Grain Yield Of Sorghum Research Articles

Effect of Carrier Volume on Grain Sorghum Response to Simulated Drift of Nicosulfuron

Research was conducted in 2010 and 2012 to determine the effect of simulated drift of nicosulfuron on growth and yield of grain sorghum. Herbicide rates represented 25, 12.5, and 6.3% of the use rate of nicosulfuron at 52 g ai ha−1. Nicosulfuron was applied in a constant carrier volume of 224 L ha−1where herbicide concentration decreased with reduction in rate, and in carrier volumes of 56, 28, and 14 L ha−1proportional to the 25, 12.5, and 6.3% herbicide rates, respectively. In 2010, grain sorghum injury and yield were greater when nicosulfuron was applied in constant compared to proportional carrier volume. Grain sorghum injury and plant height reduction increased with increasing nicosulfuron rate when averaged across carrier volume both years. In 2012, there was a greater reduction in grain sorghum yield from nicosulfuron applied in proportional carrier volume. These data indicate that simulated drift of nicosulfuron onto conventional grain sorghum causes significant height and yield reduction even at the lowest herbicide rate tested, and the effect of carrier volume may be influenced by seasonal rainfall.

Desempenho produtivo e retorno econômico da cultura do sorgo submetida à irrigação deficitária

RESUMO A irrigação deficitária é comumente utilizada em regiões de reduzida disponibilidade de água ou de energia para a irrigação e visa incrementar a eficiência de uso da água. Essa técnica pode ser adequada à cultura do sorgo, que apresenta produtividades satisfatórias, mesmo em condições limitadas de disponibilidade de água no solo. Os objetivos do trabalho foram: avaliar os efeitos de diferentes manejos de irrigação deficitária sobre o índice de área foliar, altura de plantas e rendimento de grãos do sorgo, e identificar o nível crítico de irrigação deficitária que proporciona maior produtividade da água irrigada e retorno econômico. O experimento foi desenvolvido no ano agrícola de 2012/2013, sob uma cobertura móvel, que impedia a ocorrência de chuva na área experimental. Foram testados quatro manejos de irrigação deficitária: 100; 75; 50 e 25% de reposição da evapotranspiração da cultura (ETc). A redução de 25% na reposição da ETc resultou na diminuição de 7% na altura das plantas, 5% no índice de área foliar e 17% no rendimento de grãos. A maior receita líquida da cultura foi alcançada utilizando o manejo de irrigação com reposição de 75% da ETc. A produtividade da água e o retorno econômico da aplicação de água apresentaram uma resposta linear positiva em relação à redução na reposição da ETc.

Soil Fertility Status and Productivity Trends Along a Toposequence: A Case of Gilgel Gibe Catchment in Nadda Assendabo Watershed, Southwest Ethiopia

The Impact of landscape positions and land use type on properties as well as land productivity are commonly observed in Ethiopia. The study was therefore conducted to quantify soil fertility and productivity trends under three land uses along the gradient (lower, middle and upper slope positions) of Nadda Assendabo watershed, Southwest Ethiopia. Thus field survey was covered a total of 54 composite soil samples using split plots (for soil physical properties) and split-split factorial arrangements with randomized complete block design from woodlot, grazing and crop land following topographic positions then different parameters were analyzed. The highest mean soil moisture content (56.68%) and porosity (71.09%) were observed for woodlot at the lower slope while the highest soil bulk density (1.74 g/cm³) was observed for soil crop land at the upper slope where as the lowest (0.94 g/cm³) was for woodlot at the lower slope. Sand, silt and clay fractions were significantly affected by interaction effects of slope and land uses (P≤0.01). Soil pH, electrical conductivity, organic carbon, cation exchange capacity, total nitrogen, available phosphorus, base saturation percentage and exchangeable basic cations for all land uses were increased down slope while they were affected significantly by slope steepness, land use and soil depth (P≤0.01). Therefore, electrical conductivity at middle and upper slope in grazing land and woodlot; total nitrogen, available phosphorus in crop land at lower slope was significantly different (P≤0.05) due to interaction effect. Furthermore, above ground biomass and grain yields of sorghum, maize and teff were also calculated on farm fields using split plots arrangements. Thus both yields were significantly affected by interaction effect of slope and crop type. Finally, based on the results woodlot, grazing and crop land were recommended for upper, middle and lower slopes respectively.

Effect of Tillage Methods and Foliar Fertilization (<i>Boost Extra</i><sup>TM</sup>) on Soil Physical Properties, Weed Dry Matter and Grain Yield of Sorghum in Ejiba, Kogi State, Nigeria

An experiment was carried out for two consecutive growing seasons (2012 and 2013) at the Research Site of the Lower Niger River Basin Development Authority, Ejiba, Nigeria, to examine the response of sorghum to tillage methods and foliar fertilizer (Boost ExtraTM) application. A split plot experiment was laid out in a Randomized Complete Block Design (RCBD) with three replicates to randomize the tillage methods (main plots) and foliar fertilizer application (sub-plots), respectively. The experiment comprised of three tillage methods: No Tillage (NT), Manual Tillage (MT) and convectional tillage (Ploughing, Harrowing and Ridging, PHR) and three foliar fertilizer rates: 0, 2 and 4 liters of foliar fertilizer per hectare. The parameters taken on soil physical properties and weed characters are soil moisture content (%), soil temperature (℃), weed species and weed dry weight (g). Growth and yield parameters taken are: average plant height (cm), stem girth (cm), leaf area (m2), days to 50% flowering, root dry weight (g), shoot dry weight (g), weight of 1000 seeds and grain yield per land area. Weeds were identified and harvested, and their dry weights were taken and recorded. Data were also collected from ten randomly selected plants in each plot. The data were statistically analyzed using GENSTAT. The analysis of variance (ANOVA) was carried out to find out the significance of variation among the treatments while the significant differences between mean treatments were separated using Duncan’s Multiple Range Test (DMRT) at 5% level of probability. The results obtained from this study indicated that tillage methods and foliar fertilizer application significantly affected growth and yield parameters of sorghum, consequently the yield per unit area. The results also indicated that “Manually Tilled” seedbed (MT) improved soil physical properties better than either plots with PHR or No Till plots in the study area. Foliar fertilizer application at 2 l/ha performed best in terms of growth and yield. It is therefore recommended that manual tillage should be used as a method of seedbed preparation for sorghum production. However, better and stable grain yield of sorghum could be obtained with the practice of manual tillage (MT) in combination with foliar fertilization at rate of 2 litres/ha. It is recommended that different tillage methods should be combined with foliar fertilizer application for higher grain yield in the study area.

Agropastoralist Evaluations of Integrated Sorghum Crop Management Packages in Eastern Ethiopia

On farm participatory field experiment was conducted in 2013 cropping season in districts located in eastern Ethiopia to evaluate effect of different sorghum crop management packages on grain and fodder yield of improved variety Teshale and local check Elmijam. Six different sorghum management alternatives along with agro-pastoralist indigenous management practice were evaluated in six randomly selected agro-pastoralist fields in Ethiopian Somali province Fafen administrative Zone. The result reviled that compared to agro pastoralist indigenous practices on both varieties improved production practice had significantly increased fodder and grain yield of sorghum by 60- 70%. The result also showed significant varietal differences between improved variety Teshsale and the local check Elimjema in all aspects. Therefore based on agropastoralist interest and rating production packages composed of improved sorghum and local check variety, tide-ridge planting, fertilizer (urea and DAP application at 50 kg/ha and 100 kg/ha), hand weeding once at 45 days after emergence and with recommended seed rate 10 kg/ha were selected as best management package because it balanced both grain and fodder yield with the production costs.

Effect of Tillage and Mulching on Soil Fertility and Grain Yield of Sorghum

Effect of Tillage and Mulching on Soil Fertility and Grain Yield of Sorghum

Grain Sorghum Response to Arbuscular Mycorrhiza and Phosphorus Fertilizer under Deficit Irrigation

Deficit irrigation systems have been considered as practical strategies to overcome shortage of irrigation water in arid and semiarid regions. To assess the response of grain sorghum [Sorghum bicolor(L.) Moench] to deficit irrigation and whether arbuscular mycorrhizal fungi (AMF) can moderate drought stress influence on grain yield, a 2‐yr field experiment was conducted using split‐split lay out on a randomized complete block (RCB) design. Irrigation (full and deficit) was assigned to the main plots. Subplots were allocated to two genotypes (Kimiya and Speedeh) and P sources viz: no fertilizer, sole chemical P fertilizer, seed inoculation with AMF and combined fertilizer (50% of the chemical P fertilizer + AMF) were assigned to the sub‐subplots. Results indicated that deficit irrigation reduced grain yield of Kimia and Speedeh by 16 and 26%, respectively, while improving their irrigation water use efficiency (IWUE). Grain yield adjustment by sorghum to water stress was mainly through reducing the number of grains per panicle rather than grain mass. Application of all forms of P fertilizer improved grain yield of sorghum; however, under drought stress, plants were more responsive to combined fertilizer and used irrigation water more efficiently. The root colonization percentage was greater in Kimiya than Speedeh under full and deficit irrigation, however, both genotypes showed a lower degree of root colonization under drought conditions. Application of combined fertilizer could be considered as an alternative to chemical P fertilizer when irrigation water is limited.

Stay-green alleles individually enhance grain yield in sorghum under drought by modifying canopy development and water uptake patterns.

Stay-green is an integrated drought adaptation trait characterized by a distinct green leaf phenotype during grain filling under terminal drought. We used sorghum (Sorghum bicolor), a repository of drought adaptation mechanisms, to elucidate the physiological and genetic mechanisms underpinning stay-green. Near-isogenic sorghum lines (cv RTx7000) were characterized in a series of field and managed-environment trials (seven experiments and 14 environments) to determine the influence of four individual stay-green (Stg1-4) quantitative trait loci (QTLs) on canopy development, water use and grain yield under post-anthesis drought. The Stg QTL decreased tillering and the size of upper leaves, which reduced canopy size at anthesis. This reduction in transpirational leaf area conserved soil water before anthesis for use during grain filling. Increased water uptake during grain filling of Stg near-isogenic lines (NILs) relative to RTx7000 resulted in higher post-anthesis biomass production, grain number and yield. Importantly, there was no consistent yield penalty associated with the Stg QTL in the irrigated control. These results establish a link between the role of the Stg QTL in modifying canopy development and the subsequent impact on crop water use patterns and grain yield under terminal drought.

Soil biological properties as influenced by long-term manuring and fertilization under sorghum (Sorghum bicolor) -wheat (Triticum aestivum) sequence in Vertisols

The effect of long-term manuring and fertilization on soil biological properties was studied under the long term fertilizer experiment on sorghum [Sorghum bicolor (L.) Moench] -wheat (Triticum aestivum L.) sequence conducted on Vertisols. The treatments comprised 50% RDF, 100% RDF, 150% RDF,100% RDF (-S), 100% RDF + 2.5 kg Zn/ ha to wheat crop only, 100% RD of NP, 100% RD of N, 100% RDF + FYM @ 10 tonnes/ha, 100% RDF + S @ 37.5 kg/ ha, FYM @ 10 tonnes/ha, 75% RDF and control. The assessment of soil biological properties at 40 and 70 days after sowing revealed that, significantly highest CO2 evolution was recorded at 70 DAS of sorghum under 100% RDF + FYM @ 10 tonnes/ ha ( 66.82 mg/ 100 kg). Soil microbial biomass carbon was also influenced significantly with the combined application of NPK+FYM (278.9 mg/ kg). The soil enzyme activity, viz. dehydrogenase (55.01 µg TPF/g/24 hr), urease (47.9 mg NH4/kg/ 24 hr) and cellulase (52.23 µg glucose/g/24 hr) were significantly influenced with the application of 100% RDF + FYM @ 10 tonnes/ha. Similarly, the application of 100% RDF + FYM @ 10 tonnes/ha recorded significantly higher grain yield of sorghum.

Effect of farm yard manure, fertility levels and bio-fertilizers on growth, yield and quality of sorghum

A field experiment was conducted during two consequent years (kharif) of 2010 and 2011 to assess the effect of farm yard manure (FYM), fertility levels and bio-fertilizers and their combined effect on the productivity and quality of sorghum. Two levels of farm yard manure (0 and 10 t FYM/ha), four fertility levels based on STR (0, 50, 75 and 100% NPK) and four bio-fertilizers (no inoculation, Azotobacter, PSB and dual inoculation Azotobacter+PSB) were compared. Application of 10 t FYM/ha significantly increased chlorophyll content at 60 DAS, grain yield, and protein content in grain over the control. Application of fertilizer 50, 75 and 100% NPK enhanced flowering as well as improved various growth parameters viz., plant height, chlorophyll content and HCN content at 20 and 40 days over the control. Grain yield and protein content were significantly improved up to 100% NPK, showing an increase of 44.95 and 7.66% over the control. Inoculation of Azotobacter alone and in combination with PSB increased grain yield. Grain yield was significantly increased with 100% NPK in conjunction with 10 t FYM/ha. Bio-fertilizers i. e. Azotobacter+PSB with 10 t FYM/ha significantly increased grain yield of sorghum over their individual effect.

Physiological differences among sorghum (Sorghum bicolor L. Moench) genotypes under high temperature stress

High temperature (HT) stress affects grain yield of sorghum (Sorghum bicolor L. Moench). Understanding responses to HT stress is critical for developing HT tolerant sorghum genotypes. The objectives of this study were to understand the effects of HT stress on physiological and reproductive traits of various sorghum genotypes by quantifying oxidative damage in leaves and pollen grains. Sorghum genotypes at booting were exposed to optimum temperature (OT; 30/20°C, day maximum/night minimum) or HT (38/28°C) for 10d. Photosynthetic and reproductive traits were recorded 7-d after HT stress. Results showed that HT stress decreased, quantum yield of PS II (ΦPSII), electron transport rate and transcript levels of rubisco activase; and glutathione peroxidase enzymes; and more induced cell membrane damage. HT stress decreased pollen viability, pollen germination, and seed-set. Abnormal exine ornamentation was observed in pollen grains at HT. Response of pollen to temperature varied among genotypes. Genotypes with higher ceiling temperature for pollen germination (Tmax) also had a higher percentage of seed-set under HT stress. Principal component analysis suggested that genetic variability was explained by Tmax for pollen germination, percentage seed set and thylakoid membrane damage under HT stress. Tolerant genotypes had relatively less oxidative damage in leaves and pollen grains than sensitive genotypes. Principal component analysis identified DK-54-00, Pioneer 84G62, SC 1047, and SC 1019 as tolerant of HT stress, and genotypes DK 28-E, SC 15, B 35, and TX 7078 as sensitive.

Combining effect of allelopathic Sorghum bicolor L. (Moench) cultivars with planting densities on companion weeds

Field experiments were conducted to compare the effects of allelopathic sorghum cultivars ‘Enkath’ and ‘Rabeh’ at three planting densities (6.6, 13.3 and 26.6 plant m−2) on weed growth and sorghum yields in 2009 and 2010. Sorghum planting densities suppressed average weed population by 26–42% and average weed biomass by 46–57% compared with weedy check in 2009. A similar trend in the reduction in weed population and weed biomass was observed in 2010. Planting densities at 6.6, 13.3 and 26.6 plant m−2 significantly suppressed average weed population by 26, 31 and 42% and average weed biomass by 88, 91 and 96% compared with weedy check, respectively, during 2009. A similar trend in effect was also recorded during 2010. Enkath cultivar reduced average weed density and dry biomass by 25 and 44% during 2009 and by 23 and 30% in 2010 compared with Rabeh cultivar. Root exudates of Enkath inhibited more weed growth than Rabeh. Increased planting density significantly increased average grain yield of sorghum. The highest grain yield of sorghum (12.68 t ha−1) was recorded in plots in which the planting density was 26.6 plant m−2.

Seleção de Híbridos de Sorgo Granífero Cultivados no Verão em Três Localidades

1024x768 O sorgo granifero tem apresentado significativa expansao em area e em produtividade no Brasil nos ultimos anos, em razao do aumento da demanda de graos para alimentacao animal. O melhoramento de plantas tem contribuido para o aumento de produtividade, com a oferta de novos hibridos adaptados as diversas areas de producao. O presente trabalho teve o objetivo de selecionar aqueles mais produtivos e estaveis em cultivo de verao em tres localidades. Os experimentos foram instalados em Sete Lagoas, MG, Nova Porteirinha, MG e Pelotas, RS. O delineamento experimental foi em blocos casualizados, com tres repeticoes. Os hibridos comerciais BRS 310 e BRS 330 foram usados como testemunhas. Houve diferencas significativas entre os hibridos para as quatro caracteristicas avaliadas, mostrando haver variabilidade entre os hibridos. A interacao genotipos x ambientes foi significativa para indice de colheita de paniculas e produtividade de graos. A produtividade media das testemunhas nos tres ambientes foi de 4,5 t ha 1 , sendo que 11 hibridos foram estatisticamente superiores as mesmas. Os hibridos 1099030 e 1099048 apresentaram desempenho superior aos demais hibridos, com produtividade acima de 6,0 t ha -1 , e ciclo de maturacao mais precoce do que a testemunha mais produtiva: BRS 330.

EFFECT OF LONG-TERM USE OF TILLAGE, RESIDUES AND N LEVELS IN SORGHUM (SORGHUM VULGARE (L)) – CASTOR (RICINUS COMMUNIS) CROPPING SYSTEM UNDER RAINFED CONDITIONS – CROP RESPONSES AND ECONOMIC PERFORMANCE – PART I

SUMMARYThis experiment was conducted to study the long-term effect of soil management treatments on crop yields, sustainability yield indices (SYI) and soil fertility in rainfed semi-arid tropical Alfisol at Hayathnagar Research Farm, Hyderabad, India, during the period 1995 to 2009. The experiment was conducted in a split–split plot design with conventional tillage (CT) and minimum tillage (MT) as main factors, surface application of sorghum stover @ 2 t ha−1 (SS), fresh Gliricidia loppings @ 2 t ha−1 (GL) and ‘no’ residue (NR) as sub-factors and levels of N viz. 0 (N0), 30 (N30), 60 (N60) and 90 (N90) kg N ha−1 as sub–sub factors in a castor–sorghum two-year rotation. On an average, CT maintained 30.4 and 57.0% higher grain yields of sorghum and castor, respectively, over MT. Between two residues, GL performed well in both the crops. The highest yields of sorghum (1425 kg ha−1) and castor (876 kg ha−1) were recorded at 90 kg N ha−1. CT maintained higher SYI of 0.44 compared to MT (0.38) and higher agronomic efficiency (AE) of 13.5 and 6.76 kg grain kg−1 N for sorghum and castor crop, respectively. Use of crop residue as mulch had an advantage in increasing the yield of both the crops with increase in rainfall under CT even without N application (control), probably by making the soil more receptive to water infiltration, better moisture storage and by reducing the evaporative losses. Using response functions, the optimum fertilizer N requirement was also computed for a given set of tillage and residue combinations. The revised optimum fertilizer N doses for sorghum and castor varied from 45 to 56 kg ha−1 and 46 to 74 kg ha−1, respectively, under different tillage and residue combinations and could be recommended depending upon the soil management practices.

Consórcio sorgo e braquiária para produção de grãos e biomassa na entressafra

The cultivation of sorghum and Brachiaria in the same area after the harvesting of the summer crop allows to obtain grains and biomass in off-season cultivation. Thus, the objective of this study was to identify, in off-season cultivation, the combination of crops that provide higher grain yield of sorghum and Brachiaria biomass intercropped in the row. The experiment was set up in Rio Verde, Goiás State, on February 26, 2009, using the experimental design of randomized blocks in 2x3+1+3 factorial scheme: two depths of sowing (2 and 10 cm of depth), three species of Brachiaria ( Brachiaria decumbens , B. brizantha cv. Marandu e B. ruziziensis ), plus four additional treatments related to the monoculture of sorghum and three species of Brachiaria . The sorghum used was the DKB 599. The results show that the intercropping of Brachiaria in lines of sorghum, in off-season cultivation, caused reduction in the sorghum grain yield. The intercropping, in off-season cultivation, sorghum with B. brizantha and B. ruziziensis proved to be a advantageous practice for the production of dry matter and crude protein compared to monocultures. The C/N ratio of the sorghum at intercropping was higher compared to monoculture. In intercropping, the Brachiaria provided increase in the percentage of soil covering in off-season cultivation.&nbsp

Effect of morpho-physiological traits on grain yield of sorghum grown under stress at different growth stages, and stability analysis

SUMMARYRecent trends in climate change resulting in global warming and extreme dry spells during rainy seasons are having a negative impact on grain and fodder production in rain-fed crops in India. Understanding the mechanisms of drought tolerance at various growth stages will help in developing tolerant genotypes. Crosses were made between elite and drought-tolerant sorghums, and F2and F3progenies were evaluated for drought tolerance in multiple locations. Twenty-five F4/F5derivatives along with drought-tolerant check plants (two high-yielding genotypes showing moderate drought tolerance: C43 (male parent of the commercial hybrid CSH 16, tolerant to drought) and CSV 17, (a pure line commercial cultivar released for drought-prone areas) were screened for drought tolerance under a factorial randomized block design with three replications during the rain-free months of April–June in 2007 and 2008 at Tamil Nadu Agricultural University, Kovilpatti, India. In each generation/year, four trials were conducted and water stress at different phases of crop growth,viz. vegetative, flowering and post-flowering (maturity), was imposed by withholding irrigation. Observations were recorded on grain and straw yields, plant height, number of roots, root length, leaf relative water content (LRWC), chlorophyll content and stomatal conductance under all treatments. The traits, grain yield, plant height, average root length and stomatal conductance showed significant mean sums of squares (SSs) for genotype × environment (G × E), suggesting that genotypes had significant differential response to the changing environments. Significant mean SSs due to G × E (linear) were obtained for straw yield, LRWC and chlorophyll content, indicating that the variability is partly genetic and partly influenced by environment. Grain yield was correlated with chlorophyll content (r = 0·43) at the vegetative stage, with number of roots (r = 0·49), LRWC (r = 0·51), chlorophyll content (r = 0·46) and stomatal conductance (r = −0·51) at the pre-flowering stage, and with LRWC (r = 0·50) and stomatal conductance (r = −0·40) at the post-flowering stage, under water stress. Partial least square (PLS) analysis showed that different traits were important for grain yield under water stress at different growth stages. Pyramiding the genes for the traits responsible for high grain yield under stress will help in developing stable genotypes at different stages of plant growth.

Grain yield and carbon sequestration potential of post monsoon sorghum cultivation in Vertisols in the semi arid tropics of central India

Soil fertility management and water conservation strongly impact soil quality and agronomic production of Vertisols. Thus the data from a 22-year of soil fertility management experiment conducted in semi arid tropical region of central India was used to evaluate the impact of input of crop residue carbon (C) through sorghum (Sorghum bicolor L.) cultivation in post monsoon season in Vertisols. In addition, the use of chemical fertilizers and manuring on crop yield sustainability and soil organic carbon (SOC) sequestration was assessed to 1-m depth. Retention of crop residues of sorghum, and application of farmyard manure (FYM) equivalent to 25 kg N ha− 1 along with 25 kg N ha− 1 supplied through chemical fertilizers increased and maintained the SOC stock. Green leaf manuring with Leucaena clippings along with chemical fertilizers did not increase the SOC stock. However, a conjunctive use of crop residues and Leucaena clippings increased the profile SOC stock (68.5 Mg ha− 1), an overall SOC build up (39.8%) and a high amount of SOC sequestration (14.4 Mg C ha− 1). These parameters were positively correlated with cumulative C input and also reflected in the sustainable yield index (SYI). Higher grain yield (1.19 Mg ha− 1) through the application of 25 kg N (CR) + 25 kg N (Leucaena) was obtained. For every Mg increase in SOC stock in the root zone there was 0.09 Mg ha− 1 increase in grain yield of sorghum. Stabilization of the SOC stock (zero change under cropping) requires a minimum input of 1.1 Mg C ha− 1 year− 1. Application of 50 kg N ha− 1 through chemical fertilizer also maintained the SOC stock at the antecedent SOC level. Therefore, a combined use of organic manure (crop residues and FYM) or green leaf manure along with chemical fertilizer is essential to enhancing SOC sequestration in sorghum cultivation in Vertisols during the post monsoon season in central India.

Integrated Application of Urea and Sawdust Ash: Effect on Soil Chemical Properties, Plant Nutrients and Sorghum Performance

Field experiment was carried out in Lanlate in rainforest zone of Southwest, Nigeria to study relative effects of combined use of Sawdust ash (SDA) and Urea (U) on soil chemical properties, nutrient status, growth and yield of sorghum (Sorghum bicolor (L.) Moench). The soil in the experimental site was low in nitrogen and phosphorus. The treatments were replicated three times on sorghum plant, there were six treatments; the control (no SDA, no urea), 240kg/haU, 4.5t/haSDA + 60kg/haU, 3.0t/haSDA +120kg/haU, 1.5t/haSDA+180kg/haU and 6.0t/haSDA. Combined use of SDA and urea fertilizer increased the N,P,K,Ca and Mg content of the soil. However, urea fertilizer reduced soil pH relative to control. Therefore, urea fertilizer increased soil acidity. The combined use of reduced levels of ash and urea fertilizer increased growth and yield of sorghum. The sawdust ash (SDA) and co-application of reduced levels of ash and urea increased leaf N, K, Ca and Mg status while urea alone gave highest leaf P. Urea alone at 240kg/ha (or 82kgN/ha) and 180kg/haU (111kgN/ha) + 1.5t/ha increased grain yield by 59 and 101% respectively. This work found out that SDA could be combined with urea to maximize grain yield of sorghum at 1.5t/haSDA+180kg/ha urea. This approach reduces need for urea and attendant reduction in soil pH due to the use of fertilizer. It was also found that SDA alone or combined with urea increased significantly growth of sorghum as indicated by plant height, number of leaves and stem girth. The SDA

Desempenho agronômico do sorgo em função de doses e épocas de aplicação do herbicida 2,4-D

A cultura do sorgo está inserida no plano atual de manejo dos sistemas agrícolas nos cerrados, todavia são escassos os estudos em campo quanto à seletividade e comportamento da cultura ao herbicida 2,4-D. Objetivou-se neste trabalho avaliar os efeitos do 2,4-D sobre o crescimento das plantas, a produção de fitomassa seca e fitomassa verde e a produtividade de grãos na cultura do sorgo. O experimento foi realizado entre janeiro e maio de 2008, em Nova Xavantina-MT, em Latossolo Vermelho-Amarelo distrófico. O sorgo (cultivar Buster) foi semeado em área cultivada sob sistema de plantio direto, em espaçamento de 0,50 m entre linhas, distribuindo-se 10 sementes por metro. Os tratamentos foram dispostos em esquema fatorial 4 x 4, envolvendo quatro doses de 2,4-D (0, 335, 670 e 1.005 g ha-1) e quatro épocas de aplicação (pré-semeadura, três folhas expandidas, seis folhas expandidas e pré-florescimento). Utilizou-se o delineamento de blocos casualizados com quatro repetições. O controle de plantas daninhas na cultura foi realizado manualmente, com utilização de enxada. Verificou-se efeito fitotóxico à cultura do sorgo pelo 2,4-D aos 15 dias após a aplicação (DAA), independentemente da dose ou época de aplicação. O incremento das doses de 2,4-D provocou redução linear da altura de plantas, acúmulo de fitomassa verde e acúmulo de fitomassa seca, tanto aos 30 DAA quanto no ponto de rolagem. A aplicação do 2,4-D prejudica a produtividade do sorgo, especialmente em doses acima de 1.005 g ha-1 e.a. e em aplicações tardias. De maneira geral, a utilização do 2,4-D em pré-semeadura mostrou-se uma boa alternativa no manejo das plantas daninhas na cultura do sorgo.

Selenium protects sorghum leaves from oxidative damage under high temperature stress by enhancing antioxidant defense system

Oxidative stress is commonly induced when plants are grown under high temperature (HT) stress conditions. Selenium often acts as an antioxidant in plants; however, its role under HT-induced oxidative stress is not definite. We hypothesize that selenium application can partly alleviate HT-induced oxidative stress and negative impacts of HT on physiology, growth and yield of grain sorghum [Sorghum bicolor (L.) Moench]. Objectives of this study were to investigate the effects of selenium on (a) leaf photosynthesis, membrane stability and antioxidant enzymes activity and (b) grain yield and yield components of grain sorghum plants grown under HT stress in controlled environments. Plants were grown under optimal temperature (OT; 32/22°C daytime maximum/nighttime minimum) from sowing to 63 days after sowing (DAS). All plants were foliar sprayed with sodium selenate (75mgL(-1)) at 63 DAS, and HT stress (40/30°C) was imposed from 65 DAS through maturity. Data on physiological, biochemical and yield traits were measured. High temperature stress decreased chlorophyll content, chlorophyll a fluorescence, photosynthetic rate and antioxidant enzyme activities and increased oxidant production and membrane damage. Decreased antioxidant defense under HT stress resulted in lower grain yield compared with OT. Application of selenium decreased membrane damage by enhancing antioxidant defense resulting in higher grain yield. The increase in antioxidant enzyme activities and decrease in reactive oxygen species (ROS) content by selenium was greater in HT than in OT. The present study suggests that selenium can play a protective role during HT stress by enhancing the antioxidant defense system.