Juglans Hindsii Research Articles

HETERODICHOGAMY IN WALNUTS: INHERITANCE AND STABLE RATIOS.

Dichogamy involves the maturation, by an individual plant, of male and female organs at different times. Protandry refers to the shedding of pollen prior to stigma receptivity and protogyny the reverse sequence. Both are widespread among flowering plants, with several entire families characterized by one system or the other (Knuth, 1906). The mating system of walnuts, members of the genus Juglans, exhibits a phenotypic dimorphism of protandrous and protogynous mating types. Knuth (1906, following Loew, 1895) has classified such a system as heterodichogamy. This paper presents data on the details of the flowering patterns of the mating types in walnuts, their observed frequencies, and their mode of inheritance. A genetic model is developed to predict equilibrium frequencies based on the mode of inheritance and flowering pattern. The taxonomic distribution of heterodichogamy is reviewed. This paper is concerned with heterodichogamy in two species of walnut, Juglans regia L., the cultivated English (or Persian) walnut, and J. hindsii Jeps., the northern California black walnut. Walnuts are monoecious, wind-pollinated, deciduous trees. All studies indicate that walnuts are entirely self-compatible (see Funk, 1970 for a review). Flowering time in walnuts is highly heritable (Hansche et al., 1972). If one assumes a common basis for heterodichogamy in the genus Juglans, the results from these two species can be combined into a reasonably clear and sim-

Bank Banding with Morphactin to Inhibit Tree Growth

A California supplemental registration now permits trunk bark banding with Maintain CF 125, a morphactin formulation, for tree growth inhibition. A band of equal width to the treated trunk or branch is sprayed or painted with a 1% concn of Maintain CF 125 in a specific oil carrier mixture. Pine sp. and Acacia longifolia are responsive to this level of treatment. Less responsive trees are being tested at a 2% concn, with increased band width, and with more frequent ap­plications. Calacedrus decurrens, Juglans hindsii, Platanus racemosa and Nerium oleander have not responded to in creased dosage.

Differential Sensitivity of Juglans hindsii, J. regia, Paradox Hybrid, and Pterocarya stenoptera to Waterlogging1

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.

Hendersonula toruloidea . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Hendersonula toruloidea . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On a wide range of hosts including Acacia spp., Agave sisalana, Ananas comosus, Arachis hypogaea, Citrus spp., Dioscorea spp., Ficus carica, Furcraea spp., Hevea brasiliensis, Ipomoea batatas, Juglans regia, Juglans hindsii, Malus pumila, Mangifera indica, Manihot utilissima, Melia azedarach, Morus alba, Musa spp., Liriodendron bipinnatifidum, Pithecolobium dulce, Plumeria acutifolia, Populus alba, Prunus spp., Psidium guajava, Sansevieria spp., Solanum tuberosum, Trifolium alexandrinum, Trigonella spp., Vitis vinifera (Browne, 1968 and Herb. IMI). Also pathogenic to man (Gentles & Evans, 1970). DISEASE: On plants : Causing branch wilt of fig, grapevine and walnut; dieback of apple, grapefruit, mulberry, stone fruit and walnut; canker of grapefruit, mandarin orange and mulberry; gummosis of apple, fig, grapefruit, mandarin orange, poplar and walnut; fruit rot of Cavendish banana and orange (on inoculation); associated with a rot of potato tubers ( Solanum tuberosum ) in U.K. following inoculation with roots of potato naturally infected with Phoma exigua (Herb. IMI) and a storage rot of yam ( Dioscorea spp.) in Nigeria (45, 3254). On man : The fungus has been isolated in U.K. from infections of feet and/or toe-nails of former residents of the tropics (Gentles & Evans, 1970). GEOGRAPHICAL DISTRIBUTION: Africa (Ghana, Guinea, Nigeria, Rhodesia, Sierra Leone, Sudan, Tanzania), Asia (Cyprus, India, Iraq, Malaysia, Pakistan); North America (U.S.A. : California); Central America and the West Indies (Jamaica); Europe (U.K.). TRANSMISSION: By wind-borne spores. A wound parasite of fig (43, 2007), grapefruit (34: 365), grapevine (46, 2590), mulberry (35: 647) and of banana and orange fruit (43, 1716). Germinating conidia penetrate walnut branches only through breaks in the periderm (43, 884u) especially cracks caused by sun scorch (35: 495; 44, 1757b). Hail damage also predisposes fig to branch wilt (43, 2007).

Anatomy of the Endophytic System of the Mistletoe, Phoradendron flavescens

The tissues comprising the cortical haustoria and sinkers in the endophytic system of Phoradendron flavescens were studied in plants parasitizing the walnut, Juglans Hindsii. Cortical haustoria-longitudinally oriented strands in the host bark-have a central cylinder containing xylem and phloem inclosed by a parenchymatous cortex. The xylem consists of tracheary elements and parenchyma cells. The phloem consists of sieve-tube members, companion cells, and parenchyma cells. Cortical haustoria having secondary growth contain, in addition, fibers in their secondary xylem. Sinkers-radially oriented extensions into the host wood-occur at intervals along a cortical haustorium. Each normal sinker consists of three distinct parts: (1) a parenchymatous part imbedded in the host phloem; (2) a meristem corresponding in position to the host cambium; (3) a part imbedded in host wood and composed of two kinds of cells, parenchyma cells and tracheary elements, both more or less isodiametric. Additionally, many sinkers have a centrally located, radially oriented strand of vascular tissue. The xylem of this strand extends from the cortical haustorium to near the end of the sinker. The phloem, which contains sieve elements, accompanies the xylem for a short distance; it does not extend to the meristematic region. The tracheary elements of the radially oriented strand are connected with the tracheary elements of the sinker part, which is imbedded in the host wood. The parasite elements that occur at the periphery of the sinker are in contact with tracheary elements of the host, and pits and perforations may occur between them. Thus a continuous conduit exists, connecting tracheary elements in the host with those in the cortical haustorium of the parasite. During growth at their meristems some sinkers become progressively smaller (narrower or lower or both). Such sinkers may be displaced from the cambial cylinder; thus their part within the host wood becomes separated from the continuous endophytic system. Inclusion of isolated sinker parts within the host wood and certain other phenomena suggest competition between parasite and host for space in the cambial cylinder. In the part of a sinker imbedded within the host wood, thick accumulations commonly occur in parenchyma cells on walls that are in contact with tracheary elements of the host or the parasite.

THE AMINO ACIDS OF SOME MISTLETOES AND THEIR HOSTS

The following mistletoes and their hosts were studied: Phoradendron serotinum (Raf.) M. C. Johnst. (P. flavescens [Pursh] Nutt. var. macrophyllum Engelm.) on Juglans hindsii Jeps. (California black walnut), Arceuthobium campylopodum Engelmn. f. abietinum (Engelm.) Gill on Abies concolor (Gord. and Glend.) Lindl. (white fir) and A. magnifica A. Murr (red fir), Arceuthobium campylopodum Engelm. f. campylopodum (Engelm.) Gill on Pinus sabiniana Dougl. (Digger pine), and Amyema pendula (Spleng) Tiegh. on Eucalyptus macrorhyncha F. Muell. ex Benth. (stringybark). With the exception of the Amyema leaves, the mistletoes are richer in free and bound amino acids than their hosts; moreover, their amino acid composition closely resembles that of their hosts. Nevertheless, there is no satisfactory evidence that mistletoe specificity depends on the amino acid composition of the hosts. Some mistletoes contain γ‐aminobutyric acid and asparagine, not found in all hosts. All the above mistletoes but no hosts contain free hydroxyproline. These results are discussed in relation to (1) the region in the mistletoes where hydroxyproline is formed and (2) the possibility of using certain amino acid analogs as selective poisons for mistletoes.