Master of Science / Department of Agronomy / David B. Mengel / This study was initiated to determine if potassium (K) deficiencies seen in soybeans (Glycine max (L.) Merr.) under no-till and strip-till production systems are impacting soybean yields, and if so, what fertilizer application practices including: rate of K application; broadcast or deep band methods of application; and the use of starter fertilizer at planting; could be used to correct the problem. The residual impacts of K fertilization and placement were also evaluated on corn (Zea mays L.) grown in rotation with soybeans. This research was conducted on-farm in cooperation with local producers. Soybeans sites in 2007 were near Harris, Ottawa and Westphalia, Kansas with corn planted in 2008 at the sites near Ottawa and Westphalia. Soybean sites in 2008 were located near Ottawa and Welda, Kansas. Selected sites were generally near or below the current soil test K critical level of 130 mg per kg extractable K, based on sampling histories provided by the cooperators. Sampling in the spring of 2007 confirmed these soil test (ST) K levels. Soybean leaf tissue potassium levels in 2007 were less than the critical level of 17 mg per kg in the unfertilized control plots, and were significantly greater when potassium fertilizer was deep banded or a high-rate of K fertilizer was broadcast. No significant difference in yield of soybeans due to K fertilization was seen, likely due to significant water stress during the grain fill period, which severely limited soybean yield in 2007. Soil test K levels at all the research sites increased dramatically between 2007 and 2008, even where no K was applied. Different weather conditions experienced these two years may have contributed to this occurrence. No residual impacts of K fertilization in 2007 on soybeans were seen in soil tests, corn leaf tissue K levels or corn yield in 2008. Soybean sites in 2008 also showed a dramatic increase in K ST levels in 2008 as compared to farmer records. No effects of K fertilization on soybean growth or yield were seen in 2008. The 2008 Ottawa soybean site had very low P soil tests. A significant response to P fertilization contained in the starter treatments was observed. This suggests that the dominant farmer practice of applying P and K fertilizer to corn, and not applying fertilizer directly to soybeans, even at low soil test levels, may not be supplying adequate P to soybeans, and is likely costing farmers yields and profits.

Bermudagrass (Cynodon dactylon L.) is a perennial warm-season grass that is very responsive to nitrogen (N) fertilization. Excessive N applications have negative environmental consequences and make maintaining mixed swards difficult. This study determined the effects of enhanced efficiency (EE) N fertilizers and fertilizer rate on bermudagrass yields, nutritive values, and white clover persistence. Nitrogen sources included urea, urea formulated with Agrotain® (U+A), urea with Agrotain® and dicyandiamide (SuperU), a polymer-coated urea (ESN), ESN+urea (75% ESN, 25% urea), and methylene urea (MU). In the urea formulation trial, SuperU and U+A maximized forage yields at lower N rates. The dicyandiamide in SuperU did not increase yields over U+A. Highest production efficiency was achieved at lower N rates. ESN had the lowest relative stimulate growth, which may increase clover persistence. In the clover persistence trial, the addition of N fertilizer began decreasing clover populations after 112 kg N/ha. Slow-release fertilizers (ESN, ESN+urea, MU) had higher clover percentage at the final harvest. Crude protein and in vitro digestible dry matter increased, while neutral detergent fiber and acid detergent fiber decreased with the addition of white clover. SuperU and U+A were more efficient and ESN had lower relative stimulated growth beneficial for mixed pastures.

Dissertation (PhD)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: Male fertility has for many years been defined in vitro as the ability of sperm to fertilize oocytes and to obtain early cleavage-stage embryos. Spermatozoa comprise of an extraordinary high percentage of polyunsaturated fatty acids in their plasma membrane. Due to an extremely low content of cytoplasm, sperm cells have a particularly low potential to scavenge reactive oxygen species (ROS), and are therefore highly sensitive to oxidative processes, which lead to sperm nucleus DNA damage/fragmentation. Normally, DNA fragmentation occurs in every ejaculate and can be induced by an excessive ROS production of active leukocytes or the spermatozoa themselves. Under distressed conditions, DNA fragmentation may also occur in the testis as a result of oxidative processes in the apoptotic cascade. These DNA fragmentations can be regarded as late signs of programmed cell death (apoptosis). Clinically, DNA fragmentation in spermatozoa results in significantly decreased implantation and pregnancy rates especially in patients with oligo- and/or teratozoospermia. The p-pattern normal sperm morphology has been shown to give poorer fertilization rates in vitro than the g- and n-patterns. In this study there is reported on the significant correlation found between the p-pattern normal sperm morphology and sperm DNA fragmentation as measured with the terminal deoxynucleotidyl transferase-mediated dUDP-biotin end labeling (TUNEL) assay. This finding further explains the lower fertility potential of patients presenting with p-pattern normal sperm morphology. In addition, this study explores the intricate relations between ROS in the semen, DNA fragmentation of the spermatozoa, as measured with the TUNEL assay and the sperm chromatin structure assay (SCSA ), spermatozoa apoptotic status and sperm parameters as measured with a standard semen analysis. Positive correlations were found between ROS and the apoptotic status of the sperm, as well as between sperm with non-fragmented DNA and sperm concentration and percentage motility. The results emphasize the importance of sperm selection especially when the treatment of choice is intracytoplasmic sperm injection (ICSI). An early sign of programmed cell death, also known as apoptosis, is the externalization of phosphatidylserine (PS) from the inner membrane leaflet to the outer leaflet. PS shows a high affinity to Annexin V. Apoptotic spermatozoa are able to fertilize oocytes, but embryo senescence may occur at the time when the paternal genes are activated. In this study there is reported on a novel method whereby spermatozoa can be separated on the basis of their apoptotic status through flow cytometry. Results showed that the normal sperm morphology, according to strict criteria, of the resultant nonapoptotic sperm fraction is significantly higher than that of the apoptotic counterpart. With refinement of this technique, it will be possible in future to use these separated non-apoptotic sperm cells during ICSI for fertilization. From the above it is apparent that the spermatozoon has to play a vital role in the development of the embryo from fertilization to implantation and pregnancy. It is, however, important to note that besides the gametes, there are other critical factors which contribute to a successful in vitro fertilization (IVF) cycle, among these are the in vitro culture conditions. In this regard, this study compared two sequential embryo culture systems. It was found that the more complex medium resulted in better day three embryo quality and a better blastocyst formation rate and pregnancy rate. These findings highlight the importance of a holistic perspective towards the complexity of the factors involved in affecting embryo quality and pregnancy outcome. / AFRIKAANSE OPSOMMING: Manlike fertiliteit is vir baie jare gedefinieer as die in vitro vermoë van ‘n spermsel om ‘n eiersel te bevrug om sodoende embrios te verkry. Die spermsel se plasmamembraan bestaan uit ‘n hoë persentasie poli-onversadigde vetsure. As gevolg van die klein hoeveelhede sitoplasma van die spermsel het dit ‘n beperkte weerstand teen reaktiewe suurstof spesies (ROS) en is gevolglik baie sensitief vir oksidasie. Oksidasie lei tot DNS skade/fragmentasie. DNS fragmentasie kom in spermselle van alle ejakulate voor en is gewoonlik die gevolg van ROS produksie deur die leukosiete in die semen of vanaf die spermselle self. Onder sekere omstandighede kan DNS fragmentasie ook voorkom in die testis waar dit deel vorm van apoptose. Hierdie tipe DNS skade word gesien as laat tekens van geprogrammeerde seldood (apoptose). In oligo- en/of teratozoospermiese mans lei DNS fragmentasie tot verlaagde implantasie- en swangerskapssyfers. Die p-patroon normale sperm morfologie groep gee laer in vitro bevrugting en swangerskapsyfers as die g- en n-patrone. In hierdie studie doen ons verslag oor die statisties betekenisvolle korrelasie wat gevind is tussen die p-patroon normale sperm morfologie en DNS fragmentasie soos gemeet met die ‘terminal deoxynucleotidyl transferase-mediated dUDP-biotin end labeling’ of te wel TUNEL toets. Hierdie bevinding is ‘n verdere verklaring vir die laer fertiliteits potensiaal van pasiënte wat voordoen met p-patroon sperm morfologie. ‘n Verdere doel van die studie was om die moontlike verband tussen ROS in die semen, spermatozoa DNS fragmentasie, apoptotiese status van die sperms en die motiliteits parameters van die spermatozoa te bepaal. ‘n Positiewe korrelasie is gevind tussen ROS en sperm apoptotiese status. Sperms met ongeframenteerde DNS is ook positief gekorreleer met sperm konsentrasie en motiliteit. Die resultate beklemtoon die belangrikheid van spermseleksie veral in pasiënte waar die keuse van behandeling intrasitoplasmiese sperm inspuiting (ICSI) is. ‘n Vroeë teken van apoptose is die eksternalisering van ‘phosphatidylserine’ (PS) vanaf die interne oppervlakte van die plasmamembraan na die eksterne oppervlak. PS het ‘n hoë affiniteit vir Annexin V. Apoptotiese sperms het die vermoë om ‘n oösiet te bevrug, maar kan lei tot die staking van embrio deling wanneer die vaderlike gene ‘n rol begin speel in embrio ontwikkeling. In hierdie studie het ons ‘n nuwe metode ontwikkel waarvolgens die spermatozoa in die ejakulaat op grond van hul apoptotiese status geskei kan word in apoptotiese en nie-apoptotiese fraksies. Die normale sperm morfologie van die nie-apoptotiese fraksie is betekenisvol beter as dié van die apoptotiese fraksie. Verdere verfyning van die tegniek kan daartoe lei dat dit in die toekoms toegepas kan word om vir nie-apoptotiese sperms te selekteer veral voor die uitvoering van ICSI. Uit die bogenoemde is dit duidelik dat die spermsel ‘n baie belangrike rol in die ontwikkeling van ‘n embrio, vanaf bevrugting tot implantasie en swangerskap, speel. Dit is egter ook belangrik om in gedagte te hou dat daar ander bydraende faktore tot ‘n suksesvolle in vitro swangerskap is, soos laboratorium toestande en embrio kultuursisteem. Om hierdie rede is daar ook twee kultuurmedia in hierdie studie vergelyk. Daar is bevind dat die meer komplekse medium beter kwaliteit embrios op dag drie lewer, asook meer blastosiste en ‘n hoër swangerskapsyfer. Dit is dus duidelik dat dit uiters belangrik is om ‘n holistiese perspektief te hê op die komplekse faktore wat ‘n invloed mag hê op bevrugting, embrio kwaliteit asook die swangerskapsyfer.

Thesis (D.Phil.)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: Chapter 1 provides literature based background information on the clinical importance of sperm morphology as recorded by strict criteria during the diagnostic approach of the infertile couple. Furthermore, the use of a sequential diagnostic schedule for couples in an assisted reproductive programme is emphasized. The author revisited the literature on chromatin packaging of spermatozoa and addresses this issue as an additional semen parameter providing information relating to DNA damaged spermatozoa. The chapter also includes evidence underlining the growing need for the implementation of the acrosome reaction as an important contribution to the assisted reproductive programme. Chapter 2 provides detailed descriptions of the material and methods used during the study. Chapter 3 is sub-divided into 5 sections, each of which represents a separate study that was prepared as a scientific paper. The study included 338 couples consulting for infertility treatment at various gynaecologists in Pretoria and Johannesburg. The diagnostic assisted reproductive laboratory support was provided by the Andrology laboratory of Drs du Buisson and partners from Pretoria. In the first study the role of chromatin packaging as an indicator of in vitro fertilization rates, the semen samples from 72 men were used to record their chromatin packaging quality as well as their sperm morphology classification. Significant different percentages CMA3staining (mean±SE) were recorded among the 2 morphology groups, namely 65.9%±3.5 and 44.5%±1.7 (p=0.001). Using cut off values for chromatin packaging established during the first study, the second study utilized semen from 140 men in the in vitro fertilization (IVF) and intracytoplasmic sperm injection programme (ICSI) to analyze for sperm concentration, motility, morphology and chromatin packaging (CMA3).IVF and ICSI data were stratified using 3 basic cut off values for CMA3staining, namely <44%, >44-60% and >60%. The study concluded that results on the chromatin packaging quality of spermatozoa could be used as an additional parameter of sperm quality since it could provide valuable information on decondensation status of a given sperm population. The third study aimed to establish zona pellucida induced acrosome reaction response (ZIAR) among 35 couples with normal and G-pattern sperm morphology and repeated poor fertilization results during assisted reproduction treatment. Interactive dot diagrams, divided patients into 2 groups i.e. ZIAR<15% and ZIAR>15% with mean fertilization rates of 49% and 79%, respectively. The study concluded that the ZIAR test has diagnostic potential, since it can assist the clinician to identify couples that will benefit from ICSI therapy. The forth study revisited the importance of micro-assay for acrosome reaction determinations in a diagnostic andrology laboratory. The micro-assay not only allows the use of a single zona pellucida, but also facilitates the future possibility of using recombinant zona pellucida proteins in a diagnostic test system. The final study in Chapter 3 includes results obtained from 49 couples (172 oocytes) and aimed to evaluate the role of chromatin packaging and sperm morphology during sperm-zona binding, sperm decondensation and the presence of polar bodies among 170 oocytes that failed in vitro fertilization (IVF). Odds ratio analyses indicated that being in the a group with elevated CMA3 staining i.e. >60%, the risk of decondensation failure increases 15.6 fold relative to normal CMA3 staining <44%. Chapter 4 underlines the validity of the sequential diagnostic approach and summarizes the results and value of a multistep diagnostic scheme. The chapter concludes with the recommendation that both chromatin packaging quality and zona pellucida mediation of the acrosome reaction should be part of the diagnostic tools in the assisted reproductive programme. / AFRIKAANSE OPSOMMING: Die literatuuroorsig in Hoofstuk 1 konsentreer in hoofsaak op die kliniese belang van sperm morfologie en die uitbreiding van die diagnostiese toetse en hantering van die egpaar in die reproduktiewe ondersteuningsprogram. Die kromatien pakkingskwaliteit van die spermsel word onderskryf as In belangrike toevoeging tot die diganostiese program, aangesien ONS skade dikwels saam met kromatiendefekte aangetref word. Die rol van die akrosoomreaksie word ook in detail literatuuroorsigtelik beklemtoon. Hoofstuk 2 bevat volledige inligting omtrent materiaal en metodes wat in die studie gebruik is. Hoofstuk 3 bevat die eksperimentele gegewens wat in 5 afsonderlike sub-afdelings as wetenskaplike publikasies aangebied word. Die studies bestaan uit data van 338 pasiënte, wat deur verskillende ginekoloë van Pretoria en Johannesburg gekonsulteer is waartydens drs. du Boisson en vennote van Pretoria die diagnostiese reproduktiewe laboratoriumdienste verskaf het. Die eerste studie stel dit ten doel om die belang en korrelasie van die spermsel kromatienpakkingskwaliteit van 72 mans te vergelyk met die morfologiese bou van sie sel. Aangesien morfologie reeds gevertig is as 'n kliniese voorspeller van bevrugting was dit nodig om hierdie parameter te vergelyk met die kromatienpakking van die sel. Twee afsnypunte word vir die normo-en teratozoospermiese mans identifiseer naamlik, 44.5%±1.7 en 65.9%±3.5 (p=O.001),respektiewelik. Die tweede studie gebruik die afsnypunte 44% en 66% om die in vitro bevrugting en intrasellulêre sperm inspuiting (ICSI) data te ontleed. Die resultate dui aan dat kromatienpakking In waardevolle bydrae tot die diagnostiek van die pasiënte lewer. Die derde studie stel dit ten doelom die waarde van die zona pellucida geinduseerde akrosoomreaksie (ZIAR) te bepaal. Die studie sluit die data van 35 egpare in wat almal normale of G-patroon morfologie het en verder onverklaarde swak bevrugtings resultate tydens in vitro bevrugtingsterapie. Interaktiewe punt diagram (interactive dot diagrams) verdeel die data in twee groepe naamlik, ZIAR<15% en ZIAR>15% met gemiddelde bevrugtingssyfers van 49% en 79%, respektiewelik. Die studie sluit af met die gedagte dat die ZIAR toets 'n groep pasiënte identifiseer met 'n besondere fisiologiese afwyking d.i. subnormale akrosoom respons op zona pellucida blootstelling. Die vierde afdeling van die hoofstuk onderstreep die belang van die mikro-tegniek vir die bepaling van die akrosoom reaksie, wat tydens die projek gebruik is Die vyfde afdeling van Hoofstuk 3 stel dit ten doelom 170 onbevrugde eierselle van 49 pasiënte te ontleed vir moontlike oorsake vir die mislukte bevrugting. Ondersoeke sluit in die kromatienpakking, sperm-zona binding, sperm dekondensasie en die teenwoordigheid van polêre liggaampies. Statisties blyk dit dat indien 'n kromtienpakking nie normaal is nie (>66%) het die spermsel 'n 15 keer groter kans om nie te dekondenseer nie. Hoofstuk 4 bespreek die noodsaaklikheid van die diagnostiese skedule by die hantering van die onvrugbare egpaar in.

Thesis (DSc)--Stellenbosch University, 2012. / Please refer to full text for abstract.

Thesis (PhD(Agric) (Animal Sciences))--University of Stellenbosch, 2005. / As most researchers have foreseen, and many breeders have hoped, the in vivo and in vitro production of livestock embryos and the birth of subsequent offspring never really replaced artificial insemination during the past 30 years. This was, to a large extent, due to very variable and unreliable numbers of embryos produced using these two methods. The present study was therefore undertaken to investigate certain aspects of assisted reproductive techniques (ART) to try and solve some of these difficulties. Problems addressed were the management of follicular development on the ovary by controlling the dominant follicle, and investigating alternative and more cost-effective culture media and conditions for embryo culture. A method to control the development of the dominant follicle in a cohort of follicles as well as the waves of follicular development in the ovaries of sheep, goats and cows with an estrogenic product was investigated. Estradiol cypionate (ECP) was used for this purpose, injected intramuscularly after the insertion of the progesterone or progestagen implant. ECP has a negative feedback effect on the secretion of pituitary FSH, and therefore follicular development. The animals of the three different species were randomly divided into two groups each, the ECP-group receiving the estradiol cypionate injection, and the control group receiving a saline injection. Five days after the ECP injection a program of follicular multi-stimulation with FSH hormone was initiated. The females of the different species were bred by either natural service (goats) or inseminated by laparoscopy (sheep) or trans-cervically (cows) to fertilize the ovulated ova. Embryos and unfertilized ova were collected surgically at the 8 to 16- cell stage 3 to 4 d after breeding in the sheep and goats, and trans-cervically in the cows. Significantly more CL formed, and a total number of ova and embryos, as well as transferable embryos, were collected from the ECP-group of sheep ewes and goat does compared to the control group that received no ECP (p<0.01). There was, however, no difference in the average number of unfertilized ova that were collected in the two sheep or goat groups. In the cows the number of CL counted, the total number of embryos and ova and of transferable embryos collected, were significantly greater (p<0.05) in the group that were injected with ECP compared to the group that received no ECP. The control group also had a significantly larger number of unfertilized ova than the ECP-group (p<0.05). It could therefore be concluded that more reliable numbers of embryos can be produced in vivo if the development of the dominant follicle as well as the subordinate follicles is controlled with estradiol cypionate. Since more than half a century ago, attempts have been made to culture cells and embryos outside the body (in vitro or ex vivo). This was done with different culture media and in various "incubators". Chapter 2 deals with two different culture media used: a standard TCM-199 culture medium and first trimester amniotic fluid (BAF) collected sterilely from pregnant cows after slaughter. Two different culture conditions were also investigated, the standard laboratory CO2 incubator versus culturing bovine embryos in the vagina of a goat doe. Two experiments were done: Firstly the permeability of different receptacles to CO2 gas was analyzed for possible culture in the vagina. Four-well plates and straws were used to incubate TCM-199 and BAF for a period of 120 h in the presence or absence of 5% CO2 gas. The pH values were measured every 24 h and recorded. In the second experiment pre-compacted morula stage bovine embryos were incubated in the above culture media in sealed 0.25 mL straws in a standard laboratory incubator and in the vagina of a goat doe. Evaluation was done on (1) stage of development and (2) number of blastomeres after 96 h of culture. In experiment one it was shown that the CO2 gas diffused out of the 4-well plate as well as the straws in the absence of CO2 gas, while in the presence of CO2, the pH of both media stabilized between 7.3 and 7.5. This meant that the semen straws were permeable to CO2 gas and could therefore be used as receptacles for culturing early stage bovine embryos. In the second experiment no statistical differences (p>0.05) were found in the number of Grade 1 pre-compacted bovine embryos that developed to the blastocyst stage, or the hatched blastocyst stage, neither for the culture medium used, or the method of culturing in the two incubators. Neither was there any difference (p>0.05) in the number of blastomeres that developed at the blastocyst stage between the two types of incubators used. Embryos tended to develop more blastomeres when cultured in BAF than when cultured in TCM-199 in both the standard laboratory incubator and when using the vagina of a goat doe as an incubator (p<0.05). After the collection of in vivo produced livestock embryos, they are evaluated under high magnification (minimum of 80X) with the aid of an inverted or stereo microscope. The Grade 1 embryos will give the best conception results when transferred to synchronized recipient female animals, while the Grade 3 embryos will give the worst results. The aim of the next experiment was to culture all three quality grades of in vivo produced pre-compacted morula-stage embryos of sheep, goats and cows in two different culture media and then compare the development of the embryos by evaluating the number of embryos reaching the hatched blastocyst stage. The results have shown that there were no significant differences between the development of the Grade 1 and the Grade 2 embryos from any of the three species when either cultured in TCM- 199 or heat inactivated early pregnancy-stage (<60 d) bovine amniotic fluid (BAF) were used as culture media. Significantly more in vivo produced Grade 3 pre-compacted morula-stage sheep, goat and cow embryos, however, developed to the hatched blastocyst stage when cultured in BAF with 10% FBS and antibiotics, compared to culture in TCM-199 with 10% FBS and antibiotics (p<0.05). The effect of co-culture on the survival of caprine embryos post transfer to a synchronized recipient female goat was also assessed. A total of 120 Kashmir embryos at the blastocyst stage were divided into three groups after thawing and reconstitution in four steps in glycerol and sucrose medium. The first group of embryos (G1, n=40) was individually transferred semi laparoscopically in D-PBS with 10% FBS and antibiotics to the ipsilateral horn of the CL over a period of 3 d. The second group of caprine blastocysts (G2, n=40) was similarly transferred in TCM-199 with FBS and antibiotics. The third group of frozen-thawed caprine blastocyst-stage embryos (G3, n=40) were first co-cultured for ~24 h in TCM-199 with serum and antibiotics in groups of up to five embryos inside a ~50 mm length of a semen straw in a cylindrical sponge in the anterior part of the vagina of a goat doe in her luteal phase. After the culture period these embryos were transferred in a similar way in TCM-199 without the co-culture as in G1 and G2. Ultrasound scanning showed that significantly more of the blastocyst embryos that were cocultured in the vagina (G3) before transfer developed to a pregnancy compared with the embryos transferred in D-PBS (G1). The co-culture Group 3 blastocyst-stage caprine embryos produced significantly more offspring than the non-cultured embryos transferred in both D-PBS (G1) and TCM-199 (G2) (p<0.05). The maturation of bovine oocytes to allow the oocyte to resume meiosis, is the first step in in vitro fertilization to produce IVMFC embryos. The composition of the maturation medium plays an important role in the success achieved with maturation. An investigation was therefore launched to evaluate the maturation ability of first trimester bovine amniotic fluid (BAF) to mature prophase I oocytes collected from abattoir ovaries to metaphase II oocytes, compared to a standard maturation medium such as TCM-199. In the first experiment three groups of ~100 oocytes each were matured in TCM-199 with estrus cow serum (ECS). The first group of oocytes was matured in a 50 μL micro-drop in an incubator, while the other two groups were matured in semen straws, one group in an incubator and the other group in the vagina of a goat doe in di-estrus. Six further groups of ~100 oocytes each, with BAF as maturation medium, three groups with ECS and three without ECS, were matured in the same receptacles and under the same conditions as with the TCM-199. No significant differences in number of oocytes reaching the metaphase II stage could be found for any of the nine treatment groups. In the ...

published_or_final_version / Obstetrics and Gynaecology / Doctoral / Doctor of Philosophy

<p>The chromatin integrity in sperm cells is vital for successful pregnancy. In this</p><p>study DNA-damage was evaluated in sperm cells from 50 men attending In Vitro Fertilization</p><p>(IVF) or Intra Cytoplasmic Sperm Injection (ICSI) treatment. Male semen samples were</p><p>purified with a two-shift gradient before the sperm cells were treated with the Halosperm® Test</p><p>Kit and evaluated for DNA-damage. The samples were divided in two groups according to DNAFragmentation</p><p>Index (DFI) of 30 % and the results correlated with fertilization, cleavage and</p><p>pregnancy rate. Men with DFI ≥ 30 % had a higher fertilization and pregnancy rate and a lower</p><p>cleavage rate compared to men with DFI ≤ 30 %. The conclusions were that fertilization in vitro</p><p>may be independent of the degree of DNA-damage, the embryonic development could be</p><p>seriously disrupted by damaged sperm cells, and the pregnancy rate showed no correlation to a</p><p>DFI threshold of 30 %.</p>

6 pp. / Guidelines for nitrogen fertilization of small grains are presented using crop need, calendar dates, or tissue testing. Relationship between grain protein and nitrogen fertilization is presented. Phosphorus, potassium, and other nutrients are also discussed.

A nitrogen fertilizer study was conducted in order to develop tissue testing guidelines for fertilizer application to forage sorghum. The study was conducted at the University of Arizona Maricopa Agricultural center on a sandy clay loam soil irrigated using surface flood methods. Forage sorghum was planted on 8 July 09 and fertilized with eight N rates varying from 0 to 350 lbs N/acre in 50 lb N/acre increments. The plants were sampled six times during the growing season and the lower stem, most recently developed leaf, and whole plant were analyzed for nitrogen content. Maximum yield at final harvest was obtained at 150 lbs N/acre and plant growth was highly affected by N rate. Before the initiation of rapid growth, the relationship between plant growth and N content in the various tissues was weak (R2 < 0.20), but was very strong (R2>0.50) from the initiation of rapid growth through the pre-boot stage at the time when post-plant nitrogen fertilizer application may be considered. Stem nitrate was most strongly related to yield for the tissues tested, but the relationships between plant growth and total N in the newest leaf and whole plant were also very strong. Preliminary tissue testing guidelines are suggested for nitrate in the stem tissue. The lower stem, newest leaf, and whole plant are all potential candidates for development of tissue testing guidelines for forage sorghum.