This thesis is an investigation of econometric crop yield models divided into two essays. In the first essay, I propose estimating a single heteroscedasticity coefficient for all counties within a crop-reporting district by pooling county-level crop yield data in a two-stage estimation process. In the context of crop insurance---where heteroscedaticity has significant economic implications---I demonstrate the pooling approach provides economically and statistically significant improvements in rating crop insurance contracts over contemporary methods. In the second essay, I propose a new method for measuring the rate of technological change in crop yields. To date the agricultural economics literature has measured technological change exclusively at the mean; in contrast, the proposed model can measure the rate of technological change in endogenously-defined yield subpopulations. I find evidence of different rates of technological change in yield subpopulations, which leads to interesting questions about the effect of technological change on agricultural production. / Ontario Ministry of Agriculture and Food

No description available.

This study investigated the potential of developing in-season crop yield forecasting and mapping systems based on interpretation of airborne hyperspectral remote sensing imagery by machine learning algorithms. The data used for this study was obtained over a corn (Zea mays L.) field in eastern Canada. / The experimental plots were set up at the Emile A. Lods Agronomy Research Center, Montreal, Quebec. Corn was grown under the twelve combinations of three nitrogen application rates (60, 120, and 250 kg N/ha), and four weed control strategies (Broad leaf weed, Grass weed, Broad leaf and grass weed control, and no weed control). The images of the experimental field were taken with a Compact Airborne Spectrographic Imager (CASI) at three times (June 30 for early growth stage, August 5 for tassel stage, and Aug 25 for mature stage) during the year 2000 growing season. / Two machine learning algorithms, Artificial Neural Networks (ANN) and Decision Tree (DT) were evaluated. The performance of ANNs was compared with four conventional modeling methods. For the DT algorithms, two different aspects, (i) DT as a classification method, and (ii) DT as a feature selection tool, were explored in this study.

Bibliography: leaves 216-237 / vii, 327 leaves, [31] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Physiology, 1985

In the Jistuza Studená farm, problems of soil cultivation have been solved, with respect to crop yields and ecomy of cropping.

From the Introduction. The fertilisation of pineapples in the Eastern Cape Province is still a relatively new practice which started approximately twelve years ago. Even after this time many growers still insist that pineapples can be grown without fertilisation on virgin soils. As the available virgin soil decreased, however, so the interest in fertiliser application increased. Very little basic research on the fertiliser requirements of pineapples in the Eastern Cape was done to serve as a guide to growers. The available advisory literature by le Roux (1951), Malan (1954) and Lewcock (1956) were based on overseas experience. When pineapple research was started on a large scale, in 1955, it was realised that emphasis should be placed on the nutritional requirements on virgin as well as replanted soils. From initial experiments it was clear that the main response in plant growth and yield was obtained from nitrogenous fertilisers.

Thesis (M.Sc. (Horticulture)) -- University of Limpopo, 2017. / Root-knot (Meloidogyne species) nematodes are economically destructive pathogens of over 3000 species, whereas others have resistance to Meloidogyne species. Wild watermelon (Cucumis africanus) and wild cucumber (Cucumis myriocarpus) are highly resistant to Meloidogyne species, particularly M. incognita and M. javanica. The two Cucumis species are used in inter-generic grafting with watermelon (Citrullus lanatus) as nematode resistant rootstocks. Also, the two Cucumis species are used in traditional medicine and in plant-parasitic nematode management as phytonematicides. The form of nematode resistance, which is essential in plant breeding, is not documented for the two Cucumis species. The objective of this study was to determine the form of nematode resistance in the two Cucumis species to M. incognita and M. javanica under greenhouse conditions. Four parallel experiments were each conducted under greenhouse conditions. Uniform six-week old Cucumis seedlings were transplanted into 250 ml polystyrene cups filled with 200 ml growing medium of steam-pasteurised fine sand. A week after transplanting, Cucumis seedlings were each infested by dispensing approximately 100 M. incognita second-stage juveniles (J2) or M. javanica J2 using a 20 ml plastic syringe by placing into 5-cm-deep furrow around the seedling stem and covered with growing medium. Treatments (periodic harvest intervals) were arranged in a randomised complete block design, replicated five times. Five seedlings from each experiment were harvested every second day, for 30 days, with stained roots being assessed for necrotic spot (suberised cells) number, giant cell number, proliferation of rootlet interference number and root gall number. Periodic harvest intervals were highly significant (P ≤ 0.01) on necrotic spot number, proliferation of rootlet interference number and root gall number in C. africanus-M. incognita relations, but were not significant for giant cell number. Treatments contributed 59, 64 and 50% in total treatment variation (TTV) of necrotic spot number, proliferation of rootlet interference number and root gall number, respectively. Harvest period had highly significant effects on necrotic spot number, giant cell number, proliferation of rootlet interference number and root gall number in C. africanus-M. javanica relations. Treatments contributed 55, 71, 63 and 59% in TTV of necrotic spot number, giant cell number, proliferation of rootlet interference number and root gall number, respectively. Periodic harvest intervals were significant (P ≤ 0.05) on giant cell number and highly significant on root gall number in C. myriocarpus-M. incognita relations. However, there were no significant treatment differences on necrotic spot number and proliferation of rootlet interference number. Treatments contributed 57 and 57% in TTV of root gall number and giant cell number, respectively. Harvest period had highly significant effects on giant cell number, proliferation of rootlet interference number and root gall number, but were not significant on necrotic spot number in C. myriocarpus-M. javanica relations. Treatments accounted for 67, 49 and 53% in TTV of giant cell number, proliferation of rootlet interference number and root gall number, respectively. In conclusion, the mechanism of resistance to M. incognita and M. javanica in both C. africanus and C. myriocarpus was post-infectional nematode resistance, which has attributes for introgression into commercial nematode-susceptible Cucumis cultivars. / Agricultural Research Council (ARC), National Research Foundation of South Africa; and the ARC-Universities Collaboration Centre for Smallholder Farmers

Saskatoon serviceberry (Amelanchier alnifolia Nutt.) is an ornamental Rosaceous shrub producing delicate white flowers that yield fruit similar in appearance and nutrition to blueberry (Vaccinium spp.). Most serviceberry are propagated in Canada and, as imported stocks are often expensive, clones were accessed from 70 locations in North Dakota. Following establishment, a replicated field trial of wild biotypes of serviceberry was initiated at the North Dakota State University Horticulture Research Farm (NDSU HRF) near Absaraka, ND and at the Williston Research and Extension Center (WREC) in Williston, ND. Yield data was taken upon harvest in summers 2014-2017 at NDSU HRF and 2016 at WREC. ND 1-2, ND 1-4, ND 1-6, ND 1-7, ND 48-2 often out-yielded market genotypes. ND 15-2 was high in sugar content and gelling ability, ideal for processing. Through continued selection, North Dakota growers may have quality serviceberry from a local source.

Continued migration from rural areas and the associated growth in remittance inflows are changing basic characteristics of Nepal’s agrarian economy. Using cross-sectional household survey data covering agricultural production during the 2013 growing season, this thesis investigates the linkages between migration and agricultural production in twenty districts of Nepal. This study focuses on understanding what household and farm characteristics are associated with migration decisions and destination choices using multinomial logit model. I also gauge the impact of labor migration and remittance receipts on maize yield and input levels.

No description available.