Droughty conditions are implicated in causing low yields, poor grades and germination, and an increased incidence of aflatoxin in the peanut (Arachis hypogaea L.). However, very little is known as to when in the growth cycle drought is most critical. Effects of five drought treatments on peanut leaf diffusive resistance, yield, and quality characteristics were studied on rainfall‐protected plots of Tifton loamy sand, a member of the fine, loamy, siliceous, Thermic Plinthic Paleudults. Early, middle, and late drought periods of short duration (35 days) and extended early and midseason droughts (70 days) were imposed by withholding irrigation. Yield, percent sound mature kernels (SMK), germination, leaf‐water potential, and leaf diffusion resistances were measured. Under droughty conditions, leaf‐water potential was lowest during midseason when evaporative demand was greatest. Leaf diffusion resistances, however, in creased with lateness and severeness of drought, reflecting leaf age and plant‐water stress. Leaf‐water potentials of −30 bars were recorded for several treatments during midseason, and values as low as −40 bars were recorded for the 35‐day midseason drought. Although the leaf‐water potentials of control plants decreased as the season progressed, they never became lower than −12 bars. In both stressed and nonstressed plants the diffusion resistances were frequently less on the upper than on the lower surfaces of leaves. Much of the plant‐water stress that developed during drought was relieved the day after irrigation and leaf diffusion resistances also returned to near normal. Vine weight was not decreased by any 35‐day drought, but was significantly reduced by 70‐day droughts. In general, drought progressively decreased yields as duration and lateness of occurrence in the season increased. The 70‐day extended early season drought caused the greatest reduction is SMK. The late season 35‐day and extended midseason 70‐day droughts lowered subsequent germination 5 and 9% respectively. These studies validate the importance of full‐season irrigation for peanuts in the Southeast. When full‐season irrigation may not be possible because of demands on the system, scheduling irrigation the latter part of the season appears next in importance.

Three peanut (Arachis hypogaea) varieties were maintained at soil water levels ranging from moderately wet to very dry. Pod yield and quality were significantly reduced in treatments receiving less than about 30 cm of water during the growing season. Although not statistically different, yield and quality tended to increase as irrigation amounts increased from 40 to about 60 cm. Average harvestable yields for 4 years were 4464, 5080 and 4543 kg/ha for Florigiant, Florunner and Tifspan, respectively, when irrigated to a profile depth of 60 cm when the soil moisture tension in the surface 30 cm reached 0.2 bar. This compares with yields of 2631, 3341 and 3125 kg/ha for Florigiant, Florunner and Tifspan, respectively, when the soil water tension in the surface 30 cm profile was allowed to reach 15.0 bars. Water extraction to a depth of 106 cm was recorded for all three varieties. Apparent plant use of water from profile depths greater than 60 cm was observed at about 75 days after planting. Evapotranspiration vs age relationships were developed from daily soil water measurements to a 1.2 m soil depth.

`Keystone Resistant Giant' bell pepper (Capsicum annuum L.) was grown in drainage lysimeters under controlled soil water regimes during 1982, 1984, and 1985. Three irrigation regimes were imposed on bell pepper grown on two soil types during spring and fall growing seasons. Irrigation regimes consisted of applying water when the soil water tension at 10 cm exceeded 25, 50, or 75 kPa during crop growth. Yields and water use were greatest when irrigation was applied at 25 kPa. Regression equations are presented to describe the relationships of water use to plant age and to compute the ratios of daily evapotranspiration to pan evaporation (crop factors) for bell pepper grown under the three irrigation regimes.

Florunner and Florigiant peanuts were grown and foliar inoculated with an aflatoxin producing isolate of Aspergillus parasiticus (NRRL 2999) 30 days after planting. Four replicates were grown in plots under rainfall controlled shelters with six irrigation treatments: (1) wet from day 0-145, (2) dry from days 36-70, (3) dry from days 71-105, (4) dry from days 106-145, (5) dry from days 36-105, (6) dry from days 71-145. Aflatoxin con-

An irrigation scheduling model for snap bean (Phaseolus vulgaris L.) was developed and validated. The irrigation scheduling model is represented by the equation: 12.7(i - 4) × 0.5ASW = Di-1 + [E(0.31 + 0.01i) - P - I]i, where crop age is i; effective root depth is 12.7(i - 4) with a maximum of 400 mm; usable water (cm3·cm-3 of soil) is 0.5 ASW, deficit on the previous day is Di-1; evapotranspiration is pan evaporation (E) times 0.31 + 0.01i; rainfall (mm) is P, and irrigation (mm) is I. The model was validated using a line source irrigation system with irrigation depths ranging from 3% to 145% of tbe model rate in 1985 and from 4% to 180% of the model rate in 1986. Nitrogen fertilization rates ranged from 50% to 150% of the recommended rate both years. Marketable pod yields increased as irrigation rate increased in 1985. Irrigation at 4%, 44%, 65%, 80%, 150%, and 180% of the model rate produced yields that were 4%, 39%, 71%, 85%, 92%, and 55% as great as yields with the model rate in 1986. Marketable pod yields increased as N rate increased when irrigation was applied at 80%, 100%, or 150% of the model rate in 1986, but pod yields varied less with N rate when irrigation was applied at 4%, 44%, 65%, or 180% of the model.