Stem Dry Matter Research Articles

Contribution of corticular photosynthesis to bud development in African baobab (Adansonia digitata L.) and Castor bean (Ricinus communis L.) seedlings

The African baobab (Adansonia digitata L.) and castor bean (Ricinus communis L.) are drought resistant green-stemmed succulent plants which grow in the arid and semi-arid regions of Africa. Photosynthesis in the stems of green-stemmed plants is known to contribute to plant carbon gain especially during leafless periods. To study the contribution of stem photosynthesis in stem succulent plants, the height and stem diameter of baobab and castor bean plants grown in the greenhouse were measured. The plants were completely defoliated and subjected to different treatments: Watered with open stems (WO), watered and stems covered with aluminium foil (WC) to achieve 100% light exclusion, drought and open (DO) and drought and covered (DC). Stem coverage with aluminium foil resulted in a higher stem height and diameter during drought for baobab with similar trends seen in castor bean. Light exclusion resulted in a significantly lower bud DW production and enrichment in 13C in bud dry matter of castor bean and in stem dry matter of baobab. These show that corticular photosynthesis contributes in carbon gain in these species.

Response of three Bambara groundnut landraces to pre-sowing hydration in Botswana

To investigate the response of Bambara groundnut landraces to pre-sowing hydration, three experiments were conducted on three bambara groundnut landraces; OM1, Diphiri cream (DC) and Gaborone cream (GC) in the greenhouse at Botswana College of Agriculture, Botswana, in 2011. The experimental designs were completely randomized design (CRD) with 5 pre-sowing hydration; (6, 12, 24, 48, 72 hrs) and the control, each replicated four times. Increasing hydration time from 12 to 72 hrs significantly (p≤0.01) increased the final germination for GC up to 87% and significantly increased OM1 germination up to 57% at 24 hrs. However, there was a significant decrease in final germination for DC. There were significant (p≤0.01) differences within and across the landraces for seedling emergence; GC had the highest emergence of up to 100% at 24 hrs. Across the three landraces GC and DC significantly (p≤0.05) increased stem dry diameter at 6, 12 and 24 hrs pre-sowing hydration. Moreover, pre-sowing hydration treatments had significant (p≤0.01) effect within the three Bambara landraces root dry matters and no significant (p>0.05) effect on GC and DC leaf dry matter. Hydrating seeds for 24 hrs improved germination, seedling emergence, leaf and stem dry matter accumulation of bambara groundnut landraces

Planting density and yield of cassava roots

In Mata Fresca, an area located on the border of the states of Rio Grande do Norte and Ceara, in Brazil, small farmers have a source of income from the production of cassava roots, using planting densities of around 5,000 plants ha -1 . This procedure might be helping to limit higher yields of the roots, since some studies have shown that it is possible to obtain higher yields of cassava using higher densities. The objective of this study was to evaluate the root yield and other characteristics of the cassava, as a response to planting density. The Vermelhinha cultivar was submitted to planting densities of from 5,000 to 21,000 plants ha -1 , at intervals of 2,000 plants ha -1 , in an experiment under irrigation. A completely randomized block design with four replications was used. The ideal planting densities in order to maximise leaf green matter, stems and branches, total roots, total marketable roots, number of marketable roots, marketable-root dry matter and stem dry matter, were 17,800; 17,077; 14,416; 13,594; 16,436; 12,361; and 18,149 plants ha -1 respectively. When adopting the planting density used by the farmers, a yield for marketable roots of 15,837 kg ha -1 was obtained. By using the optimal density as found in this work (13,594 plants ha -1 ), the yield was more than double that of the farmers. Increasing planting density reduced both the length of the marketable roots and the harvest index (the ratio of marketable-root dry matter to total plant dry matter).

Influence of simulated post-anthesis water stress on stem dry matter remobilization, yield and its components in rice

A field study was conducted to investigate the influence of foliar application of potassium iodide (KI) to simulate post-anthesis water stress on stem dry matter remobilization and yield. KI treatment had significantly reduced total chlorophyll content in all tested varieties and significant varietal differences were observed. KI application had no significant influence on number of spikelets per panicle or number of spikelets. However, the interaction between treatment and variety was found significant. The number of grains/panicle were reduced by KI spray and varietal difference was significant. Maximum number of grains/panicle was recorded in WGL-4 under control followed by DRR Dhan-39 under KI treatment. KI application had resulted in significant reduction in mean grain yield and the reduction was highest in PA-6129, Swarna and Akshayadhan and the reduction was comparatively less in Sampada, WGL-14, PA-6201 and PA-6444 indicating better carbon remobilization in these varieties. The mean remobilization efficiency was increased by KI application. The increase in remobilization efficiency was higher in WGL-14, PA-6201, Sampada and PA-6444 which incidentally produced higher yields under KI treatment due to increased remobilization of carbon from the vegetative organs which replenished the carbon lost due to impaired photosynthesis. Our findings suggest that KI application can be effectively used to identify rice varieties with high remobilization capacity and yield stability under post-anthesis water stress.

Light intensity on growth, leaf micromorphology and essential oil production of Ocimum gratissimum

Light conditions can promote the growth and development of plants and contribute to increase the essential oil production of commercially cultivated medicinal and aromatic species. In view of the great importance of Ocimum gratissimum L., Lamiaceae, as an aromatic plant, the objective of this work was to determine the effect of light intensities (approximately 4, 7, 11 and 20mol m−2 d−1) on growth, foliar micromorphology, essential oil content, yield and chemical composition of O. gratissimum. Biomass production of different organs, root:shoot ratio and leaf mass per area were found to linearly increase with increased light availability, whereas stem dry matter fraction, number of leaves, leaf area and plant height have increased up to 10mol m−2 d−1 and decreased from this value. The tector trichomes density increased with increased light availability, but there was no effect of light treatments on the glandular trichomes density and essential oil content. Regardless of the light level, the major component of the essential oil was eugenol. The essential oil yield per plant increased linearly with light intensity as a direct effect of increased leaf biomass under similar conditions.

EFFECTS OF CARBON DIOXIDE AND PHOSPHORUS SUPPLY ON POTATO DRY MATTER ALLOCATION AND CANOPY MORPHOLOGY

□ Data on combined effects of elevated carbon dioxide concentration (CO2) and phosphorus fertilization (P) on potato are scarce. Growth chamber studies (E1 and E2) that used three P and two CO2 levels were conducted. Leaf, stem, tuber, and stolon dry matter increased with P. Lateral-stem production was sensitive to P with a minimum 2.5-fold increase in mass. Leaf length increased an average 20.2% in E1 and 38.2% in E2 and leaf area increased an average 336% in E1 and 470% in E2 across CO2 levels. Tuber dry mass increased 22% in E1 and 38.2% in E2 in response to elevated CO2 and total dry mass by 14.1 and 15.4%. Tissue P contents increased with P but were unaffected by CO2. Effects of P on canopy branching were associated with plant N status. The studies suggest elevated CO2 levels are unlikely to alter potato P requirements on a unit mass basis.

Effect of defoliation interval on biomass yield and chemical composition of stylo ‘CIAT 184’ (Stylosanthes guianensis (Aubl.) Sw. var. guianensis)

AbstractForage legumes are considered to have potential as supplementary feedstuffs for livestock (e.g. pigs) in smallholder systems in Asian countries, but forage management is crucial in order to obtain high feed quality. Stylo ‘CIAT 184’ (Stylosanthes guianensis (Aubl.) Sw. var. guianensis) was grown for two seasons in Vientiane, Lao PDR, and subjected to three defoliation frequency treatments: four harvests (S4, 4‐week intervals), three harvests (S3, 6‐week intervals), or one harvest (S1, end of each experimental period). Leaf and stem dry matter (DM) yield, leaf proportion (DM basis) and chemical composition of the leaves, stems and forage (leaf + stem) were determined. Leaf DM yield was unaffected by treatments in 2007 (6–10 t ha−1). In 2008, treatments S4 and S3 had a higher leaf DM yield (mean 4 t ha−1) than treatment S1. Stem DM yield was highest in S1 in 2007, but did not differ between treatments in 2008. Leaf proportion did not differ between treatments S4 and S3 and was on average 55% and 60% in 2007 and 2008, respectively, while S1 had a lower leaf proportion in both years. Depending on defoliation frequency, the leaves contained 170–235 g CP kg−1 DM, which was much higher than the CP content of the stems (73–108 g kg−1 DM) and forage (85–182 g kg−1 DM). Neutral detergent fiber content of the leaves was 510–570 g kg−1 DM, which was lower than that of the stems (698–722 g kg−1 DM) and forage (583–621 g kg−1 DM). The total essential amino acid content of the leaves ranged from 45–50 g 16 g−1 N. It is concluded that the optimal defoliation interval of stylo ‘CIAT 184’ for use as a protein feed resource for growing pigs is 4–6 weeks. However, the lysine content may not be adequate for optimal growth.

Seasonal light interception, radiation use efficiency, growth and tuber production of the tuber crop Plectranthus edulis

Plectranthus edulis (Vatke) Agnew (Lamiaceae) is an ancient Ethiopian crop that produces below-ground, edible tubers on stolons. It is grown from seed tuber pieces. There is thus far little quantitative information on dry matter production of this crop and parameters determining growth and yield. The objective of this study was to understand and quantify the growth of P. edulis, and identify the processes determining and limiting yield. Two similar experiments were carried out at two sites (Awassa and Wondogenet in southern Ethiopia) in a split-plot design with five blocks and cultivar (Lofuwa and Chankua) as main factor and sampling date [20 2-weekly sampling dates from 14 to 280 days after planting (DAP)] as split factor. The crop was unknown at the start and showed an unusual growth pattern, for which reasons growth was analysed at a basic level.Maximum tuber weights were achieved 238 DAP in both cultivars and at both sites, and we consider the period up to 238 DAP as the growth period and the remaining time until the last sampling as the period of in situ storage, as is common farmers’ practice. Tuber dry weights at 238 DAP were c. 900–1000gm−2 and tuber dry matter concentrations 19–21%, corresponding to c. 4.5–4.9kgm−2 fresh tuber yield. Two processes limited the dry matter production: radiation interception by the crop and the conversion of the intercepted radiation into dry matter.Only about one third of the incident radiation was intercepted by the green leaves due to late emergence (c. 4 weeks), a slow development of the canopy after emergence until full ground cover was attained (c. 20 weeks), a short period during which ground cover was complete (c. 2 weeks) and a long period of declining ground cover starting 8 weeks before the end of the growing period.The radiation use efficiency (RUE) was established for the crops in Wondogenet and was only 1.59gMJ−1 PAR, on average across sampling dates. RUE varied across the growing period, increasing after emergence until early after tuber formation to about 2.7gMJ−1 PAR, then again decreasing because of a temporary stagnation (cv. Chankua in Awassa) or decrease (all other cultivar×site combinations) in total crop dry weight, starting 168 DAP in Awassa and 182 DAP in Wondogenet and lasting several weeks. During this period crop biomass decreased because the loss in canopy dry matter – especially stem dry matter – was not yet compensated for by an increase in tuber dry matter. Later, tuber production more than outweighed the decrease in canopy dry weight, and total dry weight and RUE increased again. During this last period the green stems might have significantly contributed to crop photosynthesis. The relative allocation of the total dry matter produced to the tuber varied between 81 and 99% at 238 DAP. Keeping the tubers in the soil after 238 DAP reduced tuber dry weights by 37–54% in 6 weeks.

Bromatological characterization of maize genotypes for silage

Since every year public and private companies bring many genotypes of maize to the market, the suitability of these genotypes for the production of silage should be evaluated. Current study evaluates the agronomic and chemical characteristics of early-normal cycle maize genotypes as well as assesses whether the genetic bases (single, double, and triple hybrids, as well as varieties and intervarietal genotypes) and the grain hardness (hard, semi-hard and dentate) modify the indication of maize genotypes for silage. The experiment was conducted at the Universidade Tecnológica Federal do Paraná, campus Dois Vizinhos, Paraná State, Brazil. Thirty-six genotypes were evaluated by a simple lattice design. Grains were harvested at the pasty to farinaceous stage and stored in micro-silos of 100-mm PVC, for 60 days. Neither the different genetic bases nor the different textures of the genotypes influenced the indication of maize genotypes. The early-normal cycle maize genotypes behave similarly for most characteristics assessed, except for the stem diameter and stem dry matter. Moreover, most maize genotypes have suitable characteristics for the production of high-quality silage.

Plant trait responses to the environment and effects on ecosystem properties

A combined analysis of plant trait responses to the environment, and their effects on ecosystem properties has recently been proposed. In this study, we related the trait composition of plant communities to soil nutrients and disturbance as environmental drivers and to productivity, decomposition and soil carbon as ecosystem properties. We surveyed two sites, one comprising intensively grazed and fertilized grasslands, the other consisting of semi-natural grassland and open heathland. Species abundance and trait values of 49 species were recorded in 69 plots, as well as parameters describing soil resources, land-use disturbances, and ecosystem properties. Our main goal was to test whether the average or the diversity of the trait values of the vegetation had stronger effects on ecosystem properties (mass ratio vs. diversity hypothesis). Structural equation modeling was used to perform a simultaneous analysis of trait responses and effects. Specific leaf area and leaf nutrient contents were always negatively correlated with stem dry matter content and canopy height, indicating greater investments in supportive and nutrient-conserving tissue as plants increased in size. In the agricultural site, disturbance was the single most important factor decreasing plant height, while leaf traits such as specific leaf area and leaf nutrient contents increased with soil resources in heathlands. Productivity was directly or indirectly driven by leaf traits, and investments in structural tissue increased standing biomass and soil carbon. Different environmental drivers in the two sites produced opposing leaf trait effects on litter decomposition. Ecosystem properties were explained by the community mean trait value as predicted by the mass ratio hypothesis. Evidence for effects of functional diversity on productivity and other ecosystem properties was not detected, suggesting that diversity–productivity relationships depend on the length of the investigated environmental gradients. We conclude that changes in community composition and dominance hierarchies deserve the most attention when ecosystem properties must be maintained.

Produção forrageira e composição bromatológica de combinações genômicas de capim-elefante e milheto

Objetivou-se com este trabalho, avaliar o comportamento agronômico de combinações genômicas oriundas do cruzamento entre capim-elefante (Pennisetum purpureum Schum.) e milheto (Pennisetum glaucum (E.) Leek), visando determinar o potencial de Pennisetum glaucum para o melhoramento da qualidade forrageira do capim-elefante. Três cultivares de capim-elefante e 11 combinações genômicas foram avaliadas para produção de matéria verde total (PMV), produção de matéria seca total (PMS), percentagem de matéria seca (%MS), produção de matéria seca de folhas (PMSF), produção de matéria seca de caule (PMSC), relação caule/folha (RFC), altura (ALT), vigor fenotípico (VF), número de perfilhos (NP), fibra em detergente ácido (FDA), fibra em detergente neutro (FDN), proteína bruta (PB) e digestibilidade in vitro de matéria seca (DIVMS). Excetuando RFC e NP, todas as demais características apresentaram diferenças significativas para os genótipos (p < 0,05), indicando variabilidade genética entre os genótipos avaliados. A combinação genômica HCM-5x-2 destacou-se entre os pentaploides quanto à produção de matéria seca de forragem e a combinação genômica HCM-4x-2 destacou-se entre os tetraploides para a mesma característica. O efeito na melhoria da qualidade forrageira em Pennisetum através da introgressão de características favoráveis do milheto foi evidenciado pelo melhor desempenho das combinações genômicas pentaploides para características bromatológicas, mostrando o potencial das mesmas para inclusão em programas de melhoramento genético.

Common ragweed (Ambrosia artemisiifolia) dry matter allocation and partitioning under different nitrogen and density levels

Dry matter partitioning and allocation is a major determinant of plant growth and its competitiveness. Common ragweed (Ambrosia artemisiifolia) is a troublesome agronomic weed species and it is also a major health concern in Europe and many other countries because of its rapid spreading and production of allergenic pollen. A field experiment was conducted in 2009 to determine the effect of nitrogen fertilizer levels (0, 100, and 200 kg ha−1) and plant density levels (1.3, 6.6, and 13.2 plants per m2) on the leaf, stem dry matter partitioning, and dry matter allocation of ragweed. With an increasing density, the stem partitioning coefficient increased, whereas the leaf partitioning coefficient decreased. The addition of nitrogen had a limited effect on the leaf and stem dry matter partitioning. The root dry matter production decreased with an increasing density and was not influenced by the addition of nitrogen. Under intraspecific competition, ragweed exhibited a stronger above‐ground competition intensity than below the ground, which resulted in a greater root : shoot ratio, compared to the low‐density stands. The level of nitrogen influenced the vertical leaf, stem, and total dry matter distribution, with a greater allocation to the top stratum of the plants, thus increasing their competition for light. The biomass allocation of ragweed to the roots in response to the nitrogen supply exhibited a low plasticity, compared to the shoots, which displayed a high plasticity. The results of this study suggested that, under intraspecific conditions and with an increasing nitrogen supply, ragweed would be more competitive in above‐ground resource acquisition.

Regulating Effect of Sowing Depth on Saline Land Oat Growth and K&lt;sup&gt;+&lt;/sup&gt; and Na&lt;sup&gt;+&lt;/sup&gt; Migration

Biological utilization of Saline soil is an effective way to improve land utilization and ecological environment. Oat is a unique crop of Inner Mongolia and has strong resistance to salt. This study setting five sowing depth of 3 cm, 5 cm, 7 cm, 9 cm and 11 cm on the morphological and physiological characteristics of two oat cultivars. The K+ /Na+ and selective absorption and migration, yield and nutrient quality, and soil salt content were measured from a field experiment. The highest yield of oat on saline land was obtained at sowing depth of 7 cm. The dry matter of stem and leaf accumulated more rapidly at 7 cm, membrane damage was less, leaf chlorophyll content was higher and kept higher photosynthetic capacity, K+ /Na+ and SK+, Na+ (migration) of stem and leaf were higher. So it showed stronger salinity adaptability and higher yield, and the yield was between 43.1% and 64.1% higher than conventional seed planting’s and it occupied between 37.2% and 42.7% of loam soil, and the crude fat content was higher. Sowing depth of 5 cm was the second choice, but sowing depth of 9 and 11 centimeter was not suitable to plant salt-enduring cultivar. The decrease sequence of oat yield and quality under salt stress was: grain yield &gt; fresh yield &gt; hay yield &gt; crude fat &gt; crude fiber. The grain yield and crude fat of salt-enduring cultivar Nei nong da you 1 were favorable for improving oat’s salinity adaptability and increasing the desalination in soil. The study can provide a theoretical basis to improve saline land utilization and high-yield cultivation of oat.

Increasing the harvest index of wheat in the high rainfall zones of southern Australia

The harvest index (HI) of wheat in the high rainfall zones (HRZ) of Australia is low compared with values in similar rainfall environments in Europe. From 2005 to 2007, we examined dry matter (DM) partitioning, yield formation, post-anthesis dry matter accumulation, and remobilization of water soluble carbohydrates (WSC) of a number of wheat genotypes (5 spring wheat and 1 winter wheat) to determine the factors influencing the HI in the HRZ of south-western Australia. Grain yield was strongly correlated with grain number (GN) in all three years and with the sum of post-anthesis DM accumulation and WSC in stems at anthesis when the amount of assimilates available to fill grains was less than 600gm−2. However, when the amount of assimilates exceeded 600gm−2, grain yield reached a plateau and did not increase with the increased availability of assimilates because of sink limitations. Genotypes with more GN tended to extract more WSC to fill grains than ones with fewer GN in 2005 and 2007. GN increased with increased spike DM at anthesis, the number of grainsg−1 of spike DM, and the duration of spike growth, but was not correlated to the fraction of DM partitioned to the spike at anthesis for individual genotypes and across the 3 years. Compared to winter wheat in the UK, Australian spring and winter wheat had a lower number of grainsg−1 spike DM and g−1 chaff DM. HI was positively related to WSC at anthesis and post-anthesis DM accumulation in the drought year of 2006, but not in average (2007) and above-average rainfall (2005) years. HI was negatively related to the proportion of stem DM to above-ground dry matter (AGDM), but positively related to the proportion of spike DM to AGDM. Dry matter partitioning indicated that the proportion of stem DM to AGDM and chaff DM to AGDM was 20% and 50% higher than that of winter wheat grown in the UK, respectively. This was related to a lack of remobilization of WSC and a net increase between spike DM at anthesis and chaff DM at maturity. Therefore, we suggest that increasing the number of grainsm−2 by breeding for more grainsg−1 spike DM, reducing dry matter partitioning into stem and chaff, and remobilizing WSC can lead to an improved HI. We conclude that the yield of wheat can be increased without increasing AGDM and the potential HI can reach 0.50 in the HRZ of south-western Australia if the number of grainsm−2 can be increased.

Crescimento e produção de cumarina em plantas de chambá (Justicia pectoralis Jacq.) tratadas com isoterápico

Este trabalho teve por objetivo avaliar a resposta a dinamizações do isoterápico Justicia no crescimento e na produção de cumarina em Justicia pectoralis. O experimento foi conduzido na Universidade Federal de Viçosa. O delineamento estatístico foi inteiramente casualizado, com quatro repetições e seis tratamentos, totalizando 24 parcelas experimentais, sendo cada parcela constituída de uma planta por vaso. Os tratamentos foram constituídos das dinamizações 3CH, 6CH, 12CH, 18CH, 24CH e 30CH, do isoterápico Justicia. A aplicação dos tratamentos iniciou após o plantio das mudas, sendo pulverizada a parte aérea, em intervalos semanais. Após quatro meses do plantio as plantas foram colhidas. Foram avaliadas a matéria fresca e seca das folhas e caules a matéria fresca e seca da inflorescência, e a matéria fresca e seca total. Foram pesadas amostras de 200 mg das folhas e caules das plantas secas. As amostras foram devidamente armazenadas até a realização das análises químicas. A quantificação da cumarina (1-2 benzopirona) nas amostras foi feita em Cromatógrafo Líquido de Alta Eficiência. A matéria fresca de folhas e caules, a matéria fresca total e o rendimento de cumarina variaram em função das dinamizações do isoterápico. Os resultados confirmam o efeito de preparações homeopáticas na planta demonstrando que a homeopatia nos vegetais, mesmo na Lei da Igualdade tem efeitos potenciais.

红光与远红光比值对温室切花菊形态指标、叶面积及干物质分配的影响

Chrysanthemum is one of the four most important cut flowers in the world and is also China′s main export flower.To study the effects of the red to far red ratio of light on the morphological index,leaf area,and dry matter partitioning of chrysanthemum,experiments were conducted in the experimental greenhouse of Nanjing University of Information Science and Technology from October 2010 to February 2011.The greenhouse was 9.6 m wide and 30.0 m long,with top and shoulder heights of 5.0 m and 4.5 m,respectively.The experimental material was Chrysanthemum morifolium Ramat.cv.'Jingba').The plants were transplanted on 6 October,when the seedlings were approximately 20 cm high with 6—10 leaves.A mixture of vermiculite and perlite with a volume ratio of 2∶1 was used as the culture substrate.The planting space was 20 cm × 20 cm in size.During the vegetative growth phase,fluorescent lamps(photosynthetically active radiation(PAR) =200 μmol·m-2·s-1) were used to supplement the light for 5 h(18:00—23:00) to extend the illumination time.When the plant height reached 50 cm,natural light was shaded using black plastic film,and LED light sources with four different R:FR ratios were used to produce short-day treatments.Each LED light source consisted of 360 evenly and proportionally arranged red and far-red LED lamps.The red(R:(660±30) nm): far-red(FR:(730±30) nm) energy ratios of the four experimental treatments were 0.5,2.5,4.5,and 6.5.The LED light sources(50 cm long × 50 cm wide) were fixed 15 cm above the canopy.Each treatment had 30 chrysanthemum plants.All plants were irrigated with a nutrient solution with a conductivity of 1.5 ms/cm(200 μg/g N;80 μg/g P;170 μg/g K).The morphological index was calculated for each plant based on leaf number,plant height,internode length,stem diameter,flower diameter,whole-plant diameter,total leaf area,and dry matter partitioning.The maximum plant leaf number,plant height,stem diameter,flower diameter,leaf area and total dry weight of chrysanthemum occurred at R:FR = 2.5,and the longest internodes were at R/FR=0.5.The relationship between the shoot dry-matter weight per plant and the value of R:FR in all treatments was best described with a exponential-linear model.As the duration of R:FR treatment increased,the shoot and root dry-matter partitioning indices did not significantly differ overall,while the leaf dry-matter partitioning index decreased,the stem dry-matter partitioning index initially increased and then decreased,and the flower dry-matter partitioning index increased.At R:FR=2.5,the chrysanthemum leaf and flower dry-matter partitioning indices were the highest,while the stem dry-matter partitioning index was the lowest;however,the stem dry-matter partitioning index was the highest and the leaf dry-matter partitioning index was the lowest at R/FR=6.5,and the flower dry-matter partitioning index was the lowest at R/FR=0.5.We conclude that increasing the far-infrared component of light was not conducive to increasing flower dry matter,but increasing the proportion of red light can promote stem dry-matter accumulation and a red: far red ratio of 2.5 can improve dry matter transfer into flowers.

Cálcio e fitorreguladores no desenvolvimento e estado nutricional de Mentha spicata x suaveolens cultivada em solução nutritiva

O trabalho teve como objetivo estudar o desenvolvimento e o estado nutricional de Mentha spicata x suaveolens cultivada em diferentes níveis de Calcio em solução nutritiva com aplicação de fitorreguladores. O experimento constou de esquema fatorial (4x4) sendo quatro níveis de Ca2+ na solução nutritiva (160, 120, 80 e 40 mg L-1) e três aplicações foliares, com intervalos de 15 dias, de ácido naftaleno acético (NAA), ácido giberélico (GA3), benzinaladenina (BA) e água destilada como testemunha. As plantas foram coletadas 60 dias após a transferência para a solução e avaliadas as variáveis, matéria fresca e seca, área foliar e número de folhas; volume, comprimento e superfície radiculares e teores de Ca, K, Mg, N e P das folhas. As variáveis foram submetidas à análise de variância e as médias comparadas pelo teste Tukey. Não foram encontradas diferenças entre os níveis de Ca para a produção de biomassa. A auxina não influenciou a matéria seca das plantas, embora tenha aumentado os teores foliares de Ca; a citocinina acarretou diminuição da matéria seca total e a giberelina aumento da matéria seca do caule. A variação de Ca2+ não influenciou os teores foliares de N, P, K e Mg. Houve resposta para aplicação de Ca2+, com teores foliares atingindo o máximo de 15,73 mg kg-1 na dose de 137,81 mg L-1 pela análise de regressão.

Effect of treating early rice straw returning to field with decomposition accelerant on yield formation of late rice

Effects of treating early rice straw returning to field with two types of decomposition accelerant,Fuganling and straw-decomposition microbe,on yield formation of late rice were studied in double cropping rice field in Changsha,Hunan.The results showed the decomposition accelerant treated early rice straw had significant promoting effect on rice yield by promoting tillering and differentiation of spike and increasing leaf area thus enhancing effective-panicle number,grain number per panicle and ratio of grain number to leaf area and dry matter accumulation correspondingly,and the yield of late rice increased 8%-12%.Compared to Fuganling treatment,effective panicle number,grain number per panicle,leaf area index(LAI) at booting stage,yield and output percent of dry matter in stem and sheath(OPDS) in treatment applied straw-decomposition microbe were increased by 1.7%,1.5%,4.3%,3.9% and 17.45% respectively,and the differences in LAI at booting stage and OPDS between the two treatments were significant.

Tolerância de cultivares de mandioca aos herbicidas fomesafen e fluazifop-p-butil

Several studies report herbicide tolerance variations of same species with different genotypes. Thus, this study aimed to evaluate the tolerance of five cassava cultivars to the post-emergence applications of fluazifop-p-butyl, fomesafen and the association of both products. In the first visual assessment of intoxication, the most visible symptoms in cassava plants of poisoning was observed at 7 days after application (DAA), caused by mixture treatment (fomesafen + fluzifop-p-butyl) and fomesafen isolated as well. At the end of the evaluation period (35 DAP), was observed reduction of intoxication signs and foliage recovery of all cassava cultivars tested. The mixture showed to be very toxic causing reductions in leaf dry matter, stem dry matter, shoots dry matter, stem diameter, leaf area and plant height. Despite a high rate of poisoning by the herbicide fomesafen, variations in dry matter accumulation was not observed Treatments based on fluazifop-p-butyl were not toxic to culture similar to plants of the check plots. There were no differences of tolerance level to herbicide treatments in the all cassava cultivars tested.

Designing resource-efficient ideotypes for new cropping conditions: Wheat ( Triticum aestivum L.) in the High Rainfall Zone of southern Australia

With the ultimate aim of developing a Crop Design Tool that will specify resource-efficient ideotypes for any environment, modelling procedures are proposed and tested here whereby wheat phenology can be optimised according to risks of abiotic damage (frost, heat and drought) to seedling establishment and grain set. Then crop growth can be estimated from availability of water and solar radiation, and optimum DM partitioning to grain can be specified by allocating a minimum of support dry matter (DM) to stems (to resist lodging), leaves (to optimise photosynthesis), and flowers (to bear grains). Ideotypes for reference regions (with mature wheat breeding programmes) of the Mallee and Wimmera in Victoria, the Canturbury plains in New Zealand and Norfolk in the UK gave estimated grain yields of 1.9, 3.0, 7.2 and 6.2 t ha −1 DM respectively, similar to those shown by current cultivars, but with earlier flowering and harvest dates, with heavier stems, and high redistribution of stem DM to grain. Ideotypes for five sites in the Australian High Rainfall Zone showed high grain yield potentials, ranging from 4.5 t ha −1 DM at Kojonup to 7.8 t ha −1 DM at Hamilton, allowing for yield loss due to abiotic stress. These were characterised by early stem extension and flowering dates but also by long crop construction periods (from the start of stem extension to anthesis) of 800–1100 °Cd and increased harvest indices compared to cultivars currently adopted from other regions. The challenges in testing these ideotypes will be in finding germplasm that demonstrates unusual phenology with short stature, and growing these to maximise light interception in spring. The main uncertainties in the estimation procedures arose from poor quality wind data, a poorly quantified association between stem material density and stem strength, and lack of data on maximum capacity to store redistributable stem DM. Sensitivity analysis showed grain yields of ideotypes to depend on maximum wind gusts during grain production as well as on plant-available water. The most effective single means of increasing potential grain yields was predicted clearly to be through increasing the conversion of radiation to DM.