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- Author or Editor: D.P.H. Tucker x
- Journal of the American Society for Horticultural Science x
Abstract
The addition of Endogone calospora to fumigated soil significantly increased shoot and root growth of citrus seedlings in the greenhouse but not in the field. The addition of E. macrocarpa significantly increased growth of transplants and seedlings in nonfumigated and in methyl bromide-, and dichloropropene-fumigated field soil. This beneficial effect did not occur in soils aerated by disking after fumigation. Within 100 days, endomycorrhizal fungi were reestablished on weed roots growing in fumigated soil. Citrus stunting was greater after methyl bromide fumigation than after dichloropropene fumigation, but seedling stunt was not as severe as that observed in some commercial nurseries. Thus our results may not be applicable to correcting citrus stunt as found in commercial nurseries
A factorial experiment begun in 1980 included `Hamlin' and `Valencia' sweet-orange scions [Citrus sinensis (L.) Osb.], and Milam lemon (C. jambhiri Lush) and Rusk citrange [C. sinensis × Poncirus trifoliata (L.) Raf.] rootstocks, tree topping heights of 3.7 and 5.5 m, between-row spacings of 4.5 and 6.0 m, and in-row spacings of 2.5 and 4.5 m. The spacing combinations provided tree densities of 370, 494, 667, and 889 trees ha. Yield increased with increasing tree density during the early years of production. For tree ages 9 to 13 years, however, there was no consistent relationship between yield and tree density. Rusk citrange, a rootstock of moderate vigor, produced smaller trees and better yield, fruit quality, and economic returns than Milam lemon, a vigorous rootstock. After filling their allocated space, yield and fruit quality of trees on Milam rootstock declined with increasing tree density at the lower topping height. Cumulative economic returns at year 13 were not related to tree density.