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Increasing the appropriate seedling density for higher yield in dry direct-seeded rice sown by a multifunctional seeder after wheatstraw return

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Journal of Integrative Agriculture 2023年第2期22卷 400-416页

作者： TIAN Jin-yu LI Shao-ping CHENG Shuang LIU Qiu-yuan ZHOU Lei TAO Yu XING Zhi-peng HU Ya-jie GUO Bao-wei WEI Hai-yan ZHANG Hong-cheng Jiangsu Key Laboratory of Crop Cultivation and Physiology/Innovation Center of Rice Cultivation Technology in Yangtze Valley Ministry of Agriculture and Rural Affairs/Co-Innovation Center for Modern Production Technology of Grain CropsYangzhou UniversityYangzhou 225009P.R.China Agricultural College Xinyang Agriculture and Forestry UniversityXinyang 464000P.R.China

Dry direct-seeded rice(DDR) sown using a multifunctional seeder that performs synchronous rotary tillage and sowing has received increased attention because it is highly efficient,relatively cheap,and environmentally ***,this method of rice production may produce lower yields in a rice–wheat rotation system because of its poor seedling *** address this problem,we performed field experiments to determine the rice yield at five seedling density levels(B1,B2,B3,B4,and B5=100,190,280,370,and 460 seedlings m-2,respectively) and clarify the physiological basis of yield *** selected a representative high-quality rice variety and a multifunctional seeder that used in a typical rice–wheat rotation area in 2016 and *** proportion of main stem panicle increased with increasing seedling *** was a parabolic relationship between yield and seedling density,and the maximum yield(9.34-9.47 t ha-1) was obtained under *** maximum yield was associated with a higher total spikelet number m-2 and greater biomass accumulation from heading to *** higher total spikelet number m-2 under B3 was attributed to an increase in panicle number m-2 compared with B1 and *** the panicle numbers also increased under B4 and B5,these increases were insufficient to compensate for the reduced spikelet numbers per *** biomass,smaller leaf area,and lower N uptake per plant from the stem elongation stage to the heading stage were partially responsible for the smaller panicle size at higher seedling density levels such as *** higher biomass accumulation under B3 was ascribed to the increases in the photosynthetic rate of the top three leaves m-2 of land,crop growth rate,net assimilation rate,and leaf area ***,the B3 rice population was marked by a higher grain–leaf ratio,as well as a lower export ratio and transport ratio of biomass per stem-sheath.A quadratic function predicted that 260-290 seedlings m-2 is the op

关键词： seedling density dry direct-seeded rice sown by a multifunctional seeder rice–wheat rotation system yield biomass photosynthetic capacity

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Study on the Relationship of seedling density and Line Spacing to Leaf-stem Ratio, DW/FW Ratio and Grass Yield of Forage Sweet Sorghum

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Agricultural Biotechnology 2017年第6期6卷 17-21,25页

作者： Hanzhang ZHOU Huan LIU Haiyan JIA Zhimin WEI Shuhong YUAN Shunguo LI Shenglin HOU National Foxtail Millet Improvement Center Institute of Millet Crops Hebei Academy of Agricultural and Forestry Science Cereal Crops Research Laboratory of Hebei Province Shijiazhuang 050035 China Shenze Agricultural Bureau of Hebei Province Shenze 052560 China

[ Objectives ] The aim was to optimize the configuration of seedling density and line spacing of forage sweet sorghum （ Sorghum blcolor （ L. ） Moench） and explore its high-yield cultivation techniques. [ Methods] Effects of such two influencing factors as line spacing and seedling density on the leaf-stem ratio, DW/FW ratio and grass yield of forage sweet sorghum were analyzed by using split-plot experiment design experiment method and LSD method of IBM. SPSS. Statis- tics. v22 stati, stics software. [ Results ~ seedling density and line spacing had no obvious effect on the leaf-stem ratio and DW/FW ratio of forage sweet sorghum but had obvious influences on the grass yield. Moreover, the optimal combination of seedling density and line spacing for high yield of forage sweet sorghum was A2 B4, that is, seedling density was 225 000 plants/hm2, and line spacing was 40 cm. [ Conclusions] The results provided a theoretical basis and technical support for high-yield cultivation techniques of forage sweet sorghum.

关键词： Forage sweet sorghum seedling density Line spacing Leaf-stem ratio DW/FW ratio Grass yield

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Impact of invasive Ageratina adenophora on relative performance of woody vegetation in different forest ecosystems of Kumaun Himalaya,India

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Journal of Mountain Science 2023年第9期20卷 2557-2579页

作者： Bhawna NEGI Kavita KHATRI Surendra S.BARGALI Kiran BARGALI Archana FARTYAL R.K.CHATURVEDI Department of Botany D.S.B CampusKumaun UniversityNainital-263002UttarakhandIndia Center for Integrative Conservation Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesMenglun 666303China

Invasive plant Ageratina adenophora(Sprengel)***&*** has invaded majority of the temperate forests in Kumaun,Central *** on *** invaded forest types,their structural attributes,population demography and regeneration status are still at rudimentary *** this,the present study was conducted to assess the impacts of *** on vegetational attributes and regeneration status of three forest types,viz.,Oak(Quercus oblongata ***),Pine(Pinus roxburghii Sarg.)and Cypress(Cupressus torulosa ***).We selected three sites for each forest type and each site was further purposively stratified into paired sampling plots of 1 ha each i.e.,*** invaded and uninvaded *** results showed large densities of cut stumps or felled trees throughout invaded sites,but with fewer fire signs in comparison to uninvaded *** uninvaded sites,total density and basal area calculated for woody species were relatively higher than those in invaded sites,although results were insignificant(p>0.05).With the exception for Cypress forests,vegetation indices showed low woody species richness and diversity in invaded Oak and Pine ***,regeneration of ***,*** and *** tree species did not differ significantly(p>0.05)between invaded and uninvaded *** insignificant differences clearly imply that ***'s presence has not entirely changed the perennial plant communities in terms of composition,structure and natural ***,tree species with poor or no regeneration status requires special attention and needs management strategies involving control of invasive species in forest ecosystems.

关键词： Ageratina adenophora seedling density Forests Population structure Regeneration

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Tree species determine soil seed bank composition and its similarity with understory vegetation in a semi-arid African savanna

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Ecological Processes 2017年第1期6卷 84-99页

作者： Zewdu Kelkay Tessema Belay Ejigu Lisanework Nigatu Rangeland Ecology and Biodiversity Program School of Animal and Range SciencesCollege of Agriculture and Environmental SciencesHaramaya UniversityPO Box 138Dire DawaEthiopia Department of Animal Sciences Faculty of AgricultureWollega UniversityPO Box 38Shambu CampusEthiopia School of Natural Resource Management and Environmental Sciences College of Agriculture and Environmental SciencesHaramaya UniversityPO Box 138Dire DawaEthiopia

Introduction:The presence of larger trees in semi-arid African savannas creates sub-habitats,which influences on herbaceous plant communities grown under their canopies differently from opened *** of seed banks accumulated in the soils over time beneath larger trees could facilitate the recovery of plant communities that might disappear due to sustained heavy grazing,prolonged fire,or other anthropogenic factors in semi-arid African ***,the impact of larger trees on soil seed bank composition and its similarity with plant communities grown under their canopies are less understood in semi-arid African ***,we studied the effect of leguminous and non-leguminous tree species and their canopies on soil seed bank(SSB)composition and its similarity with understory vegetation(USV)in a semi-arid savanna of ***:We selected 20 matured trees from 3 dominant tree species,representing one leguminous(Acacia robusta Burch)and 2 non-leguminous tree species(Ziziphus spina-Christi and Balanites aegyptiaca(L.)Del),found in isolation,a total of 60 trees for this *** each selected individual tree,the species composition of USV were recorded using 1-m2 quadrat in four directions(north,south,east,and west)under the inside and outside tree canopies during the flowering ***,soil samples in a 1-m2 quadrat were also collected under the inside tree canopies and their corresponding outside canopies,in each individual tree,for the determination of SSB composition,using a seed emergence ***,the soil was thoroughly mixed after removal of all roots and plant fragments,and spread over sand in plastic pots to a depth of 20 *** pots were placed at random in a glasshouse,examined every 3 days,for the first 2 months,and thereafter weekly for 6 months.A total of 960 soil samples were used for the determination of SSB composition during this ***:A total of 64 species were emerged from the SSB samples,of which 27 w

关键词： Functional groups Herbaceous layers Plant abundance seedling density Species composition Species diversity Tree-grass interaction

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Determination of Optimum Seed Rate of Hybrid Rice (Oryza sativa L.) Varieties in Mat-Type seedling Raising for Mechanical Transplanting

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Agricultural Sciences 2022年第10期13卷 1031-1047页

作者： Md. Anwar Hossen Md. Kamruzzaman Sharmin Islam Haimonti Paul Md. Mahir Shahriyar Arafat Ullah Khan Farm Machinery and Post-harvest Technology Division Bangladesh Rice Research Institute (BRRI) Gazipur Bangladesh

Rice is the most important and crucial to ensuring food and dietary energy security in most developing countries and is the staple food of more than half of the world’s population. This study was conducted to identify the seed rate of hybrid rice varieties for mechanical transplanting during Boro (irrigated dry season), 2021-22 season at BRRI research field, Gazipur. Slender grain type BRRI hybrid dhan3, BRRI hybrid dhan5, Ishpahani hybrid dhan6, and BRRI dhan89 were used in the study. The same growth medium was used to establish mat-type seedlings on plastic trays (280 × 80 × 25 mm) at seed rates of 80, 90, 100, 110, and 120 g∙tray−1. Walk-behind type 04 rows rice transplanter (Daedong, model-DP 488) was used during transplanting in the field at the set of the plant to plant spacing of 140 mm while line-to-line spacing was fixed to 300 mm. The result depicted that regardless of the variety, seedling density increased linearly as seed rate increased, except for the 21 days following sowing. However, the seedling density of BRRI dhan89 decreased after the seed rate of 100 g∙tray−1 due to mortality. The seedling height of the BRRI hybrids dhan5 and Ishpahani hybrid dhan6 was significantly higher than that of the BRRI hybrid dhan3 and BRRI dhan89. After 21 days, the seedling height decreased significantly with the increase in seed rate. For the seed rates of 100, 110, and 120 g∙tray−1, identical numbers of hills per unit area and plants per hill were observed. On the other hand, regardless of the variety, the percentage of missing hills considerably decreased with the increased seed rate. The yield of the BRRI hybrid dhan5 variety was significantly higher at the seed rates of 100 and 110 g∙tray−1, although the yield of the Ishpahani hybrid dhan6 variety was comparable. In terms of yield among the four varieties, BRRI hybrid dhan5 gave a higher yield followed by Ishpahani hybrid

关键词： Slender Type Grain seedling density seedling Height Missing Hill Plants Per Hill Yield

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Gap characteristics and their effects on regeneration,dominance and early growth of woody species

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Journal of Plant Ecology 2009年第1期2卷 21-29页

作者： Indra Prasad Sapkota Per Christer Oden Swedish University of Agricultural Sciences Southern Swedish Forest Research CentreTropical Silviculture and Seed Science GroupPO Box 49SE-23053 AlnarpSweden

Aims We aim to examine the canopy gap characteristics and evaluate their influence on regeneration,dominance and the early growth of woody species in seasonally dry Shorea robusta forests(Sal forests).Methods Sixty canopy gaps were surveyed in six randomly located transects belts in seasonally dry subtropical Sal forests of central *** transect belt was followed until 10 gap sites were *** equation for the area of an ellipse was used to calculate the size of canopy gap,measuring the longest axis and its perpendicular shorter ***,sizes,ages and causes of tree falls creating canopy gaps along with number and sizes of border trees were identified and *** gap inventories were carried out using square 25-m2 quadrats placed in the middle of each *** individuals>2 m in height within the quadrat were identified at the species level and their diameter at breast height was *** assigned a nested 4-m2 quadrat to the corner of each 25-m2 quadrat,within which all woody individuals>10 cm tall were identified at the species level,and counted them and their regeneration mechanisms were *** height and collar diameter of the tallest individuals were *** statistics was calculated for the variables of interests and Pearson correlation,linear regression,independent-sample t-test and chi-square test were used to relate them and to test for their *** Findings The study found mean gap size of 283 m2 and;50%gaps of 10–15 years *** created by natural single-tree falls were significantly more numerous,and their mean size was significantly smaller than those resulting from artificial causes or multiple-tree *** size correlated with the basal area of felled trees,but it did not correlate with the number of tree *** tree fall basal area was significantly positively correlated to the seed-originated seedling to resprout ratio,it was negatively correlated,along with gap area and th

关键词： canopy gap seedling density seedling growth basal area Sal forests Nepal

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