Strong Seedling Research Articles

SNP-based association analysis for seedling traits in durum wheat (Triticum turgidum L. durum (Desf.)).

In the present study, 150 accessions of worldwide originated durum wheat germplasm (Triticum turgidum spp. durum) were observed for major seedling traits and their growth. The accessions were evaluated for major seedling traits under controlled conditions of hydroponics at the 13th, 20th, 27th and 34th day-after germination. Biomass traits were measured at the 34th day-after germination. Correlation analysis was conducted among the seedling traits and three field traits at maturity, plant height, grain weight and 1000-grain weight observed in four consecutive years. Associations of the measured seedling traits and SNP markers were analyzed based on the mixed linear model (MLM). The results indicated that highly significant genetic variation and robust heritability were found for the seedling and field mature traits. In total, 259 significant associations were detected for all the traits and four growth stages. The phenotypic variation explained (R2) by a single SNP marker is higher than 10% for most (84%) of the significant SNP markers. Forty-six SNP markers associated with multiple traits, indicating non-neglectable pleiotropy in seedling stage. The associated SNP markers could be helpful for genetic analysis of seedling traits, and marker-assisted breeding of new wheat varieties with strong seedling vigor.

Onion ( Allium cepa L.) Seedling Quality Parameters as Affected by Soil and Seed Treatment at Adami Tulu, Mid Rift Valley of Ethiopia

The integrated effects of soil and seed treatment on onion (Allium cepa L.) were investigated at Adami Tulu mid rift valley of Ethiopia during hot warm season (March, April and May) 2015. Leaf number, seedlings length, weed abundance, percentage of strong and weak seedling were tested for their response. Accordingly interaction effect of seed and soil treatment affected percentage of strong and weak seedling significantly at (P < 0.01). The main effect of seed treatment was found non-significantly affected all seedling quality parameters except seedling length whereas the main effect of soil treatment affected seedling length, and leaf number at (P < 0.05) weed abundance, percentage of strong and weak seedling at (P < 0.01). The maximum percentage of strong seedling was attained while solarization combined with treated seed (seed treated with apron star) (85%) followed by treated seed with burning (77.4%) and untreated seed with solarization (77.4%). The interaction of burning and untreated seed (4) was found to maximize leaf number followed by combined effect of burning and treated seed (4). Mean weed abundance reduced from 65.9% and 41.7% when soil is treated with solarization and burning as compared to control plot, respectively. In general increased quality of onion seedling was achieved due to combined application of soil solarization and seed treated with apron star. Therefore, combined treatment of soil solarization and seed treatment with apron star is recommended for onion nursery establishment at Adami Tulu mid rift valley of Ethiopia.

Characteristics and coordination of source-sink relationships in super hybrid rice

AbstractThis paper discusses the characteristics of source and sink for super hybrid rice and how to coordinate its source-sink relationships for high-yielding cultivation. It is known that super hybrid rice possesses a higher net photosynthetic rate than non-hybrid rice because of its higher grain-leaf area ratio, better stornata traits and less midday depression. However, the sink of super hybrid rice remains large due to its large and numerous spikelets. Furthermore, the relocation of assimilates is smooth in super hybrid rice because of its well-developed vascular structure. However, due to the very large sink of super hybrid rice, it is relatively inefficient in supplying of assimilate products to spikelets, in particular to inferior spikelets. Therefore, reducing the discrepancy between source and sink in super hybrid rice is essential for developing high-yielding cultivation. This can only be achieved by planting cultivars adapted for local environments, raising strong seedling, setting up populations with a high photosynthetic efficiency for increasing the supply of source, and improving the field management in filling stages to the duration of supply of photosynthate to grains.

Early seedling vigour, an imperative trait for direct-seeded rice: an overview on physio-morphological parameters and molecular markers.

Rapid uniform germination and accumulation of biomass during initial phase of seedling establishment is an essential phenotypic trait considered as early seedling vigour for direct seeded situation in rice irrespective of environment. Enhanced role of carbohydrate, amylase, growth hormones, antioxidant enzymes and ascorbic acid brings changes in vigour and phenotype of seedling. Early establishment and demanding life form dominate the surroundings. Crop plant that has better growth overdrives the weed plant and suppresses its growth. Seedling early vigour is the characteristic of seed quality and describes the rapid, uniform germination and the establishment of strong seedlings in any environmental condition. The phenotype of modern rice varieties has been changed into adaptable for transplanted rice with thirst toward water and selection pressure for semi-dwarf architecture resulting in reduced early vigour. Decreasing freshwater availability and rising labour cost drives the search for a suitable alternative management system to enhance grain yield productivity for the burgeoning world population. In view of these issues, much attention has been focused on dry direct-seeded rice, because it demands low input. A rice cultivar with a strong seedling vigour trait is desirable in case of direct seeding. However, seedling vigour has not been selected in crop improvement programmes in conventional breeding due to its complex nature and quantitative inheritance. Molecular markers have been proven effective in increasing selection efficiency, particularly for quantitative traits that are simply inherited. Marker-assisted selection approach has facilitated efficient and precise transfer of genes/QTL(s) into many crop species and suggests a speedy and efficient technique over conventional breeding and selection methods. In this review, we present the findings and investigations in the field of seedling vigour in rice that includes the nature of inheritance of physio-morphological and biochemical traits and QTLs to assist plant breeders who work for direct-seeded rice.

Plant Recruitment and Soil Microbial Characteristics of Rehabilitation Seedings Following Wildfire in Northern Utah

AbstractOne goal of post‐fire native species seeding is to increase plant community resistance to exotic weed invasions, yet few studies address the impacts of seeding on exotic annual establishment and persistence. In 2010 and 2011, we investigated the influence of seedings on exotic annuals and the underlying microbial communities. The wildfire site in northern Utah was formerly dominated by Artemisia tridentata ssp. wyomingensis, but burned in September 2008. Experimental seeding treatments were installed in November 2008 to examine strategies for establishing native species using two drills, hand broadcasts and different timing of seed applications (resulting in 13 seeding treatments). We collected aboveground biomass of invasive annuals (Halogeton glomeratus, Salsola kali, and Bromus tectorum), other volunteer plants from the extant seed bank, and seeded species from all treatments in the second and third years after fire. We sampled soils within microsites beneath native perennial bunchgrass and exotic annuals to characterize underlying soil microbial communities. High precipitation following seeding led to strong seedling establishment and we found few differences between seeding treatments established with either drill. All seeded treatments reduced exotic biomass by at least 90% relative to unseeded controls. Soil microbial communities (phospholipid fatty acid analysis), beneath B. tectorum, Poa secunda, and Pseudoroegneria spicata microsites differed little 3 years after fire. However, microbial abundance beneath P. spicata increased from June to July, suggesting that microbial communities beneath successful seedings can vary greatly within a single growing season.

Seleção de lotes de sementes de Pinus taeda L. para a cultura de tecidos

Neste trabalho, objetivou-se identificar os principais gêneros fúngicos associados a três lotes de sementes de Pinus taeda L.; avaliar a qualidade sanitária e fisiológica desses lotes, para utilizar como critério de seleção para a cultura de tecidos e analisar o estabelecimento in vitro de explantes de origem seminal. Foi possível discriminar os lotes quanto à qualidade sanitária e fisiológica, bem como estabelecer in vitro plantas de Pinus taeda, a partir de nós cotiledonares obtidos da germinação asséptica de sementes de um lote selecionado pela qualidade sanitária e fisiológica. Os meios nutritivos MS, ½ MS e WPM são igualmente adequados para esse fim. Para a análise sanitária, os gêneros fúngicos Fusarium, Penicillium e Trichoderma são os de maior sensibilidade. Para a avaliação fisiológica mostraram-se adequadas as variáveis: plântulas anormais, plântulas normais fortes, comprimento, massa fresca e massa seca de plântulas normais fortes. As análises mostraram-se favoráveis à escolha de lotes de sementes para o cultivo in vitro e todos os meios de cultura utilizados foram adequados ao estabelecimento da espécie em cultura de tecidos.

Identification and fine mapping of quantitative trait loci for seed vigor in germination and seedling establishment in rice

Seed vigor is an index of seed quality that is used to describe the rapid and uniform germination and the establishment of strong seedlings in any environmental conditions. Strong seed vigor in low-temperature germination conditions is particularly important in direct-sowing rice production systems. However, seed vigor has not been selected as an important breeding trait in traditional breeding programs due to its quantitative inherence. In this study, we identified and mapped eight quantitative trait loci (QTLs) for seed vigor by using a recombinant inbred population from a cross between rice (Oryza sativa L. ssp. indica) cultivars ZS97 and MH63. Conditional QTL analysis identified qSV-1, qSV-5b, qSV-6a, qSV-6b, and qSV-11 influenced seedling establishment and that qSV-5a, qSV-5c, and qSV-8 influenced only germination. Of these, qSV-1, qSV-5b, qSV-6a, qSV-6b, and qSV-8 were low-temperature-specific QTLs. Two major-effective QTLs, qSV-1, and qSV-5c were narrowed down to 1.13-Mbp and 400-kbp genomic regions, respectively. The results provide tightly linked DNA markers for the marker-assistant pyramiding of multiple positive alleles for increased seed vigor in both normal and low-temperature germination environments.

EFFECT OF BIOGEIN, RHIZOBACTERIEN AND VIVA ROSE FERTILIZATION ON GROWTH AND CHEMICAL COMPOSITION OF Cupressus sempervirens, L. SEEDLINGS.

In this study, seedlings one year old of Cupressus sempervirens, planted in the nursery of Woody Trees Res. Dept., Hort. Res. Inst., Giza, Egypt. For two successive years (2011 and 2012) to investigate the best bio-fertilization treatments and the suitable doses on growth of Cupressus by Biogein or Rhizobacterien at the rates of 2.50, 5.00 and 7.50 g/ bag as well as chemical fertilizer with Viva Rose as a foliar spray at the rates of 1.00, 2.00 & 4.00 g/l .Seedlings were grown in 14 cm diameter black polyethylene bag filled with a mixture of sand plus loam (1:1, v. /v.) were used in this investigation . Results indicated that plant height and diameter, showed a significant increased by adding Biogien at the rate 2.50g/bag, compared to control. Spraying the seedlings with Viva Rose at the rate of 4.00ppm induced utmost means of number of branches and leaves /plant, compared with the control and other treatments. While untreated plants gave the longest of root length /plant. Combination treatment Biogein plus Rhizobacterien at the rate 2.50 plus 1.00ppm Viva Rose recorded high increases of fresh and dry weights of aerial parts stem and leaves. However, fresh and dry weights of roots were increased significantly by addition Biogien at the rate of 5.00g/bag and 1.00ppm of Viva Rose. Chemical compositions were highly variance in response to all fertilizer treatments compared with the untreated plants. Biogien at the rate of 2.50g/bag level increased significantly a, total chlorophyll a +b, N% and nutrient uptake. Meanwhile, Rhizobacterien at the rate of 2.50g/bag elevated contents of leaves from b, carotenoids, and total indoles. Total phenols increased by Viva Rose at the rate of 4.00ppm, but spraying Viva Rose at the rate of 2.00 ppm increased P%. While, P, K % were highly increased at the rate of 5.00g/bag Rhizobacterien. From the obtained results it could be recommended, that the addition of Biogien at 2.5 g/bags to Cupressus sempervirens seedlings (grown in 14 cm diameter bags thrice with one month interval from March to May during the growing season) resulted in the best and strong seedlings, besides to short the time in nursery in order to realization the coast of seedlings producing and to save our environment.

Genetic effects on seed quality in diallel crosses of popcorn

The failure to obtain the ideal stand is one of the causes of decreased crop yields, in this sense it is important to investigate the genetic effects related to seed quality. The aim of this study was to measure the general combining ability (GCA), the specific combining ability (SCA) and the reciprocal effects (RE) for popcorn seed quality in addition to evaluate the association between germination and vigor tests with field emergencein order to identify hybrids with better germination and vigour. Ten inbred lines were evaluated using a complete diallel cross with reciprocals. Seed quality was measured by germination tests (GT) and by modified cold vigour tests (MCV). In the GT, the numbers of strong normal seedlings (SNS), weak normal (WNS), abnormal (AS) and ungerminated seeds (UGS) were counted. In the MCV, the numbers of normal seedlings (NPC), abnormal (ASC) and ungerminated seeds (UGSC) were counted, and the plants' dry matter (DM) was measured. Analysis of variance for GCA, SCA and RE were significant for all variables. The quadratic components for SCA were higher than those for GCA for the SNS, AS, UGS, ASC and UGSC traits, which indicates higher significance for the non-additive effects. The most favourable GCA estimates, were found in lines P3 and L70. The best hybrids were P1xL70, P3xP6 and P8xL70. The RE results showed that L70 and P3 should be used as the female parent in the P1xL70 and P3xP6 hybrid crosses, respectively. The MCV was the test that was most strongly correlated with field emergence, with a magnitude of 0.667.

Characterization of Nitrogen Uptake and Utilization in Rice under Different Planting Methods

A field experiment was conducted with three planting methods including precision artificial transplanting with dry nursery middle and strong seedlings (AT), mechanical transplanting with small seedlings (MT) and direct seeding (DS) using early-maturing late japonica rice (EMLJ), late-maturing medium japonica rice (LMMJ) and medium-maturing medium japonica rice (MMMJ) (including conventional rice and hybrid rice). The results showed that the N content and uptake in plants were DSMTAT at jointing and ATMTDS at heading and maturity. Total N uptake at maturity with AT was 11.68% and 39.03% higher than that with MT and DS and that with MT was 24.49% higher than that with DS. N uptake rate was DSMTAT before jointing and ATMTDS from jointing to heading and from heading to maturity. Maximum N uptake rate of AT and MT appeared in the period from jointing to heading, and that of DS with MMMJ appeared from jointing to heading while that with EMLJ and LMMJ appeared before jointing. N periodic accumulation from jointing to heading and from heading to maturity were ATMTDS and the difference among different planting methods all reached significant or very significant level. N recovery efficiency of AT, MT and DS were 44.49%, 39.00%, and 31.41%, respectively. N recovery efficiencies among different varieties with AT and MT were EMLJLMMJMMMJ, and that with DS was MMMJLMMJEMLJ, and in the case for the same type of variety, that of conventional japonica rice was higher than that of hybrid japonica rice. N requirement for 100 kg grain of AT, MT, and DS were 1.959 (1.900–2.009), 1.842 (1.681–1.914), and 1.638 (1.540–1.721) kg, respectively. It was no significant differencebetween AT and MT while both were significantly higher than that of DS for conventional japonica rice. For hybrid japonica rice, the differences among different planting methods were all significant. N requirement for 100 kg grain among different growth type of varieties with DS was MMMJLMMJEMLJ while that with AT and MT was not significantly different. It is important to select scientific planting method and suitable variety type for achieving effective nitrogen uptake and utilization.

Relationships between seedling establishment and soil moisture content for winter and spring rapeseed genotypes

Rapeseed cultivars are important for edible oil production under semiarid area regions in Iran. However, germination and seedling establishment of rapeseed cultivars are the critical steps in successful production of this oil crop plant that are not well understood. The objective of this study was to evaluate the effect of low soil moisture on emergence and seedling establishment of 24 rapeseed genotypes including 13 cultivars and 11 doubled haploid lines. A pot experiment was conducted in a greenhouse using a factorial experiment based on a completely randomized design with three replications. The genotypes were evaluated under different soil field capacity (FC) levels (80%, 50%, 30% and 20% FC). Decreasing the soil moisture content from 50% to 20% FC resulted in reduced overall final emergence from 94.3% to 82.7%. Significant differences were observed among genotypes under different soil moisture levels for all studied characters. Seedling vigor index and shoot growth of the tolerant genotypes were significantly higher under lower soil moistures levels. Studies on identification indices of drought resistance by principal component analysis (PCA) indicated that germination rate and final emergence were most important and better indicators of establishment in rapeseed. Cluster analysis and PCA method separated the genotypes into four groups. Genotypes in group I had the greatest tolerance, cluster II the intermediate tolerance, and clusters III and IV had the least tolerance to low soil moisture. In response to low soil moisture, cluster I (included GKH2005, Opera and Okapi) showed higher final emergence, rapid emergence, strong seedling vigor, and maximum shoot growth. On the other hand, cluster II (included DH1, DH3, DH4, DH5, DH7, DH8, DH9, DH10, DH11 and DH13) showed high coefficient of germination rate. Cluster III (included Cooper, SLM046, Lilian, Billy and Karun) had greater root length, cotyledon length and width, and root-to-shoot length with high mean time to germination whereas decreasing soil moisture resulted in severe reductions of final emergence and germination rate compared with those observed for 80% and 50% FC. Also, cluster IV (Included Adriana, Oase, Savanah, Triangle, Tasilo and DH6) had lower final emergence, delayed emergence, low growth potential, and high sensitivity for shoot and root growth. The results suggest that the genetic diversity within cluster I could be used for crop breeding programs and increasing the cultivation area in arid and semiarid regions of Iran.

Stable Production of Wheat Haploid and Doubled Haploid by Wheat × Maize Cross

One of the most effective ways to produce wheat haploid is the method of crossing wheat with maize. However, the problem of unstable frequencies in haploid and doubled haploid production affects its application. In this study, 13 wheat F1hybrids crossed with maize to explore the effects of wheat growth condition, hormone treatment, culture medium, and strong seedling treatment on production of haploid and doubled haploid. The frequency of embryo formation was 23.9% and the number of embryos per spike was 6.8 for the wheat plants grown in filed and then detached before pollination and hydroponically cultured after pollination. The efficiency of this method was three times higher than that of the method with plants transplanted into pot after green recovering in early spring and then grown in the unheated greenhouse condition. Embryo formation frequencies were obviously different among wheat crosses. There was no significant difference in the frequency of embryo formation between treatments of dipping spike with Dicamba(21.5%) and 2,4-D(21.1%). However, wheat cross had significant effect on embryo formation. The mean frequency of embryo germination on B5medium was 82.0%, ranging from 70.9% to 88.3%, whereas averaged frequency of embryo germination was 76.6% on 1/2 MS medium, ranging from 70.0% to 86.0%. There was no significant difference between the two culture media in embryo germination. The efficiency of doubled haploid production for the seedlings treated with culture medium and transplanted into pot was 67.6% and 8.6%, respectively. Most of seedlings transplanted into pot had no tiller and grew weakly; this is the reason for low frequency of survival plant and very low frequency of doubling after colchicine treatment.

Tissue cultivation of tiller buds of Epimedium wushanense

To established the rapid tissue propagation system of Epimedium wushanense, in order to provide theoretical basis for industrialized seed cultivation. Tiller buds E. wushanense were used as explants, with MS, B5, WPM as basic media, and added with different concentrations of plant growth regulators such as 6-BA, NAA and GA3, in order to conduct a systematic study on induction and propagation conditions for tiller buds. The suitable method for sterilizing bud was to disinfect with 75% ethanol for 30 s, and then treated with 0.1% HgCl2 for (4 + 2) min for consecutively twice, which could control the pollution rate below 5% and the survival rate above 75%. The optimal medium for bud induction was WPM + 6-BA 2.0 mg x L(-1) + NAA 0.1 mg x L(-1) + GA3 0.5 mg x L(-1), with the induction rate of 75.5%; meanwhile, the basic medium and 6-BA showed significant effect on the induction rate. The propagation medium suitable for buds was MS +6-BA 2.0 mg x L(-1) + NAA 0.5 mg x L(-1), with the propagation rate of 3.3. The optimal growth of rooting medium was 1/2 WPM + IBA 0.5 mg x L(-1) + activated carbon which (0.05%), with the rooting rate of 90%, three to six strong seedlings in each plant. The disinfection method suitable for tiller buds and the medium combination suitable for induction, propagation and rooting of adventitious buds are screened out to establish the rapid cultivation system for tiller buds of E. wushanense.

Role of a respiratory burst oxidase of Lepidium sativum (cress) seedlings in root development and auxin signalling.

Reactive oxygen species are increasingly perceived as players in plant development and plant hormone signalling pathways. One of these species, superoxide, is produced in the apoplast by respiratory burst oxidase homologues (rbohs), a family of proteins that is conserved throughout the plant kingdom. Because of the availability of mutants, the focus of research into plant rbohs has been on Arabidopsis thaliana, mainly on AtrbohD and AtrbohF. This study investigates: (i) a different member of the Atrboh family, AtrbohB, and (ii) several rbohs from the close relative of A. thaliana, Lepidium sativum (‘cress’). Five cress rbohs (Lesarbohs) were sequenced and it was found that their expression patterns were similar to their Arabidopsis orthologues throughout the life cycle. Cress plants in which LesarbohB expression was knocked down showed a strong seedling root phenotype that resembles phenotypes associated with defective auxin-related genes. These transgenic plants further displayed altered expression of auxin marker genes including those encoding the auxin responsive proteins 14 and 5 (IAA14 and IAA5), and LBD16 (LATERAL ORGAN BOUNDARIES DOMAIN16), an auxin-responsive protein implicated in lateral root initiation. It is speculated that ROS produced by rbohs play a role in root development via auxin signalling.

Influence of Planting Methods on Root System Morphological and Physiologi-cal Characteristics of Super Rice under High-yielding Cultivation Condition

A field experiment was conducted to compare the root system morphological and physiological characteristics of two super rice cultivars(Huaidao9 and Xudao3) using three planting methods,i.e.,precision artificial transplanting with dry nursery middle and strong seedlings(AT),mechanical transplanting with small seedlings(MT) and direct seeding(DS).Results were as follows.(1) Yields of super rice under different planting methods were very significantly different.Compared with AT,yields of MT and DS reduced by 5.05% and 13.68%,respectively.(2) The population root number was DSMTAT,while the difference was decreasing with the growing process.Total population root length was shown to be DSMTAT at jointing and MTATDS at heading and maturity.Root number per stem showed no significant difference among different planting methods,and total root length per stem was ATMTDS with generally significant difference.Length of single root was of no significant difference be-tween AT and MT,though both were significantly higher than DS.As for root diameter,the result was ATMTDS and the dif-ference among different planting methods was significant.(3) Population root dry weight showed no significant difference be-tween MT and DS at jointing,that both had the extremely significantly higher value than AT.There was no significant difference among different planting methods at heading,but when at maturity it was ATMTDS and the difference was very significant.As for decreasing rate of population root dry weight after heading,it was DSMTAT with significant difference.Root dry weight per stem was ATMTDS through jointing,heading and maturity,and the difference among different planting methods was mostly very significant.Decreasing rate of root dry weight per stem after heading displayed no significant difference between DS and MT,but both of them had the significantly higher value than AT.Shoot dry weight reduced in order for AT,MT,and DS,but root-shoot ratio increased in the same order.(4) Compared with AT,roots of MT and DS were mainly distributed within the soil layer of 0-10 cm underground,especially for DS,the root proportion in 0-5 cm soil layer could sum up to 65%.Ratio of root dry weight in 0-5 cm soil layer to total root weight increased in order for AT,MT,and DS,while the ratios in the soil layers of 5-10 cm,10-15 cm and 15 cm reduced in that order.(5) Population root absorption area showed no significant difference among dif-ferent planting methods at jointing,performed as ATMTDS at heading with very significant difference,and,at maturity,showed no significant difference between MT and AT,both of which had the very significantly higher value than DS.Root ab-sorption area per stem was of no significant difference between AT and MT at jointing and maturity while both had the very sig-nificantly higher value than DS,and was ATMTDS at heading with very significant difference.(6) Population root bleeding intensity after heading increased in order for AT,MT,and DS,but root bleeding intensity per stem reduced in the same order.The results suggested that planting methods have significant influence on root morphological and physiological characteristics of super rice.The different single root length and diameter and the difference in root distribution pattern in soil layer are two most signifi-cant characteristics of rice roots under different planting methods.Compared with AT and MT,the DS method develops roots of shallower distribution,smaller single root length and diameter and higher population root number,though with shorter total root length per stem,lower root dry weight,and less absorption area and bleeding intensity after heading.Compared with AT,root diameter of MT was smaller,distribution shallower,after heading root dry weight of plant population and of single stem both lower and declining faster,and total root length and bleeding intensity per stem inferior.

Influence of Planting Methods on Grain-filling Properties of Super Rice

To explore grain-filling properties of high-yielding rice under different planting methods,we studied the grain-filling processes of superior and inferior grains of two super rice cultivars(Huaidao 9 and III you 98) with Richards equation W=A/(1+Be-Kt)1/N and three planting methods,i.e.precision artificial transplanting with dry nursery middle and strong seedlings(ATR),mechanical transplanting with small seedlings(MTR) and direct seeding(DSR).The results were as follows:(1) The super rice yields under different planting methods were significantly different,ATR was the highest,followed by the MTR,and the lowest was the DSR.Compared with ATR and MTR,the 1000-grain weight and seed-setting rate of DSR were significantly lower,but the changes between ATR and MTR were different due to different types of cultivar.(2) The grain-filling processes of superior and inferior grains of super rice under different planting methods were obviously asynchronous type.The time reaching the maximum grain-filling rate(Tmax) of superior grains was early,maximum grain-filling rate(GRmax),mean grain-filling rate(GRmean),the final weight of a kernel(A) and initial grain-filling potential(R0) were significantly greater than those of inferior grains.However,the active grain-filling period(D) and effective grain-filling time(T99) of the superior grains were significantly less than those of inferior grains.(3) Compared with ATR and MTR,the GRmax and GRmean of superior grains of DSR were significantly lower,Tmax was obviously delayed,D and T99 significantly increased.The GRmax and GRmean of inferior grains of MTR were the highest,and ATR was slightly lower than DSR.For Tmax,DSR was the earliest,MTR was the second,and the latest was ATR.D and T99 reduced in order for ATR,MTR,and DSR.(4) For grain-filling characteristics of different stages,the maximum of mean grain-filling rate and contribution rate was present at the middle stage,and the contribution rates of superior and inferior grains were up to 60.53% and 50.78%,respectively.The grain-filling days,mean grain-filling rate and contribution rate of the early,middle and late stages among different planting methods were different due to grain positions.(5) 1000-grain weight was positively correlated with maximum grain-filling rate,mean grain-filling rate and active grain-filling period of superior and inferior grains,and the correlations with maximum grain-filling rate and mean grain-filling rate of inferior grains were significant.Seed-setting rate had in a degree of positive or negative correlations with the grain-filling parameters of the superior and inferior grains,however,except the active grain-filling period of superior grains,all of the correlations were not significant.The results suggested that planting methods have significant influence on grain-filling properties of super rice.Although the grain-filling processes are all asynchronous types,the grain-filling parameters such as maximum grain-filling rate and the time reaching the maximum grain-filling rate of superior and inferior grains have great difference among different planting methods.It would play an important role in improving 1000-grain weight and grain-filling rate,especially the grain-filling rate of inferior grains under the conditions maintaining the final weight of a kernel and seed-setting rate stable.

Analysis of high yield formation of rapeseed in Hunan province and high-yield cultivation measures

According to the analysis of yield level and yield characteristics of typical block in Hunan province in 2008? 2009,preliminary results are obtained.Yield components and physiological index in different growth stages of rapeseed yielded around 3 084 kg/hm2 in Hunan are: number of siliques is 6.522×107/hm2,seed number is 20.5/ silique,thousand grain weight of rapeseed is 4.077 g.Green leaf number per plant in seedlings before winter(1/10) is nearly 10,total leaf number is 16,maximum leaf length nearly 45 cm,leaf width 18 cm,dry matter yield before winter is 4 841.85 kg/ hm2.Plant height in florescence stage is 136 cm,nodes number on the main stalk is 31.8,green leaf number on the main stalk is 17,first piece of sessile leaf length is 28.8 cm,width 13 cm,branch quantity(≥10 cm)is 10.6,the total mass of dry matter is 11 225.1 kg/hm2.Plant height in maturity stage is 180 cm,number of branch quantity is 11 and total amount of dry matter(silique removed) is 9 118.65 kg/hm2.Main cultural practices of rapeseed yielded around 3 000 kg/hm2 are: Sowing on September 7?15,cultivation technology are focused on strong rape seedling,transplanting on October 10?25.Tillage methods are used on the soil in middle fertility,45% compound fertilizer(450?750 kg/hm2) is applied,adding base boron fertilizer(15 kg).Urea application is also used as top dressing in seedling stage;Or farm manure(1.5×104 kg/hm2),25% compound fertilizer(375 kg/hm2) are used,adding base boron fertilizer(15 kg) and urea application(150?225 kg/hm2) is used as top dressing in seedling stage.Planting density is 1.2×105(or more) plants/hm2,making irrigation and drainage timely.Pest,disease and weeds control techniques must also be used.

Effect of Color Shading-Nets on the Growth and Physiological Characteristics of Chieh-Qua Seedling

With uncovered net as a control, the effect of color shading-nets (red net, blue net and silver net) and ordinary black net on growth and physiological characteristics of Chieh-qua (Benincasa hispida Cogn.var. chieh-qua How.) seedling were studied. The result showed that, shading-net covering reduced light intensity and temperature, and increased air humidity of the seedling environment, compared with the control. Shading-net covering increased plant height, stem diameter, leaf area and biomass of Chieh-qua seedling, among which covering of blue and silver shading-nets were superior to the others. Root/shoot ratio and strong seedling index were the biggest under blue net treatment, thus it indicated that blue net covering promoted seedling haleness. Specific leaf weight of Chieh-qua seedling was reduced by covering shading-net. In addition to silver net, leaf chlorophyll and carotenoids content were significantly increased by another 3 covering shading-nets. Relative conductivity (RC), malondialdehyde (MDA) content, superoxidase dismutase (SOD) and peroxydase (POD) activity of Chieh-qua seedling leaf were significantly reduced by shading-net covering. This indicated that shading-net covering in seeding nursery alleviated the stress of intensive light and high temperature, and thus increased the integrated seedling quality. Blue shading-net performed the best among all covering shading-nets.

Profiling Tree Nurseries in Northern Mindanao, the Philippines

Forestry nurseries play an important role in supporting small-scale plantations, tree farming as well as government initiated afforestation and reforestation programs. However, some major constraints have been identified in the forestry nursery sector in the Philippines, particularly in the supply of high quality planting materials. This hindrance is being investigated to formulate intervention points as part of a continuing research project on enhancing tree seedling supply via economic and policy changes, funded by the Australian Centre for International Agricultural Research (ACIAR). This paper presents baseline information regarding the profile of forestry nurseries in the Northern Mindanao region of the Philippines through personal interviews of operators of private, communal and government nurseries. Most nurseries in all three nursery types are operating on a small scale and are strategically situated based on the purpose of their existence. Private nurseries, being business oriented, are located near main roads, as are government nurseries which distribute seedlings mostly without charge but in some cases for sale. Communal nurseries are mostly situated on farms because they cater to the seedling needs of their members and are therefore established far away from main roads. In terms of stability, private and government nurseries are stable compared to communal nurseries which rely on support organizations. When the support ceases communal nurseries also cease to operate. There is no current policy that supports the production and use of high quality seedlings. Intervention points to address these problems are seen as necessary extension efforts in promoting the use of high quality seedlings, thereby creating a strong seedling market, training operators to increase their capability to produce high quality seedlings, and promoting and supporting the forestry nursery industry, including introduction of tree nursery certification.

Seed Vigor of Maize Grown on the Contaminated Soils by Cadmium

Cadmium is one of the highly toxic heavy metals in the agricultural soils. The effects of cadmium on plant growth have been reported by many authors, but the effects of cadmium content of seeds on germination and seed vigor have not been reported in the literature. A cold test study was conducted to evaluate the effects of different levels of cadmium contamination of soils on seed vigor of maize grown on contaminated soils. The experiment was designed in a randomized complete block design with a split-plot arrangement. Soil series (Comba and Reyhanli) were in the main plots and cadmium contamination levels (0, 10, 20, 40 and 60 mg kg-1) were in the sub-plots. Four replications of 50 seeds from each treatments were planted in cold test for germination and seed vigor. Germination and strong seedling ratios of maize seeds significantly decreased with increases in cadmium contents of soils and the highest germination and strong seedling ratios (90.3, 84.3%, respectively) were observed at uncontaminated soils, whereas, the lowest ratios (79.8, 70.8%, respectively) were at the highest level of Cd contaminated soils