exchange study may reveal more information for our understanding of how leaf photosynthetic performance responds to salt stress. Lima bean ( Phaseolus lunatus ) is an internationally important legume and a major crop in several regions, and its annual
V. J. Fisher and C. K. Weaver
‘Thaxter’ and ‘Fordhook 242’ lima bean (Phaseolus lunatus L.) cultivars were subjected to climatic variables in controlled-environment cabinets to determine conditions which were adverse to their reproduction. High night temperature promoted flower opening but was deleterious to pod set and retention. High humidity increased pod set and retention, apparently by promoting good pollen germination. High humidity, however, was unfavorable when it was combined with high temperature. Low night temperature was unfavorable when it was combined with low humidity. The most favorable environment for pod set and retention consisted of high humidity, low night temperature, and high soil moisture. ‘Fordhook 242’ set and retained fewer pods under environmental stress than ‘Thaxter’.
F. A. Pokorny and B. K. Henny
A standard 1:1 v/v pine bark and sand potting medium was characterized physically by particle size distribution, bulk density (BD), total pore space, porosity at 50 cm H2O tension and porosity at >50 cm H2O tension. A potting medium identical to the standard was constructed from component milled pine bark and sand particles. Phaseolus lunatus L. ‘Jackson Wonder’ plants grown in the 2 physically similar media, under a standard cultural program, were essentially identical. Construction of a potting medium from a prescribed screen analysis provides a means to quantify variation which exists within a medium assumed to be uniform.
Lih-Yuh Yueh and David L. Hensley
The influence of 12 pesticides on C2H4 reduction and modulation of soybean (Glycine max L. Merr.) and lima bean (Phaseolus lunatus L.) was evaluated. All except diazinon were innocuous at 3× the label rate. Diazinon decreased C2H4 reduction of soybean 2 days after application, but not after 7 days or at normal label rates. Nitrogen fixation of excised nodules imbibed with diazinon indicated that it may have directly affected nitrogenase function. Soybean nodule numbers were decreased by application of 3× rates of methomyl and trifluralin, but lima bean nodule numbers were decreased only by trifluralin. Trifluralin also depressed soybean but not lima bean modulation at label rates. Methomyl did not affect soybean modulation at label rate. Both chemicals were non-toxic to Rhizobium sp. in a disc inhibition study.
Andrew M. Birmingham, Eric A. Buzby, Donte L. Davis, Eric R. Benson, James L. Glancey, Wallace G. Pill, Thomas A. Evans, Robert P. Mulrooney, and Michael W. Olszewski
A mechanical planter was developed to sow seed of baby lima beans (Phaseolus lunatus) in small plots. The mechanical seeder allowed small plots to be quickly and consistently seeded at a fixed spacing. Seeds were manually spread along a 10-ft (3.0 m) base plate containing 50 holes of slightly larger diameter than the seed length and at the desired seed spacing [2.4 inches (6 cm)]. Once all the holes were filled, a slider plate below the base plate containing holes of the same diameter and spacing, but which were slightly offset, was slid horizontally so that the holes of the base and slider plates aligned and the seeds dropped to the bottom of the furrow. Compared to manual planting, the mechanical planter increased the precision of seed placement and reduced the time needed to plant 50 seeds. The planter was easy to use and transport, and was inexpensive.
Kar-Ling Tao, Anwar A. Khan, Gary E. Harman, and Charles J. Eckenrode
Several chemicals applied to dry seeds by means of organic solvents were successful in preserving seed quality as determined by germinating capability of seeds or ATP content. The fungicide (pentachloronitrobenzene)-treated, injured or healthy pea (Pisum sativum L. cv. Alaska) seeds were highly resistant to infection by Aspergillus ruber (Konig, Spiekerman and Bremer) Thom and Church (NRRL 52), a storage fungus. The insecticide, Chlorpyrifos caused the lima bean (Phaseolus lunatus L. cv. Fordhook 242) seeds to produce seedlings with reduced levels of damage from the seed-corn maggot, Hylemya platura (Meigen). The antibiotics, chloramphenicol and puromycin, slowed down the rate of deterioration of lettuce (Lactuca sativa L. cv. Grand Rapids) seeds stored under accelerated aging conditions [43°C & 85% Relative Humidity (RH)].
Mark A. Bennett and Luther Waters Jr.
Field studies were conducted to examine the effect of increasing the moisture content of lima bean (Phaseolus lunatus ‘Kingston 098’) seed prior to planting. Seed moisture was adjusted by combining seed, vermiculite, and varying amounts of water in plastic packets which were then sealed and incubated at 22°C for 3 days. Initial seed moisture ranged from 8% to 56%. Trials were planted at 2 locations in 1981 (Becker and Rochester, Minn.), and at 3 locations in 1982 (Becker, St. Paul and Waseca, Minn.). Seed moisture above the normal 8% to 10% range increased emergence and stand establishment at all locations. As a general trend, increased seed moisture up to about 40% improved percentage of emergence and stand establishment. Harvest data varied between locations. Results from one location in both years showed elevated seed moisture to increase pods per plant, total pod dry weight, and total plant dry weight. Results from harvest (yield) data did not show consistent increases in the variables measured.
Sujatha Sankula, Mark J. VanGessel, Walter E. Kee, and J.L. Glancey
Field studies were conducted in 1997 and 1998 to evaluate labeled (1×) or reduced (0.5×) rates of metolachlor plus imazethapyr preemergence either broadcast or band applications to lima bean (Phaseolus lunatus L.) planted in 30-inch (76-cm) or 15-inch (38-cm) rows for weed control, yield, harvestability, and harvest recovery. Lima bean was planted in large plots simulating a commercial production system. All 30-inch rows were cultivated once 40 days after planting in 1997 and 21 days after planting in 1998. No differences were noted in weed densities between treatments both years. Marketable lima bean yield was greater from plots thatwere spaced 15 inches apart in 1997 only. However, total hand-harvested yield in both years, machine-harvested yield in 1998, and marketable yield in 1998 were not different between treatments. Measurements on harvest recovery revealed that a greater number of unstripped pods were left on plants after harvest in 15-inch row plots that were sprayed broadcast with 1× herbicide rate in 1997 only. Weight of beans lost per unit area and trash weight from 7-oz (200-g) bean sample was similar among treatments both years. Overall, weed control, yield, and harvest efficacy of lima bean was not impacted by row spacing, herbicide rate, or method of herbicide application in a commercial production system.
Lih-Yuh Yueh and David L. Hensley
The influence of 12 pesticides on acetylene reduction (N2 fixation) and modulation of soybean (Glycine max L. Merrill cv. Williams 82) and lima bean (Phaseolus lunatus L. cv. Geneva) was evaluated. All pesticides except diazinon were found to be harmless to nitrogen fixation at 3× the manufacturer's recommended rate, Diazinon significantly decreased C2H2 reduction of soybean 2 days after application, but not after 7 days or at normal label rates, Acetylene reduction of excised nodules imbibed with diazinon indicated that the chemical may have affected nitrogenase function directly. Soybean nodule counts were significantly decreased by application of 3× rates of methomyl and trifluralin, whereas lima bean nodule counts were decreased only by trifluralin. Tritluralin also depressed soybean modulation at label rates, but had no effect on lima bean modulation. Methomyl was innocuous to soybean modulation at the recommended label rate. Both chemicals were nontoxic to Bradyrhizobium/Rhizobium sp. based on a disc inhibition study. Chemical names used: O,O -diethyl O -(2isopropyl-4-methyl-6-pyrimidinyl phosphorothiote (diazinon); S-Methul- N -((methylcarbamoyl)oxy)-thioacetimidate (methomyl); a,a,a -Trifluoro-2-6dinitro-N-N -dipropyl-p-toluidine (triflnralin).
Jelka Šustar-Vozlič, Marko Maras, Branka Javornik, and Vladimir Meglič
There is a long tradition of common bean cultivation in Slovenia, which has resulted in the development of numerous landraces in addition to newly established cultivars. The genetic diversity of 100 accessions from the Genebank of the Agricultural Institute of Slovenia (AIS) were evaluated with amplified fragment length polymorphism (AFLP) markers and phaseolin seed protein. Twenty-seven standard accessions of known Mesoamerican and Andean origin, 10 wild Phaseolus vulgaris accessions and two related species, P. coccineus L. and P. lunatus L., were also included. Ten AFLP primer combinations produced 303 polymorphic bands, indicating a relatively high level of genetic diversity. Based on the marker data, unweighted pair group method with arithmethic mean (UPGMA) analysis and principal coordinate analysis (PCoA) all P. vulgaris accessions were separated into three well-defined groups. Two groups consisted of accessions of Mesoamerican and Andean origin, while the third was comprised of only four wild P. vulgaris accessions. A set of Slovene accessions formed a well-defined sub-group within the Andean cluster, showing their unique genetic structure. These data were supported by phaseolin analysis, which also revealed additional variants of “C” and “T” phaseolin types. The results are in agreement with previous findings concerning diversification of common bean germplasm introduced in Europe.