and five- to 25-fold, respectively. Based on their results, and comparing their data with the contrasting observations from other rose salinity studies, Cabrera and Perdomo (2003) contended that rootstock selection was a key factor involved in
Raúl I. Cabrera, Alma R. Solís-Pérez, and John J. Sloan
William S. Castle, James C. Baldwin, Ronald P. Muraro, and Ramon Littell
gathered from those combined sources is assembled into summary charts that are used as a guide for rootstock selection ( Castle et al., 1993 , 2006 ; Ferguson et al., 1990 ; Newcomb, 1978 ). It is uncommon that additional or better selection criteria
Graham H. Barry, William S. Castle, and Frederick S. Davies
Juice quality of `Valencia' sweet orange [Citrus sinensis (L.) Osb.] trees on Carrizo citrange [C. sinensis × Poncirus trifoliata (L.) Raf.] or rough lemon (C. jambhiri Lush.) rootstocks was determined for fruit harvested by canopy quadrant and separated into size categories to ascertain the direct role of rootstock selection on juice soluble solids concentration (SSC) and soluble solids (SS) production per tree of citrus fruit. SS production per fruit and per tree for each size category was calculated. Juice quality was dependent on rootstock selection and fruit size, but independent of canopy quadrant. Fruit from trees on Carrizo citrange had >20% higher SSCs than fruit from trees on rough lemon, even for fruit of the same size. Large fruit accumulated more SS per fruit than smaller fruit, despite lower juice content and SSC. Within rootstocks, SS content per fruit decreased with decreasing fruit size, even though SSC increased. Rootstock effect on juice quality was a direct rather than an indirect one mediated through differences in fruit size. The conventional interpretation of juice quality data that differences in SSC among treatments, e.g., rootstocks or irrigation levels, or fruit size, are due to “dilution” of SS as a result of differences in fruit size and, hence, juice volume, is only partly supported by these data. Rather, accumulation of SS was greater for fruit from trees on Carrizo citrange than rough lemon by 25% to 30%.
Michelle M. Leinfelder and Ian A. Merwin
Apple replant disease (ARD) is a common problem typified by stunted growth and reduced yields in successive plantings of apple (Malus ×domestica Borkh.) in old orchard sites. ARD is attributed to biotic and abiotic factors; it is highly variable by sites, making it difficult to diagnose and overcome. In this experiment, we tested several methods of controlling ARD in a site previously planted to apple for >80 years. Our objective was to evaluate practical methods for ARD management. We compared three different experimental factors: four preplant soil treatments (PPSTs) (compost amendments, fumigation with Telone C-17, compost plus fumigation, and untreated soil); two replanting positions (in the old tree rows vs. old grass lanes); and five clonal rootstocks (`M.26', `M.7', `G.16', `CG.6210', and `G.30') during 4 years after replanting. The PPSTs had little effect on tree growth or yields during 4 years. Tree growth was affected by planting position, with trees planted in old grass lanes performing better than those in the old tree rows. Rootstocks were the most important factor in overcoming ARD; trees on `CG.6210' and `CG.30' grew better and yielded more than those on other rootstocks. Rootstock selection and row repositioning were more beneficial than soil fumigation or compost amendments in controlling ARD at this orchard.
Fan Cao, Yunchu Wei, Xinwang Wang, Yongrong Li, and Fangren Peng
( Carpenter et al., 1979 ). This rootstock produces vigorous and uniform seedlings that have some resistance to scab disease. Another example is ‘VC1-68’, a rootstock selection that originated near Phoenix, AZ, and is used as a popular rootstock in the western
B.S. Wilkins, R.C. Ebel, W.A. Dozier, J. Pitts, D.J. Eakes, D.G. Himelrick, T. Beckman, and A.P. Nyczepir
Twelve peach [Prunus persica (L.) Batsch] seedling rootstocks [Lovell, Nemaguard, Flordaguard, 14DR51, five Guardian™ (BY520-9) selections, and three BY520-8 selections] budded with `Cresthaven' were planted in 1994 and evaluated through 2000 to determine performance under commercial management practices. Mesocriconema xenoplax population densities were above the South Carolina nematicide treatment threshold of 50 nematodes/100 cm3 of soil after 1996. However, symptoms of peach tree short life (PTSL) were not observed. Tree mortality was less than 14% through 1999, with most of the dead trees exhibiting symptoms consistent with Armillaria root rot. About 13% of the surviving trees in 1999 were removed in 2000 due to symptoms of phony peach. There were no differences in tree mortality among rootstocks. Tree growth, photosynthesis, and suckering varied among rootstocks, but leaf conductance, internal CO2, and leaf transpiration did not. Foliar calcium, magnesium, iron, and phosphorus varied among rootstocks, but all were within the range considered sufficient for peach trees. Fruit yield varied among rootstocks, but yield efficiency did not, indicating that higher yield corresponded with larger trees. Bloom date did not vary among rootstocks, but harvest date was advanced as much as 2 days for some rootstocks, compared to Lovell. Fruit weight varied among rootstocks but skin color, flesh firmness, and soluble solids content were similar. All rootstocks performed satisfactorily for commercial peach production.
Robert C. Ebel, Bryan Wilkins, David Himelrick, Tom Beckman, Andy Nyczepir, and Jim Pitts
Twelve peach rootstocks including `Lovell', `Nemaguard', `Flordaguard', `14DR51', five `Guardian' (BY520-9) selections, and three BY520-8 selections, were evaluated under field conditions to determine their effect on performance of `Cresthaven' peach. The trees were planted in 1994. Trunk cross-sectional area of BY520-8 selections SL1923 and SL4028 was 28% larger than the rest of the rootstocks, which were similar. There was no crop in 1996 due to late spring frost. Yield in 1997 and 1998 was higher for SL1923 because of higher cropload than the rest of the rootstocks, which were similar. Yield efficiency varied across years and rootstocks. Fruit weight varied among rootstocks but all were commercially acceptable. Harvest date was advanced by two days for some rootstocks compared to Lovell and none were delayed. Percent red blush, soluble solids and firmness varied among rootstocks, but none demonstrated superior quality in all of these parameters as compared to Lovell. Ring nematode population densities were above the threshhold considered to be critical for onset of PTSL for all rootstocks in 1997 and 1998. Tree survival was at or above 86% for all rootstocks and death was not correlated with ring nematode density No trees developed symptoms characteristic of Peach Tree Short Life disease complex. Guardian selections performed adequately compared to the commonly used commercial rootstocks in this study, however, the yield date are from 2 years only.
Warren Roberts, Benny D. Bruton, Thomas W. Popham, and Wayne W. Fish
The shelf life and over-all quality of fresh-cut watermelon from two cultivars grafted onto four rootstocks were compared with fresh-cut fruit from the nongrafted cultivars. Fresh-cut cubic pieces of about 4.5 cm per side were prepared from ripe watermelons grown at the Lane Research Station and were stored at 5 °C in 35-oz PETE containers. Quality attributes of firmness, soluble solids content, lycopene content, and bacterial counts of the pieces were measured after 0, 5, and 10 days of storage. Sugar content of the cut fruit was independent of rootstock and remained constant over the ten days of storage. Lycopene content of the fruit decreased by 5% to 10% during the storage period, regardless of treatment. Bacterial count on the fruit from all treatments remained low and variable during the ten days at 5 °C. Firmness of cut pieces from fruit originating from the grafted plants was dependent upon the rootstock employed, and melons from grafted plants possessed firmer fruit than did those from the nongrafted plants. Overall, the firmness of fruit from all sources decreased 20% to 30% during the ten days of cold storage. However, the firmness of fruit from some of the rootstocks after 10 days of storage was equal to or significantly higher than that of the fruit from nongrafted plants when it was initially cut. Thus, these studies suggest that grafting to a proper rootstock will produce fresh-cut watermelon that is equal in sweetness and lycopene content to its nongrafted counterpart, but it will possess greater crispness throughout its storage on the supermarket shelf.
Kendra Baumgartner, Phillip Fujiyoshi, Greg T. Browne, Chuck Leslie, and Daniel A. Kluepfel
(root-knot nematode) and Pratylenchus vulnus (lesion nematode) ( Buzo et al., 2009 ). For management of Armillaria root disease, therefore, rootstock selection may not be the best single strategy given that none of the plant genotypes we evaluated were
Benjamin D. Toft, Mobashwer M. Alam, John D. Wilkie, and Bruce L. Topp
manipulation, for example, by pruning, limb bending, or growth regulators. The reduction in tree size by scion and rootstock selection would greatly reduce the future cost of postplanting pruning and training in high-density orchards. Variations in tree size