Effects of Different Planting Densities on the Yield of Rice Developed from Seedlings Dry Raised in Plug Trays

[Objectives]This study was conducted to investigate the effects of different planting densities on rice tillering dynamics and yield. [Methods]The effects of different planting densities on rice yield were studied based on seedlings dry raised in plug trays. [Results]Planting density had obvious effects on tillering dynamics,number of panicles per unit area,number of grains per panicle and rice yield under the condition of seedlings dry raised in plug trays. Comprehensive analysis showed that the row spacing × hill spacing = 25 cm × 14 cm,that is,the planting density of 2. 85 × 10~5 hills/hm^2,achieved the highest yield,at 9 960 kg/hm^2. [Conclusions]This study provides a scientific basis for optimizing rice cultivation techniques and achieving high yield and high efficiency in rice production.

Effects of Farming and Seedling-raising Methods on Population Growth and Grain Yield of Mechanized Transplanting Rice

The effects of farming method, rice variety and seedling-raising method were studied on the population growth quality and grain yield of the mechanized transplanting rice by way of three-factor split plot design. The results showed that the no-tillage mechanical transplanting treatment was poorer than the conventional mechanical transplanting treatment in transplanting quality in general, but the former was similar to the latter in population growth quality. In regard to grain yield, the no-tillage mechanical transplanting treatment was lower than the conventional me- chanical transplanting treatment. Raising both pot-mat seedling and plastic-tray seedling did not make much difference in population growth and grain yield of mechanized transplanting rice, so both of the seedling-raising methods can be adopted according to practical conditions.

Effect of Seedling Raising Methods on Leaf Photosynthesis and Grain Yield of Mechanically-transplanted Japonica Rice

This study was conducted to investigate the effects of seedling raising modes on photosynthetic charactedsticsand grain yield under wheat straw returning. Four representative cultivars in Huaibei area were selected as test materials. By setting potted seedlings and carpet seedlings, the effects of different nursery meth- ods on the photosynthesis of rice at different growth stages in Huaibei area were investigated. Compared with carpet seedlings, the leaf area index of potted seedlings decreased at the maturation stage, but the dry weight of leaf shewed no significant difference.The SPAD of potted seedlings had an increasing trend after transplanting, but the SPAD increased differently according to cultivars. The net photosynthetic rate, stomatal conductance and transpiration rate of the leaves of pot seeding rice were significantly higher than those of carpet seedling rice on the 85^th d after transplanting. However, theintracellular CO2 concentration and water use efficiency of leaves had no significant differences between different ＇treatments. The results indicate that the photosynthetic capacity of flag leaves of pot seedling rice is stronger in early and middle stages, but the decay rate of photosynthetic function is slightly faster than carpet seedling rice, which might be the main reason for the rice yield of potted seedlings having no remarkable difference from carpet seedlings.

Optimization of Cultivation Medium for Container Seedling Raising of Camellia oleifera

[Objective] This study aimed to investigate the optimal component of culti- vation medium for container seedling raising of Camellia oleifera. [Method] In the application of container nursery technology of Camellia oleifera grafting in emergent stocks, yellow clay soil, surface soil of pine forest, decomposed edible fungus, peat soil, dung and dirt were mixed by different proportions into five formulae as nursery substrates, with garden soil as the control, in order to investigate the influences of various substrates on the growth of annual Camellia oleifera container seedlings by using randomized block design based on variance analysis and multiple comparisons, and to screen the optimal substrate formula for container nursery of Camellia oleifera. [Result] The influences of different substrates on the transplanting survival rate, seedling height, basal diameter, height-diameter ratio and lateral root length of Camellia oleifera container seedlings were significantly different. Various growth indi- cators of Camellia oleifera container seedlings cultivated in the substrate containing 40% of yellow clay soil ＋ 15% of surface soil of pine forest ＋ 20% of decomposed edible fungus ＋ 20% of peat soil ＋ 5% of dung and dirt exceeded that of the control and other substrate formulae, which could be used as the optimal substrate formula for the container nursery of Camellia oleifera. [Conclusion] This study screened the optimal substrate formula for the container nursery of Camellia oleifera, which provided technical reference for the cultivation of Camellia oleifera container seedlings.

Organic Substrate Application in Vegetable Seedling Raising in China

To study the organic substrates substitution for turf has certain significances and has become a hot research topic. The sources of organic substrates mainly concentrate in organic waste of agriculture and forestry, animal husbandry industrial wastes and municipal sludge and so on in China. In order to better explore and utilize organic substrates resources, the authors summed up the application of organic substrates of different sources to vegetable seedling raising. The re- sults showed that the organic substrate produced by traditional and advanced tech- nology had the characteristics of stability, strong buffer capacity, comprehensive nu- trition and a good environment for root growth, which could reduce the production cost, cultivate high quality seedling and benefit cyclic utilization of resources, and replace or partly replace the turf. The prospects for future research direction were discussed to provide references for research and development on organic vegetable seedling raising technology in China.

Effects of soilless substrates on seedling quality and the growth of transplanted super japonica rice

This study was conducted to investigate the effects of soilless substrates of hydroponically grown long-mat seedlings （HLMS） on seedling quality and field growth characteristics of transplanted super japonica rice. A widely grown conventional super japonica rice cultivar （Wuyunjing 23） was selected as the test material. The effect of HLMS on seedling quality, mechanical transplantation quality, field growth characteristics, yield, and benefit-cost ratio were compared with seedlings grown in organic substrates and traditional nutritive soil, whJch was selected as the control. Root number, root twJstJng power and root activity of seedlings cultivated by HLMS were decreased compared to that of the organic substrates andcontrol. However, seedling root length as well as aboveground growth were increased compared to the organic substrates and control seed- lings. In the HLMS, the content of gibberellin acid （GA3） decreased while abscisic acid （ABA） content increased compared to that of the organic substrates and control seedlings. During the early stages after transplanting, the re-greening of HLMS was delayed compared to that of the organic substrates and control seedlings. Nevertheless, there were no significant differences in tiller dynamics and crop yield among the HLMS, organic substrates and control treatments. The effects of HLMS on seedling production were similar to those of the organic substrates and traditional nutritive soil in the present study, suggesting that HLMS have the potential to replace traditional nutritive soil in seedling production without decreasing crop yield. Finally, it is important to reduce organic substrates and topsoil dependence during rice seedling production and worthwhile to consider HLMS popularization and its application on a larger scale.

Effect of Three Treatment Measures on Harmless Seedling Raising of Pinus sylvestris var.mongolica Litv.

Three treatment measures for raising seedlings by sowing, Le. covering seeds with two layers of forest soil, culturing seedlings under full sunshine and timely sowing in late autumn, were adopted in this study. The results indicated that the three treatments were of good prevention effects on sheath blight or seedling blight, sunscald and rat damage in Pinus sylvestris var. mongolica, could avoid the pollution of agrochemicals to soil and environment as well as decrease cost for raising seedlings, and thus could promote the development of bio-agrochemicals or bio-fungicides with high efficiency and no pollution for resisting the pathogens of sheath blight.

THE STUDIES OF THE PLANT COLD－RESISTER AND ITS APPLICATION IN RECE SEEDLING RAISING

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Development Status and Countermeasures of Passiflora spp.Seedling Industry in Qinzhou,Guangxi

In recent years,the development trend of passion fruit seedling industry in Qinzhou,Guangxi is good,but on the whole,it is still in its infancy and the development of the industry is fragile.This paper briefly described the development status and existing problems of the passion fruit seedling industry in Qinzhou,Guangxi,and put forward reasonable suggestions in order to promote the healthy development of the passion fruit seedling industry,increase farmers’income and prosper rural economy.

The technology of raising rice seedlings in dry nursery in China

A new technology of raising rice seedlings in dry nursery began to be adopted in early 1980’s inChina. It expanded in Northeast of the Country and spreaded from North to South in the followingyears. In 1995, it was listed as one of the national popularization project during the ’Ninth Five-Year-Plan’ by the Country Government. The total area was up to 9.3 million hm~2 in 1996 (cover-ing 80% paddy field in the northern parts of China). The expected popularized area will be up to15.3 million hm~2 in 2000 according to the Ministry of Agriculture, half of the total rice-growingarea in China.

Different Understory Cultivation Techniques of Paris polyphylla Smith

This study was conducted for the purposes of reducing consumption of wild resources of Paris polyphylla Smith, satisfying the market demand, saving the production cost, improving utilization rate of forest land, increasing income of foresters and protecting ecological environment. Three types of fores{ land, i.e., the evergreen forest land （China fir forest）, deciduous forest land （walnut forest） and shrub land （honey suckle forest.） were selected, and seeds and cut rhizomes of Paris polyphylla Smith produced in Bamian Mountain, Hunan, were used in the study on understory seedling raising and cultivation techniques. The results showed that： when using different propagation materials, seed propagation could be adopted to reduce the consumption of wild resources and provide a large number of seedlings, and was beneficial to large-scale planting; and when conducing seedling and plantlet raising followed by transplanting and direct seeding and planting using different propagation materials in large-scale understory cultivation, direct seeding/ planting was appropriate for saving save production cost with the advantage of early production. Among the 3 different types of forest land, the best choice was broad- leaved forest land, which could achieve better economic benefit because of con- forming with the ecological habit and growth and development law of Paris poly- phylla Smith.

Supporting Nursing Technology for the Marker-Assisted Selection of Castanea mollissima Blume

[Objective] The aim was to study the supporting raising technology of Castanea mollissima Blume molecular marker-assisted selection to reduce the cost and time for chestnut breeding.[Method] To find the best cutting method,10 treatments were designed according to transverse diameter and vertical diameter of the chestnut including different cutting ratios in 1/2,1/3,1/4 and different directions about cross cutting,vertical cutting,bevel cutting and two side-cutting.The germination rate,seedling survival rate and morphological indicators of the treatments were measured;significant difference among them was also analyzed.[Result] 1/3 bevel cutting was the best,which not only could give high germination rate and survival rate,but also could guarantee high quality of nursery stock,which did not grow so differently with the untreated seedlings.[Conclusion] This way can not only reduce too much cost and time for seedling breeding,but also promote the germination of chestnut in advance,which could do much good to production.

Design and experiment of the soil-covering and soil-compacting device for seedling raising and sowing of trough type panax notoginseng

In order to improve the seedling quality of Panax notoginseng,combined with the special agronomic requirements of Panax notoginseng,a sharp angle roller soil-covering and soil-compacting device integrating the functions of soil-covering and soil-compacting was designed.Based on the theoretical analysis of seed ditch conditions,soil-covering process and soilcompacting process,the structure of soil-covering and soil-compacting device was designed.Through theoretical analysis and calculation,the diameter and length of soil-covering and soil-compacting wheel were 20 cm and 10.7-14.1 cm,respectively,the sharp angle and height range were 45°-105°and 0.8-1.6 cm respectively,and the spring stiffness was 38.54 N/mm;Using the discrete element method to simulate the soil-covering and soil-compacting process,it was obtained that when the sharp angle range was 60°-90°,the sharp angle height range was 0.8-1.2 cm,and the soil-covering effect was better;Taking the forward speed,ballast pressure,sharp angle and sharp angle height of the planter as the test factors,and taking the soil-covering thickness,grain spacing and soil compactness as the indexes,the four factor and three-level Box-Behnken Design test was carried out.The response surface test analysis method was used to establish the regression equation between the factors and indexes,and determine the best parameter combination:the forward speed was 6.5 m/min,the ballast pressure was 360.5 N,the sharp angle was 67°,and the sharp angle height was 1 cm,at this time,the soil-covering thickness was 0.64 cm,the grain spacing was 5.03 cm,and the soil compactness was 321.77 kPa.According to the soil trough test,the design of soil-covering and soil-compacting device met the agronomic requirements of plant spacing,soil-compactness and soil-covering thickness during seedling sowing of Panax notoginseng.The research results can provide a reference for the design of Panax notoginseng seedling planter integrating pressing hole(ditching),sowing,soil-covering and soil-compacting.