The International Potato Center (CIP) and Peruvian National Agricultural Research Institute (INIA) have invested a substantial amount of resources towards the development of improved potato varieties in Peru. These varieties are adaptable to the agro-ecologies of the Andes and have specific biotic and abiotic attributes. These efforts have led to the release of several prominent varieties including Canchan-INIA, Amarilis, Unica, Serranita and others. A 2013 household survey conducted by CIP was used to describe the diffusion of improved potato varieties in Peru. These data were also used to identify specific constraints to their adoption and dis-adoption. The assessment focused on a two-step adoption model, adoption and dis-adoption, by utilizing a Heckman Probit model to demonstrate two-steps of the adoption process. The Heckman Probit model was used to analyze variables affecting adoption and dis-adoption of improved varieties. Results suggest that adoption is region specific, time dependent, and in some cases relies on informal transmission methods. Risk to food insecurity and recurrent natural phenomena affect adoption and sometimes dis-adoption. Additionally, factors affecting a farmer's exposure to risk, such as information constraints and household head age, wealth, and social network were found to affect the adoption and dis-adoption of improved varieties. / Master of Science / Improved potato varieties, engineered by the International Potato Center (CIP) and Peruvian National Agricultural Research Institute (INIA), are adapted to the agro-ecologies of the Andes and have specific biotic and abiotic attributes, such as late blight resistance. There are a number of prominent engineered varieties produced by CIP and INIA including Canchan-INIA, Amarilis, Unica, Serranita and others, which have the potential to increase the yields and incomes of highland potato farmers. A 2013 household survey conducted by CIP was used to describe the diffusion of improved potato varieties in Peru. These data were also used to identify specific constraints to their adoption and dis-adoption. The assessment focused on a two-step adoption model, adoption and dis-adoption, by utilizing a Heckman Probit model to demonstrate two-steps of the adoption process. The model was used to analyze variables affecting adoption and dis-adoption of improved varieties. Results suggest that adoption is region specific, time dependent, and in some cases relies on informal transmission methods. Farmers living in areas more prone to food insecurity and natural phenomena are less likely to adopt certain improved varieties and more likely to continue to adopt these varieties after initial adoption. Additionally, factors affecting a farmer’s exposure to risk, such as information constraints and household head age, wealth, and social network were found to affect the adoption and dis-adoption of improved varieties.

ZUSAMMENFASSUNG Nematoden rufen weltweit erhebliche Verluste in der Kartoffelproduktion hervor. Der Knollenfäule-Nematode Ditylenchus destructor Thorne 1945 und das Stock-und Stangelälchen Ditylenchus dipsaci Kühn 1857 Filipjev, 1936, verursachen Läsionen an der Kartoffelknolle, was deren Qualität und Marktwert verringert. Diese Nematoden sind aufgrund ihres umfangreichen Wirtspflanzenspektrums schwierig zu kontrollieren und werden daher in vielen Ländern als Quarantäne-Nematoden geführt. In der hier vorliegenden Doktorarbeit wurden Experimente durchgeführt, um die Wechselwirkung von Kartoffel mit jeder dieser beiden Nematodenarten zu untersuchen. Verschiedene Populationen von D. destructor und D. dipsaci wurden molekular und morphometrisch charakterisiert. Die Gensequenz kodierend für die Untereinheit I der Cytochrom Oxidase (COI) auf der mitochondrialen DNA (mtDNA) wurde analysiert, um eine phylogenetische Beziehung zwischen den untersuchten Populationen darzustellen. Die Ergebnisse zeigten zwei deutlich getrennte Cluster für die D. destructor und die D. dipsaci Populationen. Eine Diskriminanzanalyse der morphometrischen Daten von Männchen und Weibchen von D. destructor und D. dipsaci Populationen verdeutlichte, dass diese beiden Arten mittels a-ratio und ihrem Durchmesser unterschieden werden können. Die sich ergänzende Kombination von molekularen und morphometrischen Untersuchungen ermöglichte die Identifikation der untersuchten Arten. Es wurden zwei Gewächshausexperimente mit 25 angebauten Kartoffelsorten durchgeführt, um diese auf Resistenz und Toleranz gegenüber Nematoden zu testen. Dazu wurde ein Standard-Screening Protokoll entwickelt. Resistenz und Toleranz wurden gemäß der derzeitigen Definition (Nematologie) bewertet. Die relative Anfälligkeit und äußere Verletzung der Kartoffelknolle stellten sich als beste Parameter für die Beurteilung der Resistenz respektive der Toleranz heraus. Alle 25 untersuchten Kartoffelsorten waren weder resistent noch tolerant gegenüber D. destructor oder D. dipsaci. Jedoch wurden Unterschiede in der Toleranz der Sorten festgestellt. Im Vorfeld zum Pflanzenexperiment wurden die Populationsdichten von D. destructor und D. dipsaci und deren Einfluss auf Ertragsverlust untersucht. Die initiale Populationsdichte hatte einen signifikanten Effekt auf den Schaden an der Kartoffelknolle und den Fortpflanzungsfaktor der Nematoden unter Gewächshausbedingungen. D. destructor verursachte Schäden bereits bei einer geringeren initialen Populationsdichte als D. dipsaci. Unter Klimakammerbedingungen wurde gezeigt, dass die Temperatur Einfluss auf die Schadensrate von D. destructor und D. dipsaci an Kartoffelknollen nimmt. Im Gegensatz zu einer Temperatur von 16°C waren 26°C sowohl optimal für die Vermehrung von D. destructor als auch für D. dipsaci. Obwohl für D. destructor und D. dipsaci unterschiedliche Temperaturanforderungen beschrieben wurden, verursachten beide Arten in ähnlichen Temperaturbereichen äußere Verletzungen an der Kartoffelknolle. Beauveria bassiana ist ein weltweit verbreiteter Pilz, der vor allem zur Bekämpfung von Insektenschädlingen in der Kartoffelproduktion Anwendung findet. Doppelbefall von Kartoffeln mit B. bassiana Sporensuspensionen im Boden mit D. destructor oder D. dipsaci begünstigte die Nematoden, was zu einer erhöhten Nematodenfortpflanzung und Knollenbeschädigung führte. B. bassiana allein war nicht schädlich für die Kartoffel. Es wurde vermutet, dass B. bassiana eine indirekte Rolle in der Wechselwirkung Nematode-Kartoffel spielt. Vorschläge für zukünftige Experimente werden angebracht, die einen weiteren Beitrag zu den hier vorgestellten Studien leisten können.

Cooperation-88 (C88) is a late blight resistant potato variety that was formally released in China in 2001 and has become popular in China's Yunnan Province. The International Potato Center (CIP) and Yunnan Normal University collaborated to produce the variety, which is one of CIP's most successful varieties. C88 is popular due to its high quality and taste, and it is used commonly in China's expanding potato chip processing market. The purpose of this study is to examine adoption of C88 in the Yunnan Province, its value chain, and economic impacts. The analysis indicates that C88 is still popular with 16.8% of the potato area in Yunnan devoted to this variety in late spring 2015. To examine factors affecting household decisions to adopt and the intensity of their adoption, village adoption, household adoption, and household intensity of adoption were assessed. A village's proximity to a metropolitan county was the most important factor explaining adoption and intensity of adoption. Households in villages closer to a metropolitan county disadopted at higher rates than those farther away. To quantify the economic benefits of C88 adoption, an economic surplus analysis was conducted. Total surplus changes ranged from $2 to 3 billion indicating significant economic benefits to consumers and producers in Yunnan. / Master of Science / Cooperation-88 (C88) is a popular late blight resistant potato variety that was released to the Yunnan Province of China in 2001. Late blight is the disease responsible for the Great Potato Famine in Ireland. The International Potato Center (CIP) and Yunnan Normal University collaborated to produce the variety, and C88 is one of CIP’s most successful varieties. C88 is popular due to its high quality and taste, and it is used commonly in China’s potato chip processing market. The purpose of this study is to examine the number and types of people who adopted C88 in the Yunnan Province, provide an understanding of the process from farm to consumer, and to determine the economic impacts of the variety. A major finding of the study is that C88 remains popular in Yunnan as of spring 2015. To study the households that grew C88 during the spring 2015 season, statistical analysis was conducted with the focus on what household traits influence the number of surveyed households who grow C88 in a village, whether a household grows C88, and the number of hectares under C88. A village’s proximity to a metropolitan county was the most important factor explaining whether a household adopted the variety and the number of hectares. Households in villages closer to a metropolitan county stopped growing C88 at higher rates than those farther away. To quantify economic benefits, a supply and demand analysis of potatoes in Yunnan was conducted, which indicated significant economic benefits to consumers and producers in Yunnan.