High Fruit Production Research Articles

Identification and analysis of spur growth in peach (Prunus persicaL. Batsch)

SummaryThe evaluation of spur growth habit in 49 peach genotypes through visual ratings and measurement of the number of spurs per unit branch length indicated a wide range of genotypic variation in this character. Most standard U.S.A. cultivars developed few spurs. The lowest spur density genotype (cv Sunhigh) had 8× the distance between spurs than did the highest spur density genotype (cv Nishiki). Spur type trees could be upright or spreading. Spur types were not necessarily short-internode trees. High fruit production was generally, but not always, associated with high spur density. The development of spur type peach cultivars appears to be genetically feasible using P. persica spur type parents.

Seed Production, Seed Populations in Soil, and Seedling Production After Fire for Two Congeneric Pairs of Sprouting and Nonsprouting Chaparal Shrubs

A study of seed production, seed storage in the soil, and seedling production after fire was undertaken for a sprouting and a nonsprouting congenerica pair of species of Ceanothus and Arctostaphylos. All species exhibited large fluctuations in annual seed production. There was a significant correlation between fruit production and precipitation in the previous year. It is hypothesized that high carbon gain in years of high precipitation results in high numbers of floral primordia which, in these species, remain dominant until the following year. It was also noted that high fruit production was not dependent upon high precipitation the same year; suggesting that the fruits were utilizing carbon stored from the previous year. All 4 species were capable of producing more seeds in a single season than were stored in the soil. Apparently the soil seed pools do not represent a steady accumulation of seeds in the soil but rather are the result of dynamic fluctuations in seed inputs and outputs. Each species also had more seeds in the soil, by several orders of magnitude, than seedlings after fire in an adjacent burned stand. The sprouting and seeding productive strategies are quite different in the two genera. The information from this study coupled with that from other studies indicate 4 reproductive modes: sprouting and seedling production (C. leucodermis), abundant seedling production (C. greggii), low seedling production but better "equipped" seedlings (A. glauca), and predominantly sprouting (A. glandulosa).