Kartul mahe- ja tavaviljeluse süsteemide võrdluskatses aastatel 2008-2012

Kartul on üheks armastatumaiks kultuuriks nii meil kui maalimas. Kartulit on läbi aegade peetud teiseks „leivaks“ ning tänapäeval ei kujutaks meist keegi ette oma toidulauda, kui sealt puuduks toidukartul. Maheviljelus on Eestis aasta-aastalt laienenud on mahekartulikasvatuse pindala siiski iga aastaga vähenenud. Uurimistöö eesmärk oli uurida kuidas erinevad viljelusviisid mõjutavad mugulate saagistruktuuri elemente ning kui suurt mõju avaldab see saagi kvaliteedile

Viljelussüsteemide mõju kartuli mugulasaagile ja kvaliteedile

A Thesis for applying for the degree of Doctor of Philosophy in AgricultureThe world’s population is estimated to exceed over 9 billion people by 2050 (FAO, 2013), thus the demand for high yielding, good quality crops as well as the “challenges for the sustainability of the ecosystems” increases (Somers and Savard, 2015). Proper crop management is a key element in achieving high yields of good quality. Crop rotation, animal manures, and winter cover crops as catch crops (CC) play important roles in sustainable plant production systems because they provide nutrients for the system (Stark and Porter, 2005). CC and animal manures are mainly used by organic producers, because these are the main nutrient-rich sources for organic crop production. Animal manures are used by conventional producers only if, in addition to crop production, they have also livestock. Conventional producers, who grow only crops, largely depend on mineral fertilizers and different synthetic agrochemicals. According to Luik et al. (2008) conventional systems might not be sustainable in the long term, because they tend to be oversimplifi ed and maximally intensifi ed. But Edwards-Jones and Howells (2001) claimed that neither conventional nor organic farming systems (FS) are sustainable because both of them require inputs from non-renewable resources and, one way or another, they both impact on the environment. For organic producers there are also two main challenges, such as managing diseases and nutrients since nutrient availability is limited and there are only a few effective pesticides available that are allowed for use (Finckh et al., 2006). Also, Nelson et al. (2009) confi rm that in organic systems nutrient transformations almost exclusively relyon soil. In conventional systems, if there are problems with diseases or pest and with plant malnutrition, synthetic agrochemicals and mineral fertilizers can be provided throughout almost the entire growing season. Despite some limitations in organic farming, organic agriculture is based on its own self-regulating production system, and the concept of a farm is as an agro-ecosystem (Lammerts van Bueren et al., 2002). But organic agriculture alone does not provide a suffi cient amount of food for the growing population (Oliver and Gregory, 2015). In contrast, conventional agriculture depends mainly on external inputs, which makes it somewhat more vulnerable. To consider farming systems to be sustainable they must be “productive and maintain their contribution to society in the long term” (Gadanakis et al., 2015). In general, the demand for agricultural practices and food security that are more environmentfriendly is increasing rapidly, which favours the development of new 10 integrated farming systems (Duc et al., 2015). Such farming systems that use integrated management practices, such as crop rotations and organic (green manure crops, leguminous crops, CC) and inorganic fertilizers, will maintain soil as well as human health (Marsh, 2000; Oliver and Gregory, 2015). Future agriculture must also evolve towards climate-smart agriculture technologies, which are more adaptive to climate change by improving resource use effi ciency and ensuring food security (Zhang et al., 2015). Achieving food security does not only mean an adequate food supply but it also means that the food must be nutritious, of good quality (Wei et al., 2015). The potato is one of the most important crops worldwide, ranking fourth in annual production (Fernie and Willmitzer, 2001). The potato can be grown in harsher climates, and it is able to give, relatively quickly, high nutritious yields compared to any of the other major food crops (Lutaladio and Castaldi, 2009). However, to be productive, the potato needs signifi cant nutrient inputs to maintain its productiveness and quality. Crop management is the main factor that infl uences crop production and disease resistance (Larkin and Halloran, 2014; Olanya et al., 2014). Previous research has shown that FS affect tuber quality characteristics such as tuber nutrients (Järvan and Edesi, 2009) as well as starch and dry matter (DM) contents (Roinila et al., 2003). Plant nutrition is an important factor that infl uences natural disease resistance. If there is a defi ciency of essential elements susceptibility to potato diseases increases (Czajkowski et al., 2011), because the plant’s natural ability to fi ght them is lowered (Mulder and Turkensteen, 2005). Nutrients affect the plant physiology and thus potential for infection with pathogens (Dordas, 2008). At the European Association for Potato Research (EAPR, 2014) conference last year it was concluded that the agronomy side of potato production has gained too little attention over the past years and needs to regain its importance, because the agronomic side of potato production determines the potato performance parameters. Potato is a crop that has been studied in Estonia extensively because of its importance in Estonians everyday diet. The fi rst true Estonian potato scientist was Julius Aamisepp who promoted the cultivation of potato and its research. The fi rst fertilization experiments were conducted by Arnold Piho in 1960–1980 which also included the potato crop. The latest potato fertilization research has been made by Kuldkepp et al. 11 (1999), by Astover and Roostalu (2003), by Järvan and Edesi (2009), by Toomsoo and Leedu (2002), by Toomsoo et al. (2009; 2012). However, such complex potato fertilization research (under different organic and conventional farming systems) presented in current thesis has not been made before in Estonia. Earlier potato research has had mainly domestic importance. In the past, besides potato fertilization, the effect of different potato pre-planting thermal treatments on the tuber yield formation has been studied by Viacheslav Eremeev. Also there has been some potato disease related research by Mati Koppel who studied the potato soft rot (Erwinia/Pectobacterium spp.) disease and by Eve Runno-Paurson who investigated the potato late blight (Phytophthora infestans). The potato meristem multiplication has been studied by Viive Rosenberg and Marje Särekanno. Potato research related to plant breeding has been conducted by Aide Tsahkna and Mati Koppel. There are many other great potato researchers in Estonia who are a true experts in their fi eld of study. Crop rotations are important tools that affect potato productivity (Carter et al., 2003) and diseases (Peters et al., 2004). Catch crops are essential to avoid nutrient losses (Stark and Porter, 2005). Brassica crops used as CC have, furthermore, been found to have a disease suppressing effect (Cohen et al., 2005). Since the potato is a high nutrient demanding crop, additional mineral or organic fertilizers must be provided. Despite nitrogen (N) being a basic potato nutrient, the selection of its appropriate application rate for the potato is quite diffi cult, due to signifi cant variation (Zebarth et al., 2009). The appropriate N demand can vary among many factors such as climatic conditions during the growth period, crop management practices the previous crops cultivated. Addressing all the aforementioned factors should ensure high potato yields of good quality. Currently, these are the following gaps in our knowledge: (i) how the yield increase through different agronomic practices affects the potato tuber mineral elements concentrations (which are considered tuber nutrients) (White et al., 2009) and overall crop quality (Wang et al., 2008), (ii) how crop rotations infl uence tuber quality parameters (Mohr et al., 2011), and (iii) how the plant nutrition and crop rotations together affect the occurrence of tuber diseases (VanderZaag, 2010). The focus of much research tends to be on organic or conventional management systems separately, it is important to investigate their infl uence together comparatively (Bernard et al., 2014). Thus, the overall aim of this thesis is to 12 investigate how different organic and conventional management practices under the same crop rotation infl uence tuber quality characteristics as well as yield.Käesoleva doktoritöö raames uuritakse, kuidas erinevad viljelussüsteemid (neli tavaviljeluse süsteemi koos suureneva mineraalse lämmastiku normiga vs kaks mahesüsteemi koos vahekultuuride ja sõnnikuga), mis järgivad sama külvikorda (punane ristik, talinisu, hernes, kartul, oder punase ristiku allakülviga) mõjutavad kartuli kogu ja kaubanduslikke saake, mugulate toiteainete (N, P, K, Ca, Mg), nitraatide (NO3–), tärklise ja kuivaine sisaldust kui ka mugulahaiguste nagu harilik kärn (Streptomyces spp.), hõbekärn (Helminthosporium solani), kuivmädanik (Fusarium spp.) ja märgmädanik (Pectobacterium spp.) esinemist, mida määratletakse ka kui mugulate kvaliteedinäitajaid. Antud töö peamine hüpotees on, et kartuli saagikus ning mugulate toitainete, nitraatide, kuivaine ja tärklise sisaldus kui ka mugulahaiguste esinemine sõltuvad kõik viljelussüsteemist, külvikorrakultuuridest ning kliimatingimustest. Tulenevalt töö hüpoteesist oli uurimustöö eesmärkideks täpsemalt (i) hinnata viljelussüsteemi mõju kartuli saagierinevustele, (ii) uurida, kuidas erinevad viljelussüsteemid mõjutavad mugulate makrotoitainete kontsentratsiooni kui ka kuivaine ja tärklisesisaldust (iii) ning mugulahaiguste esinemist. Uurimistööst ilmnes, et uuritavate aastate keskmisena oli viljelussüsteemidel usutav mõju kartuli saagikusele, mugulate N, NO3–, P ja Mg sisaldustele kui ka mugulahaiguste nagu kuivmädanik, hõbekärn ja harilik kärn (madala nakkustasemega) esinemisele. Seega viljelussüsteemide toitainetega varustatus kui ka nende allikas võivad suuresti mõjutada mõningaid mugulate kvaliteedinäitajaid. Mugulate K, Ca, tärklise ja kuivaine sisaldused kui ka märgmädaniku esinemine vastupidiselt ei olnud mõjutatud erinevatest viljelussüsteemidest ning nende toitainetega varustatusest, kui välistatakse kasvuaasta ilmastikutingimuste mõju. See, kuidas konkreetne süsteem mõjutab mugulate kvaliteediomadusi, on otseselt mõjutatud ka kasvuperioodi keskkonnatingimustest.Publication of this thesis is supported by the Estonian University of Life Science

Flavour Characterization Of Jackfruit (Artocarpus Heterophyllus L.) From Five Cultivars And Optimization Of Canning Conditions For Jackfruit Puree

The study concerns flavour characterization of five jackfruit (Artocarpus heterophyllus L.) cultivars and optimization of canned jackfruit puree production. In the first part of this study, twenty three volatile compounds extracted using dichloromethane solvent extraction were tentatively identified by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). As ripening progressed, there was an increase in volatile compound formation. Development of new volatile flavour compounds in trace amounts at day 3 after harvest indicated the start of jackfruit ripening. Data obtained showed that the ripening process of jackfruit was at its optimum at day 5 after harvest. Variation of volatile compounds in different portions (top, middle and bottom) of the fruit during ripening was too little to give any significance. The volatile profiles of jackfruit flavour in five cultivars were established using headspace solid phase microextraction (SPME) and gas chromatography-time of flight mass spectrometry (GC-TOFMS). Qualitative and quantitative analyses were carried out using divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber with an extraction time of 10 min. Thirty seven compounds were identified from the five cultivars tested. Characteristic aroma which are in higher concentrations and contributed to jackfruit flavour were found to be ethyl isovalerate, 3-methylbutyl acetate, I -butanol, propyl isovalerate, isobutyl isovalerate, 2-methylbutanol, and butyl isovalerate. The consistent occurrence of these compounds in all cultivars of jackfruit suggested their importance in contributing to the sweet and fruity note of jackfruit. Concentration of the volatile compounds present played an important role in determining the overall flavour of each fruit cultivar. Each cultivar also possessed its own unique compound which distinguished them from one to another

Perkins Green III: proposed married and graduate student housing

When I first came to Rochester Institute of Technology (R.I.T.) to study in the graduate program, I settled in an apartment supported by the school, because I was a new-comer and knew nothing about the surroundings. Racquet Club, a housing complex five minutes from school, is a 307-unit-townhouse-apartment, student housing area with three tennis courts and one large grass slope as its open space. I was very satisfied by this beautiful scene and thought it would be a good place to live and study. Later, however, I found sometimes, especially on weekends, there was too much noise from parties taking place in adjacent apartments; band concerts taking place (or rehearsing) in an apartment, drinking, talking, and amazingly loud dance music, not to mention occasional fights. These behaviors piqued my curiosity at first, but later on really irritated me. Perhaps I had homework to do; perhaps I would like to enjoy a movie on TV, to listen to my favorite classical music, or to have a chat with my house-mates and have a cup of tea; but I was bothered by the noise. Fortunately, during the weekdays this normally didn\u27t happen because everyone else was very busy

In crop rotation green manures as winter cover crops enhance ecosystem services of farming

Organic farming systems should be characterized by excellent soil fertility management to keep plant nutrient cycles short and as closed as possible. Therefore, it is extremely important to establish growing systems that have rotations with appropriate crops and intercrops to ensure fertile and biologically active soils, to enhance biodiversity and to provide high quality crop yields. Locally available organic fertilizers include green manures and animal manure. The influence of green manures as intercrops and these combined with composted cattle manure on soil properties, biodiversity indicators and crop yields was studied in a crop rotation experiment in three organic systems at the Estonian University of Life Sciences

APPLICATION OF BAYESIAN NETWORKS: WHY STUDENT PREFER FAST-FOOD, KAMPAR DISTRICT

It is common in nowadays where people eat at restaurant rather than cook or prepare meal by themselves. Comparing to home cook meal, eating at restaurant may have been ignoring the hygiene and balance nutrition issue by human for the sake of convenient and time saving. Thus, fast-food has naturally become one of the choices of their preference. We used Bayesian network to identify the factors that influence UTAR Kampar students to have fast-food as their proper meal. Bayesian Networks is one of the probabilistic graphical models and the network must be a directed acyclic graph. The network structure is formed by nodes (random variables) and they are linked by a directed arc corresponding to the causal relationship between them. In this paper, we discovered that the main reason for McD fast-food to be treated as a proper meal mostly in not because of “fast”, i.e., the time saving factor, though it is the inspiration of emerging fast-food restaurants. Besides the unexpected result, the food preference of university students is not easily influenced by friends’ suggestions. Keywords: Bayesian Network, Fast-Food, Structural Network, Directed Acyclic Graph

A discrete time relativistic Toda lattice

Four integrable symplectic maps approximating two Hamiltonian flows from the relativistic Toda hierarchy are introduced. They are demostrated to belong to the same hierarchy and to examplify the general scheme for symplectic maps on groups equiped with quadratic Poisson brackets. The initial value problem for the difference equations is solved in terms of a factorization problem in a group. Interpolating Hamiltonian flows are found for all the maps.Comment: 32 pages, LaTe