Master of Science / Department of Agronomy / Ignacio Ciampitti / Sorghum [Sorghum bicolor (L.) Moench] has greater drought resilience than many other crops, producing food in the most stressful environments. Sorghum is a reasonable crop choice for farmers working with limited-water supply. The objective of this study was to compare sorghum hybrids differing in yield strategies under varying water supply environments. Yield, biomass, grain harvest index (HI), and yield components (seed number and seed weight) were compared in both rainfed and irrigated situations. Field experiments were established in 2014 and 2015 at Topeka, Scandia, Hutchinson, Garden City, and Tribune, KS. Three sorghum hybrids (Pioneer 85Y40, Pioneer 84G62, and Dekalb 53-67) with different yield potentials at varying water supply were studied. Hybrids 85Y40 and 84G62 tended to have greater yields than hybrid 53-67 when the environment's average yield level was greater than 8.5 Mg haˉ¹. The opposite scenario where hybrid 53-67 had greater yields than the other two hybrids tended to occur for environments yielding less than 8.5 Mg haˉ¹. Both biomass and HI were significantly correlated with grain yield (r values of 0.62 and 0.32 respectively), with biomass having an overall stronger correlation than HI in all environments. In yield group 3 (<8.5 Mg haˉ¹), biomass was much more strongly correlated (r=0.85) to yield than in the yield groups 1 and 2 (>9.5 Mg haˉ¹ and 8.5-9.5 Mg haˉ¹ with r values of 0.35 and 0.52 respectively) suggesting that biomass production is of utmost importance for yield production in drought prone environments. Harvest index on the other hand had a much stronger correlation with yield in group 1 (r=0.62) when compared to group 2 and 3 (r 0.13 and 0.36 respectively) showing the importance of not only biomass, but also of HI to maximize yield in high yielding environments. Hybrids 85Y40 and 84G62 had larger HI values relating to the yield trends in the highest yielding environments. Seed number had a stronger correlation with yield (r=0.77) than seed weight (r=0.37) supporting the importance of increasing seed number to improve yield in sorghum.

A diallel analysis of eight upland cotton (Gossypium hirsutum L.) genotypes was conducted in the field over two years to determine the potential for improvement in within-boll seed yield components and fiber quality parameters. Four exotic germplasm lines from the converted race stock (CRS) collection and four commercial types representing Texas, mid-South, and Eastern production regions were crossed and evaluated in a diallel with parents but without reciprocals according to Griffing's Model I, Method 2. Significant variation for genotypic, general combining ability (GCA) effects, and specific combining ability (SCA) effects (P 0.05) were identified for all traits studied indicating potential for improvements through selection. Significant interactions of these parameters with years were also observed, suggesting that selection should be based on multiple years and or locations. In addition to effects on yield, individual seed number traits were found to respond to heat stress under controlled growth chamber conditions, suggesting their potential for use in screening genotypes for heat tolerance. These traits were not found to interact with temperature, which indicates that selection for improvements in these traits could be conducted in any environment. Improvements in seed yield components and, putatively, in heat tolerance could be achieved using CRS M-9044-0162. As expected, CRS accessions reduced fiber quality parameters in addition to other agronomic traits, suggesting that improvements for within-boll seed yield components and heat tolerance should be made utilizing a backcross approach. Also observed in this population was a superior hybrid for fiber length and fiber strength from the cross of TAM 94L-25 with PD 6186. This combination could lead to improved fiber length and strength potential in upland cotton.

A diallel analysis of eight upland cotton (Gossypium hirsutum L.) genotypes was conducted in the field over two years to determine the potential for improvement in within-boll seed yield components and fiber quality parameters. Four exotic germplasm lines from the converted race stock (CRS) collection and four commercial types representing Texas, mid-South, and Eastern production regions were crossed and evaluated in a diallel with parents but without reciprocals according to Griffing's Model I, Method 2. Significant variation for genotypic, general combining ability (GCA) effects, and specific combining ability (SCA) effects (P 0.05) were identified for all traits studied indicating potential for improvements through selection. Significant interactions of these parameters with years were also observed, suggesting that selection should be based on multiple years and or locations. In addition to effects on yield, individual seed number traits were found to respond to heat stress under controlled growth chamber conditions, suggesting their potential for use in screening genotypes for heat tolerance. These traits were not found to interact with temperature, which indicates that selection for improvements in these traits could be conducted in any environment. Improvements in seed yield components and, putatively, in heat tolerance could be achieved using CRS M-9044-0162. As expected, CRS accessions reduced fiber quality parameters in addition to other agronomic traits, suggesting that improvements for within-boll seed yield components and heat tolerance should be made utilizing a backcross approach. Also observed in this population was a superior hybrid for fiber length and fiber strength from the cross of TAM 94L-25 with PD 6186. This combination could lead to improved fiber length and strength potential in upland cotton.

The effect of source-sink relationships on the performance of tomato and hot pepper was investigated in glasshouse experiments by pruning tomato trusses and hot pepper fruit from plants trained to a single stem. The objectives were to characterize the effect of time, method and intensity of pruning on the yield and quality of tomato and hot pepper. Pruning at anthesis as compared to pruning at fruit-set had little effect on yield and fruit quality of both crops. Yield per truss increased steadily with intensity of pruning in tomato, due to increase in fruit size and fruit number per truss. Thus, total yield was not affected by pruning. In hot pepper fruit size increased with intensity of pruning but total yield was significantly reduced and total plant dry mass depressed at higher source : sink ratios (two and three fruit pruned out of a total of six). Occurrence of fruit disorders such as blossom-end rot and fruit cracking increased with increasing source: sink ratio. Pruning of one truss in tomato and one fruit in hot pepper gave the best fruit quality in terms of fruit size, pericarp thickness and freedom from defects, without decreasing total and marketable yield. Removing a middle truss of tomato (third truss) gave the highest yield as compared to removing the youngest truss (sixth truss) or the oldest truss (first truss). The yield increase (relative to the control) in the remaining individual trusses tended to decrease with increasing distance of the trusses from the pruned truss. In hot pepper removal of the youngest fruit (sixth fruit) resulted in the highest yield in comparison to removal of the middle fruit (third fruit) and the oldest fruit (first fruit). The quantity of yield increase in the remaining individual fruits had no consistent trend regarding the relative distance of the fruits from the pruned fruit. Two pruning methods were tried on hot pepper and tomato to compare yield and fruit quality. The first method involved pruning of the first three consecutive trusses of tomato and the first three consecutive fruit of hot pepper out of a total of six. The second method involved pruning of three alternating tomato trusses or hot pepper fruit. Yield and yield components did not differ significantly for the two methods, but pruning alternate trusses of tomato and fruit of hot pepper reduced occurrence of fruit disorders. / Dissertation (MSc (Agric) Agronomy)--University of Pretoria, 2007. / Plant Production and Soil Science / unrestricted

The aim of the dissertation thesis was to find out the influence of fungicide and increased amount of nitrogen on the yield components of oat. The dissertation is divided into a literary overview and the thesis as such. In 2018 a pilot research was made on the land of a farm located in the district of Tábor. Atego oat was grown in four variants there: a control variant, a variant fertilized by nitrogen (without the usage of fungicide), a variant comprising fungicide application (without nitrogen fertilization) and a variant including both nitrogen fertilization and fungicide application. The highest theoretical yield was registered in the variant which contained fungicide as well as nitrogen. Regarding the yield components of oat, the highest number of plants and panicles was registered in the variant fertilized by nitrogen (without the usage of fungicide); the highest number of stolons and the maximum weight of one thousand grains was measured in the variant including both nitrogen fertilization and fungicide application. Finally, the highest number of grains in a panicle was obtained from a control variant.

Made available in DSpace on 2017-07-10T17:37:32Z (GMT). No. of bitstreams: 1 Sergio Luiz Marchi.pdf: 7672567 bytes, checksum: fdf541fa4a63c5627694d9c2bbd207f9 (MD5) Previous issue date: 2008-07-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The corn (Zea mays L.) is considered one of the main species used in the world, once that around 150.4 millions of hectares are cultivated per year, which contribute to the production of roughly 812.2 millions tons of grains. The reduction of the photosynthetic rate after the flowering can occur due to several factors as water stress, long foggy, destruction of the leaf area (plague and illnesses) and a high population of plants. This situation needs the usage of a store, mainly from the stem to filling the grains. In this context, the current work intended to evaluate the effect of the plants population, the levels of defoliation in agronomic aspects and the yield of the hybrid corn Pioneer 30F35. An experiment was conducted on a field of Palotina PR C.Vale Experimental Field in the agricultural year of 2006/2007. It was used the delineation in blocks, at random, using a factor scheme (4 x 5), with four replications. The factors evaluated were four plants population (45.000, 55.000, 65.000 and 75.000 plants ha-1) and five levels of defoliation (without defoliation 0%, 12.5%, 25%, 37.5% and 50% of defoliation) in full female flowering (notorious stigma-style). It was found to succeed that an interaction between the plants population and the rate of defoliation to the hybrid corn studied, to the biometric variables and the productive aspects studied happened. The rate of plants remobilization was not affected by the plants population change, although, the defoliation above 25% has negatively affected this variable. The rise of the plants population resulted in plants with less diameter of stem and a rise percentage of broken plants. This enlargement of the plants population and the level of defoliation resulted in a fall of the greater part of the production components and yield of the hybrid corn Pioneer 30F35 / O milho (Zea mays L.) é considerado uma das principais culturas utilizadas no mundo, visto que anualmente são cultivados cerca de 150,4 milhões de hectares, os quais contribuem para a produção de aproximadamente 812,2 milhões de toneladas de grãos. A redução da taxa fotossintética após o florescimento pode ser ocasionada por vários fatores como estresse hídrico, nebulosidade prolongada, destruição de área foliar (pragas e doenças) e alta população de plantas. Essa situação implica na necessidade de utilização das reservas da planta, principalmente do colmo para o enchimento de grãos. Neste contexto, o presente trabalho objetivou avaliar o efeito da população de plantas e níveis de desfolha em características agronômicas e produtividade do híbrido de milho Pioneer 30F35. O experimento foi conduzido no Campo Experimental da C.Vale em Palotina - PR no ano agrícola 2006/2007. Utilizou-se delineamento em blocos ao acaso em esquema fatorial (4x5), com quatro repetições. Os fatores avaliados foram quatro populações de plantas (45.000, 55.000, 65.000 e 75.000 plantas ha-1) e cinco níveis de desfolha (sem desfolha 0%, 12,5%, 25%, 37,5% e 50% de desfolha) no pleno florescimento feminino (estiloestigma visível). Verificou-se que não houve interação entre população de plantas e índice de desfolha, para o híbrido de milho estudado, para as variáveis biométricas e características produtivas estudadas. O índice de remobilização das plantas de milho não foi afetado pela variação da população de plantas, porém, a desfolha acima de 25% afetou negativamente esta variável. O aumento da população de plantas resultou em plantas com menor diâmetro de colmo e elevação na percentagem de plantas quebradas. O aumento da população plantas e do nível de desfolha resultou em queda na maioria dos componentes da produção e produtividade do híbrido de milho Pioneer 30F35

Thesis (M.Sc. (Crop Science)) --University of Limpopo, 2012 / Organic tomatoes are increasingly popular with larger market acceptance since organic farming uses limited or no artificial chemicals. Application of organic fertilisers such as cattle manure has potential to boost organic tomato productivity particularly under low input farming systems. However, information is required on the optimum level of manure application on different tomato cultivars to help emerging tomato farmers in South Africa. The objective of this study was to determine the relative response of yield and yield components among selected determinate and indeterminate tomato cultivars using different levels of cattle manure. Two separate field experiments were conducted at the University of Limpopo during 2007 and 2008 using a split plot design with three replications. Two sets of tomato cultivars were included in which one set consisted indeterminate types (Money Maker, Ox Heart and Sweetie) and the other determinates (Roma and Floradade). Cultivars were assigned as the main plot treatments with six rates of manure (0, 10, 20, 30, 40 and 50 in gram per plant) applied as the subplot treatments to each set. Results indicated significant interactions (P ≤ 0.01) between indeterminate tomato cultivars and levels of manure applied for fruit yield and fruit size in both experiments. Plant height showed variation from 78 to168 cm in Experiment I and 87 to 176 cm in Experiment II. During Experiment I fruit number varied from 23 to 91 per plant and 23 to 97 in Experiment II. Significant differences were detected among determinate cultivars on fruit yield varying from 7928 to 3 4705 kg per hectare during Experiment I and 3 169 to 2 9840 kg per hectare during Experiment II. Overall, the best level of manure for maximum fruit yield and greater fruit size was achieved at 40 g per plant in the indeterminate cultivar Sweetie. Conversely, the best level of manure for maximum fruit yield was achieved at 30 g per plant in determinate cultivar Roma. Thus, to achieve maximum yield, tomato growers could apply 600 and 800 kg per hectare manure on the determinate and indeterminate tomato cultivars, respectively. / the National Research Foundation (NRF)

Corn (Zea mays L.) defoliation experiments have been conducted for more than 120 years. However, there is limited data on the effect of row width on defoliation in modern hybrids. A two-year experiment was conducted in Lexington, Kentucky with two hybrids (113 relative maturity (RM) and 120 RM), two row widths (38 and 76 cm) and a combination of defoliation timings and severities: 0% defoliation (control), V7-100%, V14-50%, V14-100%, R2-50% and R2-100%. No yield difference among hybrids was observed in 2012. Yields were 26% greater in 38-cm rows than 76-cm rows in 2012. For 2013, corn yield for 38-cm was 10% greater, but hybrid, row width and defoliation interacted. Lowest yields were caused by V14-100% followed by R2-100%. Defoliations of V14-50% and R2-50% reduced yields in some cases. Complete defoliations at V7 did not reduce yields in most comparisons. Light interception below 80% during the critical period was enough to attain maximum yields in defoliated plants. Kernel number and kernel weight were most reduced by V14-100% and R2-100% defoliations, respectively. There is a potential for narrow rows to reduce grain yield losses after a defoliation event, when compared with wide rows.

Finding the alternate biofuel feedstock(s) in addition to and/or replacement of traditional soybean feedstock is necessary to meet the future demand of biofuels. Two field studies were conducted in diverse environments in Texas during 2007-2011 to evaluate the yield, adaptation, and oil content of 4 cool-season crop species (rapeseed, safflower, flax, and camelina). In addition to the evaluation of yield and adaptation in these cool-season crops, two more studies were conducted during 2009-2011 to study flax yield components (field study) and the effect of vernalization and photoperiod on flowering of flax (growth chamber study). Out of two field studies conducted in Texas, the evaluation of four cool-season crops was designed as a randomized complete block with fifty-one genotypes (four species) and three replications in nine locations across the Texas. In addition to the evaluation of cool-season crops, an exclusive replicated study was conducted in flax to evaluate 20 genotypes for the yield, adaptation, and association between yield and its components in three locations in South Texas. Additionally, a growth chamber study was setup as a split-split plot design with twenty genotypes, two vernalized treatments (vernalized and unvernalized), and two photoperiods (10 hours and 14 hours). Spring rapeseed (canola) and safflower were the highest yielding crops with a maximum yield of 1372 kg ha-1 and 1240 kg ha-1, respectively. In South and Central Texas, fall - seeded flax yield averaged 1075 kg ha^-1 with a mean oil content of 38.3%. The flax genotype evaluation in Southeast Texas suggested that all genotypes developed in Texas showed relative cold tolerance compared to genotypes developed in other locations. A cross between Caldwell / Dillman (Texas genotype) was highly adapted to the environments of southeast Texas. Nekoma and York (genotypes developed in North Dakota) yielded well in non-cold years (> -2 degrees C) in College Station. Overall, flax is well adapted to growth in the area surrounding College Station, TX. The results of association of yield and its components in flax suggest that tiller number was the most significant contributing factor (p<0.05) affecting yield of flax in all three locations. However, the effect of tiller number was almost negated by the effect of pods per tiller (compensatory) in two out of three locations. The effect of vernalization and photoperiod on flowering of 20 genotypes of flax suggested that Texas genotypes delayed anthesis for 7 days or more in non-vernalized seedlings. These genotypes also delayed anthesis for 12 days or more in vernalized and short day conditions compared to vernalized and long day conditions. In summary, the spring rapeseed in diverse environments of Texas and fall-planted flax in South Texas showed promising yield and adaptation. Selection for more productive tiller number and intrinsic earliness of flowering to reduce the time of maturation would benefit the flax yields in Southeast Texas. Safflower was widely adapted to Texas and with increased oil content could have potential to the biofuel industry in Texas.

This thesis deals with yield formation with the 12 varieties of winter wheat during growing season 2013/2014. The experiment was established in four repetitions on the plot of Faculty of Agriculture, University of South Bohemia in České Budějovice. Examined yield components were the amount of spikes per 1 m2, amount of grains per spike and weight of thousand grains. Furthermore evaluated were the amount of plants per 1 m2, amount of spikelets in spike, real and theoretical yield, spike length and density. The next step was the processing of the results where the average value of all the varieties in the amount of ears per 1 m2 was 783 units/m2. The second element of the yield varieties reached the average number of grains per spike 36.2 pieces. And the mean weight of´thousand grains was 44.42 grams.