Number Of Reproductive Tillers Research Articles

Genetic variability, heretability, correlation co-efficient and path analysis of yield and yield contributing traits in bread wheat (Triticum aestivum L.)

Genetic variation, heritability, genetic advance and correlation co-efficient studied among the fifty wheat genotypes and were evaluated for eleven quantitative characters viz. , days to 50 per cent flowering, days to reproductive phase, days to maturity, plant height (cm), number of reproductive tillers per plant, spike length (cm), number of spikelets per spike, number of grains per spike, grain weight per spike (g), test weight (g) and grain yield per plant (g). All the characters under study showed considerable amount of variability, phenotypic co-efficient of variability was higher than genotypic co-efficient of variability. A persual of co-effiecient of variability indicates that PCV and GCV were quiet high for grain weight per spike. Moderate PCV and GCV were recorded in yield per plant, spike length, number of reproductive tillers per plant, number of spikelets per spike and lowest observed in days to maturity, days to 50 per cent flowering, days to reproductive phase and test weight.A high estimate of heritability was found for plant height. High genetic advance was observed for grain weight per spike (28.85g) and minimum in days to maturity (6.88). Genotypic correlation co-efficients were higher than the corresponding phenotypic correlation co-efficients for all the character combinations. Grain yield per plant showed highly positive association ship with days to 50 per centflowering, days to reproductive phase, plant height, spike length, grain weight per spike and number of grains per spike.

Effect of nanofertilizers on growth and yield of selected cereals - A review

Nanoscience coupled with nanotechnology has emerged as possible cost-cutting measure to prodigal farming and environmental clean-up operations. Nanoscale science, engineering, and technology, which is more widely known using the novel term ‘nanotechnology’, is an emerging multidisciplinary field that can have enormous potential impact on our society. Nanofertilizers facilitate slow and steady release of nutrients and thereby reduce the loss of nutrients and enhance the nutrient use efficiency. The full recommended rate of conventional and nanofertilizer (FRR-CF+FRR-NF) enhanced the plant height, chlorophyll content, number of reproductive tillers, panicles, and spikelets in rice. The magnitudes of increase over the FRR-CF were 3.6%, 2.72%, 9.10%, 9.10%, and 15.42%, respectively. In rice, an exposure to Zn NP (at 0, 25, 50, 75, 100 and 150 mg L-1) caused significant changes in root and shoot length and mass (fresh and dry mass). The ZnO nanoparticles increased the shoot dry matter and leaf area indexes by 63.8% and 69.7% respectively in mineral poor soils. The effect of TiO2 Nano particles was significant on number of corn in plant, maize dry weight and corn yield in P£0.05 in . Mean comparison showed that the highest number of corn in plant (10.10), maize dry weight (2396.35 kg ha-1) and corn yield (1744.13 kg ha-1) were achieved by flowering stage. Silver nanoparticles in 25 ppm concentration have showed significant improvement in maximum leaf area and highest grain yield while 75 ppm concentration resulted in decrease in grain yield in wheat. Maximum number of grains per spike was recorded with 25 ppm followed by 50 ppm whereas maximum 100-grain weight was obtained for 25 and 125 ppm soil applied silver nanoparticles in wheat.

Nitrogen Fertilization Effects on Biomass Production and Yield Components of Miscanthus ×giganteus.

Grasses such as Miscanthus ×giganteus and Panicum virgatum (switchgrass) can potentially be used to produce bioenergy on a large scale in the Midwestern USA. The biomass productivity of these warm-season perennial grasses, particularly M. × giganteus, can be substantial, even when grown with limited inputs. The literature, however, varies regarding the nitrogen requirements for M. ×giganteus biomass production. In addition, there is a lack of information that identifies the yield-component(s) (including total tiller number, tiller weight, total tiller diameter, total tiller height, phytomer number, reproductive tiller number, vegetative tiller number, reproductive tiller height, vegetative tiller height, reproductive tiller diameter, vegetative tiller diameter, and reproductive tiller phytomer number) that contributes to M. ×giganteus biomass yields. Thus, the objective of this study was to examine the effects of fertilization on biomass yield and individual M. × giganteus plant-yield components. Plots of M. ×giganteus were planted in 2008 in Urbana, IL, USA, and received annual applications of 0, 60, or 120 kg N ha-1. M. ×giganteus productivity increased when nitrogen was applied; between 2011 and 2014, nitrogen applications of 60 or 120 kg N ha-1 produced average annual yields of 22.0 dry Mg ha-1 compared to 11.8 dry Mg ha-1 for unfertilized M. ×giganteus. Both the total number of tillers per m2 and the tiller weight also increased as N-application rates increased. Our results indicate that increased reproductive tiller density and tiller weight with increased N fertilization increased M. ×giganteus biomass yield.

Management of consecutive cuts in the production and quality of wintergreen paspalum seeds

The objective of this study was to evaluate the practice of consecutive cuts in the production and quality of Paspalum guenoarum seeds of the Azulao ecotype. The experimental design used was in completely randomized blocks with four replications. The treatment included three cuts in succession: zero cut, one cut, two cuts, and three cuts. The variables were: number of total tillers/plant; number of vegetative tillers/plant; number of reproductive tillers/plant; percentage of reproductive tillers; number of racemes/inflorescence; weight of thousand seeds; number of seeds/inflorescence; seed production; forage dry matter; water content of seeds; germination; first germination count; and germination speed index. The largest seed production was obtained with zero cut (850.3, first year and 719.4 kg/ha-1, second year) and one cut (794.4, first year and 627.3 kg/ha-1, second year) with no statistical difference between them. The largest germination percentage was seen with the application of zero (71.0%, first year and 79.3%, second year) and one cut (69.3%, first year and 75.0%, second year). There was a decrease in the production and quality of the seeds of the second cut, especially during the first year of evaluation. The total tillers, the percentage of tillers that went through the reproductive stage, and the number of reproductive tillers are the variables that are most highly correlated with seed production.

Weed Interference Periods in Early Wheat in the Midwest of Paraná

ABSTRACT Several factors can influence wheat crop yield, they include the interference imposed by weeds is one of the most important. The objective of this study was to evaluate the critical periods of weed interference in early wheat in the midwest of the state of Paraná, Brazil. The experiment was conducted in an experimental area located in Campo Mourão - PR, during the year 2013, using the BRS Pardela cultivar. The treatments consisted of periods of coexistence and weed control in wheat. Periods of coexistence and control were 0, 7, 14, 28, 35 and the whole cycle at days after crop emergence (DAE). Number of reproductive tillers per plant, spike length, number of spikelets per spike, plant height and wheat crop yield, were significantly affected by coexistence with prevailing infestation of Raphanus raphanistrum, therefore, a critical period of interference was determined at 16 to 24 DAE.

Brachiaria decumbens intraspecific hybrids: characterization and selection for seed production

Abstract: Brachiaria decumbens has great importance in the national beef cattle scenario due to its high forage yield potential and high adaptability to acid soils and low fertility. In order to obtain new cultivars, intraspecific hybrids, previously selected by the Brachiaria breeding program, were evaluated in 2013 and 2014 for phenological characteristics and seed production potential through their production components, aiming to obtain cultivars with satisfactory production agronomic characteristics and forage yield, resistant to 'cigarrinhas-das-pastagens'(Tomaspia sp.) and good seed production. Estimates of phenotypic correlation and analysis of variance were performed using the SAS 9.3 software. From the results obtained in both consecutive years, it was observed that there was a correlation between the reproductive tiller number (RT) and the pure seeds (PS) weight in the seedbeds of the second year of production around 70% (p < 0.01), which can be considered as a parameter to estimate the production of pure seeds before the start of flowering.

Character Association and Path Analysis in Rice

Thirty one genotypes of rice were evaluated for high grain yield. The results indicated that high estimates of genotypic and phenotypic coefficient of variation were recorded for plant height, number of reproductive tillers per plant, panicle length, biological yield per plant, harvest index, test weight, number of grain per panicle and grain yield per plant. High heritability coupled with high genetic advance were revealed for plant height, number of reproductive tillers per plant, panicle length, biological yield per plant, harvest index, test weight, number of grain per panicle and grain yield per plant. Improvement in grain yield can be made by selecting these yield contributed characters having high heritability coupled with high genetic advance. Grain yield per plant showed significant and positive association with number of reproductive tillers per plant, panicle length, days to maturity, number of grain per panicle biological yield per plant and harvest index at both genotypic and phenotypic level. Thus, it can be inferred that selection based on any one of these traits either alone or in combination, will result in identifying high yielding strains. Path coefficient analysis of genotypic and phenotypic exhibited high positive and direct effect of harvest index, number of grains per panicle, test weight, biological yield per plant and plant height on grain yield per plant.

Investigation of the Stress Tolerance of Winter Wheat Genotypes Under Natural Rain-Fed and Irrigated Conditions

Drought around the world is one of the most important yield reducing factor. From the cross of winter wheat varieties (Plainsman V x Mv Magma) doubled haploid (DH) population was created consisting of 174 lines to investigate the drought tolerance of the genotypes exposed to two treatments; natural rain-fed and well-watered conditions in the field.The object of the experiment was to determine the yield production capacity of the DH lines under natural rain-fed conditions and to compare the effect of changes in the yield components due to irrigation. After ripening, the wheat plants were harvested from both treatments. The plant height, the length of last internode, number of spikelets, seed number, seed weight on the main stem; the number of reproductive tillers, seed number and weight per plant was determined.The effect of irrigation was investigated on the morphological parameters and yield properties which changed due to well watered conditions in the wheat plants. Averaged over the DH lines, the heading date was significantly affected by irrigation. Irrigation significantly increased all the morphological parameters. Not only the average, but also the minimum and maximum values increased significantly for spikelet number, reproductive tiller number and plant height. Changes in the morphological parameters resulted in significant alterations in the yield components. The irrigation significantly increased the total grain number per plant, the thousand kernel weight and the grain yield averaged over the DH lines.The results showed that the morphological parameters and yield components can still be some of the most effective features to estimate the tolerance of wheat in response to stress factors. This project was supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences and the project DROPS (EU-FP7 No. 244374).

Effect of different sowing times on the plant developmental parameters of wheat (Triticum aestivumL.)

Studies on plant development phases and yield component patterns of wheat are essential for a better understanding of adaptation in wheat. Our main aim was to carry out detailed phenological analyses of 18 wheat genotypes in three sowing times for determining the effect of sowing date on individual phenophases, and yield components. Sowing date had the single greatest effect on the start of intensive stem elongation. The longer vegetation period had a favourable effect on main spike length and on the spikelet number per spike, but had no influence on thousand-kernel weight and grain number per spike. The time between the first node appearance and start of intensive stem elongation had a significant effect on the number of reproductive tillers. A close association (R2 = 0.191) was observed during the second phase of intensive stem elongation between the boot stage-to-heading interval and the number of spikelets per spike. Two-way analysis of variance on the yield components showed that the sowing date, as a main factor, had a weaker effect on the phenophases than on morphological and developmental parameters. The insensitive allele of the Ppd-D1 gene shortened the time required for first node appearance and heading both in autumn and spring sowing.

Does Fungal Endophyte Infection Improve Tall Fescue’s Growth Response to Fire and Water Limitation?

Invasive species may owe some of their success in competing and co-existing with native species to microbial symbioses they are capable of forming. Tall fescue is a cool-season, non-native, invasive grass capable of co-existing with native warm-season grasses in North American grasslands that frequently experience fire, drought, and cold winters, conditions to which the native species should be better-adapted than tall fescue. We hypothesized that tall fescue’s ability to form a symbiosis with Neotyphodium coenophialum, an aboveground fungal endophyte, may enhance its environmental stress tolerance and persistence in these environments. We used a greenhouse experiment to examine the effects of endophyte infection (E+ vs. E−), prescribed fire (1 burn vs. 2 burn vs. unburned control), and watering regime (dry vs. wet) on tall fescue growth. We assessed treatment effects for growth rates and the following response variables: total tiller length, number of tillers recruited during the experiment, number of reproductive tillers, tiller biomass, root biomass, and total biomass. Water regime significantly affected all response variables, with less growth and lower growth rates observed under the dry water regime compared to the wet. The burn treatments significantly affected total tiller length, number of reproductive tillers, total tiller biomass, and total biomass, but treatment differences were not consistent across parameters. Overall, fire seemed to enhance growth. Endophyte status significantly affected total tiller length and tiller biomass, but the effect was opposite what we predicted (E−>E+). The results from our experiment indicated that tall fescue was relatively tolerant of fire, even when combined with dry conditions, and that the fungal endophyte symbiosis was not important in governing this ecological ability. The persistence of tall fescue in native grassland ecosystems may be linked to other endophyte-conferred abilities not measured here (e.g., herbivory release) or may not be related to this plant-microbial symbiosis.

Genetic diversity and structure of natural Dactylis glomerata L. populations revealed by morphological and microsatellite-based (SSR/ISSR) markers.

Dactylis glomerata L. is an important forage species in the Mediterranean region, and in other regions with a similar climate. Genetic material from 3 locations in north, central, and south Greece was studied, using morphological traits, SSR, and ISSR molecular markers. Morphological analysis revealed differences among the geographic locations studied for all morphological traits, except the number of reproductive tillers. Moreover, the highest phenotypic variation was observed on the accessions from south, while the lowest was observed on the accessions from the north. Although the results of the molecular marker analysis are indicative, a high level of genetic diversity at the species level was revealed by ISSRs (GST=0.291) and SSRs (FST=0.186). Analysis of molecular variance showed that a high level of genetic diversity existed for ISSRs and SSRs within populations (62 and 83%, respectively), rather than among populations (38 and 17%, respectively). Cluster analysis divided the 3 populations in 2 groups, with the population originating from the island of Crete forming 1 group, while the populations from north Greece (Taxiarchis) and central Greece (Pertouli) were clustered in a 2nd group. In general, the results indicate that SSRs are more informative compared to ISSRs about the genetic variation within a population, whereas the ISSRs were more informative about the genetic diversity among populations However, a similar trend in diversity (genotypic and phenotypic) was observed in the morphological traits and microsatellite-based (SSR/ISSR) markers at the locations studied.

Agronomic characters of some traditional rice (Oryza sativa L.) cultivars in Sri Lanka

Grain yield in rice is a complex trait and highly dependent on the other agronomic characters. Agronomic characters and grain yield of twenty traditional rice cultivars were evaluated at Faculty of Agriculture, University of Ruhuna in Maha-2010/2011 and in Yala - 2011. The experiment was conducted according to the randomized complete block design with three replicates. Twenty plants from each cultivar were evaluated for the selected characters, Plant height, Leaf blade length, Leaf blade width, Number of tillers, Number of reproductive tillers, Panicle length, Number of spikelets per panicle, Number of fertile spikelets per panicle, Number of infertile spikelets per panicle, Seed length, Seed width, 100 seed weight and Yield per plant. Recommended modern rice cultivar Bg 379/2 was used as the reference. Deviations of each character in different traditional rice cultivars from those of recommended rice cultivar Bg 379/2 were recorded. The average plant height of the tallest rice cultivar, Podihatatha was 198 cm and that of the shortest rice cultivar, Rathranwee was 68 cm. The longest leafblade and longest culm length were also belonged to (9.6 tillers per plant) and the highest average number of reproductive tillers (9 per plant), were recorded by rice cultivar Mahasudu wee. The highest value of 100 seed weight was recorded by rice cultivar Galpa wee. However, the most important economical character, the highest yield per plant(28.52g/plant) was recorded by Thanthiribalan which was significantly higher than that of in the recommended rice cultivar Bg 379/2 (26.5 g/plant). Significant correlations were found between the yield per plant and the characters such as number of reproductive tillers (r = 0.692), panicle length (r =0.565) and number of spikelets per panicle (r = 0.761). Agronomic data collected in the present study would be important to understand the suitability of an individual rice cultivar for the farmer field. DOI: http://dx.doi.org/10.4038/jur.v1i1.6150 Journal of the University of Ruhuna 2013 1(1): 3-9

Impacts of grazing and mowing on reproductive behaviors of Stipa grandis and Stipa krylovii in a semi-arid area

Disturbance can affect biomass allocation of plants, but can it influence plant reproductive behavior? To address this issue, we performed field plant community investigations and explored the reproductive behaviors of Stipa grandis and Stipa krylovii in response to grazing and mowing treatments at Maodeng pasture of Xilinguole League of Inner Mongolia, China during 2007–2009. The results showed that, with a similar niche width for the two plant species under mowing and grazing treatments, mowing significantly increased the ratio of ramet to genet number of S. krylovii and the carbon to nitrogen ratio of S. grandis, and grazing significantly decreased the ratio of vegetative to reproductive tiller biomass of S. grandis and increased the ratio of vegetative to reproductive tiller number of S. krylovii. Regression analysis showed that the significantly positive effect of root to shoot biomass ratio was stronger on the ratio of vegetative to reproductive tiller number of S. grandis than on that of S. krylovii. These results indicated that grazing and mowing influenced the reproductive manner and the process of sexual reproduction of S. grandis and S. krylovii.

Shifts of Sexual Reproductive and Vegetative Growth Allocation in <i>Stipa grandis</i> along a Climate Gradient in Inner Mongolia Steppe

Trade-off between vegetative growth and reproduction is an important plant adaptive strategy to environmental variability. The study investigated the Stipa grandis resource allocation and the relationship between its sexual reproduction and climate factors among three sites located along a typical environmental gradient in the Inner Mongolian Plateau. The results show that different climatic characteristics among three habitats cause the growth differentiation of S. grandis. S. grandis exhibits a prominent change on the resource allocation patterns. The number of reproductive tillers and panicles biomass allocation are significantly increased along the gradient of water availability and temperature whereas the number of vegetative tillers and root biomass allocation are reduced. The rate of the percentage increase is prominently reduced although the foliage allocation increased. It suggests that under the environments with drought and high temperature, S. grandis allocates more resources to sexual reproduction but reduces the investment in vegetative growth and asexual reproduction. Moreover, the amount of precipitation in April and May are significantly correlated with the sexual reproductive allocation of S. grandis.

Climate warming and precipitation redistribution modify tree–grass interactions and tree species establishment in a warm‐temperate savanna

Savanna tree-grass interactions may be particularly sensitive to climate change. Establishment of two tree canopy dominants, post oak (Quercus stellata) and eastern redcedar (Juniperus virginiana), grown with the dominant C4 perennial grass (Schizachyrium scoparium) in southern oak savanna of the United States were evaluated under four climatic scenarios for 6years. Tree-grass interactions were examined with and without warming (+1.5°C) in combination with a long-term mean rainfall treatment and a modified rainfall regime that redistributed 40% of summer rainfall to spring and fall, intensifying summer drought. The aim was to determine: (1) the relative growth response of these species, (2) potential shifts in the balance of tree-grass interactions, and (3) the trajectory of juniper encroachment into savannas, under these anticipated climatic conditions. Precipitation redistribution reduced relative growth rate (RGR) of trees grown with grass. Warming increased growth of J. virginiana and strongly reduced Q. stellata survival. Tiller numbers of S. scoparium plants were unaffected by warming, but the number of reproductive tillers was increasingly suppressed by intensified drought each year. Growth rates of J. virginiana and Q. stellata were suppressed by grass presence early, but in subsequent years were higher when grown with grass. Quercus stellata had overall reduced RGR, but enhanced survival when grown with grass, while survival of J. virginiana remained near 100% in all treatments. Once trees surpassed a threshold height of 1.1m, both tiller number and survival of S. scoparium plants were drastically reduced by the presence of J. virginiana, but not Q. stellata. Juniperus virginiana was the only savanna dominant in which neither survival nor final aboveground mass were adversely affected by the climate scenario of warming and intensified summer drought. These responses indicate that climate warming and altered precipitation patterns will further accelerate juniper encroachment and woody thickening in a warm-temperate oak savanna.

Seed yield variation in plains rough fescue (Festuca hallii (Vasey) Piper) populations and its relation with phenotypic characteristics and environmental factors

AbstractPlains rough fescue (Festuca hallii (Vasey) Piper) is a dominant grass in the endangered Fescue Prairie of North America. Infrequent and unpredictable seed production presents a challenge for the use of this species in restoration and rangeland seeding. The objective of this study was to compare seed yield of different plains rough fescue populations and to determine the dependence of seed yield on phenotypic characteristics. Effect of weather conditions during the floral induction and initiation period of different years of the study was also compared. In 2007, a completely randomized field plot experiment was established from eleven populations of plains rough fescue at Swift Current, SK, Canada. In 2007, 2010 and 2011, individual plant seed yield, reproductive tillers, above‐ground biomass, plant height and crown diameter were measured, and plant vigour was scored. All measured variables differed significantly (P ≤ 0·05) among populations. Four populations were identified as having higher seed yield potential. Plants in these four populations also had characteristics of good plant vigour, taller stems, more reproductive tillers and greater biomass. Seed yield increased linearly with increasing plant height, crown diameter, above‐ground biomass and number of reproductive tillers (r2 ranged 0·17–0·67, P < 0·001), but number of reproductive tillers (r2 = 0·53–0·67, P < 0·001) was a better predictor for selection of lines with higher seed yield. Although seed yield varied among years, populations with higher seed yield tended to produce greater amounts of seed over the period of the study.

Preliminary study on the adaptation of wild Guinea grass (Panicum maximum) to different agro-climatic regions in Hambanthota District

Guinea grass (Panicum maximum Jacq.) was introduced to Sri Lanka in the 1820s for forage and has become naturalised in most ecological zones, ecosystems and habitats. This is generally called “Wild Guinea Grass” and has become common and valuable forage especially in the Southern area. Two main varieties are found: a coarse, broad leaved, hairy, stemmy, robust grass up to 3 meters high, known locally as Guinea-“A” and a finer, narrower leaved, leafy grass with smaller culms of 1-2 meters known as Guinea-“B”. Naturally, it now overruns road and railway sides, natural forests, crop plantations, natural grasslands and scrubland at low and mid elevations. Therefore, the objectives of this study were to compare the morphological and proximate properties of wild Guinea grass grown in Katuwana (IL1b) and Sooriyawewa (DL5) respectively intermediate and drought regions in Hambanthota District where it was used as sole cattle feed especially during drought periods. Random samples of Guinea grass were collected from three representative places of each from Katuwana and Sooriyawewa areas. Morphological parameters such as plant height, number of tillers, number of reproductive tillers, leaf width, leaf length, stem diameter, panicle length, panicle width, spikelet width (from base) and, root depth were investigated in the field itself. Proximate analysis was done for both post and pre blooming stages of P. maximum. It was revealed that height of P. maximum plants in Sooriyawewa area (231.33a ±16.0cm) were shorter than (P>0.05) that of Katuwana area (172.3b ± 17.5cm), may be attributed with the prolonged drought stress. Similarly, as water stress enhanced the tillering habit, numbers of tillers and reproductive tillers per plant were (27.67a ± 4.04 and 8.33 a ± 2.52 respectively) greater in (P>0.05) Sooriyawewa area as compared with Katuwana (7.333b ± 1.155 and 1.667b ± 0.577 respectively). When compared the inflorescence characters panicle length showed significantly higher value for Katuwana area (65.00a ± 12.00cm) as compared to Sooriyawewa (42.00b ± 5.00cm) while the panicle length and spikelet width (from base) were also slightly higher in Katuwana area. Dry matter (DM) content of Guinea samples was slightly higher in Sooriyawewa in both pre and post blooming stages. Furthermore, in crude protein (CP) content was also slightly higher in pre blooming stage in drought area (10.094% ± 0.624) than intermediate climate (8.54% ± 2.50) but it is opposite in post blooming stage as 5.429% ± 0.839 in drought area and 6.52% ± 1.75 in intermediate climatic area. The results revealed that drought stress could effect on phenotypical characters of wild Guinea grass therefore, yield could be affected but not the quality by means of dry matter and crude protein contents. However, further investigations should be carried out to find out whether those characters are genetically heritable or not.

Número e peso de perfilhos no pasto de capim-braquiária sob lotação contínua

The experiment was conducted to study the relationship between the number and weight of tiller categories in Brachiaria decumbens cv. Basilisk pasture managed under continuous stocking with cattle. The pasture was managed with an average height of about 25 cm. Plants of four different heights (10, 20, 30 and 40 cm) were evaluated by means of the randomized block design with two replications. The number of vegetative tillers, both live and total, reduced linearly according to the plant height. The number of reproductive tillers increased linearly according to pasture plant height (from 8 to 84 tillers m-2 when comparing plants 10 to 40 cm high). Vegetative and reproductive tiller weight increased linearly according to pasture plant height. Vegetative tiller weight (0.316 g average) was lower than the reproductive tiller weight (0.401 g average). A linear and negative relationship was found between the number and weight of the vegetative tillers, whereas a linear and positive one was found for the reproductive tillers. There are fewer vegetative tillers, and a greater number of reproductive and dead tillers in places with tall plants. At the places with high B. decumbens plants, tillers are heavier.

Produção de sementes de quatro ecótipos de Paspalum nativos do Rio Grande do Sul

O objetivo neste trabalho foi estudar os componentes da produção e da produção de sementes de duas espécies de Paspalum. Foram avaliados dois ecótipos de Paspalum notatum (André da Rocha; e Bagual) e dois de Paspalum urvillei (André da Rocha; e Eldorado do Sul). O delineamento experimental foi completamente casualizado, num esquema fatorial (ecótipos x dias após o plantio), com cinco repetições aninhadas dentro dos dias após o plantio. Cada espécie foi analisada separadamente para determinação dos componentes da produção e produção de sementes, realizada por amostragens semanais entre 7/11/2006 e 31/3/2007. Foram avaliadas as seguintes variáveis: número de perfilhos vegetativos; número de perfilhos reprodutivos/m²; porcentagem de perfilhos férteis; número de racemos/m²; peso de mil sementes; número de sementes/ inflorescência; número de sementes/racemo; e rendimento de sementes/área. A produção de sementes de Paspalum é prejudicada pelo longo período de florescimento e pela capacidade de retenção das sementes na inflorescência. A produção de sementes difere entre ecótipos, uma vez que os valores médios foram de 47,17 kg/ha (Paspalum notatum André da Rocha), 61,01 kg/ha (Paspalum notatum Bagual), 30,60 kg/ha (Paspalum urvillei André da Rocha) e 47,95 kg/ha (Paspalum urvillei Eldorado do Sul). A produção de sementes dessas espécies é altamente influenciada pelo número de perfilhos reprodutivos, pela porcentagem de perfilhos férteis e pelo peso de mil sementes.

CARACTERÍSTICAS ESTRUTURAIS DE PERFILHOS VEGETATIVOS E REPRODUTIVOS EM PASTOS DIFERIDOS DE CAPIM-BRAQUIÁRIA

The aim of this work was to compare the structural characteristics of vegetative and reproductive tillers on Brachiaria decumbens cv. Basilisk pastures diferred for 73, 95 and 116 days. Randomized block design in a split plot scheme with three replications was used. The stockpiling period did not influence (P>0.10) the number of vegetative tillers (VT) but increased (P<0.10) the number of reproductive tillers (RT) (from 16 to 117 tillers/m2). On pastures diferred for up to 95 days, RT were heavier (P<0.05) than VT. Contrarily to VT, the relation between the number and weight of reproductive tillers was positive (P<0.10). A linear increase (P<0.01 and P<0.10) for tiller pseudostem length in relation to the diferring periods of the pasture was found. The number of living leaves (NLL) per tiller was not increased (P>0.10) by the deferring period. The RT revealed (P<0.05) a higher pseudostem length, higher number of dead leaves (NDL) and lower NLL when compared to VT. RT showed (P<0.05) higher percentages of stem and dead leaf as well as a lower percentage of living leaf (P<0.05) than VT. VT showed a better morphological composition than RT. The deferring period alters the structural characteristics and worsens the morphological composition of tillers on deferred Brachiaria decumbens cv. Basilisk pastures.KEYWORDS: Brachiaria decumbens, leaf number, morphological composition, tiller number, tiller weight.