Agricultural Science Commons^™

Effects Of Micro-Rates Of 2,4-D And Dicamba On Lettuce And Pumpkin In Nebraska, Xinzheng Chen

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Off-target herbicide injury from dicamba and 2,4-D is an increasingly common problem for specialty crop growers in the Midwestern United States. Both lettuce (Lactuca sativa L.) and pumpkin (Cucurbita spp.) are common specialty crops grown in Nebraska, and their proximity to corn and soybean production makes these crops susceptible to herbicide drift injury and yield loss. The objectives of this thesis research was to quantify crop injury and yield loss in greenhouse- and field-grown lettuce and field-grown pumpkins at different growth stages after exposure to sub-lethal doses of dicamba or 2,4-D. Dose response curves were generated to determine …

Genetic Diversity And Population Structure Of Sugarcane (Saccharum Officinarum L.) Collected From Seven Philippine Regions For Use As Breeding Stocks For Crop Improvement, Jan Leandro Acedera, Jhun Laurence Rasco, Jemimah Banganan, Antonio Lalusin

The Philippine Agricultural Scientist

Selection of parents for hybridization relies on the information on their genetic relationship and diversity which are essential in any breeding program. This study aimed to estimate the extent of genetic diversity and population structure of 76 sugarcane accessions from seven regions in the Philippines using 57 morphological characters and 50 microsatellite markers. The sugarcane collections exhibited moderate to high diversity with mean of H’ = 0.72 for qualitative and H’ = 0.75 for quantitative morphological characters, respectively. This is corroborated by the analysis of variance (ANOVA) of agronomic parameters, except for stalk length. Unweighted Pair Group Method with Arithmetic …

Data From A Public–Industry Partnership For Enhancing Corn Nitrogen Research, Curtis J. Ransom, Jason Clark, Gregory Mac Bean, Chris Bandura, Matthew E. Shafer, Newell R. Kitchen, Et.Al

Agronomy, Horticulture and Plant Science Faculty Publications

Improving corn (Zeamays L.) N managementis pertinent to economic andenvironmental objectives. However, there are limited comprehensive data sources to develop and test N fertilizer decision aid tools across a wide geographic range of soil and weather scenarios. Therefore, a public-industry partnership was formed to conduct standardized corn N rate response field studies throughout the U.S. Midwest. This research was conducted using a standardized protocol at 49 site-years across eight states over the 2014–2016 growing seasons with many soil, plant, and weather related measurements. This note provides the data (found in supplemental files), outlines the data, summarizes key findings, and highlights …

Three Lc-Ms Plant Metabolomics Studies Of Hop (Humulus) Species: Wild H. Neomexicanus, Drought Stress, And Agricultural Terroir, Taylan Morcol

Dissertations, Theses, and Capstone Projects

The hop plant (Humulus L., Cannabaceae) is a dioecious, perennial, twining vine with a long history of human use. Nowadays, hop plants are generally grown for their inflorescences (“cones”), which are used in brewing for their phytochemical metabolites. Many of these metabolites are involved in plant stress response and communication. Genetics and environment are two major factors that affect plant metabolism. In three separate metabolomics studies, this project examined the effects of both genetic and environmental factors on hop phytochemistry.

In the first study, 23 hop genotypes were grown in two different locations in the Pacific Northwest region of …

How Is Organic Farming Performing Agronomically And Economically In Sub-Saharan Africa?, Christian Schader, Anja Heidenreich, Irene Kadzere, Irene Egyir, Anne Muriuki, Joseph Bandanaa, Joseph Clottey, John Ndungu, Christian Grovermann, Gianna Lazzarini, Johan Blockeel, Christian Borgemeister, Adrian Muller, Fred Kabi, Komi Fiaboe, Noah Adamtey, Beate Huber, Urs Niggli, Matthias Stolze

All Peer-Reviewed Publications

The potential of organic agriculture and agroecological approaches for improving food security in Africa is a controversial topic in global discussions. While there is a number of meta-analyses on the environmental, agronomic and financial performance of organic farming, most of the underlying data stems from on-station field trials from temperate regions. Data from sub-Sahara Africa in particular, as well as detailed real-farm data is scarce. How organic farming is implemented in sub-Saharan Africa and how it performs in a smallholder context remains poorly understood. We applied a novel observational two-factorial research design, which allowed to evaluate the impacts of i) …

Evaluating Livestock Farmers Knowledge, Beliefs, And Management Of Arboviral Diseases In Kenya: A Multivariate Fractional Probit Approach, Paul Nyamweya Nyangau, Jonathan Makau Nzuma, Patrick Irungu, Menale Kassie

All Peer-Reviewed Publications

Globally, arthropod-borne virus (arbovirus) infections continue to pose substantial threats to public health and economic development, especially in developing countries. In Kenya, although arboviral diseases (ADs) are largely endemic, little is known about the factors influencing livestock farmers’ knowledge, beliefs, and management (KBM) of the three major ADs: Rift Valley fever (RVF), dengue fever and chikungunya fever. This study evaluates the drivers of livestock farmers’ KBM of ADs from a sample of 629 respondents selected using a three-stage sampling procedure in Kenya’s three hotspot counties of Baringo, Kwale, and Kilifi. A multivariate fractional probit model was used to assess the …

Estimating Maize Lethal Necrosis (Mln) Severity In Kenya Using Multispectral High-Resolution Data, Kyalo Richard, Elfatih M. Abdel-Rahman, Sevgan Subramanian, Johnson O. Nyasani, Michael Thiel, Hossein J. Jozani, Christian Borgemeister, Bester T. Mudereri, Tobias Landmann

All Peer-Reviewed Publications

Maize lethal necrosis (MLN) is a severe disease in maize that significantly reduces yields by up to 90% in maize-growing regions such as Kenya and other countries in Africa. The disease causes chlorotic mottling of leaves and severe stunting which leads to plant death. The spread of MLN in the maize-growing regions of Kenya has intensified since the first outbreak was reported in September 2011. In this study, the RapidEye (5 m) imagery was combined with field-based data of MLN severity to map three MLN severity levels in Bomet County, Kenya. Two RapidEye images were acquired during maize stem elongation …

Predicting Non-Native Insect Impact: Focusing On The Trees To See The Forest, Ashley N. Schulz, Angela M. Mech, Matthew P. Ayres, Jamal J.K. Gandhi, Nathan P. Havill, Daniel A. Herms, Angela M. Hoover, Ruth A. Hufbauer, Andrew M. Liebhold, Travis D. Marsico, Kenneth F. Raffa, Patrick C. Tobin, Daniel R. Uden, Kathryn A. Thomas

Department of Agronomy and Horticulture: Faculty Publications

Non-native organisms have invaded novel ecosystems for centuries, yet we have only a limited understanding of why their impacts vary widely from minor to severe. Predicting the impact of non-established or newly detected species could help focus biosecurity measures on species with the highest potential to cause widespread damage. However, predictive models require an understanding of potential drivers of impact and the appropriate level at which these drivers should be evaluated. Here, we used non-native, specialist herbivorous insects of forest ecosystems to test which factors drive impact and if there were differences based on whether they used woody angiosperms or …

Effect Of Fungicide Application On Seed Yield Of Perennial Ryegrass, Piotr Goliński

IGC Proceedings (1977-2023)

In four plot experiments established according to random blocks, application effectiveness of propiconazol + carbendazim (Tilt), propiconazol + fenpropimorph (Archer), flusilazol + carbendazim (Alert) and epoxiconazol + crezoxim-metil (Juwel) pesticides regarding the infection by fungal diseases of plant inflorescence structure, biological floret site utilisation, thousand seed weight and harvested seed yield of perennial ryegrass cv. Anna (2n) and cv. Maja (4n) was analysed. The Archer preparation was found to be the most effective, both in the case of Anna and Maja cultivars. Its application was found to increase seed yield in Anna and Maja cultivars by, respectively, 21,5% and 14,5%. …

Genetic Control Of Parthenogenesis In Kentucky Bluegrass: Results From A Sexual X Apomictic Cross, E. Albertini, G. Barcaccia, A. Porceddu, D. Rosellini, Mario Falcinelli

IGC Proceedings (1977-2023)

Apomixis, as it exists in Poa pratensis L., permits to combine genotype fixation with propagation by seed. The process of apomictic seed production involves the formation of embryo sacs without meiotic reduction (apospory) and embryos without egg cell fertilization (parthenogenesis). Further information on the genetic control of apomixis was obtained by analyzing aposporous parthenogenesis and the segregation of molecular markers in a progeny resulting from a “sexual” (S) x “apomictic”(A) cross. Data from the 35 F₁ plants examined so far have shown that parthenogenesis segregated 1:1, confirming control by a dominant gene, simplex in the parthenogenetic parent. Analysis of …

Effects Of Water Stress On Seed Production In Ruzi Grass (Brachiaria Ruziziensis Germain And Everard), N. Wongsuwan, A. C. P. Chu, B. R. Watkin

IGC Proceedings (1977-2023)

Water stress at different stages of reproductive development influenced seed yield in Ruzi grass differently. Under mild water stress, the earlier in the reproductive developmental stage the stress was applied (before ear emergence) the faster the plants recovered and the less the ultimate damage to inflorescence structure and seed set compared with the situation where water stress occurred during the later stages after inflorescences had emerged. Conversely, severe water stress before ear emergence had a severe effect in damaging both inflorescence numbers and seed quality. Permanent damage to the reproductive structures resulted in deformed inflorescences. Moreover, basal vegetative tillers were …

Effect Of Temperature On Phenology In Triple-Awned Grass (Stipagrostis Plumosa), Hossein Azarnivand, H. Dastmalchi

IGC Proceedings (1977-2023)

Phenology of triple-awned grass in different stages of vegetative growth, flowering and seed falling was investigated. Each phenological stage was related to minimum and maximum air and soil surface temperatures. Soil surface temperature was measured two times per day during different seasons. Climate data were obtained from the nearest weather station. The study was carried out in sand dunes of band-e-rig of Kashan in the central region of Iran. This species is important in terms of wind erosion control and livestock feeding in arid areas. The results showed that air temperatures ranged from –22 ^oC to 41.5 ^oC …

Morphogenesis And Growth Analysis Of Mombaçagrass (Panicum Maximum) During Establishment And Regrowth, Carlos A. M. Gomide, J. A. Gomide, C. A. M. Huaman

IGC Proceedings (1977-2023)

Mombaçagrass grown in pots was evaluated regarding leaf appearance, elongation and senescence rates; leaf area indices, photosynthetcly active radiation (PAR) interception and the growth indices: leaf area ratio (LAR), net assimilation rate (NAR) and relative growth rate (RGR). Three growths were considered: seminal growth and regrowth after harvest take on the 16^th and 37^th day of the seminal growth.

The seminal growth exhibited the highest values for leaf appearance, elongation and senescence rates as compared to aftermath growths. LAI rose linearly from the 20^th to the 77^th day of the seminal growth, as well as during …

Tillering Dynamics In Mombaça Grass (Panicum Maximum, Jacq.) Under Grazing, E. M. Coelho, V. R. Herling, M. A. Gomes, R. J. Schmidt, C. G. Lima

IGC Proceedings (1977-2023)

An experiment was conducted in Pirassununga, Southeastern Brazil, to observe tillering pattern of Mombaça grass (Panicum maximum Jacq.) after grazing. A complete randomized block design was used with treatments arranged in factorial (3 herbage allowances X 2 grazing periods). There was high and positive correlations between the total tiller population and the number of tillers until the third week after grazing, giving evidence of a higher tillering until the second week and a slight reduction on the third one. The Mombaça grass tillering dynamics alters along the weeks according the allowance level adopted.

Response Of Mombaça Grass (Panicum Maximum Jacq.) To Nitrogen Doses And Clipping Frequency, Gustavo J. Braga, P. H. C. Luz, V. R. Herling, R. J. Schmidt, C. G. Lima

IGC Proceedings (1977-2023)

The present experiment had the objectives of determining the response of Mombaça grass (Panicum maximun Jacq.) to three levels of nitrogen fertilizer (0, 250, 500 kg/ha) and two clipping frequencies (28 and 42 days). Dry matter yield (DMY), density and the average weight of tillers and the mean stage count (MSC), value that represents the quantity of the plant phenological development were evaluated. Nitrogen levels affected DMY, with the 500 kg/ha of N resulting in highest yield, and highest MSC as well. The number of tillers responded positively until the 250 kg/ha level. The 42-day frequency gave higher numbers …

Herbage Allowance And Nitrogen Fertilization Effects On Morphological Characteristics Of Paspalum Notatum Flügge, P. Boggiano, G. E. Maraschin, Carlos Nabinger, J. Riboldi, Mónica Cadenazzi

IGC Proceedings (1977-2023)

The grazing study was conducted at the Estação Experimental Agronomica – UFRGS, 30^o S, on a native pasture, to evaluate the leaf area index and structural morphological traits of bahiagrass (Paspalum notatum Fl.), within the requirements of a Central Composite Rotatable experimental design, providing for equal precision, with two blocks, encompassing two factors at five levels each, namely: Herbage Allowance (HA) = 4.0; 5.5; 9.0; 12.5 and 14.0 kg green dry matter per 100 kg liveweight per day (% LW), in association with Nitrogen (N) fertilization levels of 0; 30; 100; 170 and 200 kg ha^-1 as …

Influence Of Fertilization On Botanical Composition And Productivity Of Rangeland In A Semi-Arid Climate Of South Africa, Hennie A. Snyman, I. B. Oosthuizen

IGC Proceedings (1977-2023)

The objective of this study was to determine the short-term response of rangeland to fertilization rangeland (all combinations of 0; 10; 30 and 50 kg ha^-1 nitrogen, with 0 and 10 kg ha^-1 of phosphorus) in terms of dry matter production and botanical composition. After three years of fertilization, the botanical composition of the high-N fertilized plots changed completely from a climax to sub-climax vegetation. Wire grass (Elionurus muticus) showed the greatest decrease in frequency (62%) due to N fertilization. Phosphorus fertilization had an insignificant influence on species composition over the three years. The increase (P< 0.01) in production with increased N fertilizer, peaked in the second season, declining afterwards. With N and P fertilizer applied together, the production increased constantly and peaked in the last season. After three years the production increased (P≤ 0.01) with the application of N together with P, compared to the applying of only N. The higher the amount of fertilizer, the more sensitive to drought the climax grasses became. The results confirm the vulnerability of native grasses in dry areas, due to change in soil fertility.

Defoliation And Water Deficit: Their Influence On Pasture Growth And Water Use Of White Clover, F. H. Santiñaque

IGC Proceedings (1977-2023)

With the objective of understanding the physiological basis of defoliation and water use relationships of white clover (Trifolium repens L.) pastures during water deficits, an experiment in controlled conditions was carried out. Outdoors nine liters pots were filled with a loam-clay soil with a water content at field capacity (FC), of 35%(w/w), at a bulk density of 1.1 g/cm³. Pre-germinated and inoculated clover seeds were transplanted, and the number of plants was adjusted to permit the development of full plant cover. The level of P in the soil did not limit plant establishment or growth. The …

Seasonal Botanical Composition And Available Forage Of Natural Grasslands In The Southeastern Range Region Of Rio Grande Do Sul, Brazil, J. C. L. Reis, H. Alfaya, O. J. W. Siqueira, C. B. Farias Jr.

IGC Proceedings (1977-2023)

The objective of the study was to verify the influence of climatic seasons on botanical composition and on available dry matter of grasslands in the physiographic region known as Serra do Sudeste (Southeastern Range), RS, Brazil. The climate is Cfb according to Koëppen`s classification. The experiment was conducted in two natural grasslands submitted to two pre-experimental stocking rates [area 1: 0.65 AU ha^-1 (normal grazing); area 2: over 2.0 AU ha^-1 (overgrazing); AU: Animal Unit = 500kg live weight]. Stocking rates throughout the experimental period (June 1996–July 1997) were 0.4 and 0.65 AU ha^-1, over winter …

Effect Of Sowing Time On Phytomass Production During Early Growth Of Two Varieties Of Stylosanthes Guianensis (Aubl.) Sw., M. L.S. Paterniani, T. J. D. Rodrigues, G. T. Pereira, L. R. A. Rodrigues

IGC Proceedings (1977-2023)

The objective of this research was to determine the effect of two sowing times on phytomass production of two varieties of Stylosanthes guianensis (var. pauciflora and var. vulgaris). Two experimental periods were studied (1: January - May/1998 and 2: November/1998 - March/1999) using a completely randomized factorial design 2 x 2 x 14 (two periods, two varieties and fourteen ages of evaluation), with four replications. The results showed a difference between the periods concerning the growth and development of Stylosanthes, and that period 2 was the most favourable to this forage plant. There was, also, different adaptability between …

Influence Of Water Stress On Protein Concentration In Themeda Triandra Forsk. In A Semi-Arid Climate Of South Africa, I. B. Oosthuizen, Hennie A. Snyman

IGC Proceedings (1977-2023)

The objective of this study was to determine the influence of four water treatments (T1 = 75-100%, T2 = 50-75%, T3 = 25-50% and T4 = 0-25% of Field Water Capacity) on the concentration of water-soluble protein as growth reserve during three growth stages (vegetative, pipe and reproductive) in three plant parts (roots, stubble and leafs). The water-soluble protein concentration (WSPC) in the plants under the four water treatments differed (P≤0.01) among the plant parts as well as among growth stages (P≤0.05). WSPC in leafs increased (P≤0.01) with increased water stress from T1 to T4 for the pipe growth stage. …

Effects Of Photoperiod, Low Temperature And N Nutrition On Vsp Accumulation In Taproot Of Alfalfa, J. C. Avice, C. Noquet, A. Ourry, J. J. Volenec

IGC Proceedings (1977-2023)

In Medicago sativa L., vegetative storage protein (VSP), specifically accumulated in taproot, are strongly involved in nitrogen storage. How the accumulation of such VSPs is regulated remains largely unknown. Experiments were designed with non-nodulated alfalfa to determine if length of the photoperiod, a decrease of temperature, or high availability of mineral nitrogen may induce the accumulation of VSPs. ¹⁵N labelling was used to quantify nitrogen uptake and its further relative translocation within the plant while VSPs accumulation was analysed by ELISA quantification. Results showed that environmental factors such as shortening daylength or low temperature changed biomass allocation within the …

Fructans From Elongating Leaf Bases Are A Source Of Carbon For Regrowth After Defoliation In Lolium Perenne, A. Morvan-Bertrand, J. C. Avice, M. P. Prud'homme

IGC Proceedings (1977-2023)

A detailed study of carbohydrate metabolism in perennial ryegrass (Lolium perenne L.) during the first 48 h of regrowth showed that the decline in fructan concentration occurred not only in the differentiation zone (30-60 mm from leaf base), but also in the elongation zone of the elongating leaf bases. Unlike other soluble carbohydrates, the net deposition rate of fructose remained positive and even rose during the first day following defoliation. FEH (fructan exohydrolase) activity, which was maximum in the differentiation zone before defoliation, increased in all segments but peaked in the elongation zone after defoliation. Taken all together, these …

Effect Of Climatic Factors On The Plant Population Dynamics In Temperate Pasture Implantation, B. Martin, R. Refi, S. Montico, M. Costanzo

IGC Proceedings (1977-2023)

The objective of this experiment was to determine the environmental influence on seedling emergence of alfalfa and fescue in mixture. We hypothesized that the temperature and precipitation data could be used to estimate field emergence of alfalfa and fescue. A field trial was carried out at Zavalla, Argentina and consisted of sowing a tall fescue – alfalfa mixture at different seeding date (March, April and June). Relationships between the range of temperature, rainfalls and alfalfa and fescue seedling emergence were described by linear regression models. Patterns of emergence and death of alfalfa and fescue seedling were found in the different …

Seed Production And Quality Of Buffelgrass (Cenchrus Ciliaris) Selections, N. F. G. Rethman, W. H. Boshoff

IGC Proceedings (1977-2023)

As seed production and quality are critical considerations in the commercialization of new cultivars, an evaluation programme of promising Cenchrus ciliaris (Buffelgrass) accessions placed particular emphasis on these parameters. Accessions identified for registration proved to be superior in both respects, although storage of seed or cleaning of fresh seed reduced the differences in germination between accessions. The refinement of seed cleaning processes should receive greater emphasis by commercial concerns.

Effect Of The Hierarchical Position Of Individuals In A Medicago Sativa Stand On Shoot Respiration, M. Lötscher, Hans Schnyder

IGC Proceedings (1977-2023)

The influence of the hierarchical position on the relationship between C gains and C losses (respiration) of individuals was investigated in a alfalfa (Medicago sativa) stand. The hierarchical position that an individual occupied was defined by its height relative to the stand height. Stands were established by arranging potted individual plants at a density of 400 plants m^-2. Stands were grown in growth cabinets. ¹³C steady-state labelling was used to assess C fixation (C_new) by individuals during a photoperiod of 16 h. Respiration of shoots was measured during the following 8 h dark …

Patterns Of Development And Nitrogen Reserves Mobilization During Regrowth Of Defoliated Clover, F. Le Dily, E. Goulas, P. Lainé, E. Le Deunff

IGC Proceedings (1977-2023)

Contribution of nitrogen reserves to regrowth following defoliation was studied in white clover plants (Trifolium repens) according to the morphological pattern of differentiation of the aerial parts during the same period. Low temperature and short day lengths were used as a pre-treatment in order to increase branching and enhance new sites of leaf production during a further 25 d period of regrowth. Pre-treated plants exhibited a large reduction in leaf area largely counterbalanced with a high increase in leaf pool size during the first 10 d of regrowth. The mobilization of nitrogen reserves during regrowth of defoliated clover …

Resistance To Drought In Shore Elurope (Aeluropus Litoralis) And Weeping Alkaligrass (Puccinellia Distans), Mohammad Jafari, A. G. Firouzabadi

IGC Proceedings (1977-2023)

Two rangeland grass species, Shore Elurope (Aeluropus litoralis) and Weeping Alkaligrass (Puccinellia distans) were studied. The research was done under a split plot experiment and completely randomized design. Plants were grown under two irrigation treatments (seven and fourteen day periods of irrigation treatments). Morphological response included determination of wilting percentage, leaf water potential, production of yield, root dry weight, weight ratio of root/stem and finally total dry weight of species. Anatomical studies included leaf descriptive structure such as comparison of stomata and their density in area unit, study of vascular structure, mesophyl tissues and epiderm. Results …

Allelopathic Influence Of Eragrostis Curvula Water Extract On Seed Germination And Seedling Growth Of Two Other Species, R. W. Coelho, R. E. Schmidt

IGC Proceedings (1977-2023)

Weeping lovegrass (Eragrostis curvula Schrad. Nees) is a very agressive tropical species and does not grow well with other species. This study was set up to investigate the allelopathic effect of various extract concentrations of weeping lovegrass on seed germination of white clover (Trifolium repens L.) and bentgrass (Agrostis stolonifera L.) and the seedling development of white clover. Labotatory and growth chamber studies were conducted. Extract concentrations of 13.6, 27.2, 40.8, 54.4, and 62.0 g/100mL of water were studied. Treatments were arranged in a completely ramdomized design with three replications. The allelopathic effect of weeping lovegrass was …

Effect Of Aging In Tillers Of Panicum Maximum On Leaf Elongation Rate, D. D. Carvalho, C. Matthew, J. Hodgson

IGC Proceedings (1977-2023)

Two cultivars of Guinea grass (P. maximum, Jacq.), Mombaça and Tanzânia, were cultivated in five litre pots, as single plants, in a green house. Plants were subjected to three defoliation levels (100, 200 and 400 mm height) for five successive monthly harvests. The experimental design was a 3x2 randomised block with five replicates. Three types of tiller (main, primary and secondary) were selected, at random, on each plant and leaf elongation rate (LER) above cutting height was measured, weekly, between harvests. There were significant differences (P < 0.05) in LER between tiller types in cv. Mombaça in all periods, but only in period two in cv. Tanzânia. In the last period tillers were classified, at random, as old (over four months age) mature (between two and four months) and young (between one and two months). Old tillers had a lower (P < 0.05) LER than the other two categories in both cultivars and lower (P < 0.05) SLA (specific leaf area) in Mombaça.