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Seeds of three peanut (Arachis hypogaeaL.) cultivars from two growing seasons, 1974 and 1975, and four locations in Texas were tested for germinability and ethylene production. Because ethylene is an important regulator of peanut seed germination, we attempted to correlate its production with differences in early seedling growth. We found three growth distributions and ethylene production patterns. 1) When the majority of the seeds in the population had a high degree of vigor (78±8% of the seedlings had a hypocotyl‐radicle length >20 mm at 70 hours of germination), they also had a characteristic ethylene production maximum at 21 hours of germination. 2) When the majority of the seeds in the population had a low degree of vigor (only 30% of the seedlings had a hypocotyl‐radicle length >20 ram), ethylene production was reduced at 21 hours and the maximum occurred at 45 hours of germination. 3) When a majority of the seeds were in intermediate growth between 1) and 2), ethylene production was reduced by about 50% at 21 hours for the high ethylene‐producing cultivars ‘Starr’ and ‘Tamnut 74’, but was not significantly changed for ‘Florunner’, a comparatively low ethylene‐producing cultivar. Reduced seedling vigor was significantly correlated with decreased ethylene production at 21 hours for Start and Tamnut 74, but not for Florunner. Both seedling growth and ethylene production were altered by growing season and location. The majority of the seeds in the population, however, showed vigorous growth when the ethylene production rates exceeded a critical minimum level.

The possibility of introgressing Arachis spegazziniiKrap. & Greg. nom. nud. (GKP 10038, PI 262133) into three botanical varieties of A. hypogaeaL. was examined. Ease of crossing, chromosome number segregation, and the penetrance and segregation of morphological characters are reported. The amphiploid (A. spegazzinii✕ A. hypogaea) (6x) was backcrossed to three cultivars representing three botanical varieties of peanut. Ease of crossing with the amphiploid plant was successively less from A. vulgarisHartz (spanish) to A. fastigiataWaldron (Valencia) to A. hypogaeaL. (Virginia). Variations in crossing success were also found among plants within a cultivar. Most of the backcross progeny had 50 chromosomes, but aneuploids were also identified. Second‐generation hybrid progenies from the first backcross (BC1F2) varied in chromosome number from 41 to 57, and the BC1F3plants varied from 40 to 58. No BC1F2plants had a stable chromosome number. Plant type, flower color, and fruit form gave evidence for the presence of exotic germplasm. Agronomically desirable fruit characters were found in BC1F3plants.

A triploid hybrid (2n = 30) from a cross between Arachis hypogaeaL. (2n = 40) and F1hybrid (2n = 20) from A. cardenasiiKrap. et Greg. nom. nud. and A. chacoensisKrap. et Greg. nom. nud. was male fertile, and produced up to 92% stained, uniform pollen grains. Meiotic analyses of the fertile triploid revealed that meiosis I was irregular, with the univalents lagging at anaphase and all 30 chromosomes were incorporated into one cell after anaphase I. Telophase I was not observed in these cells. Meiosis II resulted in dyad formation instead of tetrads. Normal appearing pollen grains were formed which transmitted 30 chromosomes to progeny produced from artificial cross pollinations with A. hypogaea