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Inheritance of the multifoliolate leaf (MFL) characteristic (leaves containing more than three leaflets) in tetraploid alfalfa was studied. Also, the effects of temperature and short-term aging of a few weeks on the expression of the MFL trait were determined. Broad sense heritability of the trait was also estimated. Two sets of diallel reciprocal crosses were intially made in the greenhouse using vacuum pump and alcohol for emasculation of the seed parent. There were six different clones in each set. Set I contained ML₁, ML₂ ML₄₉, ML(G), Lew-1, and Hayden-1 clones. The average number of leaflets per leaf for the above mentioned clones was 5.65, 4.52, 3.55, 3.20, 3.00, and 3.00, respectively. Set II was composed of ML₇, ML(F), ML₁₂, ML₅₂, N₁, and N₂ clones with the average number of 4.75, 4.15, 3.50, 3.25, 3.00 and 3.00 leaflets per leaf. Based on the F₁ and S₁ progenies, it was hypothesized that at least three major and independent genes, each with equal contribution to the expression of the MFL trait, were involved. This hypothesis was later substantiated by the observed segregation ratios of the 75 F₂ families from the cross Lew-1 x ML₁ which closely fit the expected ratios. These three genes, LA, LB, and LM showed incomplete dominance with additive gene action. No evidence for epistasis was found. There was a positive association between the number of dominant alleles and the degree of expression of the MFL trait. This association was so specific that plants with less than four, four, five, six, seven or more dominant alleles had an average number of 3.0, 3.1, 3.2-3.4, 3.5-4.0, and 4.1 or more leaflets per leaf respectively. Analysis of the 11 reciprocal crosses between trifoliolate (TFL) and MFL clones showed that only two reciprocal crosses produced a significantly higher number of MFL than TFL plants when the female parent was a MFL clone. Maternal or cytoplasmic effects were negligible. The average frequency of MFL leaves of the two clones (ML(G), ML₂) studied did not significantly change under warm (34°C, 25°C) and cool (17°C, 15°C) temperatures. There was no significant change in the expression of the MFL leaf frequency trait in these two clones from the first harvest scoring to the next. Plants were scored before harvesting at full bloom. Calculated broad sense heritability of the MFL trait was 86%. This indicates that the recurrent selection method for several cycles should increase the frequency of MFL plants in an alfalfa population very rapidly. There are excellent opportunities for improving the quality of commercially grown alfalfa by incorporating the MFL trait.

Thesis (Ph. D.)--University of Adelaide, 1984. / Mounted ill. Includes bibliographical references (leaves 263-265).

Thesis (Ph. D.)--University of Adelaide, 1994. / Includes bibliographical references (leaves [70]-79).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1939. / Typescript. Includes abstract and vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 58-59).

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1987. / Vita. Abstract. Includes bibliographical references (leaves 113-122). Also available via the Internet.

Die Eden- en Overbergdistrik in die Suid-Kaap vorm die mees suidelike substreke van die winterreëngebied. Dit is geleë tussen 33° 45‟ en 34° 50‟ suiderbreedte en tussen 19° 0‟ en 23° 45‟ oosterlengte. Die westelike grens van die substreek word gevorm deur die Villiersdorp-Botrivier-gebied. Aan die noordekant word die substreek begrens deur die Sonderend-, Lange- en Outeniquabergreekse. Die oostelike grens word gevorm deur die Bloukransrivier. Die Indiese Oseaankuslyn vanaf Nature‟s Valley in die ooste tot by Kleinmond in die weste vorm die suidelike grens. In die Suidkusstreek word 54.5% van die Wes-Kaapse melkproduksie en 24% van Suid-Afrika se melkproduksie deur 1900 melkprodusente geproduseer (Dowrey 2005). Ses en dertig persent van die bruto jaarlikse veeproduk is afkomstig vanaf suiwelprodukte wat hoofsaaklik vanaf aangeplante weiding geproduseer word. Aangeplante weiding beslaan 37.7% van die totale oppervlakte van die vee- en saaigebiede van die Suidkusstreek (Botha 2003). Weens beperkte, skaars besproeiingswater in groot dele van die Suid-Kaap, word heelwat weiding slegs aanvullend besproei (Protopapas 2004). Voervloeiprogramme vir melkproduksie onder aanvullende besproeiing bestaan hoofsaaklik uit kikoejoe (Pennisetum clandestinum) en lusern (Medicago sativa) (Botha 2003). Die droëmateriaalproduksie en weikapasiteit van lusern volg, soos kikoejoe, „n baie sterk seisoenale tendens met „n piek in die somer / herfs en „n laagtepunt in die winter (Durand 1993; Botha 1998; Botha 2003). Voervloeiprogramme met lusern of kikoejoe as hoofkomponente het gewoonlik voertekorte gedurende die winter tot gevolg. Hoofsaaklik om dié rede het boere uit die lusernproduserende gebiede van Heidelberg, Riversdal, Herbertsdale en Mosselbaai, deur hul onderskeie boereverenigings, „n versoek aan Outeniqua Navorsingsplaas gerig om ondersoek in te stel na moontlike oorsaaipraktyke wat die droëmateriaalproduksie van lusernstelsels gedurende die winter kan verhoog. Kikoejoeweiding word reeds die afgelope aantal jare suksesvol met Westerworldsraaigrasse oorgesaai vir beter herfs-, winter- en lenteproduksie. Anders as by kikoejoeweidings bestaan daar huidiglik geen beproefde oorsaaipraktyke wat die produksiepotensiaal van lusern in die winter en vroeë lente kan verhoog nie (Anoniem 2002).

In the hope of finding male-sterile alfalfa strains for use in the production of hybrid alfalfa, a microscopic study of the pollen produced by approximately 1000 lines of alfalfa grown at the University of British-Columbia was conducted. This study revealed 4 lines that consistently showed an absence of viable pollen under different environments. 2 of the male-sterile lines produced no seed on selfing and 2 produced very small quantities of seed. In plants grown from open-pollinated seed of the 4 male-sterile lines, the F₁ segregation for male-sterile to male-fertile were as follows: 1:7.9, 1:7.3, 1:6.8, and 1:8.3, for an incomplete count. These ratios suggest that the male-sterility is controlled by cytoplasmic factors in addition to recessive genes. However, the mode of inheritance will only be factorially interpreted by F₂ and backcross data. It appears that the sterility is caused by a breakdown in meiosis, as the pollen sacs are full of an amorphous material suggestive of arrested development of the pollen grains. The male-sterility should eventually prove of great economic value in the production of hybrid alfalfa seed. Male-sterility has not previously been isolated in alfalfa, although it is common in the plant kingdom. Over the past 10 years the Witches' Broom virus disease of alfalfa has developed into serious proportions in the Interior of B.C. - this was first pointed out by quadrat results obtained in 1942-44. The disease is known to be distributed throughout the low rainfall areas of the province where it is widespread although sporadic. The disease is shown to be the same disease that occurs in Washington and in Australia. Witches' Broom of Alfalfa causes severe dwarfing of the affected plants and a decimation of alfalfa stands. Drastic shortening of internodes and reduction in size of leaves is accompanied by proliferation of crowns and nodes. Up to 3000 thin spindly shoots are commonly produced by a single diseased crown. Typically, leaves are marginally chlorotic; inflorescences are reduced to 3-4 florets per raceme; and, very little, if any, seed is produced. Crowns and roots are symptomless until late stages of the disease are reached, when they show severe rotting. Affected plants gradually die in a period of 3 months to 2 years. However, 2 plants were shown to apparently recover from the disease when brought into the U.B.C. greenhouse from the Nicola Valley. A histological comparison of the healthy and diseased plants showed gummosis of the xylem vessels, a breakdown and degeneration of the chloropasts of the affected leaves, and a mechanical breakdown of the palisade layer in the outer edge of diseased leaves. Storage of starch in the crowns of plants was found to be depleted according to the stage of the disease, with no storage starch present in severely diseased crowns. However, sucrose was found to be present in storage in diseased crowns but not in healthy crowns. The disease was found to be easily transmitted by crown grafts. Out of 142 attempted grafts, union of scion and stock was achieved in 31 cases with positive transmission in 27 cases. Seed transmission and inoculations by expressed crown juice have given negative results to date. Quadrats were plotted in 1950 in the interior of B.C. to further study the disease. Twinning experiments were set up to study natural resistance of the members of the genus Medicago. Results from both of these studies will not be ready for publication for at least 2 more years. A nursery plot was established at U.B.C. and a replicate plot at Kamloops, B.C. One year after planting the Kamloops plot, several of the alfalfa plants were found producing symptoms of the disease, and to be badly diseased in 15 months time. None of the plants at U.B.C. showed any signs of the disease. From a potted plant yield trial conducted at U.B.C. the diseased plants were shown to have a statistically significant reduction in yields as compared to healthy plants. / Land and Food Systems, Faculty of / Graduate

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