Search Results

You are looking at 1 - 10 of 208 items for :

  • Juglans regia x
Clear All

Persian (english) walnut ( Juglans regia L.) orchards can incur serious economic loss from attack by several soilborne pathogens, including Agrobacterium tumefaciens Smith and Townsend (causal agent of crown gall disease), Armillaria mellea

Free access
Author:

Juglans regia L. is typical of Juglandaceae in that it is monoecious, wind-pollinated, and self-compatible. Despite its self-compatibility, breeding and research programs have encountered difficulties acquiring sufficient quantities of pollen

Free access

). The high N inputs used in walnut production ( Gupta et al., 2012 ; Simorte et al., 2001 ; Weinbaum and Van Kessel, 1998) and the high susceptibility to P. cinnamomi reported in Juglans regia L. ( Guajardo et al., 2017 , 2019 ) highlight the need

Free access

seed or by grafting on rootstocks ( Vahdati, 2003 ). Hence, there is huge genetic diversity among rootstock traits. For example, there are many old Persian walnut ( Juglans regia L.) trees in Iran that have been planted on the banks of rivers. The long

Free access

Twenty-five random decamer primers were used to evaluate the level of polymorphism between Persian walnut and the Northern California black walnut. Sixty-six randomly amplified polymorphic DNA (RAPD) markers were identified using an interspecific walnut backcross population [(Juglans hindsii × J. regia) × J. regia]. Segregation data from these polymorphisms were joined to a previously published set of restriction fragment-length polymorphism (RFLP) marker data to expand the genetic map of walnut to 107 markers in 15 linkage groups.

Free access

Abstract

Intergeneric hybrids between wingnut (Pterocarya sp.) and walnut (Juglans regia) were developed by regenerating plants from somatic embryos produced on immature cotyledons of seed from control-pollinations. Hybridization was confirmed by isozyme analysis using starch gel electrophoresis. To the best of our knowledge, this is the first report of hybrids between wingnut, which has a high level of resistance to Phytophthora spp. and nematodes, and walnut. Wingnut may now be used as a source of germplasm for improving walnut rootstocks.

Open Access

Two management systems were initiated in a 10 year old Juglans regia cv. Hartley orchard planted 8 m. × 8 m. in 1977. Annual dormant selective pruning was practiced for the next 8 years on all trees within one treatment (pruning) compared to dormant severe pruning on alternate temporary trees with no pruning on adjacent permanent trees (thinning). Temporary trees were removed in the thinning treatment in 1985.

Yield, trunk cross sectional area, pruning weight and nut quality factors were evaluated each year from the 5 replicate, completely randomized trial.

Yield and nut quality factors did not differ between the two treatments during the 15 years.

In 1990 the pruned trial was again pruned causing a 20% drop in production (p=.06). With no additional pruning yield returned to slightly above the thinned treatment in 1991.

This trial demonstrates that Hartley walnut trees (terminal bearing habit) continue to produce satisfactory crops under crowded canopy management but a tree thinning program offers other advantages which also should be considered.

Free access

Abstract

In a 16-year field study, all graft combinations of Persian walnut, Juglans regia scions with other rootstock species were susceptible to blackline. ‘Sinensis #5’, a selection of J. regia, did not exhibit symptoms of blackline when used as an interstock. In no case was blackline observed in graft combinations between J. regia.

Open Access

Abstract

Seedlings of Juglans hindsii Jeps. and J. regia L. reacted similarly and were much more sensitive to waterlogging at root temperatures of 33°C than those of Pterocarya stenoptera DC. At 23°C,J. regia expressed symptoms of waterlogging earlier than J. hindsii. Paradox plants, hybrids between the 2 walnut species, were more tolerant than J. hindsii but are still considered highly sensitive to anaerobiosis. These results support the contention that use of J. regia seedlings as rootstocks to avoid blackline introduces greater potential for damage if soils become saturated. Some plants of each type which demonstrated increased tolerance have been selected. Levels of abscisic acid, or changes therein did not appear to be useful parameters in screening walnut seedlings for tolerance to waterlogging. Phenolic compounds decreased in roots of waterlogged plants. Although the magnitude of change in phenols was the same in Juglans and Pterocarya plants, it occurred over a much longer period with the latter. Phenols lost from roots may be a secondary phenomenon but contribute to hypersensitivity of Juglans to waterlogging.

Open Access

Abstract

Kernels from Juglans regia walnuts stratified at 0°C were sampled at weekly intervals and extracted with methanol. The extracts were partitioned into 4 phases which were water, neutral ether, acidic ether and acidic butanol, then bioassayed for cytokinins, gibberellins, auxins and inhibitors. No cytokinins nor gibberellins were found in the tissue. There was activity analogous to that from auxins. An inhibitor which diminished during stratification was found. This inhibitor is believed to be abscisic acid, on the basis of UV absorption spectrum, Rf values established by co-chromatography on paper and silica gel plates, and derivatives analyzed by gas liquid chromatography.

Open Access