Citrus Scion and Rootstock, Topping Height, and Tree Spacing Affect Tree Size, Yield, Fruit Quality, and Economic Return

Abstract

<jats:p>A factorial experiment begun in 1980 included `Hamlin' and `Valencia' sweet-orange scions <jats:italic>[Citrus sinensis</jats:italic> (L.) Osb.], and Milam lemon <jats:italic>(C. jambhiri</jats:italic> Lush) and Rusk citrange <jats:italic>[C. sinensis</jats:italic> × <jats:italic>Poncirus trifoliata</jats:italic> (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.</jats:p>

Effect of row spacing on vegetative structure, fruit characteristics and oil productivity of N–S and E–W oriented olive hedgerows

“…Connor and Gómez-del-Campo (2013), who simulated radiation-limited yield response of various N-S oriented rectangular olive hedgerows, also found maximum oil yield with D/A = 1, with decrease at lower values due to shorter length of productive hedgerow per unit orchard area and slight oil yield increase at values greater than 1. There are many reports in fruit crops suggesting that light limitation in lower parts of overcrowded canopies (i.e., high D/A) reduces yield (Wheaton et al, 1995;Farina et al, 2005;He et al, 2008). In olive, Pastor et al (2007) found significant reduction of fruit number and fruit oil content in lower canopy layers of narrow olive hedgerows when D/A exceeded 1.25.…”

Performance of an Ultrasonic Tree Volume Measurement System in Commercial Citrus Groves

“…The formula used for MV was based on one-half of an ellipsoid considering canopy diameters parallel and perpendicular to the row (near ground level) and maximum canopy height (Wheaton et al, 1995;Tumbo et al, 2002;Schumann and Zaman, 2005).…”

“…However, early yield advantages tend to diminish as the trees increase in size and competition for space, light, water and nutrients becomes more intensified in closely spaced groves (Savage, 1965;Carry, 1977;Tucker et al, 1991). The results of numerous studies indicated that, when practised in moderation, higher planting densities (closer spacing) and techniques to control tree size can be of considerable benefit, not only in ensuring high yields during early life of trees but also in increasing the efficiency of harvesting and spraying operations (Childers, 1978;Wheaton et al, 1995). Therefore, proper control of tree size is essential to the success of closely spaced groves (Tucker and Philip, 1967).…”

“…Manual measurement of tree volume using many tree dimensions (Albrigo et al, 1975;Wheaton et al, 1995) is laborious and time consuming. One possible reliable and rapid method is ultrasonic-based tree size measurement (Giles et al, 1988;Tumbo et al, 2002;Zaman and Salyani, 2004).…”

Delineating productivity zones in a citrus grove using citrus production, tree growth and temporally stable soil data

“…Fertilizer application practices in citrus production in Florida are based on tree age and projected yield (Obreza et al 2008a) and these properties can be related directly to tree size. The manual measurement of citrus tree canopy volume (Wheaton et al 1995) for individual trees is laborious and time consuming. A rapid alternative method, is ultrasound-based measurement of tree canopy volume .…”