The effect of pollen of 4 different male palms belonging to Phoenix dactylifera, L. upon the time of maturity and the quality of ‘Zehdi’ date fruit was studied. It was found that pollen from both ‘Ghannami’ and ‘Werdi’ shortened the yellowing time of the Khalal stage and increased the percentage of matured fruit of the ‘Zehdi’ palms. Pollen from both ‘Rissasi’ and ‘Werdi’ resulted in increased fruit setting compared with the other two males. Fruit pollinated with ‘Werdi’ had the lowest percentage of seed weight (the highest edible portion). Fruit pollinated with ‘Ghannami’ pollen had the highest percentage of soluble solids. According to the results obtained in this experiment, it is possible to consider both ‘Ghannami’ and ‘Werdi’ as better male varieties than ‘Rissasi’ and ‘Simsimi’.
Lipoxygenase (LOX) activity was assayed on hypodermal- and middle-mesocarp tissues from netted muskmelon (Cucumis melo L.) fruit 10, 20, 30, and 40 days postanthesis and after 12 days of storage at 4 or 21C. Highest LOX activity was obtained using a phosphate buffer at pH 7 and 20C. LOX activity was detected only in hypodermal-mesocarp (hypodermic) tissue at 30 days postanthesis, and activity increased with fruit age and storage temperature. Antioxidants, which inhibit LOX, were detected only in hypodermic tissue from 10 through 30 days postanthesis fruits. Linoleic plus linolenic free fatty acids, substrates for LOX, in hypodermic tissue had declined at 30 days postanthesis, as did plasma membrane integrity, and both continued to decline in association with increased LOX activity.
The properties of sucrose synthase (SS) isozymes partially purified from immature fruit (SS I) of Japanese pear (Pyrus serotina Rehder var. culta Rehder) were different than those of mature fruit (SS II). A clear difference in elusion pattern during DEAE-cellulose chromatography was observed, although the apparent molecular weight of the native proteins extracted from both stages was 350 kD. The Km value of SS II for UDP was similar to that for UDP-glucose; while with SS I, the Km for UDP was lower than that for UDP-glucose. This suggests that SS II activity favors sucrose synthesis compared with SS I, which favors sucrose cleavage. The optimum pH for activity toward sucrose synthesis was 8.0 for SS II and 8.5 to 9.5 for SS I. SS II from mature fruit may be an isozyme of SS occurring during periods of rapid sucrose accumulation, while SS I from immature fruit is more similar to the typical SS which functions mainly toward sucrose cleavage in many plants.
Uneven-ripening ‘Concord’ grapes were treated with 250 ppm gibberellic acid (GA3) about 2 weeks prior to harvest. “Green” berries responded with increased rate of ripening over untreated “green” berries as measured by soluble solids and anthocyanin content. GA3-treated berries also developed a callus-like layer between the pedicel and the skin which delayed drop also resulting in more evenly ripened clusters. In uneven-ripening clusters, “green” in contrast to “colored” berries had significantly fewer seeds and many of these seeds had aborted.
Abscisic acid (ABA) levels in seeds of tomato (Lycopersicon esculentum Mill.) fell about 10-fold during fermentation to remove mucilaginous tissue. Imbibing seeds in 20 µg/ml ABA prevented germination and increased ABA content of the seed 15-fold. Subsequent germination in water averaged greater than 90%.
New Mexican Chile peppers (Capsicum annuum L. `New Mexico 6-4') were harvested at weekly intervals beginning 20 days after flowering (DAF), and were evaluated for ethylene (C2 H4) production, respiration rates, chlorophyll content, degradative enzyme activity (cellulase, polygalacturonase, ß-galactosidase), and fruit firmness. Morphological and physiological changes were most apparent in peppers harvested 54 to 69 DAF. ß-galactosidase activity increased rapidly beginning 54 DAF and reached a peak by 89 DAF. Fruit firmness was highest (36 newtons) at 54 DAF and had decreased significantly by 69 DAF. Carbon dioxide production and chlorophyll content were highest in young pods harvested 20 DAF and decreased steadily thereafter. A climacteric increase of CO, was absent. There were two peaks in C2 H4 production: one associated with rapid fruit growth and the other with color change (61 to 69 DAF). Fruit harvested on the same day but at different developmental stages (green to red) were similar to those observed in fruit harvested over the season for the physiological characteristics tested. Separation of pepper fruit soluble proteins on SDS-PAGE demonstrated increased intensity in protein bands at 27, 35, and 40 kDa and decreased intensity of 51 kDa band as the fruit matured. Several biochemical processes appeared to be enhanced in Chile pepper fruit from 47 to 69 DAF.
Firmness, soluble solids concentration (SSC), starch index, and internal ethylene concentration were measured in the ‘Starkrimson’, ‘Oregon Spur’, ‘Redchief, ‘Royal Red’, and ‘Topred’ strains of ‘Red Delicious’ apple (Malus domestica Borkh) between 130 and 150 days after full bloom (DAFB). Firmness was significantly correlated with DAFB, although there were increases and decreases between 130 and 144 DAFB. SSC increased and was correlated with DAFB. The starch index increased linearly most of the time. There were differences in starch index between the 1983 and 1984 seasons, but no consistent differences among strains. Internal ethylene concentration began to change later than the other characteristics, but was correlated with DAFB in 90% of the comparisons. Fruit attributes that were significantly correlated in 80% or more of the comparisons were firmness with starch index, SSC with starch index, and starch index with internal ethylene. Firmness was correlated with starch index in 90% of the comparisons, SSC in 85%, and internal ethylene in 60%. Superficial scald was consistently correlated only with DAFB. Changes in firmness during storage were not correlated with any of the characteristics measured.
As the pistachio (Pistacia vera L. cv. Kerman) nut matured, kernel moisture, respiration rate, and total protein content decreased, while kernel dry weight increased. At optimum maturity, ether-extractable fat and total sugar contents reached a peak. Either or both of these constituents may be useful as a maturity index, in addition to ease of hull separation, to determine optimum harvest date for pistachio nuts. Nut quality was acceptable for harvest during a 2- to 3-week period bracketing the time when the hull separates easily from the shell. Compositional analyses of hulls indicated some limitations on their potential use as animal feed.
Application of ethephon at 200 to 2,000 ppm was made to the grape cvs. ‘Tokay’ and ‘Emperor’, and at 1,000 ppm to ‘Thompson Seedless’ and ‘Carignane’. The soluble solids were significantly increased in some fruits of ‘Carignane’ but not in the other cultivars. Ethephon treatment resulted in reductions in acidity in some fruits of all cultivars. This increased soluble solids to acidity ratios in some ethephon-treated fruits. An increase in anthocyanin content of the colored berries occurred, but not significantly so in ‘Tokay’. Optimum time for treatment was about 2 weeks after initiation of coloring.
Muskmelon [Cucumis melo L. (Reticulatus Group)] fruit sugar content is the single most important consumer preference attribute. During fruit ripening, sucrose accumulates when soluble acid invertase (AI) activity is less then sucrose phosphate synthase (SPS) activity. To genetically heighten fruit sugar content, knowledge of sugar accumulation during fruit development in conjunction with AI and SPS enzyme activities and their peptide immunodetection profiles is needed. Two netted muskmelon cultivars [`Valley Gold' (VG), a high sugar accumulator, and `North Star' (NS), a low sugar accumulator] with similar maturity indices were assayed for fruit sugars, AI, and SPS activity and immunodetection of AI and SPS polypeptides following 2, 5, 10, 15, 20, 25, 30, 35, and 40 (abscission) days after anthesis (DAA). Both cultivars, grown in spring and fall, showed similar total sugar accumulation profiles. Total sugars increased 1.5 fold, from 2 through 5 DAA and then remained unchanged until 30 DAA. From 30 DAA until abscission, total sugar content increased, with VG accumulating significantly more sugar then NS. In both cultivars, during both seasons, sucrose was detected at 2 DAA, which coincided with higher SPS activity than AI activity. At 5 through 25 DAA, SPS activity was less then AI activity resulting in little or no sucrose detection. It was not until 30 DAA that SPS activity was greater than AI activity resulting in increased sucrose accumulation. VG at abscission had higher total sugar content and SPS activity and lower AI activity than NS. Total polypeptides from both cultivars 2 through 40 DAA, were immunodetected with antibodies: anti-AI and anti-SPS. NS had Al isoforms bands at 75, 52, 38, and 25 kDa that generally decreased wtih DAA. One isoform at 52 kDa remained detectable up to anthesis (40 DAA) VG had the same four Al isoforms, all decreased with DAA and became undetectable by 20 DAA. It is unclear if one or all AI isoforms correspond with detected enzyme activity. VG and NS had one SPS band at 58 kDa that increased with DAA and concomitantly with SPS activity. VG had a more intense SPS polypeptide band at abscission then did NS. Thus, netted muskmelon sugar accumulation may be increased by selecting for cultivars with a specific number of AI isoforms, which are down-regulated, and with high SPS activity during fruit ripening.