A. rubrum (7.2 m2/ha) and Pinus strobus (eastern white pine; 4.4 m2/ha). These same four species also comprised 78% of the live aboveground biomass, which averaged 245.2 Mg/ha, and were significantly clumped at distances up to 50 m within the plot. Spatial distributions of A. rubrum and Q. rubra showed negative intraspecific correlations in diameters up to at least a 150-m spatial lag, likely indicative of competition for light in dense forest patches. Bivariate marked point-pattern analysis showed that T. canadensis and Q. rubra diameters were negatively associated with one another, indicating resource competition for light. Distribution and abundance of the common overstory species are predicted best by soil type, tree neighborhood effects, and two aspects of land-use history: when fields were abandoned in the late 19th century and the succeeding forest types recorded in 1908. In contrast, a history of intensive logging prior to 1950 and a damaging hurricane in 1938 appear to have had little effect on the distribution and abundance of present-day tree species.

Features of subsequent forest regeneration on the cuttings of south-west Karelia

Цель исследования – выявить особенности последующего лесовозобновления хвойных пород на вырубках Карелии в связи с конкуренцией живого напочвенного покрова, лиственных пород, подлеска. По численности древесно-кустарниковых растений почти на всех вырубках первые три места занимают береза, осина и подлесок, причем береза количественно многократно преобладает. Подлесок в основном представлен рябиной. Успешность последующего возобновления сосны и ели на вырубках юго-запада Карелии связана с конкуренцией за свет и почвенные ресурсы с травами (злаками), с подростом лиственных пород и подлеском. Особенно активно разрастание конкурирующей растительности, в первую очередь, березы, происходит на дренированных местообитаниях с относительно плодородными почвами (типы леса кисличники, черничники свежие и брусничники). По исходным типам леса и составу древостоя, определяющим эффективное плодородие почв, можно уверенно прогнозировать успешность последующего естественного лесовосстановления главных пород на вырубках. Однако в подавляющем большинстве типов леса Карелии количество хвойного подроста последующего возобновления является недостаточным для формирования хвойных древостоев без дополнительных лесохозяйственных мероприятий. При отсутствии подроста сосны и ели предварительного возобновления достаточное для естественного лесовосстановления количество подроста хвойных пород присуще следующим исходным типам леса: сосняки беломошники (сосна), ельники черничники влажные (ель; сосна), ельники черничники свежие (ель совместно с сосной). На вырубках остальных исходных типов леса необходимо комбинированное или искусственное лесовосстановление с проведением рубок ухода в молодняках. The aim of the study is to reveal the features of the subsequent reforestation of conifers on the logging of Karelia in connection with the competition of live native cover, hardwood, undergrowth. In terms of the number of wood and shrub plants on almost all cuttings the first three places are occupied by birch, aspen and undergrowth, and birch quantitatively predominates. The undergrowth is mostly represented by a ripple. The success of the subsequent resumption of pine and spruce on the cuttings of the south-west of Karelia is associated with competition for light and soil resources with herbs (grains), hardwoods and undergrowth. The growth of competing vegetation, primarily birch trees, occurs especially actively in drained habitats with relatively fertile soils (types of woodlands, fresh blueberries and cranberries). According to the original types of forest and the composition of the tree, determining the effective fertility of the soil, it is possible to confidently predict the success of the subsequent natural reforestation of the main rocks on the cuttings. However, in the vast majority of the Karelia forest, the amount of conifers that have followed the resumption is insufficient to form coniferous trees without additional forest activities. In the absence of a pargn of pine and ate pre-resumption sufficient for natural reforestation the amount of adulterous breed is inherent in the following original types of forest: pine whiteness (pine), spruce cranberries moist (spruce; pine), spruce fresh (spruce together with pine). On the cutting of other original types of forest, a combination or artificial reforestation is required, with the logging of care in young people.

Modeling light competition in the Amazon forest: the effects of high CO2 in functional diversity and biogeochemical cycle.

&lt;p&gt;The increase of CO&lt;sub&gt;2&lt;/sub&gt; concentrations implies direct and indirect (by changing climate) impacts on the terrestrial ecosystem. Several Dynamic Global Vegetation Models (DGVMs) have been developed to better understand the response of vegetation to climate change. However, the representation of plant diversity through a small set of Plant Functional Types (PFTs) adopted by the majority of DGVMs undermines their ability to represent functional diversity and fundamental interactions between these different life strategies of plants, like competition, which has been shown to be paramount in determining ecosystem functioning. Studies have shown that increasing CO&lt;sub&gt;2&lt;/sub&gt; concentration may determine the outcome of vegetation competition and, as a consequence, the ability to adapt to the environment, functional diversity, and community assembly mechanisms. Thus, the inclusion of competitive dynamics in these models becomes strategic to improve predictions and understanding the effects of climate change on vegetation and how it affects change in carbon fluxes and stocks in the community. In that sense, this project aims to contribute to the development of a light competition module within CAET&amp;#202; model (&lt;strong&gt;C&lt;/strong&gt;Arbon and &lt;strong&gt;E&lt;/strong&gt;cosystem functional &lt;strong&gt;T&lt;/strong&gt;rait &lt;strong&gt;E&lt;/strong&gt;valuation model) which involves the implementation of allometric relations between plant organs. As a trait-based model, CAET&amp;#202; seeks to represent plant functional diversity in a less discrete way through the usage of variant values for functional traits. For this purpose, two key functional traits that are closely related to competition for light are employed as variants: &lt;em&gt;wood density &lt;/em&gt;(WD) and &lt;em&gt;specific leaf area &lt;/em&gt;(SLA). The main objective is to understand how light competition related to plant functional traits alters the response of Amazon plant communities under changing environmental conditions. As preliminary results, the algorithms containing the allometric and competition equations were developed outside the main model code and represent plant dynamics trade-offs between the variant functional traits and plant physiology and survivorship: WD relates to strategies of mortality and height growth. For example, high values of WD [1g/cm&lt;sup&gt;-3&lt;/sup&gt;] are related to low heights [~30m.] and, low heights incur higher mortality rates; SLA relates to light competitive effect, Leaf Economics Spectrum, and LAI (leaf area index) determination, one of the most important parameters that determine the absorption of light by different life strategies. These trade-offs allow the representation of different plant life competition strategies. We expected that the light restriction for some functional strategies may incur a decrease in functional dominance and photosynthesis rate, consequently changing net primary productivity and after all the functional structure of the community. For functional diversity, it is expected changes in functional richness and functional divergence (related to the strength that competition exerts in the community) in order to favor strategies that better deal with the new environmental conditions simulated by CAET&amp;#202; with increasing [CO&lt;sub&gt;2&lt;/sub&gt;] to 600 ppmv, for example. Finally, it is expected that this approach may contribute to improving the representation of competition for light in DGVMs to more assertively obtain the effects of climate changes on vegetation and ecosystem dynamics. Final results will be obtained until the EGU Congress takes place.&lt;/p&gt;

Competition for Light Affects Alfalfa Biomass Production More Than Its Nutritive Value in an Olive-Based Alley-Cropping System

Cropping among trees with perennial legumes is one option for increasing agro-ecosystem services, such as improving the nitrogen supply and increasing soil protection by herbaceous vegetation. Moreover, cropping under the canopy of olive trees should diversify the farm production, compared to the traditional fallow management. Among perennial legumes, alfalfa (Medicago sativa L.) produces abundant biomass under Mediterranean rainfed condition. Based on this, a two-year field experiment was implemented in southern Tuscany in a rainfed olive orchard to test the competition for light effects on alfalfa biomass production and nutritive value. Light availability under the tree canopy was measured by hemispherical photos. In both years, the alfalfa yield of under-canopy varied according to the tree presence. A significant relationship between biomass production and light availability was recorded. The nutritive value of under-canopy alfalfa was similar to that of the open-grown alfalfa. However, same significant differences did however occur, between shaded and sole crop. When differences were found, under-canopy herbage was characterised by a higher content of crude protein and a lower content of fibre with respect to open-grown. In a hilly silvoarable olive orchard, alfalfa biomass accumulation was reduced mainly due to scarce light availability, therefore tree management such as pruning and plantation layout can enhance the herbage productivity. Studying shade tolerant forage legumes in order to enhance the yield and nutritive value of herbage production in rainfed agroforestry systems is essential.