The objective of this investigation was to determine the dynamics of carbohydrate use as revealed by soluble sugar and starch concentration in leaves, inflorescence buds, rachises, nuts, current and 1-year-old wood, and primary and tertiary scaffold branches and roots (≤10 mm in diameter) of alternate-bearing `Kerman' pistachio (Pistachia vera L.) trees that were in their natural bearing cycles. Two hypotheses were tested. First, carbohydrate concentration is greater early in the growing season in organs examined from heavily cropping (“on”) than light cropping (“off”) trees. This hypothesis was affirmed as judged by soluble sugar and starch concentration in leaves, inflorescence buds, rachises, nuts, current and 1-year-old wood, and primary and tertiary branches and roots of “on” compared to “off” trees. Second, carbohydrate concentration remains high in “on” tree organs as the first wave of inflorescence bud and nut abscission occurs early in the growing season. This hypothesis was also affirmed. In fact, soluble sugars and starch remained high in “on” trees through full bloom FB + 60 days (FB + 60) as inflorescence bud and nut abscission occurred. In the persisting “on” tree inflorescence buds, sharp decreases in soluble sugars and starch were evident by the final sample date when “off” tree inflorescence buds contained a 13 times greater concentration of soluble sugars and starch than “on” tree buds. At that time, “off” tree inflorescence buds contained 50% more dry mass than “on” tree inflorescence buds. After FB + 60, “on” tree soluble sugars and starch declined in all organs as nut growth occurred. During the same time period, organs of “off” trees began to accumulate greater concentrations of soluble sugars and starch and exceeded concentrations measured in organs of “on” trees.

The biosynthesis of Mg protoporphyrin monoester, protochlorophyll and chlorophyll a and b by crude homogenates, isolated etioplasts, and differentiating chloroplasts has recently been described by . In the present communication we wish to report briefly on the capacity of subchloroplastic fractions to form free porphyrins and metal porphyrins. MATERIALS AND METHODSCucumber seeds (Cucumis sativus L. cv. Alpha Green) were germinated in vermiculite (Terra Lite) at 24 C in complete darkness for 4 days (7,8). Cotyledons were harvested with full hypocotyl hook as previously described (2). They were placed in beakers with enough distilled H20 to keep them moist and were irradiated with white fluorescent light for 4 hr (8). De The reaction was stopped by the addition of 15.0 ml of acetone:0.1 N NH4OH (9:1 v/v) and centrifuged at 39,000g for 10 min. The pellet was saved for the extraction of free porphyrins and the acetone: NH4OH supernatant containing metal porphyrins and free porphyrins was extracted with an equal volume of hexane. The hexane extracted most of the ,8-carotene and chlorophyll. The metal porphyrins remaining in the hexane-extracted acetone: NH4OH supernatant were transferred to ether as previously described (6). The proteinaceous pellet and the aqueous acetone phase that was left after metal porphyrins extraction were pooled and used for the extraction of free porphyrins as described previously (6).Free porphyrins were separated by ascending paper chromatography on Whatman No. 3 MM paper in 2,6-lutidine:0.05 N NH4OH (5:3.5 v/v). Metal porphyrins, in ether, were separated on thin layers of Silica Gel H in benzene-ethyl acetateethanol (8:2:2 v/v). All fractions were routinely monitored by their absorption spectra and recorded with a Beckman double beam spectrophotometer Model DK-2A. All absorbancies used in quantitative determinations were derived from the appropriate spectra.The amount of uroporphyrin in acidified, saturated sodium acetate (pH 2.5) was estimated from absorbancy at 402 nm using the molar extinction coefficient (5.41 X 106) and the correction factors reported by Rimington and Sveinsson (10) for uroporphyrin in 0.5 N HCI.The copro + protoporphyrin fraction in ether containing mostly coproporphyrin was estimated from its absorbancy at 401 nm and a molar extinction coefficient of 1.8 X 105 (6). When protoporphyrin was predominant in this fraction, its absorbancy at 404 nm and a molar extinction coefficient of 1.5 X 105 were used instead (6).

No abstract

We investigated the development of leaf area (LA) and the distribution of dry matter within branches of 25-year-old, alternate-bearing `Kerman' pistachio (Pistacia vera L.) trees that were in their natural “on” (heavy) or “off” (light) bearing cycles to determine the immediate and delayed effects of fruiting on shoot growth. Compared to “off” trees, individual leaves of “on” trees were greater in number and expanded twice as fast during the first 30 days after full bloom (FB) (FB + 30). Mature, fully expanded leaves of “on” trees were smaller (124.1±3.26 cm2) than those from “off” tree (163.3±3.40 cm2), indicating delayed demands of fruiting on initial leaf growth. Total LA per current shoot was greater in “on” than “off” trees because shoots of “on” trees averaged eight leaves, compared with six for “off” trees. More inflorescence buds per shoot (seven vs. three buds) abscised from “on” than from “off” trees. About 60% of the young developing nuts had abscised by FB + 30 when they weighed <250 mg each and another 25% abscised between FB + 30 and FB + 60 when individual nuts weighed ≈400 mg. The average total dry mass (DM) of individual branches of “on” trees increased 1322% (5·9 to 83·9 g) compared to 598% (4·2 to 29·3 g) in “off” trees. Besides nuts, leaves accumulated the greatest amount of dry matter within individual branches followed in decreasing order by current wood, 1-year-old wood, and inflorescence buds. DMs of individual leaves of “on” trees averaged between 15% and 48% greater than leaves of “off” trees. “Off” trees invested 4.6 g of dry matter into individual 1-year-old wood and 2.1 g into current wood. “On” trees, however, invested 1.3 g of dry matter into 1-year-old wood and 4.3 g of dry matter into current wood. One-year-old wood was an important major source of carbohydrates for developing leaves, current wood, rachises, and nuts. The immediate demands of fruiting on individual components of a branch were measured as losses in DMs. Individual leaves, current wood, 1-year wood, and rachises lost 1.1%, 0.3%, 1.1%, and 1.0%, respectively, of the average total DMs of individual branches of “on” trees. This loss was equivalent to 5.7%, 5.9%, 26.7%, and 16.4%, respectively, of the seasonal average peak DMs of the respective individual components of the branch.

Early fall (September) defoliation and late spring (early June) shading of “off” and “on” pistachio trees were used to test two hypotheses: that 1) fall defoliation would reduce carbohydrate storage sufficiently to suppress spring growth and 2) spring shading would reduce carbohydrate status and increase inflorescence bud abscission. Defoliation suppressed initial leaf area expansion the following spring on current year shoots of “off” but not “on” trees respectively. Suppression of leaf size was correlated with the initial low concentration of carbohydrates in organs of individual branches of the tree. Fruiting and artificial shading in June had more dramatic effects on growth parameters than defoliating. Shading “off” trees for 14 days in early June accelerated abscission of inflorescence buds, reduced dry mass of individual leaves, buds, current year and 1-year-old shoots. Shading also reduced the concentration of total nonstructural carbohydrates (TNC) of these organs in “off” and “on” trees. Fruiting suppressed leaf size and leaf dry mass by 20% and 30% among individual branches of undefoliated and defoliated trees respectively. Low carbohydrate concentrations in individual branches and inflorescence buds following shading were closely correlated with the abscission of inflorescence buds.