The Effect of Canopy Architecture and Seasonal Variations on Several Seed Quality Attributes in Soybean (Glycine Max L. Merr.)

Producing high quality soybean seed in the hot humid tropics is no easy task. During seed production, several environmental factors and plant morphological characteristics can exert their influences on seed quality. A study was undertaken at Universiti Putra Malaysia to study the effect of canopy architecture and seasonal variations on several seed quality attributes in soybean (GZycine max L. Merr.). Four soybean cultivars namely, Palmetto, AGS190, Deing and Cikurai were grown in the field for four seasons during 2003 and 2004. Four levels of defoliation treatments [0% defoliation (*170.89pmol m'2s" light intensity), 25% defoliation (*324.33pmol m'2s-' light intensity), 50% defoliation (*473.01pmol m-2s-' light intensity) and 75% defoliation (+642.84pmol m'2s" light intensity], were iniposed at the pod initiation stage (R3). Weather factors such as light intensity, canopy, air and soil temperatures, canopy and air relative humidity, soil moisture and leaf area index were recorded at seven-day intervals starting from the imposition of defoliation until plants reached physiological maturity (R7). Seeds harvested at harvest maturity (R8) were used to determine seed yield, viability, vigour, 1 00-seed weight and for Phomopsis bioassay. Phomopsis sp. seed infection was predicted using weather factors and leaf area index. Scanning electron microscopy (SEM) was used to study the progression and colonization of Phomopsis sp. on the stem, pod and seed starting from R3 until R8. Defoliation treatments were found to have inconsistent effects on seed yield (kg ha-') and pods per plant for AGS190, Deing and Palmetto. Pod number of Palmetto was affected during season Ill only whereas the pod number for Cikurai was significantly affected for all seasons. However, defoliation treatments affected 100-seed weight for all cultivars except for AGS 190 (season I), Deing (season IV) and Cikurai (season 111). From the combined analysis of data over the four seasons, defoliation improved percent seed germination from 6.8 to 13.2%. Increasing the level of defoliation resulted in increasing percent germination and 3-day seedling height and reduced Phomopsis incidence for all cultivars. The highest germination was recorded during season I1 which coincided with the least level of Phomopsis sp. seed infection. Moreover, this disease was influenced by seasonal variations. The disease incidence was high during seasons Ill (51.3%) and IV (49.5%) characterized by high rainfall during seed development and maturation as compared to seasons I and 11 which encountered low rainfall situations (33.3% and 32.5%, respectively). AGSl90, a large seeded cultivar, was severely affected by the seed-borne disease (51.5% infection) whereas Deing, a small seeded cultivar, was the least affected (34.7%). Defoliation treatments increased light intensity within the plant canopy for all cultivars studied. Light intensity and canopy temperature revealed negative correlation with percentage Phomopsis incidence indicating that high light intensity and temperature inside plant canopy reduced Phomopsis sp. seed infection. On the contrary, positive relationship was observed between canopy and air relative humidity, soil moisture and leaf area index with percentage Phomopsis incidence. From the stepwise multiple regression analysis, Phomopsis sp. seed infection can be predicted by leaf area index, soil moisture and canopy relative humidity; while its reduction can be predicted by increased light intensity and canopy temperature during seed development and maturation. Scanning electron microscopy revealed that hngi progression and colonization started at different growth stages for different plant parts. Stems were infected during the early reproductive stage (R3) whereas pods became noticeably infected during the full seed stage (R6) and seeds were the last to be infected. The hngi were internally- borne within the infected seeds. Fungal hyphae were observed externally on the surface of the plant parts studied and internally both in the pod and in all the three layers of the seed coat: palisade cell, hourglass cell and parenchyma cell layers. Fungi colonization was highest at the late plant growth stages of R7 and R8. A progressive increase in pod and seed infection was detected during subsequent growth stages between R6 and R8. From the pod, the pathogen can infect and colonize the seed. The SEM results suggested that the reproductive growth period of R6 to R7 was more critical with respect to Phomopsis sp. seed infection than earlier reproductive growth periods, since more severe colonization of pods and seeds took place at the later stages of plant growth. SEM revealed that stem infection allowed buildup of inoculum for subsequent infection of the pod, whereas pod infection was necessary for further infection of seeds. Since pod infection is the prerequisite for seed infection, this study suggests that fbngicide would be best applied between R4 and R5 before the seed-borne fungi reach the seed during R6 and the subsequent growth stages. Prediction model based on four seasons' data accurately described the relationship between the environmental conditions and leaf area index during seed development and maturation and the levels of seed infection by Phomopsis sp. Moreover, the model fitted well with the field and laboratory data collected. However, this model needs to be tested at multilocational trials for validity. The results of the present study have shown that plant canopy modification through defoliation appears to improve quality of seeds produced under wet and warm tropical environments. In addition, the study also suggested that growing of soybean cultivars with open canopies and having low leaf area index, coupled with rain-free harvesting seasons can result in the production of high quality seeds. Although the prediction model so developed in this study needs to be tested for validity at different locations and variable environments, it has the potential to be used as a practical tool in plant disease forecasting programs

Interaction of a two-level atom with squeezed light

We consider a degenerate parametric oscillator whose cavity contains a two-level atom. Applying the Heisenberg and quantum Langevin equations, we calculate in the bad-cavity limit the mean photon number, the quadrature variance, and the power spectrum for the cavity mode in general and for the signal light and fluorescent light in particular. We also obtain the normalized second-order correlation function for the fluorescent light. We find that the presence of the two-level atom leads to a decrease in the degree of squeezing of the signal light. It so turns out that the fluorescent light is in a squeezed state and the power spectrum consists of a single peak only.Comment: 9 pages and 9 figures, in press, Opt. Commu

A zoonotic focus of cutaneous leishmaniasis in Addis Ababa, Ethiopia

<p>Abstract</p> <p>Background</p> <p>Cutaneous leishmaniasis (CL) is endemic in the highlands of Ethiopia, and almost always caused by <it>Leishmania aethiopica</it>. Hitherto, Addis Ababa (the capital city of Ethiopia) was not considered endemic for CL, mainly due to absence of epidemiological and field ecological studies. This report summarizes the preliminary epidemiological investigation that proved the existence of active transmission in southeastern Addis Ababa.</p> <p>Results</p> <p>Active case finding surveys were conducted in 3 localities, Saris, Kality, and Akaki, which are found in and around Bulbula-Akaki river gorges. During the surveys conducted in January 2005 - May 2006, a total of 35 cases with 9 active and 26 healed skin lesions were identified. Eighteen of the cases (51.4%) were found in Saris; while 10 (28.6%) and 7 (20%) cases were from Kality and Akaki respectively.</p> <p>Ten colonies of rock hyraxes (<it>Heterohyrax brucei</it>) were identified in the vicinities of the 3 localities. Three of the 48 hyraxes (6.3%) trapped from the surroundings harbored natural infections of <it>Leishmania aethiopica</it>. Confirmation of the <it>Leishmania </it>species of the 3 isolates was achieved by PCR amplification and RFLP analysis of the ribosomal DNA internal transcribed spacer (ITS) sequences. Based on sandfly species composition and proximity of resting sites to human settlements, <it>Phlebotomus longipes </it>is circumstantially proven to be the vector of CL in south east Addis Ababa.</p> <p>Conclusion</p> <p>The study proves the existence of isolated zoonotic foci of CL in south eastern Addis Ababa, with <it>P. longipes </it>as the likely vector and <it>H. brucei </it>as the natural reservoir host.</p

Higher order antibunching is not a rare phenomenon

Since the introduction of higher order nonclassical effects, higher order squeezing has been reported in a number of different physical systems but higher order antibunching is predicted only in three particular cases. In the present work, we have shown that the higher order antibunching is not a rare phenomenon rather it can be seen in many simple optical processes. To establish our claim, we have shown it in six wave mixing process, four wave mixing process and in second harmonic generation process.Comment: 6 pages, no figure, Latex 2

Constructing 3D crystal templates for photonic band gap materials using holographic optical tweezers

A simple and robust method is presented for the construction of 3-dimensional crystals from silica and polystyrene microspheres. The crystals are suitable for use as templates in the production of three-dimensional photonic band gap (PBG) materials. Manipulation of the microspheres was achieved using a dynamic holographic assembler (DHA) consisting of computer controlled holographic optical tweezers. Attachment of the microspheres was achieved by adjusting their colloidal interactions during assembly. The method is demonstrated by constructing a variety of 3-dimensional crystals using spheres ranging in size from 3 µm down to 800 nm. A major advantage of the technique is that it may be used to build structures that cannot be made using self-assembly. This is illustrated through the construction of crystals in which line defects have been deliberately included, and by building simple cubic structures

Generalized structure of higher order nonclassicality

A generalized notion of higher order nonclassicality (in terms of higher order moments) is introduced. Under this generalized framework of higher order nonclassicality, conditions of higher order squeezing and higher order subpoissonian photon statistics are derived. A simpler form of the Hong-Mandel higher order squeezing criterion is derived under this framework by using an operator ordering theorem introduced by us in [J. Phys. A. 33 (2000) 5607]. It is also generalized for multi-photon Bose operators of Brandt and Greenberg. Similarly, condition for higher order subpoissonian photon statistics is derived by normal ordering of higher powers of number operator. Further, with the help of simple density matrices, it is shown that the higher order antibunching (HOA) and higher order subpoissonian photon statistics (HOSPS) are not the manifestation of the same phenomenon and consequently it is incorrect to use the condition of HOA as a test of HOSPS. It is also shown that the HOA and HOSPS may exist even in absence of the corresponding lower order phenomenon. Binomial state, nonlinear first order excited squeezed state (NLESS) and nonlinear vacuum squeezed state (NLVSS) are used as examples of quantum state and it is shown that these states may show higher order nonclssical characteristics. It is observed that the Binomial state which is always antibunched, is not always higher order squeezed and NLVSS which shows higher order squeezing does not show HOSPS and HOA. The opposite is observed in NLESS and consequently it is established that the HOSPS and HOS are two independent signatures of higher order nonclassicalityComment: 14 pages, 7 figure

First report of the enset root mealybug Paraputo ensete (Williams & Matile Ferrero) (Hem.: Pseudococcidae) on banana in Ethiopia.

Enset root mealybugs, a major pest affecting the cultivation of the enset crop in the Ethiopian highlands, have for the first time been observed on banana mats indicating the potential host status of Musa spp. These observations were made under natural conditions in backyard gardens in the Gedeo zone, southern Ethiopia, on the root system of banana mats of the ‘Pisang Awak’ (local name ‘Feranji Muz’, ABB genome group) landrace. Here, we confirm the identification of the collected enset root mealybug specimens on banana mat root systems as Paraputo ensete (Williams & Matile-Ferrero) (Hemiptera: Pseudococcidae) through DNA analysis

Zoonotic Transmission of Tuberculosis Between Pastoralists and Their Livestock in South-East Ethiopia

Despite huge global efforts in tuberculosis (TB) control, pastoral areas remain under-investigated. During two years sputum and fine needle aspirate (FNA) specimens were collected from 260 Ethiopian pastoralists of Oromia and Somali Regional States with suspected pulmonary TB and from 32 cases with suspected TB lymphadenitis. In parallel, 207 suspected tuberculous lesions were collected from cattle, camels and goats at abattoirs. All specimens were processed and cultured for mycobacteria; samples with acid-fast stained bacilli (AFB) were further characterized by molecular methods including genus and deletion typing as well as spoligotyping. Non-tuberculous mycobacteria (NTM) were sequenced at the 16S rDNA locus. Culturing of AFB from human sputum and FNA samples gave a yield of 174 (67%) and 9 (28%) isolates, respectively. Molecular typing was performed on 173 of these isolates and 160 were confirmed as Mycobacterium tuberculosis, three as M. bovis, and the remaining 10 were typed as NTMs. Similarly, 48 AFB isolates (23%) yielded from tuberculous lesions of livestock, of which 39 were molecular typed, including 24 M. bovis and 4 NTMs from cattle, 1 M. tuberculosis and 1 NTM from camels and 9 NTMs from goats. Isolation of M. bovis from humans and M. tuberculosis from livestock suggests transmission between livestock and humans in the pastoral areas of South-East Ethiopi

Higher order antibunching in intermediate states

Since the introduction of binomial state as an intermediate state, different intermediate states have been proposed. Different nonclassical effects have also been reported in these intermediate states. But till now higher order antibunching or higher order subpoissonian photon statistics is predicted only in one type of intermediate state, namely shadowed negative binomial state. Recently we have shown the existence of higher order antibunching in some simple nonlinear optical processes to establish that higher order antibunching is not a rare phenomenon (J. Phys. B 39 (2006) 1137). To establish our earlier claim further, here we have shown that the higher order antibunching can be seen in different intermediate states, such as binomial state, reciprocal binomial state, hypergeometric state, generalized binomial state, negative binomial state and photon added coherent state. We have studied the possibility of observing the higher order subpoissonian photon statistics in different limits of intermediate states. The effect of different control parameters have also been studied in this connection and it has been shown that the depth of nonclassicality can be tuned by controlling various physical parameters.Comment: 12 Pages LaTeX 2e, 11 figure

Assessing the host status of banana and other plant species to the enset root mealybug Paraputo ensete (Williams & Matile-Ferrero) (Hem.: Pseudococcidae) in Ethiopia.

Ninety backyard gardens in the south-eastern Ethiopian highlands with enset (Ensete ventricosum (Welw.) Cheesman), banana and various annual crops were assessed for the presence of enset root mealybugs (Paraputo ensete (Williams & Matile-Ferrero)). This study presents the first observation of enset root mealybugs on banana. This pest has until now been exclusively recorded on enset in Ethiopia. In the Dilla Zuria district of the Gedeo zone, southern Ethiopia, infested banana mats of the ‘Pisang Awak’ (ABB genome) landrace were observed adjacent to infested enset plants in three small-holder backyard gardens. As roots of banana mats and enset plants were overlapping and intertwined, and large numbers of mealybugs were observed on enset roots, possibly representing an overpopulation, the observed mealybugs on banana might have represented a “chance infestation". The smaller size of mealybugs on banana roots might indicate a non-optimal host status of this crop. Experimental choice and no-choice pot trials however provided another indication of the possible host potential of ‘Pisang Awak’ and of an additional banana cultivar ‘Matooke’ (AAA-East African Highland). The enset root mealybug was able to fully develop, produce viable offspring and survive on both banana cultivars. Not all investigated banana cultivars presented this host status, and the susceptibility of most Musa cultivars remains low