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Thesis ((MSc. Agriculture (Agronomy)) -- University of Limpopo, 2015 / An experiment was conducted to evaluate the effect of vermicompost on cabbage growth and yield. Vermicompost (VC) was applied at 2500 kg/ha and was compared to one organic {vita grow (VG) [N:P:K 2:3:2 (16)] and one chemical fertiliser (CF) (N:P:K 2:3:2(22)]} which were both applied at 1500 kg/ha. The other treatments were prepared as mixtures of the three fertilisers (i.e. vermicompost and vita grow; vita grow and chemical fertiliser as well as vermicompost and chemical fertiliser) at 50% recommended rate, with no fertiliser treatment as a control. The trial was laid out in a randomised complete block design with three replicates. Chemical fertiliser achieved the highest chlorophyll content (80.6 nmol/mg) which was significantly higher than the other treatments. Vermicompost and the control had the least chlorophyll content at 58.6 and 55.8 nmol/mg, respectively. VC+VG, CF and CF+VC achieved the highest numbers of marketable heads while the control had the least. VC+VG, CF and CF+VC had more than 60% of the plants producing marketable heads whilst VC and VG had less than 40% of the plants producing marketable heads. The control only had 19.93% of the plants producing marketable heads. Range of marketable heads ranged from 2.82 t/ha for the control to 12.7 t/ha for CF. VC+VG, CF and CF+VC achieved marketable yields above 10.0 t/ha.VC and VG achieved 5.45 and 8.28 t/ha. The results thus show that use of chemical fertiliser or the combinations of VC and VG and that of CF and VC are the ones that can be recommended for cabbage production. Key words: vermicompost, growth, yield, cabbage, fertiliser

(1) The experiment as a whole showed that pH determinations may be made at any time throughout the year with assurance of being reliable as a relative indicator of lime requirement. (2) A comparison of the pH determinations made in 1928 with those made in 1930-31, show that the plats have become more acid. (3) The pH values of the soil paralleled the quantity of lime applied. Where no lime was applied the soil was found to be very acid, but increasing applications of lime brought the reaction gradually to the neutral point. (4) There appears to be a definite relation between pH and crop yield. For each crop the yields increased up to a certain pH; beyond which they decreased again. The optimum pH for the crops grown in the experiment reported here are as follows; Alsike clover 5.8 Red clover 6.3 Sweet clover 6.5 Soybeans 6.3 Wheat 6.2 Barley 6.2 Rye 5.9 Corn 6.3 Potatoes 5.4 / M.S.

The agriculture sector in Amhara National Regional State is characterised by producing cereal crops which occupy the largest percentage (84.3%) of the total crop area cultivated in the region. As a result, it is imperative to investigate which factors influence the yields of cereal crops particularly in relation to the five major types of cereals in the study region namely barley, maize, sorghum, teff and wheat. Therefore, in this thesis, using data collected by the Central Statistical Agency of Ethiopia, various statistical methods such as multiple regression analysis were applied to investigate the factors which influence the mean yields of the major cereal crops. Moreover, a mixed model analysis was implemented to assess the effects associated with the sampling units (enumeration areas), and a cluster analysis to classify the region into similar groups of zones. The multiple regression results indicate that all the studied cereals mean yields are affected by zone, fertilizer type and crop damage effects. In addition to this, barley is affected by extension programme; maize crop by seed type, irrigation, and protection of soil erosion; sorghum and teff crops are additionally affected by crop prevention method, extension programme, protection of soil erosion, and gender of the household head; and wheat crop by crop prevention methods, extension programme and gender of the household head. The results from the mixed model analysis were entirely different from the regression results due to the observed dependencies of the cereals mean yields on the sampling unit. Based on the hierarchical cluster analysis, five groups of classes (clusters) were identified which seem to be in agreement with the geographical neighbouring positions of the locations and the similarity of the type of crops produced. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

In this study several free-living diazotrophs (FLD) were isolated and screened for their nitrogen fixing ability on a range of crops grown in greenhouse, hydroponics and field trials. Rhizosphere isolates of free-living diazotrophs (FLD) may be effective biofertilizer inoculants, and may improve plant health where crops are grown with little or no fertilizer, as is the case in the Developing World. FLD isolates from rhizospheric soils in KwaZulu-Natal were assessed by growing them on N-free media, which is a key isolation method. They were then evaluated for their nitrogenase activity by quantifying ethylene production from acetylene by gas chromatography (GC). The free living isolates that produced greater quantities of ethylene were detected by an acetylene reduction assay (ARA). These were further assessed for colony formation on N-free media with different carbon sources, and at a range of temperatures (20, 25 and 300C) and pH values (6.0, 7.0 and 8.0). Isolates G3 and L1 were identified using DNA sequencing by Inqaba Biotechnical Industries (Pty) Ltd as Burkholderia ambifaria Coenye et al, and Bacillus cereus Frankland, respectively. These isolates grew significantly better on an ethanol medium, at temperatures of 20, 25 and 300C and pHs of 6.0, 7.0 and 8.0. Isolates B3 (Burkholderia sp.) and D6 (Bacillus cereus Frankland) also grew well on an ethanol medium, but only at 200C and at a pH of 6.0 and 7.0, respectively, while Isolate E9 (Burkholderia cepacia Frankland) grew well on an ethanol medium only at 300C, and pH 6.0 and 7.0. Temperature and pH strongly influence FLD growth on N-free media using different carbon sources. Further trials were conducted to screen the best isolates under greenhouse condition, using both seed treatments and drenching application techniques onto several crops. The drenching application resulted in an increase in the growth and N-total of all the evaluated crops, relative to an unfertilized control. Growth and N-total of maize and sorghum increased with seed treatments, but did not increase the growth of lettuce and zucchini. Drenching of FLD isolates at 106cfu ml-1, applied on weekly basis, resulted in an increase in the growth of lettuce. Increased doses and frequency of application of the FLD bacteria resulted in a decrease in lettuce growth. This led to the conclusion that application of FLD bacteria at high doses and short intervals may create a situation where the applied FLD bacteria and the resident rhizosphere microbes compete for root exudates. High doses at low frequencies and low doses at high frequencies may be more effective on lettuce. Inoculation of Isolate L1 (B. cereus) at 106cfu ml-1 or in combination with Eco-T® (Trichoderma harzianum Rifai), significantly increased growth of lettuce. This result may have been due to nitrogen fixation, or to secretion of growth promoting substances by both the FLD and T. harzianum, and to biocontrol effects of Eco-T®. Application of Isolate L1 (B. cereus) at 106cfu ml-1 with or without Eco-T® was an effective tool for enhancing plant growth and nitrogen fixation. An FLD, Isolate L1 (B. cereus), was applied to lettuce plants together with a complete hydroponics fertilizer at 25% strength (Ocean Agriculture 3:1:3 (38) Complete), with the N level at 25mg l-1. These plants grew significantly better than the control plants grown on 25% of normal NPK fertilization, or with an inoculation of L1 alone. This indicates that it may be possible to integrate FLD applications with the application of low levels of commercial fertilizers, which is what resource poor farmers can afford. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

Sugarcane plants (cultivar NCo376) were studied to assess the effects of temperature and season (spring and autumn equinox) on the morphological and physiological response of stalk components. Plants were grown from single-eyed setts for ca. five months and then placed into three temperature controlled glasshouses (22/12°C (C), 27/17°C (W) and 32/22°C (H) day/night temperatures). The plants were sampled twice weekly over a one month period., and intemodes 4, 6 and 10 of the primary haulms of each plant sampled for growth and sugar analysis. During spring, the leaf emergence rates were 0.0303, 0.1095 and 0.1682 leaves d(-1) at temperatures C, W and H, respectively; and 0.0327, 0.0824 and 0.113 leaves d(-1) in autumn. The phyllochron intervals were 114°Cd in spring and 147°Cd in autumn. Highest green leaf blade area of the primary haulms was achieved at H (438.0 and 511.7 cm2 in spring and autumn, respectively). The stalk extension rates were 1.22, 1.02, 0.38 cm d(-1) (spring) and 1.35, 0.98, 0.45 cm d(-1) (autumn), respectively, in descending order of temperature. Total biomass and stalk biomass per plant were not affected by temperature, despite the differences in stem elongation. Internodes of plants at C were shorter but thicker and heavier than the comparable internodes of plants at W and H. In autumn, the mature internode sucrose concentrations were 35.5, 29.2 and 25.5% at C, W and H, respectively; corresponding to mean RS% of 5.7, 9.8 and 13.3%, and fibre % of 58.8, 61.1 and 61.3%, at the respective ascending order of temperature. Sucrose % in the mature internodes in spring were 27.8, 20.9 and 19.9% at C, W and H, respectively; corresponding to RS% of 5.9, 9.76 and 10.9% and fibre % of 66.3, 69.4 and 69.2% at the respective ascending order of temperature. Temperature effect on the concentration of the stalk components of the immature internodes was in general not significant. Sucrose partitioning coefficients in the mature internodes were 0.25, 0.21 and 0.20 in spring and 0.50, 0.32 and 0.21 in autumn (at C, W and H, respectively). Data that resulted from this study, which is isolated to temperature and cultivar NCo376 can be used in models of sugarcane that simulate leaf appearance and senescence, assimilate partitioning between leaf and stalk and assimilate partitioning between the stalk components namely sucrose, reducing sugars and fibre. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

Inoculation with diazotrophic bacteria is well documented as a means to enhance growth and increase yields of various crops, especially when used as an alternative or a supplement to the use of nitrogenous fertilizers and agrochemicals for sustainable agriculture. Nitrogen is the most limiting nutrient for increasing crop productivity, and the use of chemical sources of N fertilizers is expensive, and may contribute to environmental pollution. Therefore, there is a need to identify diazotrophic inoculants as an alternative or supplement to N-fertilizers for sustainable agriculture. The search for effective diazotrophic bacterial strains for formulation as biofertilizers has been going on for over 40 years and a number of inoculant biofertilizers have been developed and are commercially available. In the current study, 195 free-living diazotrophic bacteria were isolated from soils collected from the rhizosphere and leaves of different crops in different areas within the KwaZulu-Natal Province, Republic of South Africa. Ninety five of the isolates were selected for further screening because they were able to grow on N-free media using different carbon sources. Isolates that were very slow to grow on N-free media were discarded. Of these, 95 isolates were screened in vitro for growth promotion traits tests including tests for ammonia production and acetylene reduction. The best 20 isolates that were also able to reduce acetylene into ethylene were selected for growth-promotion trials on maize under greenhouse conditions. Of the 20 isolates, ten isolates enhanced (P = 0.001) growth of maize above the Un-inoculated Control. Molecular tests were conducted to identify the ten most promising isolates selected in the in vitro study. In the greenhouse study, these diazotrophic isolates were screened for their ability to enhance various growth parameters of maize (Zea mays L.), following various inoculation techniques (drenching, seed treatment, foliar spray and combination of these). Inoculations with the five best diazotrophic isolates by various methods of application increased dry weight and leaf chlorophyll content (P < 0.001, P = 0.001), respectively, compared to the Untreated Control. Although, all methods of application of diazotrophic inoculants used in this study resulted in increased dry weight and leaf chlorophyll content, combined methods of application (seed treatment + drenching) and sole application (seed treatment) were significantly more (P < 0.05) efficient. The best five most promising isolates were identified for growth promotion of maize under greenhouse conditions. They were also assessed for their effects on germination of wheat in vitro and were further tested in combination with various levels of nitrogenous fertilizer for growth-promotion of wheat (Triticum aestivum L.). These five isolates were also investigated for their potential to enhance growth and yields of maize and wheat crops in field trials, when combined with a low dose of nitrogenous fertilizer. These isolates were further studied for their contribution for enhancing plant growth through nitrogen fixation by predicting N content in leaves using a chlorophyll content meter (CCM-200) and correlated to extractable chlorophyll level at R2 = 0.96. In this study, relative to the Un-inoculated Control, the best five isolates enhanced growth of maize and wheat when combined with a 33% N-fertilizer levels for a number of growth parameters: increased chlorophyll levels and heights of maize, shoot dry weight of maize and wheat; and enhanced root and shoot development of these crops in both greenhouse and field conditions. The best contributions of diazotrophic bacteria was achieved by Isolate LB5 + 0% NPK (41%), V9 + 65% NPK (28.9%), Isolate L1 + 50% NPK (25%), Isolate L1 + 25%NPK (22%) and LB5 + 75% NPK (15%) undergreenhouse conditions. At 30 or 60 DAP, isolates with 33%N-fertilizer caused relatively higher dry weight than the 100%NPK. Inoculation of Isolate StB5 without 33N% fertilizer cuased significant (P<0.005) increases in stover dry weight. In field studies, inoculation of diazotrophic bacteria alone or with 33%N-fertilizer resulted in relatively greater increases of dry weight, stover dry weight, number of spikes and yield at different growth stages higher than the Un-inoculated or Unfertilized Control. However, the increases were not statistically significant. The use of microbial inoculants in combination with low doses of nitrogenous fertilizers can enhance crop production without compromising yields. The isolates obtained in this study can effectively fix nitrogen and enhance plant growth. The use of microbial inoculants can contribute to the integrated production of cereal crops with reduced nitrogenous fertilizer inputs, as a key component of sustainable agriculture. / Ph.D. University of KwaZulu-Natal, Pietermaritzburg 2013.

1. Seventy-five samples of soils were taken in Washington County, Virginia. These samples were taken while the soil survey was in progress. In this group thirty-one different soil types were included. The samples were taken from all parts of the county. Notes were made of the soil type, slope of the land, drainage conditions, erosion, and land utilization. When samples were taken from cultivated fields, the yield of the crop was estimated. When samples were taken from pasture, notes were made of the type and condition of the vegetation. 2. The following properties were determined and studied in relation to soil type and plant growth: pH, available phosphate, available potash, percent organic matter, percent colloids, base exchange capacity, exchangeable hydrogen and present base saturation. The results of these determinations were used in conjunction with the physical properties, which had been determined by the soil survey, in studying the various relationships. 3. The laboratory methods of determination were devised by soil investigators. The reliability of these methods was discussed by means of reference to literature. 4. Soils of the same textural class varied widely in percentage colloids. 5. Soils that are relatively high in available potash varied widely in base exchange capacity, pH, percent base saturation, and available phosphate. 6. Soils at like pH values showed no relationship of percent organic matter to percent base saturation. 7. Soils above pH 6.0 contained 125 pounds per acre or more available potash; they were above 65 percent base saturation and were widely variable in available phosphate and organic matter. Soils at similar pH values showed wide variations in available phosphate. 8. Within the same textural class, and under similar conditions of land utilization, soils varied widely in percent organic matter. 9. There was some variation in pH values of residual soils of limestone origin. However, the average values of five samples of each were very close together. The average for Dunmore was 5.4, Hagerstown 5.5, and Clarkesville 5.6. 10. Available phosphate and potash, as well as pH, were closely related to yield of corn and tobacco. 11. Available phosphate and closely related to quality of meadow. In soils where available phosphate was above 50 pounds per acre quality of meadow was good. Potash was present in sufficient quantity not to be a limiting factor. 12. A close relationship was found between some of the soil properties studied. The coefficient of correlation between base exchange capacity and percent organic matter was .7191 ± .0376; between pH and exchangeable hydrogen -.6500 ± .0450; between pH and percent base saturation .9008 ± .0147. This high degree of correlation of pH and percent base saturation, it appears, would hold only for a large number of soils. Within this group, soils at like pH values vary considerably in percent base saturation. There was little relationship between percent colloids and base exchange capacity. 13. In all cases, in pasture soils, where available phosphate was below nine pounds per acre, pastures were of poor quality. There was a gradual decline in the minimum range of available phosphate and potash in the soils from the good, medium and poor quality pastures. There is also a gradual decline in the average pH values as quality of pasture declines. 14. Evidence is shown that, within a soil type, the properties of the soil, under varying conditions of soil management vary widely. The soil type name gives no indication of the fertility of the soil at the present time. However, associated with the type name are certain physical properties which determine, largely, the possibilities or limitations of that soil type, or the degree of productivity that the type may be built up to under ideal conditions of soil management. / Master of Science