Surface sealing and hardpans in loam soils are problematic in the Mid-South U.S. because of intense tillage. Two experiments quantified the effects of soil management practices on infiltration and maize yield in loam soils. The first study measured the impacts of in-row subsoiling frequency × furrow irrigation frequency. In-row subsoiling significantly improved the infiltration of irrigation but not the infiltration of precipitation. In-row subsoiling with low irrigation frequency is optimal to achieve profitable maize yields while encouraging groundwater conservation. In the second study, six soil management treatments were imposed. For single-ring infiltrometer tests, infiltration rates were different between the two measurement dates but not between measured treatments. In 2022, neutron attenuation data indicated no differences in soil water content between measured treatments. Based on both studies, in-row subsoiling was proven to be an economically viable option in comparison to other Mississippi Delta on-farm conservation practices in the short term.

<p dir="ltr">Routine testing of nutrient concentrations via plant tissue is an important component of in-season fertilizer management in maize (<i>Zea</i> <i>mays </i>L.) cropping systems. Accuracy of results are critical for nitrogen (N), phosphorous (P), potassium (K), and sulfur (S) management, yet there is little scientific guidance on which leaf to sample during mid- to late-vegetative growth stages. Additionally, the whole-plant status of each macro-nutrient may be best represented by a different leaf position due to mobility differences among nutrients. Mobility of each nutrient and allocation within the plant may also be influenced by environmental factors, management strategies, and genotype selection. Field experiments were conducted in West Lafayette and Windfall, Indiana in 2021 and 2022. The objectives were to (1) evaluate N, P, K, and S concentrations of specific leaf positions and whole plants in response to N fertilizer rate (NR), planting density (PD), and genotype (G) treatments at multiple growth stages, and (2) determine the ability of various leaf positions to predict whole-plant concentrations of N, P, K, and S across multiple NR, PD, and G environments. The West Lafayette study compared three NR treatments applied as urea-ammonium nitrate (UAN, 28-0-0) at the V5 growth stage and included (1) Control, no N applied, (2) 151 kg N ha^-1, and (3) 241 kg N ha^-1. The Windfall study compared two side-dress UAN rates of (1) Control, no N applied, and (2) 224 kg N ha^-1 at two planting densities (sub-plot) of 49,400 plants ha^-1and 89,000 plants ha^-1 with 4 Pioneer^® genotypes (sub-sub-plot) including two historical double-cross hybrids and two modern single-crosses. Tissue sampling included the top-collared leaf and whole-plant at V8, the 8^th leaf, top-collared leaf, and whole-plant at V12, and the 8^th leaf, 12^th leaf, ear-leaf, top-collared leaf and whole-plant at R1. Tissue N concentrations were consistently responsive to NR and PD treatments at all stages, but bottom leaves better reflected NR changes. As a mobile nutrient, N concentrations were highest in the uppermost leaf positions by R1 (ear-leaf and top-leaf), yet regressions between individual leaf and whole-plant N% were highest in the lower leaf positions (8^th and 12^th leaf positions). This suggested that the more likely a specific leaf was to exhibit nutrient deficiency symptoms, the better it would be at predicting whole-plant concentrations of that nutrient. Regressions between individual-leaf and whole-plant N% (modern genotypes only) increased from V8 to R1 and regressions were best with the 12^th leaf position at both V12 and R1. Tissue S concentration responses to NR increased at later growth stages, and top-leaf S was a stronger reflection of whole-plant S than the 8^th leaf. Despite S concentration differences among leaf positions at R1, the strength of regressions between each leaf position and whole-plant S were similar. There was no optimal leaf position to represent whole-plant S. While leaf N and S concentrations were above whole-plant concentrations, leaf P and K concentrations exhibited the opposite dynamic. There was little leaf P response to experimental treatment factors, and although regressions for leaf P versus whole-plant P concentrations were far weaker than for N, S or K, the 8^th leaf position was preferred at V12 and R1 (R² of just 0.27 and 0.36, respectively). Potassium concentration response to NR was weak. However, leaf K% and whole-plant K% were highly related via regression, irrespective of NR, at all three stages. Prediction of whole-plant K was strongest with the 8^th leaf at V12 and the 12^th leaf at R1. In summary, optimum leaf sampling position was shown to vary with individual macronutrients and growth stages in maize. Although more research is essential, these preliminary results indicate that traditional sampling methods involving selection of the top fully-expanded leaf from V8 to silking, and the ear-leaf during post-silking stages, may not be the most reliable indicators of whole-plant nutrient status.</p>

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

Följande uppsats redogör för ett produktutvecklingsprojekt som har resulterat i ett förslag till ett handredskap för framställning av majsmjöl, tänkt att användas av kvinnorna i Malawi. Dock har det huvudsakliga fokuset i projektet varit metoder för produktutveckling för utvecklingsländer. Problemområdet som projektet har fokuserat på; framställning av majsmjöl, valdes efter en studie i Malawi. Problemområdet valdes eftersom det är ett viktigt område, då 50 procent av människornas kaloriintag i Malawi består av majs. Målgruppen för projektet är kvinnorna i byn Muthumba, som framställer majsmjölet idag. Framställningen av majsmjöl sker i flera olika etapper. När majsen slutligen ska malas till majsmjöl har byborna att välja mellan att vandra till ett annat samhälle, som har elektricitet, för att få sin majs mald i en maskin, eller att stöta majsen i en mortel, vilket kräver två personers styrka och tid. Att ta majsen till det andra samhället innebär att byborna får vandra med majsen på huvudet i timtal, då majoriteten av byborna inte innehar något transportmedel. Projektet kan delas in i tre olika etapper. Teoriläsning inför resan. Observationer och intervjuer i Malawi under 8 dagar. Denna etapp var planerad till 21 dagar, men på grund av sjukdom fick studien avbrytas tidigare, syftet med studien var att observera ett problemområde. Den sista etappen utfördes i Sverige. Den innehöll teoriläsning, kompletterande intervjuer samt utveckling av redskapet. Uppsatsen behandlar litteratur kring ämnet produktutveckling/design för utvecklingsländer samt metoder för detta. Saker som framkom var att förståelse för människan och dess livssituation är avgörande för hur lyckat slutresultatet blir. När ämnet design för utvecklingsländer diskuteras finns det många olika åsikter i ämnet, och den här uppsatsen tar upp några. Projektet resulterade i ett handdrivet verktyg, riktat till kvinnorna byn Muthumba i södra Malawi. Redskapet krossar majsen genom valsning. Några av de metoder som använts för att få fram nya sätt att framställa majsmjölet är idégenereringsmetoder, hämta inspiration på nya platser, intervjuer och skissning. En annan viktig del i utvecklingsarbetet har varit att göra funktionsmodeller för att testa olika funktioner. / The following essay describes a product development project, which has resulted in a proposal for production of maize flour, intended for use by women in Malawi. The main focus of the project has been methods of product development for developing countries. The problem area that the project has focused on is: the production of maize flour, this was chosen after a study in Malawi. The problem area was chosen since it is an important area; 50 percent of the people's calorie intake in Malawi consists of corn. The target groups are women in the village Muthumba, a producer of maize flour today.Production of maize flour is done in several steps. When the maize will be grinded in to maize flour, the villagers can choose to walk to another village, which has electricity, to get their maize grinded or they have to pound the maize in a mortar, which requires the energy and time of two people. To take the maize to the other society means that the villages have to walk with the maize on their head for hours, as the majority of villagers do not own a bike.The project can be divided into three stages: theory studies before the trip, observations and interviews in Malawi for 8 days (this phase was scheduled for 21 days, but due to illness was the study stopped earlier, the purpose of this study was to observe a problem area) and the final stage, realization, was conducted in Sweden. The third stage included theory sessions, additional interviews and developing the tool.The essay reviews the literature on the subject of what to consider in the development/design for developing countries and methods for this. Understandings that emerged were the incredible importance of deeper insight in humans and their life situation. When the topic design for developing countries is discussed, there are many different opinions on the subject, and this essay considers some.The result of the project is a hand-powered tool. The target group is the women in the village Muthumba, in south of Malawi. The tool grinds the maize by rolling. Some of the methods used to develop new ways to produce corn flour are brainstormings, finding inspiration in new places, interviews and drafting. Another important part of the development has been to make functional models to test various functions.

Diplodia ear rot (DER) of maize (Zea mays L.) caused by the fungus, Stenocarpella maydis (Berk.) Sutton has increased in incidence in localized fields over the past decade. My research focused on screening for resistance by examining the development of DER following inoculations prior to flowering, analyzing a diallel cross for DER resistance, and examining the genetic variability of the fungus from isolates collected from the U.S. and the Republic of South Africa. DER developed in maize following inoculations with a spore suspension prior to flowering in both greenhouse and field evaluations. A spore suspension gave a better differentiation of resistance responses than dried preparations of colonized millet, colonized ground popcorn, or kernels from a diseased maize ear, all applied in the whorl 10 to 15 days prior to flowering (V12 for inbreds), and natural occurrence of disease. General combining ability was significant for both 1994 and 1995 growing seasons in an analysis of the F₁ of the diallel cross, indicating that additive gene action may be responsible for resistance and could be introduced into commercial cultivars. Specific combining ability was significant in 1995 and indicates that dominant gene action or epistasis may play role in DER resistance. There were minimal numbers of isozyme polymorphisms found in my S. maydis collection. Two isolates were polymorphic for esterase, two isolates were polymorphic for hexokinase and malate dehydrogenase and one isolate was polymorphic for hexose kinase. Fungi that have limited isozyme polymorphisms often are biotrophs or fungi with formae speciales which are usually limited to one host. These groups of fungi usually have races and this may indicate that a gene-for-gene interaction exists. These findings suggest that i) the whorl inoculation separates genotypes into resistant, intermediate, and susceptible groupings; ii) additive gene action is predominant form of inheritance, and iii) there are few isozyme polymorphisms in the population of S. maydis sampled. / Ph. D.