Plant Density Conditions Research Articles

Maize seedling performance as a potential index for drought tolerance

Twenty-six maize landraces were tested in order to evaluate maize seedling performance as an index for drought tolerance in adult plants. Samples were subjected to polyethylene glycol-induced osmotic stress at the early seedling stage. Grain yield was obtained in field experiments under well-watered (OC) and a combination of drought and high plant density (HD) conditions. Osmotic stress caused a reduction in seedling growth (length, fresh and dry weight), and increase in the shoot and in particular the root proline contents in the majority of landraces, and variations in root peroxidase (POD) activity. Genotypes displaying more pronounced root growth reduction and higher proline contents exhibited decreased POD activity under osmotic stress. Direct positive correlations between the proline content and growth inhibition, and between the proline and soluble protein content were established. Correlations between the changes in POD activity and growth parameters were significant and positive, and significant but negative with the changes in the proline content. In the field, water stress led to a reduction in grain yield in all of the tested landraces. Correlations between grain yield from both experimental sets (OC and HD) and osmotic-induced changes in seedling root growth were negative, which was opposite to the highly significant and positive correlations between the changes in the seedling root proline content and yield. Also, genotypes with the highest seedling root proline content increase under osmotic stress, exhibited the highest stress tolerance index (STI) based on grain yield achieved under both field conditions. Our results indicate that lower changes in POD activity and especially an increased proline content after exposure to osmotic stress during the early seedling stage could be considered as useful indices to facilitate selection efficiency for drought tolerance in adult plants.

Erect panicle super rice varieties enhance yield by harvest index advantages in high nitrogen and density conditions

The erect panicle (Ep) type is an important characteristic for japonica super rice in Northeast China and plays a significant role in enhancing yield. The Ep type is considered to be a genetic ideotype resource to the japonica super rice group by virtue of its agronomic advantages such as grain number per panicle and biomass. This study addresses the effects of nitrogen and planting density conditions on yielding performance regarding panicle type (PT) using the recombinant inbred line (RIL) population derived from the cross between an Ep variety Liaogeng 5 and non-Ep variety Wanlun 422. The genetics underlying the Ep type proved to be robust not only for panicle-type optimization but also plant height, panicle length, flag leaf length and seed density. We also found that regardless of nitrogen and density, correlation between harvest index (HI) and plant height was not significant in Ep type whatever the nitrogen and density. The application of Ep type provides a potential strategy for yield improvement by increasing biomass through HI maintainable in rice.

Circulatory Management of Nutritional Substance Growing Sunflower and Extracting Nutrition by Hot-compressed Water Treatment

Sunflowers are grown as an ornamental plant and a catch crop beside an oilseed crop in Japan. Seed residues after oil milling are recycled as a feed for livestock and a fertilizer. After harvesting, crop residue such as stem and leaves are returned to the soil by the tillage in conventional cultivation. This report discusses the appropriate circulatory management of crop residues and plant nutrition considering them as a new commodity and plant nutrients resource for activating small agriculture. To study the characteristics of the nitrogen uptake from soil, sunflower cultivar named Hybrid Sunflower was grown with fixed row distance of 70 cm and varying hill distance of 10, 20, 30, 40 and 50 cm in a 5 m * 5m plot at a university farm, Tokyo, Japan. Growth survey was carried out every week. Sunflower whole crops sampled at each plot were dried in the oven at 70 °C for 1 day soon after the blanching treatment and stored until the extraction experiment. Sunflower sample at the growth stage of after flowering had the largest mass compared with the stage of before flowering and seed harvesting. Total dried matter of whole crop in 10cm-plot was the largest among the planting density conditions for each growth stage. The dried matter of crop residue at the growth stage of seed harvesting was 613, 408, 323, 281 and 279 g/m2 for the plot of 10, 20, 30, 40 and 50 cm, respectively. Nitrogen contained in sunflower stem was 2.5 to 5.5 g-N/m2 and that in seed was almost double, 5.9 to 7.5 g- N/m2. Sunflowers were processed to extract nitrogen by the hot-compressed water (HCW) treatment. Ground sample of sunflower stem mixed with water was heated at temperature of 180, 200 and 220 °C with gas pressure of 2 MPa in a pressure tight reactor for 5 and 30 min to release nitrogen from the solid fibre. Sample was separated into the solid matter fraction and the liquid matter fraction after the treatment. Extracted nitrogen as liquid matter was 37.9, 45.5 and 49.4 % at temperature of 180, 200 and 220 °C, respectively. Approximately 40 to 50 % of nitrogen contained in sunflower stem was recovered as the liquid matter. The liquid matter can be returned to the soil as a fertilizer while the solid matter containing cellulose and hemi- cellulose can be used as a raw material for bioethanol production.

Detection of water abundance in Baluran National Park with landsat satellite imagery analysis

Indonesia is one of the mega-biodiversity countries that have a great responsibility in maintaining the balance of the global climate and forest ecosystems. Drought causes shifting of ecosystems causing disturbances on animal life leading to death of species. Alongside fires in the savanna, drought is a recurrent problem in the park, which occurs every year. This study aims to detect the abundance of water by using satellite imagery in Baluran National Park (BNP). The research analyzed using Landsat satellite imagery ETM7 + in 1999 and 2010 and three (3) main factors that have great potential abundance of water, are: (1) plant density (GI = Greenness Index), (2) soil moisture (WI = Wetness Index), and (3) soil conditions (SBI = Soil Brightness Index). Three factors are summed and divided by three to get 5 levels of water abundance: 1) Very abundant, 2) Abundant, 3) Medium, 4) Few, and 5) Very little. The results showed that the abundance of water decreased between 1999 and 2010 for moderate conditions from 85% to 38%, if the abundance of low water (slightly) increased from 15% to 60%. The level of accuracy of the abundance of water in the field of more than 80% is exactly 91%. The extreme drought conditions will be very dangerous for the survival of flora and fauna in Baluran National Park that are in desperate need of water and potentially in danger of a fire. Construction of water reservoirs and water supply continuously using a water tank in the dry season is very necessary in the Baluran National Park.

Optimized tillage practices and row spacing to improve grain yield and matter transport efficiency in intensive spring maize

Subsoiling tillage practices and wide-narrow planting patterns could greatly improve grain yield through increasing post-silking dry matter accumulation of spring maize (Zea mays L.) under high plant density. However, the relationship between increased yield and vascular bundles structure, post-silking matter transport efficiency has not been unknown. Therefore, a field experiment was conducted on the Northeast plain of Liaoning Province in China in 2013 and 2014 to investigate the effects of four cultivation modes on post-silking matter transport under high plant density (105,000 plants ha−1). A widely grown maize hybrid Zhongdan 909, which exhibits high grain yield and tolerance to high plant density, has been used in our study. The four cultivation modes were (1) traditional rotary tillage (20cm) plus uniform plant spacing (60cm; RU; control); (2) subsoiling tillage (35–40cm) plus uniform plant spacing (60cm; SU); (3) traditional rotary tillage (20cm) plus wide-narrow (80+40cm) plant spacing (RW); and (4) subsoiling tillage plus wide-narrow plant spacing (SW). Compared to RU, wide-narrow planting (RW, SW) significantly optimized the canopy structure at silking, while SU and SW significantly optimized the soil structure, thus improved the photosynthetic rate and canopy radiation use efficiency (RUE), and post-silking dry matter accumulation (+5.2% [SU], +6.5% [RW], and +13% [SW]), and simultaneously reduced the C/N ratio in stems at maturity (−4% [SU], −27% [RW] and −39% [SW]), which led to the balancing of C and N in organs of maize at grain filling stage. Moreover, it also enhanced the differentiation of the vascular bundle system at the early growth stage, and maintained its function after silking by the better environmental conditions, which greatly improved the matter transport efficiency (+42%), and increased the grain filling rate. As a result, the yield for SU, RW, and SW increased by 5%, 7.5%, and 22%, respectively, compared to RU. These suggested that the optimization practices noticeably increased the canopy RUE after silking for spring maize by improving matter transport efficiency, stem vascular structure, and maintaining the balance between C and N metabolism, which eventually increased the grain yield under high plant density conditions. It might provide information of appropriate cultivation practices in enhancing grain yield for maize.

Genetic analysis of leaf morphology underlying the plant density response by QTL mapping in maize (Zea mays L.)

Maize yield increase has been strongly linked to plant population densities over time with changes in plant architecture, but the genetic basis for the plant architecture response to plant density is unknown, as is its stability across environments. To elucidate the genetic basis of the plant architecture response to density in maize, we mapped quantitative trait loci (QTLs) for leaf morphology-related traits in four sets of recombinant inbred line (RIL) populations under two plant density conditions. Forty-five QTLs for six traits were detected in both high and low plant density conditions. Thirty-seven QTLs were only detected when grown under high plant density, and 34 QTLs were only detected when grown under low plant density. Twenty-two meta-QTLs (mQTLs) were identified by meta-analysis, and mQTL1-1, mQTL3-2 and mQTL8 were identified when grown under high and low plant densities, with R 2 of some initial QTLs > 10 %, suggesting the mQTLs might be hot spots of the important QTLs for the related traits under planting density stress conditions. The results presented here provide useful information for further research and the marker-assisted selection of varieties targeting increased plant density and will help to reveal the molecular mechanisms related to leaf morphology in response to density.

Source and sink indicators for determining nitrogen, plant density and genotype effects on oil and protein contents in sunflower achenes

Given the diversification of oilseed-based products, sunflower is a competitive crop for obtaining high oil and protein concentrations; however, both are subject to genotypic and environmental variability. We analyzed individual and interaction effects of nitrogen (N), plant density (D) and genotype (G) in a 2-year field experiment. A set of “sink” (oil, protein, and hull concentrations and quantities) and “source” (leaf area duration, nitrogen uptake, nitrogen and biomass remobilizations) indicators were measured at harvest in a split-split-plot design with contrasting nitrogen (N+: 150kgha−1; N−: no fertilization), plant density (D1: 3 and D2: 4.5 plants m−2) and genotype (cv. LG5451HO in 2011, cv. Olledy in 2012 and cv. Kerbel in both years) treatments. We found that nitrogen had a significant positive effect on protein concentration and plant density had a positive effect on nitrogen uptake after flowering. Oil concentration was not related to oil weight but was related to plant dry matter at flowering and biomass remobilization. Protein concentration was related to protein weight and nitrogen nutrition index at flowering and to nitrogen uptake and leaf area duration after flowering. Significant interaction effects were identified on sink (N×D, D×G) and source (N×G) indicators in the 2012 experiment, which was only partly explained by differences in initial states at flowering. In this study, the genotype that maximized oil concentration depended on nitrogen and plant density conditions, while the genotype that maximized protein concentration was the same regardless of cropping conditions. We highlight the importance of analyzing effects of determining factors on oil accumulation during grain filling.

Context-dependent patterns, determinants and demographic consequences of herbivory in an invasive species

Non-native invasive plants often lose many of their specialist herbivores in their invaded ranges, but new enemies may be recruited from the local generalist fauna, or from enemies themselves introduced to the same region. As a result, few invaders are free of herbivore damage; however, the incidence of this herbivory and its consequences for plant demography may depend on an array of biotic and abiotic factors. In Alliaria petiolata, a non-native invasive forb in Canada, we quantified the incidence of leaf herbivory, rosette survival and seed production along with conspecific plant density and environmental site conditions in wild populations in mesic forest understory and moist grasslands. We complemented the field survey by a laboratory experiment with Trichoplusia to test whether the palatability of leaf tissue of A. petiolata varies with plant life stage and habitat type. Incidence of herbivory was significantly higher in adults than in rosettes, and significantly higher in grasslands than in forest understory. The palatability experiment confirmed that leaves of adults were more palatable to a generalist herbivore than leaves of rosettes. Path analysis revealed negative plant density-dependent herbivory of adults in forest understory but positive density-dependent herbivory in grasslands. Incidence of herbivory in rosettes was positively associated with soil moisture in grasslands, but not in forest understory. Seed production was significantly positively associated with herbivory in adults and soil moisture, whereas rosette survival was significantly negatively associated with conspecific plant density. We conclude that the patterns, determinants and demographic consequences of herbivory in invasive Alliaria may strongly depend on a plant’s life stage and plant density and may further be confounded by landscape heterogeneity.

Effects of mutual shading on the regulation of photosynthesis in field-grown sorghum

In the field, close planting inevitably causes mutual shading and depression of leaf photosynthesis. To clarify the regulative mechanisms of photosynthesis under these conditions, the effects of planting density on leaf structure, gas exchange and proteomics were carefully studied in field-grown sorghum. In the absence of mineral deficiency, (1) close planting induced a significant decrease in light intensity within populations, which further resulted in much lower stomatal density and other anatomical characteristics associated with shaded leaves; (2) sorghum grown at high planting density had a lower net photosynthetic rate and stomatal conductance than those grown at low planting density; (3) approximately 62 protein spots changed their expression levels under the high planting density conditions, and 22 proteins associated with photosynthesis were identified by mass spectrometry. Further analysis revealed the depression of photosynthesis caused by mutual shading involves the regulation of leaf structure, absorption and transportation of CO2, photosynthetic electron transport, production of assimilatory power, and levels of enzymes related to the Calvin cycle. Additionally, heat shock protein and oxygen-evolving enhancer protein play important roles in photoprotection in field-grown sorghum. A model for the regulation of photosynthesis under mutual shading was suggested based on our results.

Yield of bolting winter beet (Beta vulgaris L.) as affected by plant density, genotype and environment

Winter beet roots and shoots might be a favorable substrate for biogas production in Central Europe. However, detailed information about the attainable yield of this crop is lacking. Thus, the impact of plant density, genotype and environmental conditions on total dry matter yield of winter beet crops that bolt after winter was investigated. A significant increase of the dry matter yield (esp. shoot) was expected by harvesting the 1st shoot after flowering in June followed by a final harvest of the whole plant in July. In 2009/10, 2010/11 and 2011/12, three series of field trials with (i) 3 target plant densities (148, 246, 370 thousand plants ha−1) and (ii) 3 different sugar beet genotypes were conducted at Göttingen (Lower Saxony, GER) and Kiel (Schleswig-Holstein, GER); (iii), additional field trials with 5 different sugar beet genotypes cultivated at 2 target plant densities (148, 246 thousand plants ha−1) were conducted in 2011/12, to investigate the relation between maximum taproot diameter and the shoot and taproot yield of bolting winter beet. The total dry matter yield considerably varied between 4 and 23tha−1. It was predominantly affected by the environment and to a substantially lower extent by plant density. Increasing plant densities increased the total dry matter yield, resulting in a significantly higher total dry matter yield at plant densities ≥300,000plantsha−1 compared with lower plant densities. Genotypic differences in total dry matter yield were negligibly small. Pruning in June substantially increased the total dry matter yield in July by ca. 8tha−1 only in one out of three environments.Final yield in June (without pruning) and July (pruning in June) was positively related with cumulated temperature and global radiation, but also with taproot dry matter yield before winter. The taproot, shoot (1st, 2nd) and total plant yield were positively correlated with maximum taproot diameter.In conclusion, high dry matter yields close to yields of established energy crops grown over winter were obtained with winter beet roots and shoots only under very favorable conditions (climate, single plant size). High yields can be achieved after good pre-winter development. However, for sufficient frost tolerance the taproot size of plants must be rather small. Hence, the cultivation of bolting winter beet under Central European climate conditions has to face a severe conflict of goals concerning winter survival and yield formation.

Effect of cultural practices and environmental conditions on yield and quality of herbal plants: Prospects leading to research on influence of nitrogen fertilization, planting density and eco-physiological parameters on yield and quality of field-grown bush tea (Athrixia phylicoides DC.)

Herbal plants are grown in diverse regions of varying climates with growth and productivity being influenced by both biotic and abiotic factors. Cultural practices have a significant influence on growth and productivity of these plants. In order to maximize yield and quality of tea as an herbal plant, cultural practices such as fertilization and planting density should be optimized. Fertilization improves growth, total polyphenols, tannins and total antioxidant content of herbal tea. In particular, nitrogen fertilization increases the production of new shoots and the content of nitrogenous compounds, such as free amino acids, which are the major quality indicators of herbal tea. Plant population density also plays role in tea productivity. In addition dense planting may increase the initial yield and revenue. This review discusses the effects of nitrogen fertilization, timing of nitrogen fertilization, planting density and climatic conditions on growth and productivity of herbal teas and other medicinal plants. Key words: Fertilization, light intensity, planting density, tea quality, temperature.

Selection at ultra-low density identifies plants escaping virus infection and leads towards high-performing lentil (Lens culinarisL.) varieties

SUMMARYCultivated lentil (Lens culinarisL.) landraces offer a challenge to exploiting their genetic variability and deriving new pure-line varieties. For insect-transmitted viruses, low densities favour increased virus spread. The objective of the present work was to evaluate a selection procedure applied within a landrace under ultra-low plant density and low-input conditions toward the isolation of high-performing genotypes that escape virus infection. Field trials were conducted through four growing seasons (2006–2011) in the Democritus University of Thrace research farm in Orestiada, Greece. Selection of individual plants for high grain yield was applied for three generations, while virus presence was tested by enzyme-linked immunosorbent assay in the seeds used or the plants selected in each selection cycle. Early high plant-to-plant phenotypic variability, reflected by high coefficient of variation (CV) values, was partly attributed to virus infection. However, sister lines were consistently higher yielding and of lower CV than the mother population (MP). Second generation lines yielded up to 136 and 23% more than the source landrace at the ultra-low density and dense stand, respectively.Pea seed-borne mosaic viruswas detected in the seeds of the MP, whereasbean yellow mosaic virusandbean leafroll viruswere mainly involved in the subsequent selection rounds. In general, the highest-yielding plants were free of the viruses detected during experimentation. It was concluded that selection at ultra-low density of the highest-yielding plants from the sister lines with the lowest CV constitute an effective way to improve the health status of the seeds produced and result in high yielding and potentially virus-tolerant pure-line varieties.

Phytochemical composition, antioxidant and cytoprotective activities of essential oil of Salvia lavandulifolia Vahl

The use of aromatic plants for food flavoring and medicinal purposes began a long time ago. The chemical composition of two essential oils from Salvia lavandulifolia from Spain differing in plant density conditions (sample S-1 — high density and sample S-2 — low density) was evaluated. Moreover, the antioxidant and cytoprotective effects of both essential oil samples were investigated. The essential oil of S-1 was characterized by a rich content in 1,8-cineole, whereas the essential oil of S-2 contained high amounts of camphor. The two essential oil samples exhibited a potent antioxidant capacity by ROS scavenging, enhancing the endogenous antioxidant system and inhibiting lipid peroxidation in a H2O2-induced oxidative stress model in astrocytes. S-1 was the most effective essential oil, suggesting that the higher the plant density, the higher the antioxidant effect.

Varietal Difference in Early Vegetative Growth during Seedling Stage in Soybean

Rapid development after emergence is important for seedling establishment and early vegetative growth, especially at a low planting density or inferior environmental conditions. This study was conducted to understand the varietal difference in the growth parameters during the seedling stage in soybean. Twenty-seven soybean varieties originating from six countries were examined in 2009 and 2010. The pots were arranged in a completely random block design with 5 replications (10 pots per variety), and the seedlings were sampled at 14 and 28 days after sowing (DAS). The shoot dry weight at 14 and 28 DAS was highly correlated with seed size, cotyledon digestion, and leaf area. However, no positive correlation was found between shoot dry weight and photosynthetic rate at 28 DAS. Chamame, a Japanese cultivar, with the largest seed size grew rapidly, and showed the heaviest shoot dry weight, greatest cotyledon digestion, fast leaf expansion and high photosynthetic rate. However, Moyashimame, a medium-seed-size cultivar, also grew rapidly with a high photosynthetic rate. Some varieties such as Tachinagaha (Japan), Hefeng (China), Parana and Pérola (Brazil), had a large or medium seed size, and high photosynthetic rate but showed a relatively small leaf area and light shoot dry weight. These results suggested that big seeds with rapid cotyledon digestion developed a wider leaf area and therefore large dry matter production, indicating that the conversion of stored energy was more important than the leaf photosynthetic activity for early growth.

Limits of pine forest distribution at the treeline: herbivory matters

Herbivores can affect future forest composition by feeding selectivity. At temperature-sensitive treelines, herbivory can exacerbate or constrain climate-driven distributional shifts in tree species. This study analyses the impact of herbivory in a Mediterranean treeline of widespread Pinus sylvestris and P. nigra pinewoods, testing whether herbivory damage reinforces or inhibits the climatic responses of these trees. We used naturally occurring sapling pairs of similar size and age of both species, thereby isolating plant characteristics from environmental effects in herbivore behaviour. Herbivory damage by ungulates proved higher than that caused by insects in saplings of both species. Low plant density and extreme abiotic conditions at the treeline could in part be responsible for the observed low incidence of insect herbivory. Ungulates preferred P. sylvestris over P. nigra, implying heavier browsing damage for a large number of P. sylvestris saplings, suffering reduced internode growth as a consequence. In addition, P. sylvestris could not compensate height-growth reductions due to browsing with higher growth rate than P. nigra. In fact, P. sylvestris showed similar or lower relative height growth with respect to P. nigra. Under a scenario of increasing aridity and maintenance of ungulate populations, the upward migration of P. sylvestris in its southern range could be restricted by higher drought vulnerability than P. nigra, a situation exacerbated by ungulate herbivory. Our results indicate that ungulate herbivory reinforces climatic response of coexisting P. sylvestris and P. nigra at treeline, favouring a potential change in community dominance towards Mediterranean P. nigra.

Identification of genetic factors affecting plant density response through QTL mapping of yield component traits in maize (Zea mays L.)

It is generally believed that grain yield per unit area of modern maize hybrids is related to their adaptability to high plant population density. In this study, the effects of two different plant densities (52,500 and 90,000 plants/hm2) on 12 traits associated with yield were evaluated using a set of 231 F2:3 families derived from two elite inbred lines, Zheng58 and Chang7-2. Evaluation of the phenotypes expressed under the two plant density conditions showed that high plant density condition could decrease the value of 10 measured yield component traits, while the final grain yield per hectare and the rate of kernel production were increased. Twenty-seven quantitative trait loci (QTLs) for 10 traits were detected in both high and low plant density conditions; among them, some QTLs were shown to locate in five clusters. Thirty QTLs were only detected under high plant density. These results suggest that some of the yield component traits perhaps were controlled by a common set of genes, and that kernel number per row, ear length, row number per ear, cob diameter, cob weight, and ear diameter may be influenced by additional genetic mechanisms when grown under high plant density. The QTLs identified in this study provide useful information for marker-assisted selection of varieties targeting increased plant density.

The Significance of Pollination Services for Biodiesel Feedstocks, with Special Reference to Jatropha curcas L.: A Review

The importance of pollination services for insect-pollinated crops in general, and for the major biodiesel crops, such as Jatropha curcas L., in particular, is reviewed. The dependence of the major biodiesel feedstocks on pollinators ranges from almost zero to low dependence in soybean, through low to medium dependence in rapeseed, and up to high dependence in the African oil palm and in J. curcas. Currently, the basic requirement of J. curcas for pollination services is largely neglected. In light of the enormous scale of existing and future plantations of J. curcas, and of the effective pollination by native pollinators in most commercial crops, it is clear that the local insect fauna of any given habitat, on any continent, will not be able to satisfy the pollination requirements of any plantation, once it becomes established and starts blooming. It is suggested that the best way to address the pending catastrophe of severely reduced yields in J. curcas plantations that would result from reduced reproductive success would be to use honeybees as the prime pollinators, regardless of the pollination services provided by the local insect fauna. Basic research on the contribution of honeybees to the reproductive success of J. curcas should be carried out and used as a guideline for planning future provision of proper honeybee pollination services in any given plantation, characterized by its specific size, age, planting density, soil type, irrigation, fertilization, and climatic conditions.

Genetic and Environmental Variations in Baicalin, Baicalein and Wogonin Contents in Scutellaria baicalensis

Scutellaria baicalensis has long been used to treat fever, cough, diarrhea and infection in Chinese medicine, and flavonoids such as baicalin (BA), baicalein (BE), and wogonin (WO) have been identified. To understand genetic and environment-dependent variations, 15 Scutellaria baicalensis landraces were collected from Korea and China, and cultivated under different nitrogen fertilizer application and planting density conditions, and resultant changes in BA, BE, and WO were evaluated. Tested 15 landraces exhibited BA, BE, and WO contents ranging 4.56 to 13.59%, 0.28 to 5.54%, and 0.50 to 1.63% with an average of 9.66%, 2.09%, and 0.52%, respectively. Among tested 4 levels (0 to 500kg/ha) of nitrogen fertilizer application 300kg/ha resulted in highest BA (10.3%) and BE (1.3%), as well as WO (0.4%) contents, corresponding to about 10% increment compared to 0kg/ha. Six different levels of planting density (2 and 3 Rows x 1, 5, 10cm distance), however, showed no difference in flavonoid contents. Similarly no difference in flavonoid contents could be observed between Scutellaria baicalensis harvested from early June 6th to Aug. 3rd. When flavonoid contents in different plant parts were compared, leaf and stem of Scutellaria baicalensis showed no BE and WO under our experimental conditions, while relatively low BA (0.67% in leaf and 1.56% in stem) could be found in leaf. Higher composition of BA could be observed in top part of the root, while higher WO could be observed in lower root part close to root hair.

Natural Regeneration in Plantations of Native Trees in Lowland Brazilian Atlantic Forest: Community Structure, Diversity, and Dispersal Syndromes

Plantations of native‐tree species are often recommended for ecological restoration, but the understanding of how these techniques catalyze natural ecological processes is limited. We investigated natural regeneration in five plantations of native trees in the Poço das Antas Biological Reserve (PABR) in the state of Rio de Janeiro, Brazil. The plantations were 9–11 years old, and contained 8–14 native‐tree species with different compositions and relative density of species. We analyzed floristic composition, structure (density and basal area) of overstory and understory strata, as well as other ecological attributes (dispersal syndromes, fruit or seed size, and the availability of fruit for frugivores). Zoochorous species comprised 77% of the community, with a prevalence of the two smallest size classes of propagules (< 0.6 and 0.6–1.6 cm) in natural regeneration. The density of zoochorous plants in the understory was positively correlated with their density in the overstory, indicating their influence on natural regeneration (r2 = 0.36; p < 0.0002). Fruit availability for frugivores (density and richness of plants fruiting during the year) was also positively correlated with the density of stems in the understory. Therefore, attributes such as dispersal syndrome and fruiting season should be considered in selecting species to be planted. The differences in natural regeneration observed in each of the native‐tree plantations indicated that the performance of plantations as a restoration strategy may differ, depending on initial species composition, planting density, and site conditions.

Effects of row spacing on soil water and water consumption of winter wheat under irrigated and rainfed conditions

The results of two seasons' work on soil water content (SWC), evapotranspiration (ET), total dry matter (TDM), and harvest index (HI) of crops under different row spacing (RS), as well as possible ways to improve water utilization, have been reported. Field experiments were carried out at the Experimental Farm of Shandong Agricultural University (36°09'N, 117°09'E) in 2006–2007 and 2007–2008. Four types of RS were treated under two different water conditions (rainfed and irrigated) and set up in a randomized plot design. RS did not exhibit any obvious effects on SWC during the study period. SWC was enhanced evidently by irrigation, especially in the 10–60 cm soil layer. Irrigation increased the ET of crop. At the seeding-jointing stage, the ET of RS14 was significantly higher than those during other treatments (P < 0.05). Irrigation increased yields, ET, and TDM, while it decreased water use efficiency and HI. There were significantly negative correlations between TDM and RS (P < 0.05). The HI of the rainfed crop was higher than that of the irrigated crop. Results showed that high yields of wheat could be achieved in northern China by reducing RS under uniform planting density conditions.