In the pistachio cv. Kerman an average of 26% of the fruits contain no seeds or only poorly developed ones at maturity. A study of aberrations revealed; a) pollen tubes sometimes entered the embryo sacs at the chalazal end (the pistachio is chalazogamous), which may result in eventual degeneration of endosperm or zygote nuclei; b) frequent degeneration of zygote (or egg) or young endosperm nuclei from unknown causes; c) occurrence of a brown spot on the funiculus of many young seeds in some years, the necrosis usually spreading to the embryo sac; d) and hypertrophy of nucellar cells in some older seeds was frequently accompanied by proliferation of other nucellar cells, both limiting development of embryo and endoperm. In cv. Bronte a frequent aberration is protrusion of endosperm or embryo through a greatly distended endostome.
Juice expressed from plum and apricot cultivars may differ significantly in H+ concentration, titratable acidity, soluble solids content, and concentration of specific organic components from juice obtained from the same fruits by comminution. In fact, the H+ concentration of comminuted juice may be more than 100 times higher. Expressed juice, notwithstanding the lesser contribution of organic acids to soluble solids, contains more soluble solids (higher refractive index) than does comminuted juice. Data presented in relation to these findings, and information on individual organic acids, are used to speculate on the primary sources (vacuolar, cytoplasmic, extracellular) of juice obtained by the 2 extraction methods. Possible implications of membrane permeability and integrity are considered. We suggest that the procedures outlined may be useful as tools to increase information concerning membrane permeability and distribution of certain organic materials within and without the cell.
Apricots on branches sprayed with Ethrel at the beginning of pit hardening abscised, whereas similar treatment with 2,4,5-T stimulated fruit growth and decreased drop. In the stem, gum ducts were formed in the xylem after treatment with Ethrel but not with 2,4,5-T, both at 100 ppm concentrations. Both Ethrel and 2,4,5-T stimulated cambial activity in petioles and midveins, thus increasing phloem and xylem tissues. Both growth regulators induced tylosis formation in petiole xylem. 2,4,5-T treatment caused increase in petiole diameter and leaf blade thickness, through increasing endopolyploidy and thus cell size in ground tissue of the petiole, and in mesophyll, epidermis and vascular bundle sheathes in the leaf blade. Ethrel caused little if any increase in cell size in those tissues, and therefore no obvious increase in petiole diameter and leaf blade thickness.
Gibberellic acid (GA) applied as an aqueous spray to 4-year-old ‘Ascolano’ olive trees at concentrations of 250 or 500 ppm promoted shoot growth, mainly through internode elongation. Indoleacetic acid (IAA) at the same concentrations caused curling of young leaves and suppressed terminal bud growth for 10 to 14 days. Shoot growth promotion by GA was counteracted by IAA.
GA at 100, 250 or 500 ppm significantly promoted xylem differentiation and development in newly developed regions of olive shoots. GA + IAA, both at 250 or 500 ppm, had a synergistic effect. IAA at all concentrations had no effect in this respect. Xylem lignification was normal in all treated shoots. It is suggested that the endogenous gibberellin level was the limiting factor for xylem development and that a certain balance between auxin and gibberellin is required to stimulate cambial activity with subsequent xylem development. Secondary phloem development was not influenced by IAA and/or GA. GA alone or in combination with IAA stimulated precocious periderm formation
As with most other drupe fruits, curves representing growth in length and diameter of seeded pistachio nuts reveal 3 distinct periods, 2 cycles of rapid growth separated by 1 of slow growth. Growth curves of seedless pistachios, however, are similar to those of almond (a dry drupe) in which a rapid growth phase is followed by one of inconsequential growth. Embryo development in the pistachio is delayed longer than in other drupes; it is not evident macroscopically until about 30 days after completion of the initial period of pericarp growth. Seedlessness, the symptoms of which are not manifest until after most pericarp growth has occurred, frequently appears to be associated with necrosis of the apical portion of the funiculus supporting the seed, and consequent seed abortion.
Pollen tube growth in the styles following self- and cross-pollination was studied in self-incompatible ‘Ne Plus Ultra’ almond (Prunus amgdalus Batsch) and 5 unnamed self-fertile almond selections derived from back-cross hybridization with peach (P. persica (L.) Batsch).
Self-incompatibility of ‘Ne Plus Ultra’ was expressed morphologically by failure of all tubes to grow through the style, failure of many tubes to penetrate the style, presence of swollen pollen tube ends and retrogression with time at higher temperatures. Rates of pollen tube growth in self-fertile selections was consistently less than after cross-pollination, but the ratios of self/cross varied. Thus, selections ranged from those approaching selfincompatibility to those approaching self-compatibility.
Optimum temperatures for ‘Ne Plus Ultra’ were 15°C when selfed and 25° when crossed. For the self-fertile selections selfed, it was 25° for all but one, which was 15°. When crossed, it was always 25°. One selection showed a high degree of ovule under-development independent of self-compatibility.