Screenhouse Experiments Research Articles

Reduction of initial occurrence of rice blast (Pyricularia oryzae) inocula on seeds by microbial and hot water seed treatments

Rice blast disease resulting from infected rice seed can be avoided by using treated seeds. Seed treatment using chemical fungicide has many limitations such as development of resistance to pathogens, damage to the natural environment and the health of farmers and consumers. Such limitations have raised the need for alternative non-chemical seed treatment methods such as antagonist microbial agents and hot water. Laboratory and the screen house experiments were carried out with the aim of evaluating the efficacy of 'Trichoderma asperellum', 'Bacillus subtilis' and hot water (50 degreesC/15 min) seed treatments against rice blast disease inocula on rice seeds. The results showed that, seeds treated with microbial agents ('T. asperellum', 'B. subtilis') and hot water reduced the percentage of infected rice seeds by 4.3 to 52.7% relative to non-treated seeds. The germination percent and seedling vigour index increased from 12.3 % to 17.1 % . Rice seeds treated with 'B. subtilis' reduced the incidence and severity of rice blast disease from 10% to 72.4 %. Seed treatment using 'B. subtilis' followed by 'T. asperellum' were the best in reducing the number of infected seeds and rice blast disease incidence and severity on rice seedlings. Therefore, the use of these microbial agents has a potential for effective management of rice blast disease.

Influence of neutron irradiation and phosphorus on the performance of groundnut [<i>Arachis hypogaea</i> (L.)] genotypes grown on a P-deficient alfisols at Samaru, Nigeria

There is a dearth of information on the effective irradiation dose for inducing variability in groundnut genotypes. A screen house experiment was conducted at the Department of Soil Science, Ahmadu Bello University, Zaria (ABU). It was to investigate the effect of induced genetic variability (by neutron irradiation) and four phosphorus rates (0, 20, 40 and 60 kg P2O5 ha-1) on the performance of some groundnut [(Arachis hypogaea (L.)] genotypes grown on a P-deficient Alfisols at Samaru, Zaria. A fraction of each of the two genotypes (SAMNUT 24 and SAMNUT 26) was irradiated, in a 5-Curie Americium-Beryllium (Am-Be) isotope neutron source, having a thermal neutron flux of 2.7387 x 104 n cm-2 sec-1 for six days, at the Centre for Energy Research and Training, ABU. The irradiated (G1A and G2A) and nonradiated (G1B and G2B) seeds; and the P rates were laid out in a randomised complete block design (RCBD), in a screen house, and replicated thrice. Data collected during the study included; plant height, numbers of branches, flowers, nodules, leaves and chlorophyll content (CC). Both G1A and G2A significantly (P<0.0001) produced the highest CC, highest numbers of branches, leaves, flowers, nodules and effective nodules; and the tallest plants. Treatment with 60 kg P2O5 ha-1 significantly (P<0.0001) increased the number of leaves, flowers, branches and plant height. The irradiated genotypes were generally observed to significantly perform better than their non-radiated counterparts under the application of both 60 kg P2O5 ha-1 and 20 kg P2O5 ha-1. Thus, application of 20 kg P2O5 ha-1 is recommended for optimum plant height, flowers and CC in groundnut production; while 60 kg P2O5 ha-1 is recommended for optimum numbers of branches and leaves, especially when the irradiated SAMNUT 24 and SAMNUT 26 are to be used for production of both seeds and biomass.Keywords: Alfisols, Chlorophyll content, Neutron irradiation, SAMNUT

Does artemether\u2013lumefantrine administration affect mosquito olfactory behaviour and fitness?

BackgroundArtemisinin-based combination therapy (ACT) is the recommended treatment against uncomplicated Plasmodium falciparum infections, and ACT is widely used. It has been shown that gametocytes may be present after ACT and transmission to mosquitoes is still possible. Artemether–lumefantrine (AL) is a broadly used artemisinin-based combination medicine. Here, it is tested whether AL influences behaviour and fitness of Anopheles mosquitoes, which are the main vectors of P. falciparum.ResultsDual-choice olfactometer and screenhouse experiments showed that skin odour of healthy human individuals obtained before, during and after AL-administration was equally attractive to Anopheles coluzzii and Anopheles gambiae sensu stricto, apart from a small (but significant) increase in mosquito response to skin odour collected 3 weeks after AL-administration. Anopheles coluzzii females fed on parasite-free blood supplemented with AL or on control-blood had similar survival, time until oviposition and number of eggs produced.ConclusionsBased on the results, AL does not appear to influence malaria transmission through modification of vector mosquito olfactory behaviour or fitness. Extending these studies to Plasmodium-infected individuals and malaria mosquitoes with parasites are needed to further support this conclusion.

Pathogenicity and in vitro extracts inhibition of fungi causing severe leaf blight in Thaumatoccocus danielli (Benn.) Benth

Isolation and identification of fungi associated with severe leaf blight of Thaumatococcus danielli was conducted. The fungi were subjected to pathogenicity test in the screenhouse experiment. Laboratory assessment of antifungicidal activities of; Ficus asperifolia, Psidium guajava, Mormodica charantia and Anarcadium occidentales prepared at 25, 50 and 75 mg/mL concentrations against the three most virulent pathogens was carried out on PDA, V8 Agar, CZA, and MEA culture media. Data gathered were subjected to ANOVA. Aspergillus niger, A. flavus, Pythium sp., Penicillium sp., Fusarium oxysporum, Macrophomina phaseolina, Trichoderma viride, T. koniigi and T. harzianum were the fungi found associated with the diseased parts and the rhizospheric soil. M. phaseolina, A. flavus and A. niger were the most virulent obtained in the pathogenicity test. Growths of these pathogens were mostly inhibited by M. charantia as its efficacy increased with increase in the concentration levels. Mycelia growths were mostly supported by MEA medium.

Evaluation of banana germplasm and genetic analysis of an F1 population for resistance to Fusarium oxysporum f. sp. cubense race 1

Fusarium wilt of bananas (Musa spp.), caused by Fusarium oxysporum f. sp. cubense (Foc) causes up to 100% yield loss in bananas. Foc race 1 in particular is very devastating to dessert bananas in Uganda. One of the effective control strategies for the disease is the development of resistant cultivars through breeding. The objectives of this study were to identify suitable banana germplasm for generating a segregating population for resistance to Foc race 1 and understand the mode of inheritance of resistance to Foc race 1. Twenty-two banana accessions sourced from the National Agricultural Research Organisation in Uganda were challenged with Foc race 1 in a screen house experiment. Monyet, resistant to Foc race 1 and Kokopo, susceptible, were selected and crossed to generate 142 F1 genotypes. These F1 genotypes were also challenged with Foc race 1 in a screen house experiment. Data were collected on rhizome discoloration index (RDI), leaf symptom index (LSI) and pseudo-stem splitting (PSS), and analysed for variability. The banana accessions evaluated showed varying degrees of resistance to Foc race 1. Segregation ratios for resistant versus susceptible progenies fitted 13:3 (χ2 = 0.12, P = 0.73) for RDI and 11:5 (χ2 = 3.04, P = 0.08) for PSS. Estimated broad sense heritability was 27.8% for RDI, 13.9% for LSI and 14.7% for PSS. The results suggest that resistance to Foc race 1 in banana is controlled by at least two dominant genes with epistatic interaction and that heritability of resistance to Foc race 1 is low in Musa spp.

Current Status of Cashew Leaf and Nut Blight Disease (Cryptosporiopsis spp.) and Screening of Elite Cashew Hybrids Developed in 1996 and 1998 against the Disease in Eastern and Southern Tanzania

Cashew (Anacardium occidentale L.) is an export crop and source of income in Tanzania. However, its productivity is challenged by insect pests and diseases. Cashew Leaf and Nut Blight Disease (CLNBD) caused by Cryptosporipsis spp. has been cited as one of the most devastating diseases in Tanzania. Studies were conducted to investigate incidences and severities of CLNBD on cashew in farmers’ fields and elite cashew hybrids developed in 1996 and 1998 in eastern and southern zones of Tanzania. Furthermore, a screen house experiment was conducted to screen these hybrids against CLNBD at Naliendele Agricultural Research Institute (NARI), Mtwara, Tanzania. The results indicated significant differences (P<0.001) in CLNBD incidences and severities in cashew in farmers’ fields across Bagamoyo, Nachingwea and Mtwara districts. Further, there were significant differences (P<0.001) among hybrids in CLNBD severities in the screen house experiment. In ranking the elite cashew hybrids, 38 were tolerant and 14 were susceptible to CLNBD. This observation suggests that elite cashew hybrids developed in 1996 and 1998 are more tolerant to CLNBD compared to cashew found in farmers’ fields. These findings strongly suggest that the elite cashew hybrids can be recommended for commercial farming in Tanzania.

Effects of Rice-Bran Compost on Growth and Yield of Soybean (Glycine max) on an Alfisol in Ibadan, Nigeria.

Farmers in the tropical environment face the acute problem of using mineral fertilizers due to their unsustainable attributes ranging from scarcity and high cost of the material to the adverse effects on tropical soil which resulted to soil acidity and pollution of underground water. This study evaluated the effects of rice-bran compost on the growth and yield of improved variety of soybean on an Alfisol, in Ibadan, Nigeria. The investigation involved a screen house experiment conducted at the Department of Agronomy, University of Ibadan. The experiment comprised five rates of compost (0, 2.5, 5.0, 7.5 and 10 t/ha) replicated four times with two pots per replicate in a Completely Randomized Design (CRD) using soybean (TGX 1740- 1F) variety with a total of 40 pots in all. The data collected were subjected to analysis of variance ANOVA and Duncan multiple range test was used to separate the means. The experimental results showed significant differences (p˂0.05) among the levels of compost on soybean; however, 10 t/ha gave the highest value on the number of leaves while 7.5 t/ha performed better in respect of plant height compared with the other treatments. Also, rice bran compost at 10 t/ha produced statistically highest root and grain yields followed closely by 7.5 t/ha. However, 10 t/ha of rice bran compost promoted shoot performance. Soybean yield increased with higher rates of rice-bran compost. Soybean growth and yield are improved with a compost of rice- bran and cattle dung up to 7.5 t/ha to supply 95 kg N, 169 kg P and 12 kg K.

Optimizing Sowing and Flooding Depth for Anaerobic Germination-Tolerant Genotypes to Enhance Crop Establishment, Early Growth, and Weed Management in Dry-Seeded Rice (Oryza sativa L.).

Poor crop establishment, high weed infestation, and consequent yield loss are major concerns for dry-seeded rice (DSR). Flooding after seeding helps in managing weeds but reduces seed germination and crop stand. Anaerobic germination (AG)-tolerant rice genotypes could overcome these problems in DSR. Screenhouse experiments were established to evaluate the effect of seed sowing depth (SD) (0.5 cm, 1 cm, and 2 cm) and flooding depth (FD) (saturated, 2 cm, and 5 cm) on crop establishment, early growth, and weed competitiveness in DSR using AG-tolerant genotypes (Khao Hlan On, Ma-Zhan Red, IR64+AG1, and IR64). Echinochloa crus-galli, Ludwigia hyssopifolia, and Cyperus difformis were used in the weedy treatment. Rice plants reached maximum emergence 9–13 days later under flooding compared with saturated conditions. Crop emergence decreased by 12–22% at 0.5 and 1 cm SD and by 48–60% at 2 cm SD, when combined with 2 or 5 cm FD compared with saturated conditions. The 2 cm SD reduced seedling emergence by 23–42% in Khao Hlan On and Ma-Zhan Red, by 62–70% in IR64+AG1, and by 90–92% in IR64 under flooding. Initial growth in rice plant height was slow under flooding but increased progressively after the seedlings emerged from water and the final height was not affected by FD. Leaf area, total shoot biomass, tiller density, and leaf number per pot of rice were higher at 1 cm SD (P< 0.05), but decreased drastically at 2 cm SD under flooding. The emergence of E. crus-galli and L. hyssopifolia decreased by 53–65% and 89–95%, respectively, but increased by 49–68% in C. difformis under 2 and 5 cm FD, respectively, compared with saturated conditions. The shoot biomass of the weeds followed the same trend. Khao Hlan On showed the highest weed-competitive ability under all FD while the biomass of IR64+AG1 and IR64 decreased by 10–14% due to weed competition under 2 cm FD. The 1 cm SD showed better growth for all genotypes under different FD. The 2 cm FD is sufficient to have a significant control of problematic weed species. The tolerance of AG of rice genotypes should be further enhanced to increase their weed-competitive ability.

Identification of sources of resistance to Alectra vogelii in cowpea [Vigna unguiculata (L.) Walp.] germplasm from Burkina Faso

In Burkina Faso, cowpea serves as both a food and cash crop generating significant income for stakeholders. However, cowpea production is seriously hampered by several constraints among which is the parasitic weed Alectra vogelii. There is therefore an urgent need to identify Alectra-resistant genotypes, possessing farmers’ desired traits, in cowpea germplasm in Burkina Faso. Cowpea genotypes were screened under artificial (screen house) and natural (field) A. vogelii infestation for their reaction to the weed. For the screen house experiment the data were collected on parameters such as days to cowpea flowering and maturity, days to Alectra shoots emergence, the severity of Alectra attack. Cowpea grain yield, Alectra shoots count and severity were scored from the field experiment. These data were subjected to analysis of variances in SAS 9.4. Correlation analysis was also run to determine the association between Alectra infestation parameters and cowpea yield. Twenty Genotypes including KVx414-22-2, KVx165-14-1, Komcalle, IT99K-573-2-1, IT98K-205-8, IT86D10-10, IT93K-693-2 and B301 were identified to be resistant to A. vogelii. Variety Komcalle, IT99K-573-2-1 and IT98K-205-8 are improved and farmers’ adopted varieties. Therefore, these varieties can be recommended for Alectra-infested areas. The other genotypes showing resistance are potential donor parents for resistance to A. vogelii.

Soil manganese dynamics and its uptake in wheat (Triticum aestivum) influenced by chloride and manganese application

Manganese (Mn) is one of the essential micro-nutrients having an important contribution in paddy (Oryza sativa L.)-wheat (Triticum aestivum L.) cropping systems. Wheat is an important cereal crop of Haryana State and is highly susceptible to Mn deficiency. During submerged paddy, solubility of Mn increases appreciably because of its reduction and continuous leaching from upper to lower soil layers which in turn results in its deficiency in the succeeding winter season crops especially wheat. Often, Mn fertilization under salinity stress is of main concern to be investigate, especially in arid and semi-arid regions of Haryana. So, in order to evaluate soil manganese dynamics and its uptake in wheat influenced by chloride (Cl-) and Mn application, laboratory as well as a screen house experiment was conducted at CCS HAU, Hisar, Haryana. Results revealed that a decreased grain and straw yield and Mn uptake in wheat with graded doses of Cl- application. The highest grain and straw yield of wheat were recorded with 25mg Mn/kg and without chloride application. However, maximum Mn content and its uptake in wheat was recorded under treatment of 50 mg Mn/kg. Among all Mn fractions in post-harvest soils, maximum Mn was associated with residual (RES) fraction followed by MnOX &gt; AFeOX &gt; CFeOX &gt; EX &gt; CARB &gt; OM fractions. Organic matter bound (OM) showed a very little amount of Mn content due to low content of organic carbon in experimental soil. Thus, chloride application along with Mn fertilizers showed antagonistic effect on wheat yield and its uptake as well as Mn dynamics in soil.

Risks Posed by Intercrops and Weeds as Alternative Hosts to Xanthomonas campestris pv. musacearum in Banana Fields

Alternative host plants are important in the survival and perpetuation of several crop pathogens and have been suspected to play a role in the survival of Xanthomonas campestris pv. musacearum (Xcm) and perpetuation of Xanthomonas wilt (XW) disease of banana and enset. This study determined the potential risk posed by two weeds (Canna spp. and wild sorghum) and common banana intercrops (maize, millet, sorghum, taro, and sugarcane) as alternative hosts to Xcm. The study employed screenhouse experiments, laboratory procedures and diagnosis of banana fields in XW-affected landscapes. Typical XW symptoms were only observed in artificially inoculated Canna sp., with an incidence of 96%. Leaf lesions characteristic of xanthomonads occurred on millet (50%) and sorghum (35%), though the plants recovered. No symptoms occurred in maize, sugarcane, taro or wild sorghum. However, Xcm was recovered from all these plant species, with higher recoveries in Canna sp. (47%), millet (27%), sugarcane (27%), and wild sorghum (25%). Only isolates recovered from Canna sp., millet, sorghum and wild sorghum caused disease in banana plantlets. The presence and incidence of XW on-farm was positively associated with the presence of susceptible ABB Musa genotypes and negatively with number of banana cultivars on farm and household access to training on XW management. Only 0.02% of field sampled Canna spp. plants had Xcm. Risk posed by Canna spp. on-farm could be limited to tool transmission as it has persistent floral bracts that prevent insect-mediated infections. Given the high susceptibility, perennial nature and propagation through rhizomes of Canna sp., it could pose a moderate-high risk, thus warranting some attention in the management of XW disease. Sugarcane could offer a low-moderate risk due to its perennial nature and propagation through rhizomes while risk from maize, millet, and sorghum was deemed zero-low due to their annual nature, wind-mediated mode of pollination and propagation through seed. Understanding the interactions of a crop pathogen with other plants is thus important when diversifying agroecosystems. The study findings also suggest other factors such as cultivar composition and management of the disease at farm and landscape level to be important in the perpetuation of XW disease.

Symbiotic Effectiveness of Rhizobia Strains Isolated from Nigerian Savanna

Laboratory and screenhouse experiment were conducted to assess the symbiotic effectiveness (SE) of rhizobia isolated from southern Guinea savanna, northern Guinea savanna and Sudan savanna of Nigeria and response of promiscuous soybean varieties, TGx1448-2E, TGx1835-10E and TGx1955-10E to inoculation with ten indigenous rhizobia isolates. The soybean varieties were grown on sterilized sand at the screenhouse of the Department of Soil Science and Land Management, Federal University of Technology Minna and watered using Sandsman’s nutrient solution. The treatments were un-inoculated control, mineral nitrogen (urea) and ten rhizobia isolates arranged on a Completely Randomized Design (CRD) and replicated three times. The rhizobia isolates were Sg4, Sg6-3, Gw5, Gw3-2, Bg3, Bg1-4, Sk2-3, Am2, Am6-3 and Kr5-5 isolated from Sabon-gida, Gwada, Birnin-gwari, Shika, Amawa and Karaye sites of Nigerian savanna. The results obtained were subjected to Analysis of Variance using statistical analysis system (SAS 2008) computer software. The treatments mean was separated using Least Significant Different (LSD) at 5% probability. Nodulation and biomass yield of the varieties were assessed at six weeks after planting. Nodules were only produced in inoculated plants, SE was calculated. The result obtained showed that nodule dry weight, SE and shoot dry weight were significantly affected by the interaction between inoculation and promiscuous soybean varieties. Generally, inoculated plants gave higher shoot biomass gain than the un-inoculated control but lower than those treated with urea. The difference between those inoculated and those treated with urea was associated to environmental specificities and higher temperature during the period of the experiment. The SE was highest in northern Guinea savanna isolate reaching 67% and lowest in southern Guinea savanna isolate Sg6-3 recorded 53%. The result showed an SE of less than 100% in all the isolates which implies that the indigenous rhizobia isolates were not superior to the mineral nitrogen.

Availability and dynamics of organic carbon and nitrogen indices in some soils amended with animal manures and ashes

PurposeThe study evaluated dried manures and manure ashes as alternative products from animal manures, and determined the dynamics of soil nitrogen availability indices and organic carbon release in some soils amended with dried manures and ashes under laboratory incubation, screen-house and field experiments.MethodsCattle, goat and poultry manures were collected and air dried to produce dried manures after which part of the dried manures were burnt in open space at a temperature range of 320–450 °C to produce manure ashes. Treatments which were no amendment (control), dried manures of cattle, goat and poultry manure ashes of cattle, goat and poultry and NPK 15-15-15 at 120 kg N ha−1 were applied to soil. Samples were taken fortnightly after amendment incorporation in the incubation experiment; in screen-house experiment and field experiments, plant seeds were established after amendment incorporation; thereafter, soil samples were taken fortnightly. Soil samples were analyzed for soil organic carbon (SOC), NH4+–N and NO3−–N using a spectrophotometer.ResultsIncineration of manures increased pH, exchangeable cations and carbon, while nitrogen in manures ashes was comparable to nitrogen in dried manures. The application of manure ash increased SOC, NH4+–N and NO3−–N by 182, 102, 128% in incubation experiment while 64 and 628% increase in SOC and NH4+–N was recorded in screen-house experiment, respectively, relative to the control. In the field experiment, a significant increase in NO3−–N was recorded at the onset of incorporation; nitrification was more pronounced than ammonification under incubation and field conditions.ConclusionDried manures are not superior to manure ashes and incorporation of manures ashes increased the SOC, NH4+–N and NO3−–N though changes with increasing weeks were erratic.

Effect of biochar on the nutrient contents and metal recovery efficiency in sorghum planted on landfill soils

The study investigated the quality and bioaccumulation of selected heavy metals in sorghum grown in biochar-treated landfill soils. Composite soil samples were collected from the three main landfill sites in Lagos State, Nigeria. All soil samples were obtained at 0–15 cm soil depth, and a control site was established at 3 m downstream of each of the site. The soil samples were air-dried and analysed for physico-chemical properties and metals concentrations using standard methods in the laboratory. Sorghum seeds were planted in five landfill soil pots, treated with wood biochar at 5 t ha−1 interval, from 0 to 20 t ha−1, and replicated thrice for each soil in a completely randomized design approach for a screenhouse experiment. The plants were harvested at 12 weeks after planting and later oven-dried at 70 °C for 48 h before they were digested and analysed. The results showed that Cu and Pb concentrations in the landfill soils exceeded standard guidelines for agricultural soils, but these reduced with biochar application rate in the soils. Biochar applications at 10–15 t ha−1 also produced the best growth performance and tissue nutrient in the sorghum. Assessment of the biomass efficiency indicated greater performance in the capacity to immobilize more metals concentrations at 20 t ha−1 and was worse at 5–10 t ha−1 biochar applications. The study concluded that the use of biochar as organic amendment on contaminated soils can be vital for soil remediation in polluted environments.

English

Screen house experiment to determine the effect of the aqueous leaf extract of Jatropha on the control of Meloidogyne javanica infections on tomato (Solanum lycopersicum) was conducted at Federal College of Agriculture, Ishiagu in, 2016. UC82B tomato was used as the test crop. The test crop was planted in pots filled with 5 kg sterilized soil. Each pot was inoculated with 3000 M. javanica eggs collected from the infected roots of begonia plant. The aqueous extract was used at three concentrations of 150, 300 and 450 g/l and applied to each pot with water as the control. The parameters evaluated were plant height (cm) and number of leaves at 50% anthesis, stem girth (cm), fruit weight (kg), number of galled roots and root gall index at harvest. The leaf extracts increased significantly (P<0.05) the plant height, number of leaves, stem girth and the fruit weight. There were significant (P<0.05) reductions in the number of galled roots and root gall indices with increase in the concentrations of the leaf extract. The extract at 450 g/l showed better potential in the control of M. javanica infections on tomato and could therefore be recommended to tomato farmers for trial under field conditions. Key words: Inoculated, sterilized soil, test crop, galled roots.

Comparative Evaluation of Animal Manures and Their Ashes on Soil pH and Electrical Conductivity in some Southwestern Nigerian Soils

ABSTRACTTo promote the use of animal waste in agriculture and prevent environmental pollution, an alternative product from the waste should be appraised. This necessitated the study to characterize animal manure ashes and determine its effect on soil pH and electrical conductivity (EC) dynamics. Dried manures of cattle, goat, and poultry, their ashes, and nitrogen (N)–phosphorus​–potassium were applied to soil at 120 kg N ha−1.​ Soils collected fortnightly were analyzed for pH and EC. Results indicated that nutrients in manure ashes were comparable to that of dried manures. Changes in pH and EC were not predictable, application of manure ash increased pH by 12% and 13%, 23% and 14%, 20% and 3% while EC increased by 616% and 109%, 1274% and 156%, 2992% and 458%, relative to dried manures and control during incubation, screenhouse, and field experiments, respectively. It was concluded that incorporation of manure ashes increased soil pH and EC although dynamics were unpredictable.

Remediation of phytotoxic effect of chromium by different amendments in berseem crop grown in sewage and tubewell water irrigated soils

A screen house experiment was carried out to study the direct effect of chromium(Cr) application in the presence and absence of amendments in berseem crop grown on sewage and tube well water irrigated soils with three replications under factorial completely randomized block design. The results indicated that berseem dry matter yield (DMY) decreased significantly due to direct effect of Cr application but the presence of amendments increased the dry matter yield up to 80 mg/Kg of applied Cr. No harvestable yield was obtained at higher levels of chromium application. The chromium content and chromium uptake also increased significantly with increase in levels of applied chromium. The application of amendments decreased the chromium content and uptake. The toxic effect of Cr on crop could be mitigated more effectively with FYM application than lime and reduce risk of health hazards for human beings and animals.

Resistance and tolerance to the brown planthopper, Nilaparvata lugens (Stål), in rice infested at different growth stages across a gradient of nitrogen applications

High resource availability can reduce anti-herbivore resistance (a plant’s ability to defend against herbivores and reduce damage) in rice, Oryza sativa L, but may also increase tolerance (a plant’s ability to withstand damage by, for example, compensatory growth). Through a series of greenhouse, screenhouse and field experiments, this study examines fitness (survival and development × reproduction) of the brown planthopper, Nilaparvata lugens (Stål), on resistant (IR62) and susceptible (IR22) rice varieties and age-related rice tolerance to planthopper damage under varying resource (nitrogenous fertilizer) availability. Planthoppers reared on IR62 in the greenhouse had lower fitness than planthoppers on IR22. IR62 became increasingly resistant as plants aged. IR22 was generally more tolerant of planthopper damage, and tolerance increased in IR22, but declined in IR62, as the plants aged. Rice plants infested at pre-tillering stages (3–4 leaf stage) in the screenhouse had greater losses to root, shoot and grain yield per unit weight of planthopper than plants infested at tillering stages, particularly in IR22. These trends were mainly due to the impact of planthoppers during pre-tillering stages and the length of exposure to the planthoppers. High nitrogen compromised IR62 resistance, particularly in tillering plants in the greenhouse study; however, high nitrogen did not increase planthopper biomass-density on IR62 in greenhouse or field cages. Tolerance to damage in IR62 at mid-tillering stages declined under increasing levels of nitrogen, but nitrogen increased tolerance during late-tillering stages. Planthopper damage to IR22 in field cages was severe and hopperburn (plant death) occurred in 83% of IR22 plants under high nitrogen (60–150 kg N ha−1). In contrast, despite planthopper infestations, damage to IR62 was low in field-grown plants and productivity (tillers, roots, shoots and grain) increased in IR62 under increasing nitrogen. Our results indicate that, whereas nitrogenous fertilizer increases planthopper fitness on susceptible and resistant varieties, the net effects of high nitrogen on IR62 include decreased planthopper biomass-density (apparent in all experiments) and higher tolerance to damage during later growth stages (observed in the greenhouse, and during one of two seasons in field cages).

Performance of &lt;i&gt;Glomus clarum&lt;/i&gt; and &lt;i&gt;Tithonia diversifolia&lt;/i&gt; compost in improving growth and yield of tomato (&lt;i&gt;Lycopersicum esculentum&lt;/i&gt; Mill)

Screen house experiments were conducted at the Institute of Agricultural Research and Training, Ibadan, on a sandy loam soil in two years, to assess the effect of arbuscular mycorrhizal fungus ( Glomus clarum ) and compost (sunflower) on the growth and yield of tomato plants. The experimental design was laid out in a Complete Randomized Design (CRD) with nine treatments replicated three times. Arbuscular mycorrhizal fungi (AMF) and Compost (CMP) were applied into 8 kg soil each at the levels of 2.5, 5.0, 7.5 and 10 tonnes/ha each (2.5 g, 5.0 g, 7.5 g and 10 g respectively), while the control had 0 tonnes /ha (0 g). Results showed that plants treated with 5.0 tonnes/ha AMF produced highest cumulative weight of harvested fruits per plant and number of fruits per plant which were significantly higher (P<0.05) than other treatments. Application of 2.5 tonnes/ha CMP significantly (P<0.05) produced the highest number of tomato leaves per plant, while the highest number of flowers per plant was significantly higher for 7.5 tonnes/ha CMP. The tallest plants and plants with highest number of branches were also recorded for 5.0 tonnes/ha AMF. This study showed that 5.0 tonnes/ha is the optimum level of AMF required for the cultivation of tomato plant which could have arisen from optimum uptake of phosphorus in the soil. Keywords : Compost, Glomus clarum, fertility, tomato, yield

Effect of Heterodera sacchari on growth and yield of selected upland NERICA rice in Nigeria

Pot and field trials were conducted in 2012 and 2013 cropping seasons in Nigeria to determine the damage of Heterodera sacchari on the growth and yield of upland New Rice for Africa (NERICA) derived from hybridisation of Oryza sativa and O. glaberrima. NERICA rice (NR) cultivars selected were NR1, NR2, NR3, NR8 and NR14. In screenhouse experiments, rice seedlings were inoculated with 2500, 5000 and 10000 eggs and second-stage juveniles of H. sacchari, three weeks after sowing. In addition, two consecutive field experiments were carried out on a naturally infested field. Data on plant growth, yield, and final H. sacchari population densities were taken at the end of the experiments. Significant reductions of 34, 60 and 78% were observed in plant height, fresh root and total seed weights, respectively. Infected plants also produced chlorotic tillers and showed delayed panicle emergence. In field experiments, rice yield was reduced by approximately 50 and 85% in the first and second cropping seasons, respectively. Nematode population densities in soil and roots of rice plants increased significantly in infected plants compared to the controls. The results of this study indicate that H. sacchari is a serious pathogen of susceptible upland NR cultivars and may cause total crop failure when NR is continuously cultivated in cyst nematode infested fields.