Life Sciences Commons^™

N2-Fixation In Alfalfa (Medicago Sativa L.) Seedlings And Rhizobium Meliloti L. Grown In Vitro Under Salt And Drought Stresses, Ramzi Muhiddin Mohamad

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Alfalfa, Medicago sativa L., cultivars, breeding lines and germplasm releases (populations) and Rhizobium meliloti L. strains that exhibit nitrogen fixation efficiency and tolerance to salinity and drought stresses should enhance seedling establishment, increase yields, reduce nitrogen dependency on petroleum-based nitrogen fertilizers, and allow wider use of irrigated lands in semiarid and a rid regions. In vitro experiments were conducted to determine relative salt (sodium chloride -- NaCl) tolerance: l) during germination and early seedling growth of 229 alfalfa populations from North Africa, the Middle East and the United States, 2) survival and growth of 92 rhizobial strains obtained from different …

Investigations Of Field Performance And Physiological Effects Of Metsulfuron And Metsulfuron Combinations On Field Bindweed (Convolvulus Arvensis L.), Hamid Rahimian Mashhadi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Field bindweed (Convolvulus arvensis L.) is a noxious perennial weed of many fallow and cropland fields all over the world. Present control methods are not satisfactory for field bindweed. Metsulfuron, 2[[[[(4-methoxy-6-methyl-1,3,5-triazine-2-yl) amino] carbonyl] amino] sulfonyl] benzoic acid, is a new herbicide that has been shown to have activity on bindweed especially when tank mixed with other herbicides. This study was conducted to investigate the field performance and some physiological effects of metsulfuron on field bindweed.

Neither metsulfuron alone nor metsulfuron combinations gave persistent control of field bindweed. Metsulfuron usually increased the activity of other bindweed herbicides. Herbicide application to …

Effects Of Drought On The Survival Of Rhizobium Leguminosarum Biovar Trifolii And The Nodulation Of Subterranean Clover In An Acid Soil, Carmen Bueno

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Twenty-nine Rhizobium leguminosarum biovar trifolii strains were tested for acidity tolerance in acidified liquid medium. Only 41% of the strains grew at pH 4.1. One acid-tolerant strain, USDA 2160, and one acid-sensitive strain, 162-X-103 from Nitragin Co., were inoculated on seeds of 'Nungarin', 'Seaton Park' and 'Clare' subclover cultivars. The inoculated and pelleted seeds were sown in potted Cluff soil with pH 5.7. Three desiccation levels were imposed by delaying watering for 0, 15 or 30 days. Four gravimetric soil water contents (6.0, 6.6, 10.5 and 12.5%) were maintained under a greenhouse line-source sprinkler system for 7 weeks. The desiccation …

Effects Of Phosphorus On No-Till, Minimum-Till, And Conventional Till Irrigated Field Corn, John A. Mckay

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This investigation involved three tillage treatments, fall plowed (conventional) (moldboard IS-centimeter depth), fall chiseled (ripped) (25-centimeter depth), and no-tillage (zero tillage) replicated four times on an established alfalfa field. Rye was planted in the fall and harvested prior to planting the corn. Soil samples contained an average of 5.9 ppm phosphorus in the 0-30 centimeter soil layer, indicating the need for additional phosphorus. Within each tillage treatment, six rows received 11 kilograms/hectare phosphorus with the seed and 34 kilograms/hectare phosphorus side-dressed. Six rows received 45 kilograms/hectare phosphorus side-dressed, and four rows received 0 phosphorus. All 16 rows received 64 kilograms/hectare …

Disturbed Alpine Ecosystems: Seedling Establishment Of Early And Late Seral Dominant Species, Jeanne C. Chambers

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study examined the effects of seedbed and seedling environment on establishment of early and late seral dominant alpine species. Species studied included late seral dominant forbs (Geum rossii, Artemisia scopulorum, and Polemonium viscosum), early seral dominant forbs (Potentilla diversifolia and Sibbaldia procumbens), a late seral dominant grass (Festuca idahoensis), and early seral dominant grasses (Calamagrostis purpurascens and Deschampsia cespitosa). Germination responses of each species to wet vs. dry cold stratification and light vs. dark conditions were investigated. No statistical differences were observed in the seed germination of early and late …