Days After Emergence Research Articles

English

The aim of this work was to evaluate the growth of sesame BRS 196 CNPA G4 in different irrigation depths (305, 436, 567 and 698 mm), applied on the basis of crop evapotranspiration– ETc (the depth of 567 mm was equal to 100% ETc). It was conducted at Embrapa Cotton, in Barbalha County, Ceara State, Brazil, 2012. The experiment was in randomized blocks, with treatments distributed in plots with three replications. The ETc was calculated by multiplying the reference evapotranspiration (ETo), determined by the Penman-Monteith method, by the crop coefficients (Kc), recommended for each phenological stage of the crop and by FAO. For the other irrigation treatments, the ETc was multiplied by 0.4, 0.7 and 1.3 (40, 70 and 130% of ETc). Primarily, height, stem diameter, leaf area and leaf area index were measured at 27, 48, 69 and 90 Days After Emergence (DAE), and then the absolute and relative growth rates in height, stem diameter and leaf area were estimated. It was concluded that height, stem diameter, leaf area and leaf area index of sesame BRS 196 CNPA G4 increased with irrigation; the highest growth occurred until 70 or 75 DAE, and the greatest growth was obtained, in general, in 698 mm of irrigation depth. Key words: Sesamum indicum L., evapotranspiration, growth rates, water stress.

Transcriptomic profiling of taproot growth and sucrose accumulation in sugar beet (Beta vulgaris L.) at different developmental stages.

In sugar beet (Beta vulgaris L.), taproot weight and sucrose content are the important determinants of yield and quality. However, high yield and low sucrose content are two tightly bound agronomic traits. The advances in next-generation sequencing technology and the publication of sugar beet genome have provided a method for the study of molecular mechanism underlying the regulation of these two agronomic traits. In this work, we performed comparative transcriptomic analyses in the high taproot yield cultivar SD13829 and the high sucrose content cultivar BS02 at five developmental stages. More than 50,000,000 pair-end clean reads for each library were generated. When taproot turned into the rapid growth stage at the growth stage of 82 days after emergence (DAE), eighteen enriched gene ontology (GO) terms, including cell wall, cytoskeleton, and enzyme linked receptor protein signaling pathway, occurred in both cultivars. Differentially expressed genes (DEGs) of paired comparison in both cultivars were enriched in the cell wall GO term. For pathway enrichment analyses of DEGs that were respectively generated at 82 DAE compared to 59 DAE (the earlier developmental stage before taproot turning into the rapid growth stage), plant hormone signal transduction pathway was enriched. At 82 DAE, the rapid enlarging stage of taproot, several transcription factor family members were up-regulated in both cultivars. An antagonistic expression of brassinosteroid- and auxin-related genes was also detected. In SD13829, the growth strategy was relatively focused on cell enlargement promoted by brassinosteroid signaling, whereas in BS02, it was relatively focused on secondarily cambial cell division regulated by cytokinin, auxin and brassinosteroid signaling. Taken together, our data demonstrate that the weight and sucrose content of taproot rely on its growth strategy, which is controlled by brassinosteroid, auxin, cytokinin, and gibberellin.

Age at sexual maturity of male and female banana weevils, Cosmopolites sordidus Germar (Coleoptera: Curculionidae)

AbstractThis study was to determine the age at sexual maturity and the relationships between age and internal reproductive organs of Cosmopolites sordidus. Male banana weevils become sexually mature 18 days after emergence (DAE), that is after 2 weeks of adult eclosion, in spite of the fact that spermatogenesis is completed at emergence. A positive correlation exists between age and male internal organs, for example for mean testis diameter (r = .849, p ≤ .001), mean seminal vesicle diameter (r = .679, p ≤ .001), mean accessory gland length (r = .561, p ≤ .01) and mean accessory gland diameter (r = .498, p ≤ .05), respectively. Significant differences were recorded between sexually mature and immature weevils with respect to mean testis diameter (T = 4.471, p ≤ .001) and mean seminal vesicle diameter (T = 3.939, p ≤ .001), but not with mean accessory gland length and mean accessory gland diameter (T = 1.899 and 1.661). Male internal organs were visibly underdeveloped at emergence but became significantly enlarged and developed on attainment of sexual maturity. Female C. sordidus, on the other hand, are sexually mature at 5 DAE. There was also a strong, positive correlation between age of females and mean ovariole length (r = .656, p ≤ .001), and significant differences existed between mean ovariole lengths of sexually mature and immature females (T = 4.306, p ≤ .001). Increasing age of females witnessed progressive increases in ovariole lengths and developmental changes within female ovarioles and calyces. The findings made here may be helpful in Musa germplasm screening works, as weevils bred on susceptible cultivars may reveal similar results, while those bred on resistant ones may experience possible delays in their reproductive developments.

Effect of the Insecticide Dinotefuran on the Ultrastructure of the Flight Muscle of Female Sogatella furcifera (Hemiptera: Delphacidae).

Sogatella furcifera Horváth (Hemiptera: Delphacidae), is a major migratory pest of rice crops in Asia. The ultrastructure of the flight muscle directly affects the flight ability of insects. The ultrastructure of the flight muscle of some insects can be affected by insecticides. However, the ultrastructure of the flight muscle of S. furcifera and the effect of insecticides on the flight muscle of S. furcifera are not well understood. The present study was conducted to determine the effect of the insecticide dinotefuran on the ultrastructure of the flight muscle of S. furcifera females. In this study, the cross-sectional area and the diameter of the myofibril cross-sections of dinotefuran-treated S. furcifera females increased with the number of days after emergence (DAE), and they were higher than in untreated females. The sarcomere length of myofibrils increased with the number of DAE, and it differed from that of the untreated females. On the first day after emergence, the higher the concentration of dinotefuran, the smaller was the extent of decrease. On the third day after emergence, the higher the concentration of dinotefuran, the larger was the extent of enhancement. For the percentage of mitochondria, those of LC10 and LC20 dinotefuran-treated S. furcifera females increased with the number of DAE and were higher than in untreated females. LC10 dinotefuran-treated S. furcifera females exhibited the largest increase. Thus, our results suggest that the flight ability of S. furcifera increased with time. Some concentrations of dinotefuran can enhance the flight capacity of S. furcifera.

Control of Dichelops melacanthus with insecticides associated with sulphur applied in different times in corn

The stink bug Dichelops melacanthus has become an important pest for corn crop and it has been causing several losses even in the initial phase of the crop. The objective of the experiment was the evaluation of effectiveness of the insecticides on the control of D. melacanthus in corn by adding of sulfur or not, in different control times. In order to evaluate the effect of the insecticide by adding or not sulfur on the control of D. melacanthus, 17 treatments with 4 different insecticides (with and without sulfur, in two different control times plus control) were used to get the results. The experimental design used was the randomized blocks, with four repetitions. The evaluation of effectiveness on stink bugs control was gotten by visual evaluation of the symptoms at 6, 13 and 20 days after emergence (DAE). Analysis of variance by F test (Anova) was done and the averages compared through Scott-knott test (p≤0,05). The pulverization of insecticides was more effective when it was done 4 (DAE), reducing the symptoms and injuries occasioned by the stink bug D. melacanthus and the mortality of damaged plants. The insecticide bifentrina+carbosulfano showed the higher effectiveness on stink bug control. To conclude, the use of sulfur associated to insecticides did not present a significant effect.

Phyllochron and leaf appearance rate in oat

Abstract Phyllochron and leaf appearance rate are both important parameters in the production efficiency of agricultural crops. The objectives of this study were to determine the phyllochron and leaf appearance rate in 4 oat cultivars (Avena sativa L.) in 3 sowing dates and verify the variability of phyllochron and leaf appearance rate among cultivars and sowing dates. The experimental design was the completely randomized with 12 treatments and 20 repetitions. Treatments were formed by the combination of 4 cultivars (URS Charrua, URS Taura, URS Estampa, and URS Corona) and 3 sowing dates in 2014 (April 28, May 28, and July 14). In each plant (repetition) of each treatment, the number of expanded leaves (NEL) was counted 3 times per week from the first leaf emission until flowering. For each plant, cultivar, and sowing date, linear regression was adjusted between NEL and accumulated thermal time (ATT) and between NEL and number of days after emergence (DAE). Phyllochron was determined by the inverse of the angular coefficient of the linear regression between the NEL and ATT. The leaf appearance rate was determined by the inverse of the angular coefficient of the linear regression between NEL and DAE. In oat, there is variability of phyllochron and leaf appearance rate among cultivars and sowing dates. Phyllochron oscillates between 95.88 and 117.70 °C day∙leaf−1 and leaf appearance rate, between 6.41 and 9.65 days∙leaf−1. The oat cropping management in function of phyllochron and leaf appearance rate is dependent on cultivars and sowing dates.

Critical period of weed control in radish (<i>Raphinus sativus</i> L.)

A field study was carried out at Crop Farm of the Eastern University of Sri Lanka to determine the critical period for weed control and the effects of weed interference in radish in the regosols of the Batticaloa District. An increasing series of the duration of weed interference and length of the weed-free periods were imposed weekly from 0 to 40 days after emergence (DAE). The beginning and the end of CPWC were based on 5, 10 and 20% acceptable yield loss levels (AYL), which were determined by fitting logistic and Gompertz equations to relative yield data, representing increasing duration of weed-interference and weed-free periods. The critical period for weed control increased to 31 days, starting at 7 days and ending at 38 days, at 5% yield loss level. At 10% and 20% yield loss levels, the CPCW decreased to 12 and 8 days respectively, starting at 18 DAE and ending at 30 DAE, and beginning at 13 DAE and ending at 21 DAE, respectively.

Selectivity of Herbicide Associations with Chemical Protector in the Treatment of Sweet Sorghum Hybrid Seeds

ABSTRACT Sweet sorghum culture is an alternative to sugar and ethanol production. With the aim of evaluating herbicide tank-mix selectivity associated or not to sweet sorghum seed treatment with naphthalic anhydride, two experiments with ESX5200 and EJX7C5110 hybrids were performed in red oxisol (clayey) field conditions, in the municipality of Campo Mourão, Paraná state. A randomized block design was used, with 4 x 2 factorial scheme, with four replications. The first factor represented three herbicide associations and a control sample without herbicide, and the second factor was constituted by the absence or presence of seed treatment with naphthalic anhydride (5.0 g kg-1). Herbicide treatments were tank-mixes of atrazine + S-metolachor (2,640 + 480 g ha 1) (pre-emergence); atrazine + S-metolachlor + isoxaflutole (2,640 + 480 + 11.25 g ha-1) (pre-emergence) and atrazine + S-metolachlor (1,500 + 384 g ha-1) (post-emergence). The following characteristics were evaluated: intoxication, plant height, stalk diameter, number of internodes per stalk and plant density, performed 60 days after emergence (DAE); stalk yield and Brix, were evaluated on day 85 DAE. Atrazine + S-metolachlor tank-mix applied in pre or post-emergence did not affect growth, development, yield and stalk quality of the ESX5200 and EJX7C5110 sweet sorghum hybrids. Sweet sorghum seed treatment with naphthalic anhydride provided partial protection against the action of atrazine + s-metolachlor + isoxaflutole tank-mixes, being more evident for the ESX5200 hybrid.

Influência da matéria orgânica na fitorremediação de solo contaminado com sulfentrazone

A matéria orgânica exerce influência nos atributos químicos, físicos e biológicos do solo e também pode influenciar na taxa de degradação e sorção de herbicidas. Objetivou-se avaliar o efeito da adição de composto orgânico ao solo sobre a capacidade da Canavalia ensiformis (L.) (feijão-de-porco) em remediar solo contaminado com sulfentrazone. O trabalho foi conduzido em duas etapas, na primeira, os tratamentos foram compostos pela combinação de quatro níveis de composto orgânico e aplicação ou não do herbicida sulfentrazone. Após o preparo do solo aplicou-se à superfície o herbicida. Posteriormente, procedeu-se a semeadura da espécie fitorremediadora C. ensiformis. Aos 75 dias após a emergência (DAE) foram colhidas amostras da parte aérea, raiz e de solo. Todo material colhido foi congelado a aproximadamente -20ºC e, em seguida determinou-se a acumulação do herbicida na planta e no solo por meio da cromatografia. Na segunda etapa, foi semeado o Pennisetum glaucum (L.) (milheto), planta indicadora de resíduo de sulfentrazone no solo, e foram realizadas avaliações biométricas aos 30 e 60 DAE. Não foi encontrado resíduo de sulfentrazone na parte aérea e raízes da espécie fitorremediadora avaliada, todavia detectou-se no solo. O aumento nos níveis do composto orgânico contribuiu para o crescimento e acúmulo de biomassa do milheto, quando cultivado em sucessão a espécie fitorremediadora C. ensiformis, no entanto, não favoreceu a fitorremediação.

Partitioning of Competition for Resources Between Soybean and Corn as Competitor Plant

ABSTRACT Plants compete for resources present below and above the soil surface. The objective of this work was to separate the individual effects of the competition for resources between soybean and corn as competitor plants. The experiment was conducted in a greenhouse, in 2014/2015. The treatments consisted of soybean cultivars (TEC 5718 and TEC 6029) in competition conditions with corn (no competition, competition for soil resources, competition for solar radiation and total competition). The variables evaluated were plant height at 7, 14, 21, 28, 35 and 42 days after emergence (DAE), stem/culm diameter, leaf area, shoot dry mass, root dry mass and the chlorophyll index, at 42 (DAE). The competition for soil resources between soybean and corn is pronounced, being that short cultivars with determinate growth habit, such as TEC 5718, invest more in root biomass, specific leaf area and leaf area ratio when in competition. The soybean cultivars do not suppress corn, but allow it to benefit when associated to its root system, increasing the shoot and root dry mass, leaf area and chlorophyll index.

Biometric variables and productive attributes of wheat: mapping and correlation among variables

The aim of this study was to evaluate the relationship between biometric variables quantified along the phenological development of the wheat crop with grain yield and production components. The study was carried out in an area of 4.7 ha. Initially the area was georeferenced and divided into a sampling grid of 50 x 50 m, resulting in 18 sample points. At each point three subplots of 2 x 1 m were marked. The emergency of plants seven days after emergence (DAE) (stage 1), number of plants, number of tillers, number of leaves per plant, root length, height, root dry mass, dry mass of the aerial part and number of nodes at 35 (stage 5), 57 (stage 8) and 80 (stage 10.3) DAE were evaluated. The yield component was determined regarding the number of spikes; 1000 grain weight; number of grains per spike and grain yield at 130 DAE (stage 11.4). Biometric differences in wheat plants from phenological stage 8 affect the productive components of crop. Wheat plants higher (height and number of nodes) and reduced root length showed higher productivity.

Accumulation of nutrients and growth in castor bean plants

Information about nutrient uptake and accumulation by different crops during development stages allows iden­tifying periods of higher demand and an adequate fertilization management. An experiment under field condi­tions was carried out in order to evaluate macro and micronutrient accumulation in castor bean leaf tissue, as well as to identify nutrient uptake critical stages of this crop. Treatments were consisted of evaluation periods with samples collected every ten days until 160 days after emergence of crop. Castor bean plants showed higher macronutrient accumulation in descending order: N > K > Ca > S > Mg > P and the following micronutri­ents Fe > Mn > Zn > B > Cu > Mo. The highest accumulation rates of N, P and K nutrients occur from 20 to 110 days after emergence (DAE) with the highest N uptake from 30 to 40 DAE, remaining high until approximately 110 DAE. Regarding potassium, the highest uptake occurs between 40 and 50 DAE, with high uptake rates until approximately 110 DAE. The highest phosphorus uptake was between 80 and 90 DAE. The majority of macro and micronutrients were accumulated in leaves during most part of evaluation cycle.

Effects of NPK source on the dry matter partitioning in cool season C3-cereals (wheat, rye, barley, and oats) at various growth stages

ABSTRACTDry matter (DM) partitioning into root, leaf, stem, shoot dry weight plant−1 response in four cool season C3-cereals viz. wheat (Triticum aestivum L.), rye (Secale cereale L.), barley (Hordeum vulgare L.) and oats (Avena sativa L.) was investigated at 30, 60 and 90 days after emergence (DAE) under eight nitrogen, phosphorus and potassium (NPK) sources: S1 = 20-20-20, S2 = 20-27-5, S3 = 7-22-8, S4 = 10-10-10-20S, S5 = 11-15-11, S6 = 31-11-11, S7 = 24-8-16, and S8 = 19-6-12 in pot experiment at Dryland Agriculture Institute, West Texas A&M University, Canyon, Texas, USA during winter 2009-10. A considerable variation in DM partitioning into various plant parts was observed in the four crop species at different growth stages and NPK source. At 30 DAE, 27% of the total DM per plant (TDMPP) was partitioned into roots and 73% into shoots (19% stems + 54% leaf). Only16 % of the TDMPP was partitioned into roots and 84% into shoots (18 % stem + 66 % leaf) at 60 DAE. At 90 DAE, 29% of TDMPP was partitioned into roots and 71 % into shoots (33 % stems + 38 % leaf) at 90 DAE. Percent DM partitioning into stems ranked first (33%) at 90 DAE > at 30 DAE (19%) > at 60 DAE (18 %). With advancement in crops age, DM partitioning into various crop parts increased. The root DM plant−1 (RDMPP) increased from 11.5–722 mg plant−1; stem DM plant−1 (STDMPP) from 8.3–889.0 mg plant−1; leaf DM plant−1 (LDMPP) from 23.1–1031.0 mg plant−1; shoot DM plant−1 (SHDMPP) from 31.3–1921 mg plant−1, and TDMPP increased from 42.9–2693.0 mg plant−1 at 30 and 90 DAE, respectively. Because of the higher N contents in S7 (24:8:16) and S6 (31:11:11) reduced the DM partitioning into various plants parts as well as TDMPP at all three growth stages. The adverse effects of S6 and S7 on DM partitioning was more on oats > rye > wheat > barley. The S4 with 10:10:10 (NPK) and :20S was not toxic at 30 DAE, but at 60 and 90 DAE it became toxic that adversely affected the DM partitioning as well as TDMPP probably may be due its high sulfur (20%) content which lacking in other NPK sources. The DM partitioning to various parts of barley and wheat was more than oats and rye at different growth stages (barley > wheat > rye > oats). Since the DM portioning values were determined on the average of five plants in pot experiment under organic soil at field capacity; in case of field experiments more research is needed on various crop species/varieties under different environmental conditions particularly under moisture stress condition.

GROWTH AND YIELD OF COMMON BEAN AS AFFECTED BY SEED INOCULATION WITH RHIZOBIUM AND NITROGEN FERTILIZATION

SUMMARYTwo field experiments were conducted during the rainy seasons of 2013 and 2014 to evaluate the effects of biological nitrogen fixation (BNF) and/or sowing N fertilization on the growth and yield of Phaseolus vulgaris L. In addition, leaf soluble protein content (LSPC) was measured at four growth stages in both seasons. Plants were subjected to the following treatments: only fertilized with 20 kg N ha−1 at sowing and with 40 kg N ha−1 at 25 days after emergence (DAE) (F); only inoculated with Rhizobium tropici strain SEMIA 4080 at sowing and fertilized with 40 kg N ha−1 at 25 DAE (I+N); and inoculated and fertilized with 20 kg N ha−1 at sowing and with 40 kg N ha−1 at 25 DAE (IF). An additional treatment was done only in the second season and plants were inoculated with no N fertilization at any phase (I−N). Crop growth rate and leaf area index were enhanced by IF and F treatments as compared to I+N treatment, however, net assimilation rate did not differ among the treatments. At the pollination and flowering stages for seasons, LSPC was significantly increased by IF treatment, which also caused the highest final yield compared with the remaining treatments in both seasons. Therefore, the fertilization with 20 kg N ha−1 at sowing together with inoculation and 40 kg N ha−1 at 25 DAE is recommended for obtaining high yield in bean cultivation with high technology. As the inoculation with Rhizobium at sowing and fertilization with 40 kg N ha−1 at 25 DAE (I+N) had the same crop yield as plants fertilized at sowing and at 25 DAE (F), it can be recommended for a low-cost technology cultivation employed by small farmers.

Hemispherical photography to estimate biophysical variables of cotton

ABSTRACT The Leaf Area Index (LAI) is a key parameter to evaluate the vegetation spectral response, estimating plant nutrition and water requirements. However, in large fields is difficult to obtain accurate data to LAI determination. Therefore, the objective of this study was the estimation of LAI, biomass and yield of irrigated cotton through digital hemispherical photography. The treatments consisted of four nitrogen doses (0, 90, 180 and 270 kg ha-1) and four phosphorus doses (0, 120, 240 and 360 kg ha-1). Digital hemispherical photographs were collected under similar sky brightness conditions at 60 and 75 days after emergence (DAE), performed by the Digital Plant Canopy Imager - CI-110® of CID Inc. Biomass and LAI measurements were made on the same dates. LAI was also determined by destructive and non-destructive methods through a leaf area integrator (LI-COR® -LI-3100C model), and by measurements based on the midrib length of all leaves, respectively. The results indicate that the hemispherical images were appropriate to estimate the LAI and biomass production of irrigated cotton, while for the estimation of yield, more research is needed to improve the method.

GENOTYPIC VARIABILITY OF PEANUT LINES IN RESPONSE TO WATER STRESS, BASED ON BIOCHEMICAL DESCRIPTORS

ABSTRACT Seven biochemical descriptors were used to estimate the genotypic variability of peanut in response to moderate water stress. Six genotypes, constituted by four lines and two cultivars, were grown in pots, each containing two plants. At 15 days after emergence (DAE), the treatment differentiation was carried out: Control-plants maintained with daily watering, and Stress-plants submitted to water stress by complete suspension of watering for 15 days. The experimental design was completely randomized with factorial scheme 6 x 2 (genotype x water treatments), with five replications. The biochemical variables evaluated were: catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), free proline, total carbohydrates, soluble proteins, and amino acids. Results obtained by biochemical analysis and estimation of genotypic variability indicated that proline is the most appropriate descriptor for selecting genotypes tolerant to water stress, which led to identification of L81V and L108V as promising lines for drought tolerance breeding program.

Application of digital images for nitrogen status diagnosis in three Vigna unguiculata cultivars

The SPAD chlorophyll meter is widely used to indirectly monitor the nitrogen (N) status of various crops, which is important to ensure proper management of N fertilizers. Here, we propose that the freely available digital foliar analysis software AFSoft may be used to monitor N status with the same effectiveness as the SPAD meter. To verify the usefulness of AFSoft, we employed both SPAD meter readings and AFSoft note to estimate relative chlorophyll content in cowpea beans exposed to different N fertilization rates. The experiment followed a completely randomized design comprised of four replicates carried out in a factorial scheme, with five N fertilization rates (0, 50, 100, 200 and 300 mg pot -1 ) applied to three cowpea bean cultivars (BRS Itaim, BRS Guariba and BRS Novaera). At 45 days after emergence (DAE) of the plants, SPAD readings were obtained on the second trifoliate leaf. The whole leaf was subsequently digitally photographed and dried for the determination of total N concentration by applying acolour scale using AFSoft ® software. There was no significant interaction observed between N fertilization rate and cultivar for the evaluated variables. For all cultivars, increasing the rate of N fertilization increased the total observed N concentration as determined by both SPAD index and AFSoft note. The AFSoft note value was positively correlated with the total N concentration (r=0.95, P≤0.05; r=0.80, P≤0.01; r=0.86, P≤0.01) and the SPAD readings (r=0.99, P≤0.01; r=0.97, P≤0.05; r=0.97, P≤0.05) for the Itaim, Guariba and Novaera cultivars. These results suggest that N concentration in the leaves of cowpea bean cultivars can be estimated using AFSoft, which may serve as an alternative to SPAD meter readings.

Growth, Development and Seed Production of Goosegrass1

ABSTRACT E. indica is one of the most problematic weeds in the world because it is present in almost every continent, and there are reports of multiple resistance to herbicides by some biotypes. The objective of this paper was to analyze the growth, the development and the production of this plant's seeds, in order to generate information about its biology that can be useful for management. The experiment was carried out in a greenhouse from May to September 2015. Sixteen samples were taken during the development cycle of the plant: 3, 10, 17, 24, 31, 38, 45, 52, 59, 66, 73, 80, 87, 94, 101 and 108 days after emergence (DAE). The response variables were based on a leaf area and dry matter of each one of the parts of the plant and the number of seeds produced per plant. At 12 DAE, 80% of the seedlings of E. indica had emerged, and each plant produced more than 120 thousand seeds, closing their cycle at 120 DAE. Between 38 and 43 DAE, the plant had fast emission of new tillers, exponential accumulation of the total dry matter and substantial increase of the absolute growth rate. Due to the data observed here, we concluded that the management of E. indica must be done preferably before 38 DAE due to the exponential growth after this period, preventing the plant from producing seeds and spreading to other places.

Impact of weather variables on drymatter accumulation and yield of mungbean [Vigna radiata (L.) Wilczek] varieties under different dates of sowing

A two year experiment was conducted at the BCKV with four mungbean varieties (Pant Mung-5, Bireswar, RMG-62 and Sukumar) sown under three dates (15th February, 1st and 15th March) in a split plot design where dates of sowing and varieties were allotted to main and sub plot treatments respectively with three replications. PAR was recorded with the help of line quantum sensor. Dry matter accumulation, yield attributes and yield were measured. Canonical correlation and correspondence analysis showed that absorbed PAR during 32 to 46 days after emergence (DAE) increased dry matter, pod and seed yield. PAR use efficiency (PARUE) of mungbean ranged from 0.75 to 0.88 g MJ-1 for seed yield. PARUE for dry matter production was maximum during 39 to 46 DAE. According to PARUE and heat use efficiency, Pant Mung-5 should be sown within 1st March in this zone. Growing degree day requirement gradually increased with delayed sowing.

Economics of herbicide weed management in wheat in Ethiopia

Effective use of herbicides for the control of annual grass and broadleaf weeds in wheat ( Triticum aestivum L.) was not a reality in Ethiopia, until in recent years. This study aimed at evaluating different post-emergence herbicides against annual grasses and broadleaf weeds in wheat for selection and incorporation into an integrated weed management (IWM) system. The study was conducted at Kulumsa Agricultural Research Centre main station, Bekoji and Lole farm fields. Treatments included herbicides, namely, Mesosulfron methyl+Idosulfuron methyl sodium (liquid) 1 lit ha -1 a.i. Pyroxsulam (liquid) 0.5 l ha -1 a.i. hand weeding twice (30-35 and 55-60 days after emergence (DAE)); and a weedy check. Among the annual grass weeds, Snowdenia polystachya, Avena fatua, Bromus pectinatus, Phalaris paradoxa and Setaria pumila ; and most broad leaf weeds like Polygonum nepalense, Guizotia scabra, Galinsoga parviflora and Gallium spurium were controlled with herbicide efficacy ranging from 75 to 100%. Mesosulfron methyl +Idosulfron methyl sodium, Pyroxulam and hand weeded twice plots outyielded the weedy check by 63, 58 and 53%, respectively. Maximum wheat grain yield (5,184 kg ha -1 ), biomass (12,808 kg ha -1 ), thousand kernel weight (48.55) and hectoliter weight (74.2) were obtained due to the application of Mesosulfron methyl+Idosulfuron methyl sodium. In addition, the herbicide had a yield advantage over Pyroxsulam, two hand weedings and the weedy check by 12, 21 and 63%, respectively. Application of Mesosulfron methyl + Idosulfuron methyl sodium (US$1,596.31 ha -1 ) had the highest net field benefit compared to Pyroxsulam (US$1,379.21 ha -1 ), two hand weeding (US$1,126.7 ha -1 ) and weedy check (US$574.1 ha -1 ) by 13.6, 29 and 64%, respectively. Moreover, the herbicide was also economically profitable to farmers, providing a marginal rate of return (MRR) of 1,737%. Sensitivity analysis (aMRR) also remained the most profitable even when the price of herbicide increased by 20%. Hence, Mesosulfron methyl +Idosulfuron methyl sodium at a rate of 1 lit ha -1 is thebest herbicide for the effective control of annual grasses and broad leaf weeds in wheat and can be used as one of the component in Integrated Weed Management Program (IWM) in wheat fields. Key Words : Idosulfuron methyl sodium, Mesosulfron methyl, Triticum aestivum