This laboratory manual assumes no previous knowledge of the biological sciences on the part of the student. It is designed for use in a one-semester or one-quarter introductory course in plant biology and shorter introductory botany courses open to both nonmajors and majors. Both the principles of biology and the scientific method are introduced, using plants as illustrations. The exercises demonstrate the underlying unity of all living organisms at the cellular level. The manual is designed so that students can work independently. Instructors are free to require different drawings or other assignments and may also omit some of those suggested within each exercise. Students are encouraged to read the laboratory exercise before coming to class. Laboratory preparation quizzes are provided at the end of each exercise. Answers to the laboratory preparation quizzes are discernible within the particular exercises and should not require checking other sources. Each exercise includes suggested learning goals and exercise review questions.

This research was designed to study the effects of drought on pigeon pea [Cajanus cajan (L.) Millsp.] morphology, biomass, and vessel diameter. Cultivated seeds of pigeon pea (cv. Georgia-II) were germinated, maintained in an environmental chamber, and arranged as a split-plot design with four replications; harvest was the main effect and watering regimens were tested against residual error. Plants were watered every 2, 4, 8, 16, or 32 days. Number of stems and leaves, as well as total plant height, were measured weekly. Dry weight (DW) of roots, stems, and leaves were recorded at each harvest, and root cross sections were viewed to determine vessel diameter. Results indicated that plant morphology, biomass, and vessel diameter were significantly affected by harvest and watering regimen. Plants watered more frequently had more stems and leaves, grew taller, accumulated greater DW, and had larger diameter vessels within root tissue.

Chickpea [Cicer arietinum (L.)] cultivars 'ICCV-2' and 'Sarah' were studied along with a control, multistrain, TAL 1148, and TAL 480 Bradyrhizobium strains to determine the effect(s) of cultivar and inoculum on dry weight (DW) and nitrogen (N) content of the legume, as well as soil mineral N, DW, and N content of wheat [Triticum aestivum (L.) emend. Thell.] in a continuous wheat-legume rotation. Chickpeas were planted during the summer and harvested in the fall of 1992, 1993, and 1994. Vegetative growth from chickpeas was incorporated into the soil prior to wheat planting, and soil cores were taken at 35 to 48 d after chickpea harvests. Additional summer fallow treatments for the winter wheat part of the experiment received 0, 45, and 90 kg N ha(-1) each year. Wheat plants were removed the following spring and stubble was incorporated into the soil before planting chickpeas in the summer. 'Sarah' chickpeas accumulated about the same or more shoot DW and shoot N compared to 'ICCV-2'; whereas 'ICCV-2' generally produced more pod DW and pod N compared to 'Sarah.' Inoculum had no significant effect on chickpea DW or N content. Wheat DW and N following legumes increased marginally after growing 'Sarah' chickpeas, as evidenced by higher values of some treatments. Only the multistrain or absence of inoculum in 'Sarah' chickpeas resulted in significantly greater wheat DW or N content compared to the fallow wheat receiving no added N fertilizer. The contributions from 'ICCV-2' chickpeas to wheat DW and N content were not significant. Soil mineral N, as well as wheat DW and N content, fluctuated or increased during this three-year study, which demonstrated some benefit from incorporation of chickpeas into a wheat-legume cropping system.

Pigeon pea (Cajanus cajan (L.) Millsp.) seedlings compete poorly against the rapid growth of warm-season annual weeds. Weed control is required before this heat and drought-tolerant legume can be reliably grown in the U.S. southern Great Plains as a potential source of livestock hay between annual plantings of winter wheat (Triticum aestivum L.). Currently, no herbicides are labeled for use on pigeon pea grown in the U.S. Three years of replicated field experiments were conducted to determine the effects of applications (1× and 2× rates) of herbicides (pre-emergence, sulfentrazone+chlorimuron and metribuzin; post-emergence, imazapic and sethoxydim) on weed suppression, pigeon pea dry matter, and carry-over effects on a winter wheat crop. The most abundant summer weeds were broadleaf, and all herbicide treatments, except sethoxydim (grass herbicide), reduced weed densities compared to untreated plots without adversely affecting pigeon pea stands. Imazapic treatments provided the most effective weed control. Overall average pigeon pea dry matter ranged from 75 to 256gm−2 with sethoxydim and the untreated control≤metribuzin≤sulfentrazone+chlorimuron≤hand weeded control≤imazapic. Compared to the hand-weeded control, imazapic treatments greatly reduced wheat dry matter (1×, 65% and 2×, 91%) and grain yield (1×, 59% and 2×, 93%). Imazapic should not be used unless nontransgenic imidazolinone herbicide tolerant wheat cultivars are planted. While the other herbicides decreased negative effects of weeds on pigeon pea dry matter without greatly affecting productivity of a following wheat crop, appropriate labels for each of these herbicides will be required prior to their use by southern Great Plains pigeon pea producers.

ABSTRACT F + strains of Escherichia coli infected with donor-specific bacteriophage such as M13 are sensitive to bile salts. We show here that this sensitivity has two components. The first derives from secretion of bacteriophage particles through the cell envelope, but the second can be attributed to expression of the F genes required for the formation of conjugative (F) pili. The latter component was manifested as reduced or no growth of an F + strain in liquid medium containing bile salts at concentrations that had little or no effect on the isogenic F − strain or as a reduced plating efficiency of the F + strain on solid media; at 2% bile salts, plating efficiency was reduced 10 4 -fold. Strains with F or F-like R factors were consistently more sensitive to bile salts than isogenic, plasmid-free strains, but the quantitative effect of bile salts depended on both the plasmid and the strain. Sensitivity also depended on the bile salt, with conjugated bile salts (glycocholate and taurocholate) being less active than unconjugated bile salts (deoxycholate and cholate). F + cells were also more sensitive to sodium dodecyl sulfate than otherwise isogenic F − cells, suggesting a selectivity for amphipathic anions. A mutation in any but one F tra gene required for the assembly of F pili, including the traA gene encoding F pilin, substantially restored bile salt resistance, suggesting that bile salt sensitivity requires an active system for F pilin secretion. The exception was traW . A traW mutant was 100-fold more sensitive to cholate than the tra + strain but only marginally more sensitive to taurocholate or glycocholate. Bile salt sensitivity could not be attributed to a generalized change in the surface permeability of F + cells, as judged by the effects of hydrophilic and hydrophobic antibiotics and by leakage of periplasmic β-lactamase into the medium.

Pigeon pea [Cajanus cajan (L.) Millsp.] cultivars, ‘Georgia-1’ and ‘ICPL-87’, were grown without inoculation and with Bradyrhizobium inoculation (multistrain, TAL 1127, or TAL 1132) to evaluate legume dry weight (DW) and nitrogen (N) content, soil mineral N, and subsequent wheat (Triticum aestivum L.) productivity. Pigeon peas were grown during summer and ‘TAM 101’ wheat was grown during winter, along with summer fallow controls fertilized with 0, 45, and 90 kg N ha− 1, in 36-cm diam. 20-L pots from 1992 to 1995. Representative pigeon peas were harvested in the fall and remaining plants were incorporated into the soil. Wheat was planted and soil cores were collected at 35 to 48 d after pigeon pea harvest. Wheat was harvested the following spring. Factors affecting DW and N content of both crops included length of growing season, environmental variation, and contribution of residual N. Among pigeon pea cultivars, Georgia-1 occasionally demonstrated higher DW and N content compared with ICPL-87. Estimation of N provided by pigeon pea to the last wheat crop in the third sequence of yearly rotations was 30 kg N ha− 1. Pigeon pea treatments demonstrating highest DW, N content, and contribution to soil N generally produced winter wheat with higher yield and N content compared with other treatments. While yield and N content of winter wheat fertilized at 90 kg N ha− 1 either decreased or stayed the same from 1993 to 1995, these same measurements in wheat following pigeon peas demonstrated a 3- to 4-fold increase over the same time period and warrant further research in field rotation systems of the southern Great Plains.

Chickpea [Cicer arietinum (L.)] and pigeon pea [Cajanus cajan (L.) Millsp.] were grown outside in large clay pots from 1992 to 1995 in Edmond, Oklahoma. Plants were studied to evaluate nodulation, nitrogenase activity, and shoot dry weight (DW) of 'ICCV-2' and 'Sarah' chickpea inoculated with multistrain, TAL 1148, and TAL 480 Bradyrhizobium, as well as 'Georgia-1' and 'ICPL-87', pigeon pea inoculated with multistrain TAL 1127, and TAL 1132 Bradyrhizobium. Following wheat [Triticum aestivum (L.) emend. Thell.] harvests in the spring, legumes were planted in the summer and harvested at three successive dates during the following months. Leaves and stems fi om remaining plants were incorporated into the soil after the last harvest. Across year, chickpea measurements were sensitive to temperature and precipitation whereas pigeon pea measurements were sensitive to length of growing season as well as climate. Pigeon pea consistently demonstrated higher nitrogen-fixing capacity and shoot DW compared with chickpea. Nodule and shoot DW of both species increased with plant age whereas nodule count and nitrogenase activity generally increased with plant age and leveled off or decreased at flowering. Sarah chickpea demonstrated higher nodule count and nodule DW than ICCV-2, as did the Georgia-1 pigeon pea compared with ICPL-87. Shoot DW of Georgia-1 pigeon pea was generally higher than that of ICPL-87. Multistrain inoculum improved nodulation and shoot DW of chickpea, and TAL 1127 improved nodulation of pigeon pea compared with other treatments. These results indicate that specific chickpea and pigeon pea cultivars, along with appropriate Bradyrhizobium strains, may improve nitrogen fixation and DW of these species.

Ten eastern gamagrass [Tripsacum dactyloides (L.) L.] entries from Kansas, Oklahoma, and Texas, were evaluated for in vitro dry matter digestibility (IVDMD), protein concentration, lignin concentration, and phenylalanine ammonia lyase (PAL) activity. Whole plants were harvested in Spring 1992 and 1995 from 4 replicates of each entry and divided into leaf and stem (plus sheath) components for analyses. Entry significantly affected all measurements except PAL; whereas the entry by year interaction significantly affected stem IVDMD, protein, and PAL. Across entries, stem IVDMD in 1992 (56.3% to 66.4%) and 1995 (55.9% to 64.9%) demonstrated greater variation than leaf IVDMD in 1992 (62.2% to 68.0%) and 1995 (66.7% to 71.0%). In 1992 and 1995, average leaf IVDMD and protein concentration were generally higher than average stem IVDMD and protein concentration. In 1992, lignin concentration was generally higher and varied more in stems (3.27% to 4.99%) than in leaves (3.54% to 4.11%). In 1995, lignin concentration was about the same and varied more in leaves compared with stems. Stem IVDMD was significantly correlated with lignin concentration in 1992 (r = -0.92) and 1995 (r = -0.83) as well as with protein concentration (r = 0.83) in 1995. Activity of PAL in 1995 was correlated with stem IVDMD and protein. When all data were combined, IVDMD was significantly correlated with protein concentration (r = 0.82). These results indicate that gamagrass entries demonstrate significant variation in forage quality, particularly in stems. Potential exists for development of new gamagrass cultivars with high IVDMD and protein.

ABSTRACT Selected pest control treatments, consisting of hand removal, horticultural oil, pyrethrum, and Bacillus thuringiensis var. kurstaki (Bt), were evaluated for sweet basil, Ocimum basilicum L. Treatments began 38 days after planting and continued weekly from July through October in Piedmont, Oklahoma. Herbage yield, enzyme activity, trichome number, and relative insect damage were measured at 57 (pre-anthesis) and 93 (post-anthesis) days after establishment of field plots. Yields did not differ significantly among treatments during the first harvest, but phenylalanine ammonium lyase (PAL) activity was lower in untreated control plants and syrin-galdazine oxidase (SAO) activity was significantly lower in both control and Bt-treated plants, as compared with other treatments. At the second harvest, both control and Bt-treated plants had significantly higher herbage yield than the other treatments. PAL and SAO activities were influenced by harvest date and pest control treatment. Control and Bt-treated plants exhibited high trichome density and low insect damage compared with other treatments at the first harvest. Although Bt appeared to be the best treatment for controlling lepidopteran pests, the innate ability of sweet basil to discourage herbivory may be sufficient when insects are not abundant.

In addition to enabling manipulation of plant growth and development, growth regulators have potential for increasing forage digestibility. This study focuses on the use of gibberellic acid (GA3), α-naphthalene acetic acid (NAA), 6-benzylaminopurine (BA), o-benzylhydroxylamine (OBHA), and monocetyl phosphate (C16P) to alter growth, dry weight (DW) yield, and in vitro digestible dry matter (IVDDM) of forage grasses and legumes grown in a greenhouse. Screening experiments revealed that GA3, NAA, and OBHA at rates of 1.6, 160, and 0.51 g a.i. ha−1, respectively, were more effective in altering regrowth of potted alfalfa (Medicago sativa L.) and orchardgrass (Dactylis glomerata L.) compared with other treatments. Subsequent experiments with increasing dosages of GA3, NAA, and OBHA on alfalfa and smooth bromegrass (Bromus inermis Leyss.) confirmed that these regulators can be used to manipulate forage growth. Increasing concentrations of GA3 increased growth and DW yield but decreased IVDDM, whereas high concentrations of NAA decreased growth and DW yield but increased IVDDM. OBHA treatments resulted in little or negative change in IVDDM. Results generally showed that plant growth regulators can be used to manipulate forage growth, but that there is a trade-off between herbage yield and digestibility of forage tissues.

In some instances, lignin content may not be significantly correlated with phenylalanine ammonia lyase (PAL) activity because: (1) PAL is not committed exclusively to lignin, and (2) the time of maximum PAL activity may not coincide with maximum lignin deposition. This study evaluates correlations and timing of PAL activity and lignin deposition during legume stem maturation. Three forage legumes, alfalfa (Medicago sativa L.), birdsfoot trefoil (Lotus corniculatus L.), and red clover (Trifolium pratense L.), were established, and basal stem regrowth was sampled, biweekly, for 10 wk, for dry weight (DW), cell wall (CW), lignin, and PAL analyses. Nonlinear regression of lignin content by the Gompertz function indicated that lignin increased sigmoidally, and PAL activity by the third-order quadratic demonstrated rapid initial increases in activity, followed by decreases, as a function of regrowth days. First derivative of the Gompertz function demonstrated that changes in lignin deposition closely resembled changes in PAL activity. Among species, peak deposition of DW and CW content occurred 3–11 d prior to maximum lignin deposition. Time of maximum PAL activity occurred 8 d prior to maximum lignin deposition in birdsfoot trefoil and red clover and 3 days after maximum lignin deposition in alfalfa. Across species, lignin content was not positively correlated with PAL activity on a protein basis. However, lignin deposition was positively correlated with PAL per unit protein (r = 0.76, P < 0.05) and lignin content was positively correlated with PAL on a per plant basis (r = 0.60, P < 0.05). These results indicate that the activity of PAL is related to lignin deposition in a cause-and-effect relationship. Key words: Alfalfa, birdsfoot trefoil, cell wall, lignin, phenylalanine, ammonia lyase, red clover

Cell-wall (CW) components greatly influence digestibility of forages as they mature. There is only limited information on the timing of rates of deposition of CW components. This investigation examined differences in CW and CW component deposition in greenhouse-grown alfalfa (Medicago sativa L.), birds-foot trefoil (Lotus corniculatus L.), red clover (Trifolium pratense L.), orchardgrass (Dactylis glomerata L.), smooth bromegrass (Bromus inermis Leyss.), and switchgrass (Panicum virgatum L.). Plant material was sampled from the basal 10 cm of forage after harvesting at 3–5 cm above the soil level. Samples analyzed included sheaths from orchardgrass, sheaths and stems from bromegrass and switch-grass, and stems from all legumes. After establishment and herbage removal, samples were collected biweekly between 2 and 10 wk of regrowth. Results indicated that, except for orchardgrass, maximum rates of CW and CW component deposition usually occurred earlier in legumes compared with those of grasses. Maximum CW deposition for all species occurred within 1–3 d of maximum dry weight deposition. Among CW components in grasses and legumes, maximum deposition of hemicellulose occurred first, followed by that of cellulose (1–6 d later), and then lignin (up to 14 d after maximum hemicellulose deposition). Maximum cellulose deposition in all species occurred at the same time as maximum CW deposition.Key words: Cell wall, deposition, cellulose, hemicellulose, lignin, forage