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Opryski C2H4 i AOA a zwiększony podział komórek i wzrost plonu

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Opryski C2H4 i AOA a zwiększony podział komórek i wzrost plonu pomidora

Wątek na ten temat na haszyszu - https://www.forum.haszysz.com/agrostym-480-sl-harvest-przed-czasem-t54716.html

http://www.agrsci.unibo.it/wchr/wc5/attaaly.html

1Departments of Horticulture, Faculty of Agriculture, Ain Shams University, Shoubra El-Khema, Cairo and 2National Research Center, Dokki, Giza, Egypt.


Abstract: Tomato (Lycopersicon esculentum Mill.) plant cv. Castel Rock were flower sprayed with 100 ppm C2H4, 0.5 mM AOA (aminooxyacetic acid) or water (control) two days after anthesis. The period of cell division (CD) was extended up to 16-18 days with C2H4 application but shortened to only 6-8 days with AOA application as compared to that of control, which completed its CD in 10-12 days. Fruit received C2H4 treatment produced ethylene and contained ACC (1-aminocyclopropane-1-carboxylic acid) levels higher than those of control during the first two weeks after anthesis and at the stage of climacteric, while those of AOA treatment behaved oppositely at the same stages. The positive impact of C2H4 application was also found in terms of cells number / mm2 while an opposite trend was obtained with AOA application. As a result of C2H4 application, fruit diameter and weight were significantly increased by about 8 and 34%, respectively, and ripened 10 days later than control. Fruit of AOA treatment, however, was significantlyuit of AOA treatment, however, was significantly less in size and weight but ripened faster than control. When same treatments were applied to the whole plant, similar results were obtained and the fruit yield was increased by about 15%. No significant differences were found among all treatments in terms of flower or fruit abscission. It's indicated from this work, therefore, that ethylene regulates tomato fruit transmission from CD to cell enlargement (CE). In addition, fruit CD is terminated only when endogenous ethylene reduced to its basal level allowing CE to dominate and proceed. The ripening delay of C2H4 treated fruits may be due to the longer time required for the increased cells number to reach maturation. This may suggest the possibility of using low level of C2H4 application at tomato early fruiting stage for increasing fruit yield through increasing fruit size and consequently its quality.


Introduction

During its ontogeny, tomato fruit passes through certain developmental stages. First and directly after set, fruit passes through a short period of growth characterized by its slow rate. This slow rate of growth during such very early period due entirely to the dominant process of CD (Davis and Cooking 1985, Gillaspy et al. 1993). Fruit was then passed through a long period of rapid growth as fruit cells transmit to the stage of CE (Iwahori 1967, N cells transmit to the stage of CE (Iwahori 1967, Nitsch and Nitsch 1961). The length of such rapid growth period is strongly controlled by either tomato cultivar or the environmental coincide factors (Lacheene 1990). The third developmental stage was then occurred and last for about two additional weeks of a slow growth rate by which the fruit gained little more weight and reached maturation (Abdel-Rahman 1977). Two or three days later, fruit ripening was initiated (Atta-Aly et al. 1992). These facts strongly indicated that tomato fruit growth pattern followed the single sigmoid growth curve (Rhodes 1980). This may also lead to the demonstration that the ultimate size of tomato fruit is determined during its very early stages of development (Houghtaling 1935). The extent and relative importance of CD and expansion may, therefore, play a pivotal role, as key factors, in controlling not only tomato fruit size and shape but also fruit total yield.

Ethylene, as a plant hormone, is produced by many fruits even during their early stages of growth and development (Atta- Aly 1988, Burg and Burg 1965). It was thought that this early production of ethylene is responsible for young fruit abscission until Maxie and Crane (1968) revealed that the increased level of ethylene produced by young fig fruit was the reason behind early fruit growth. It was then believed that ethylene may has major and significant roles in fruit development during its ontog roles in fruit development during its ontogeny. The increased levels of ethylene production during fruit early stages of development was observed in many fruit species including tomato (Abdel-Rahman 1977, Atta-Aly 1988, El-Beltagy et al. 1976), sycamore fig (Maxi and Crane, 1968), peach (Looney et al. 1974) and apple and cherry (Blanpied 1972). In tomato, the early peak of endogenous ethylene occurred during the very early stage of fruit development was shortly followed by a gradual decrease, reaching a stable low level until ripening onset when another increase was observed with the beginning of climacteric rise (Abdel-Rahman 1977, Atta-Aly 1988, El-Beltagy et al. 1976). Same trend was also found regarding tomato fruit content of ACC (Atta-Aly 1988) as an immediate ethylene precursor (Adams and Yang 1979).

It has been reported that exogenous ethylene application induced CD in potato tubers (Ilker et al. 1977), pine (Barker 1979) and aquatic plants (Metzer 1984) as well as CE in rice (Ku et al. 1970, Smith and Robertson 1971), aquatic plants (Metzer 1984) and fig fruits (Maxi and Crane 1968). In pea apex and root (Apelbaum and Burg 1972) as well as fig fruit (Maxi and Crane 1968), however, exogenous ethylene application depressed only CD but increased CE. Increasing or inhibiting ethylene levels at a certain developmental stage may, therefore, but used as a tool for magnifying or modifying fruit growth pattern.

Thg or modifying fruit growth pattern.

This present work, therefore, was designed to study the impact of modifying tomato fruit ethylene level during its very early developmental stages on fruit CD and consequently fruit final size, ripening and yield.


Materials and Methods

Plants


Tomato (Lycopersicon esculentum, Mill., cv. Castle Rock) seeds were sown in foam trays filled with a mixture of peatmoss and vermiculite (1:1 volume) on March 1, 1994 and 1995, for the first trial and on March 17, 1995 and 1996, for the second trial. Trays were then kept under unheated greenhouse conditions at Shalakan farm, Faculty of Agriculture, Ain Shams University, Egypt. One tray was sown 15 days a head to serve as an indicator for monitoring seedlings water need in greenhouse, as well as plant flowering dates and other fruit development stages in the field. During soil preparation, the experimental field of each trial was designed as a complete randomized blocks in four replicates, each was 42 m2 in area. Thirty-day-old seedlings were transplanted 50 cm a part in 7.5 m long rows of 80 cm width with a capacity of 7 rows / replicate. All agricultural managements were then carried out as usually recommended for tomato production in the open field.

Treatments


When flowers of the first cluster reached their maximum blooming, they were tagged. Tagging was also carried om blooming, they were tagged. Tagging was also carried out for the subsequent bloomed clusters continuously for a period of 2 weeks (the last 2 weeks of May and the first 2 weeks of June for the first and second trials, respectively). This was carried out to ensure enough fruits number required during the first trial for different laboratory analysis, particularly during the early stages of fruit development or for calculating the percentage of abscised flowers during both trials.

In the first trial, tagged flowers were sprayed at early mornings with distilled water (control), 100 ppm C2H4 or with 0.5 mM AOA, until solution runs-off the flowers. These treatments were conducted 2 days after tagging (anthesis) which is the approximate time for tomato fruit set (El-Beltagy et al. 1976). Same treatments were carried out during the second trial, but the freshly prepared solutions were used for spraying the whole plant one-week after the anthesis of the first cluster's flowers.

While fruits of the first trial were periodically harvested and analyzed in 4 replicates throughout the subsequent stages of fruit development, fruits of the second trial were left for recording flower or fruit abscission, fruits number / plant, fruit average weight and total fruit yield.

Flowers or Fruits Abscission

Using randomly selected 10 plants in each replicate, fruits and the previously hanged paper labels (flowers) werand the previously hanged paper labels (flowers) were counted 3 weeks after tagging, and the percentage of abscised flowers and fruits were calculated in both trials. In the first trial, plants selected for abscission recording were left with out fruit sampling.

Fruit Analysis

1. Fruit fresh weight: Fruits were harvested with calyx attached throughout the whole period of fruit development starting 2 days (6 h after application) up to 55 days after anthesis. Fruits were harvested and directly weighed every other day during the first 12 days, followed by 6 days intervals during the subsequent 18 days and then every 5 days until fruits reached 53 days old (55 days after anthesis). Ten fruits were used in each replicate for measuring fruit average weight during the first 12 days. This number was reduced down to 4 fruits / replicate during the subsequent stages (18 - 55 days after anthesis) of fruit development.

2. Fruit dry weight: After fresh weight recording, same fruits were exposed to 70°C / 72 h and re-weighed again for determining fruit average dry weight. Fruit fresh and dry weights were then recorded in grams.

3. Fruit diameter: Ten days after anthesis, 15 fruits were re-tagged in each replicate using labels of coloured paper. These fruits were then used, while attached, for measuring fruit diameter development following the same age order of the fruitelopment following the same age order of the fruit that previously described in fruit fresh weight measurements. The first 8 days after anthesis were excluded in this analysis due to the minute differences between treatments.

4. Ethylene and ACC sampling and analysis: Following the same sampling procedures and capacity previously described for fruit fresh weight recording, fruits were harvested at the same ages and divided into 2 equal groups. Fruits of the first group were incubated for ethylene analysis, while those of the second group were immediately dipped in liquid nitrogen and then kept at -20 °C for ACC analysis.

For ethylene analysis, fruits younger than 22 days old were placed, immediately after harvesting, inside 225 mL glass vessels while older fruits were incubated inside 375 mL glass jars. The incubating containers were directly sealed and carefully transferred to the Horticultural Department of the above-mentioned institute. One-mL gas samples were withdrawn, after an incubating period of 4 h from the incubator headspace and injected into a Varian 6000 gas chromatograph for ethylene analysis. Data were then recorded as nL of C2H4 / g. h.

Two g of frozen fruit tissues were homogenized in 10 mL TCA (trichloroacetic acid) for ACC analysis using a mortar and pestle (a little washed silica sand was used to assist the grinding). The mixture was centrifuged at 7000 rpmrinding). The mixture was centrifuged at 7000 rpm for 10 min. The supernatants were decanted and the aliquots were assayed for ACC using the procedure of Atta-Aly et al (1987) as a modified version of Lizada and Yang (1979). Data were then recorded as nM / g.

5. Anatomical measurements: Tomato fruits were harvested 6, 9, 12, 15 and 18 days after anthesis. Triangular pieces from the middle portion of fruits pericarp tissues were cut into transver sections using shaving stainless steal blade and immediately immersed in killing and fixing solution FAA (Formalin 5 mL, acetic acid 5 mL, and 90 mL 70 % ethyl alcohol. The normal procedures of paraffin method technique (Johansen 1940) was followed Sections of paraffin-embedded samples were obtained using rotary microtome. Transverse sections of 10-12 micron were fixed on microscopic slides by means of albusol adhesive (Sass 1951). Staining was attained using a double combination of saffranin and light green. Sections were then mounted in canada balsam. Photomicrographs were then obtained using a camera mounted on CARLZEISS (Jena) microscope. Using micrometer slides, cells number as well as enlargement were examined and calculated.

Cells number of the mesocarp was estimated in 1 mm2 . Using 5 randomized replicates of the external mesocarp (distance between exocarp and vascular bandles), cells number were calculated. Same procedure was also used to estimate cells nue procedure was also used to estimate cells number of the internal mesocarp (distance between vascular bandles and internal epidermis).

For CE, measurements, 20 randomized cells were measured at the maximum cell length using different loci of external and internal mesocarp.

6. Days to reach red-ripe stage: This was calculated in days starting 2 days after tagging (fruit set) until fruits reached red-ripe stage using the same 10 plants used for recording flower abscission and left without fruit sampling.

Fruit Yield

With ripening initiation, fruits of the second trial were harvested at weekly intervals. At each harvest, fruits of each replicate were counted and weighed. At experiment termination, average fruit weight (g), fruits number / plant and total fruit yield (kg / plot) were calculated and recorded.

Experimental Design and Statistical Analysis

Experiments were of a complete randomized blocks in four replicates. Data means were paired as combined analysis for the results of each trial (tow seasons). Since the results followed a similar trend, they were analyzed for significant statistical differences using LSD test at 5 % level (Little and Hills 1978).


Results

First Trial

Tomato fruit diameter (Table 1) as well as fresh and dry weights showed an early period of slow growth during the first 6-8 dhts showed an early period of slow growth during the first 6-8 days after anthesis. These parameters of tomato fruit growth significantly increased during the period of rapid growth occurred when fruit passed the age of one week after anthesis and last for 3 additional weeks. By that time, a second period of fruit slow growth was occurred and dominated until fruit reached its maturation (Tables 1 & 2). When tomato flowers were exposed to ethrel or AOA application 2 days after anthesis, all measured parameters of fruit growth showed a strong response to both treatments. During the early period of fruit growth (2-4 weeks after anthesis), fruits of AOA treated flowers produced fruits of the largest diameter (Table 1) and heaviest fresh and dry weights (Table 2), while those received 100 ppm ethrel resulted in the smallest and the lightest fruits as compared to those of control (H2O treated flowers). Furthermore, no significant differences were found among all treatments in terms of flower or fruit abscission measured 3 weeks after anthesis (33+ 2% abscission for all treatments). Such significant descending order of fruit growth obtained with AOA, H2O and ethrel applications was diminished 4 weeks after anthises and totally reversed to an ascending order as fruit age passed 30 days after anthises (Tables 1& 1& 2). This new ascending significant order strongly emphasized as fruit reached its red-ripe stage (Tables 1 & 2). Furthermore, fruits of AOA treated flowers reached its red-ripe stage faster than control and both were faster than those resulted from ethrel treated flowers (i.e., 45, 50 and 60 days after anthesis, respectively) following the same growth ascending order (Table 2). It was also noticed that the time between red colour initiation (breaker) and red-rip stages (Table 2) was also extended but only in the fruits of ethrel treated flowers (Table 2) as compared to other treatments (10 vrs 5 days, respectively).

According to the histolgical studies, the transection of tomato fruit during its early stages of growth and development showed that fruit pericarp tissues consisted of exo and mesocarp tissues. Exocarp tissue is formed from uniecuate parenchymatous cells coated with cuticle with 2-3 layers of cells located under the epidermis called hipodermis (Plate. 1). Mesocarp tissue, on the other hand, was formed from 2 different layers defined as outer and inner mesocarp layers. The outer mesocarp layer is located in the distance between the hypoderms and the vascular bundle of pericarp tissues while the inner mesocarp tissue is entirely paranchymatous cells locatissue is entirely paranchymatous cells located under the vascular bundle and extended to reach the loci of the ovules (Plate 1). It was also noticed that the transition phase from CD to CE is mostly happened in the outer and inner mesocarp layers (Plate 1).

Fruits resulted from ethrel treated flowers showed the highest level of CD in the outer mesocarp followed by control while fruits of AOA treated flowers were significantly the lowest (Plate 1). The inner mesocarp however, did not show CD activity 6 days after anthesis in all treatments with the exception of ethrel treatment (Plate 1). To define such results, number of cells / mm2 were counted as presented in Table (3). Number of cells / mm2 were significantly higher with ethrel application than that of control, while AOA significantly produced the lowest cells number (Table 3). These results were existed in both inner and outer mesocarp up to 12 days after anthesis. Number of cells / mm2 in outer mesocarp remained significantly higher with ethrel application than those of control up to 18 days after anthesis and both were significantly higher than AOA treatment. In the inner mesocarp tissues however, number of cells / mm2 in fruits of ethrel application remained significantly higher than other treatments while the differences between control and AOA treatments were diminished 15 days after OA treatments were diminished 15 days after anthesis (Table 3). It was also noticed that outer mesocarp exhibited higher cells number / mm2 than those of inner mesocarp. On the other hand, CE can be easily observed as early as 6 days after anthesis with AOA treatment and it was more pronounced in internal than external mesocarp in comparison with those of control and ethrel treated ones (Plate 1). In addition, AOA treatment showed the highest level of CE, in both outer and inner mesocarp, followed by control while the lowest level was occurred with ethrel application as early as 6 days after anthesis (Table 3).

In terms of ethylene production, tomato fruits produced their highest ethylene level at the stage of fruit set (2 days after anthesis). At this stage, fruits of ethrel treated flowers produced superior ethylene level as compared to those of control (Fig. 1). Meanwhile, fruits of AOA treated flowers produced significantly the least ethylene level (Fig. 1). Shortly after anthesis, ethylene production was sharply reduced to its basal level (the lowest constant level). Fruits of AOA treated flowers were the first in reaching their basal level of ethylene production since the time required was only 6 days after anthesis. Fruits of control and ethrel treated flowers, however, reached their basal level, which was comparable to that of AOA level, which was comparable to that of AOA treated flowers, 10 and 18 days after anthesis, respectively (Fig. 1). Furthermore, ACC content in the fruits of all treatments followed the same pattern of ethylene production (Fig. 2). The only exception was that of ACC gradual increase during the first 8-10 days after anthesis which was parallel to ethylene continuous drop (Figs. 1 & 2).

Ethylene production and ACC content of the fruits resulted from all treatments remained in their basal level until fruit reached the age of 35 days after anthesis. At the age of 40 days after anthesis, however, both ethylene and ACC levels re-stored their significant increases following the same significant increase order noticed with AOA, H2O and ethrel treatments during the early stages of fruit development (Figs. 1 & 2).


Second Trial

When tomato plants received AOA, H2O or ethrel treatment, only one week after flowers anthesis of the first cluster, fruit of AOA treated plants reached their harvest peak 4 and 12 days earlier than that of control or ethrel treated plants, respectively (Fig. 3). Furthermore, fruit yield of AOA treated plants was significantly higher than other treatments only during early harvests. An opposite trend however was obtainearly harvests. An opposite trend however was obtained in the late harvests when ethrel treated plants became superior in their yield than those of control and both were significantly higher than AOA treated plants (Fig. 3). In addition, no significant differences were found among all treatments in terms of flower or fruit abscission (Fig. 4) which emphasize the results obtained during the first trial. Similarly, no significant differences between treatments were found in terms of fruits number / plant (Fig. 4). Fruit average weight, however, significantly reduced with AOA application but markedly increased with ethrel application as compared to that of control (Fig. 4). Fruit yield followed the same pattern of fruit average weight since AOA application reduced tomato fruit yield by about 7 %, while 15 % increase was obtained with plant ethrel application (Fig. 4).


Discussion

First Trial


Parameters of tomato fruit growth, measured as fruit diameter as well as fresh and dry weights showed a period of slow growth during the first week after anthesis. This was followed by a period of rapid growth up to 40 days after anthesis when the second slow growth period was occurred and last until fruit reached its maturation (Tables 1& 2). During the early priA>& 2). During the early priod of tomato fruit slow growth, CD took place (Davis and Cooking 1965, Gillaspy et al. 1993), while fruit rapid growth period due entirely to CE (Iwahori 1967, Nitsch and Nitsch 1961). Data presented in Plate (1) showed an almost termination of CD activity with a rapid progress in CE 6 days after anthesis. This was noticed in a time parallel to the remarkable drop in ethylene production (Fig. 1). These findings, therefore, strongly suggested that the transition phase from CD to CE in tomato fruit cv. Castel Rock may be an ethylene dependent process. It was also found that tomato fruit produced a remarkable level of ethylene during the stage of CD while an opposite trend was occurred during CE and the remarkable drop in ethylene level was parallel in time to the noticed transition phase between both developmental processes (Table 3, Fig. 1 and plate 1).

It has been reported that ethylene induced CD in rice (Metzer, 1984), pine (Barker, 1979) and potato tubers (Ilker et al., 1977), while an opposite result was obtained by Apelbaum and Burg (1972) in pea apex and its root meristem. Oppositely, Maxie & Carne (1968) reported that ethylene inhibited CD and promoted CE in fig fruit. In addition, El-Beltagy et al., (1976) suggested that ethylene induced the transition from CD to CE during early stages of fruit devel CD to CE during early stages of fruit development by inhibiting the first and promoting the last process.

In a preliminary experiment, conducted earlier in this work, it was found that applying ethrel, as an ethylene releaser, to tomato flowers 2 days after anthesis with concentrations higher than 100 ppm induced flower abscission while concentrations of 50 ppm or less had no impact on fruit growth as measured by fruit diameter and fresh weight. Applying 100 ppm however, proved to be the best ethrel concentration to be used in terms of eliminating flower abscission and shifting fruit growth pattern measured as fruit diameter and fresh weight. Therefore, and to test the impact of ethylene on CD and CE as well as the transition phase between both developmental processes, tomato flowers were sprayed at set (2 days after anthesis as previously reported by El-Beltagy et al., 1976) with 100 ppm ethrel, 0.5 mM AOA and H2O (as control). AOA is known by its inhibition to ethylene biosynthesis through inhibiting ACC synthesis (Yang, 1980). It has also been found that 0.5 mM is the most suitable concentration of AOA to be used for inhibiting ethylene biosynthesis in tomato fruits (Atta-Aly, 1992).

According to the growth parameters measured during the early stages of tomato fruit growth and development, it was found that fruit of AOA, H2O and ethrel treated flowers followed a significant descending orded flowers followed a significant descending order, as they orderly mentioned , in their growth parameters measured as fruit diameter (Table 1), fruit fresh and dry weights (Table 2). This significant descending order of growth was occurred as early as 8-10 days and last up to 24 days after anthesis. This was strongly established through the significant increase in fruit cell size occurred with AOA application and measured as cell elongation in fruit outer and inner mesocarp tissues (Table 3). In contrast to the parameters of fruit and cell growth described above, fruits of ethrel treated flowers showed the most significant CD activity followed by control and then fruits of AOA treated flowers (Plate 1). This was true for the outer mesocarp tissue. In the inner mesocarp tissue however, CD was terminated 6 days after anthesis in treatments other than ethrel (Plate 1) which indicated the expanded period of CD occurred with ethrel application. In contrast to the results obtained by Maxie and Crane (1968) on fig fruits which reported that ethylene inhibited CD and promoted CE, AOA treatment shortened the period of CD (Plate 1) and accelerated fruit transition to CE. This may due to the differences between tomato and fig fruits in their response to their basal level of ethylene. In addition, number of cells / mm2 in outer and inner tomato mesocarp tissues (Table 3) showed that fruits of ethrel treated flowers significantly produced the highest cells number / mm2 followed by control while the lowest cells number was produced by the fruits of AOA treated flowers (Table 3). These data strongly indicated that ethrel exogenous application at the stage of tomato fruit set, induced CD and delayed the transition phase to CE by extending the period of CD. Inhibiting ethylene biosynthesis however, shortened the period of CD and strongly induced CE. This was also supported by measuring ethylene emanation by such fruits since, in all treatments, the onset of fruit rapid growth period (Tables 1&2) as well as the significant increase in CE (Table 3) and the almost termination of CD (Plate 1) proved to be coincide with the time of ethylene drop to its basal level (Fig. 1). Data presented in Fig (1) showed that fruits of AOA treated flowers reached its basal level of ethylene production as early as 6-8 days after anthesis. By that time such fruits reached the onset of its rapid growth period as indicated by the significant increase in fruit fresh and dry weights (Table 2), and CE as well as the almost termination of its CD (Table 3 and Plate 1). This was also noticed in conand Plate 1). This was also noticed in control and in fruits of ethrel treated flowers but after 10 and 18 days from anthesis, respectively. It is of interest to note that the early drop in ethylene production, regardless the sort of treatment, due mainly to the strong inhibition of ethylene biosynthesis since the level of ACC followed the same pattern of C2H4 drop by a period of about 24 h (Figs. 1 & 2). Fruits of AOA treated flowers showed the earliest ACC drop, noticed 10 days after anthesis, followed by control and those of ethrel applied fruits 12 and 18 days after anthesis, respectively (Fig. 2). The higher ethylene and ACC levels noticed during the early stage of fruit development with ethrel application in comparison to those of control or AOA treated ones, may due to the higher levels of ethylene positive feed back mechanism (Atta-Aly et al., 1994). On the other hand, the significant increase in ACC level of all treatments during fruit early development, may due to the low levels of ACC conversion to C2H4 since a marked drop in ethylene production was obtained during such period (Figs. 1 & 2). It is also of interest to note that the degree of ACC accumulation during such period negatively correlated with ethylene production as affected by the different flower treatments.fected by the different flower treatments.

Differences in the parameters of fruit growth obtained with AOA, H2O and ethrel application at fruit set (i.e., fruit fresh and dry weights as well as diameter) were eliminated 30 after anthesis (Tables 1& 2). Furthermore, the descending order in fruit growth noticed with AOA, H2O and ethrel treatments, respectively as mentioned, during the first 4 weeks after anthesis was reversed to an ascending order 35 days after anthesis until fruit reached red-ripe stage. Therefore, delaying or enhancing the transition phase from CD to CE in tomato fruit with AOA or ethrel application, respectively, strongly affected fruit growth pattern toward its maturation.

Based on fruit response to C2H4 releaser or inhibitor applied at fruit set, fruit growth, therefore, can be divided into 2 periods of response. First is the period when fruit growth negatively responded to C2H4 which occurred after fruit set up to 30 days after anthesis. Second is the period of positive growth response to C2H4 and occurred 30 days after anthesis until fruit maturation. During the first period of growth, inhibiting C2H4 production by the fruit with AOA application at fruit set shortened the period of CD and accelerated CE process. Such treatment resulted higher rate process. Such treatment resulted higher rates of fruit growth only during the first period of growth while an opposite trend was obtained with ethrel application. During the second period of growth however, fruits of AOA treated flowers became limited in their growth (Tables 1&2) and cells number (Table 3) as a reselt of CD short period (Plate 1). In contrast, fruits of ethrel treated flowers passed through longer period of CD and produced larger fruits as they reach maturation or table-ripe stage. It was also evident, based on the data presented in Tables (1&2), that ethrel application, at fruit set, produced fruits larger in diameter and heavier in fresh weight than those of AOA treated flowers by about 19% and 52%, respectively. These values were reduced down to 8 and 34%, respectively, but still highly significant as compared to those of control, respectively.

It seems that there is a positive correlation between the period fruit spent in CD and days to reach red-ripe stage since extending the period of CD, by ethrel application, delayed fruit ripening by about 15 days than those of AOA treated flowers and by about 10 days as compared to control fruits (Table 2). This may also indicate that ethrel application, at fruit set, extend not only the period of CD but also the period of CE and fruit of CD but also the period of CE and fruit maturation.

Fruits of ethrel treated flowers kept their level of C2H4 production (Fig. 1) and ACC content (Fig. 2) higher than those of contor or AOA treated flowers during fruit early and last period of growth. It has also been suggested by Atta-Aly (1988) that tomato fruit ripened when its sensitivity to C2H4 rose up to meet its basal C2H4 level. Increasing fruit basal level of C2H4 with early ethrel application, therefore, may increase the gap between ripening sensitivity and the new basal C2H4 level and this may be the reason behind ripening delay in the fruits of ethrel treated flowers and the ripening enhancement of those produced from AOA treated flowers. This was also emphasized by the time required for breaker fruits resulted from ethrel application to reach red-ripe stage as compared to those obtained with AOA application (Table 2).

It could be concluded from such results that ethrel application, at fruit set, extended the period of tomato fruit CD and delayed the transition phase to CE as well as increasing fruit size and fresh weight with pronounced delay in ripening while an opposite trend was obtained with the early inhibition of C2H4 production by AOA application.

Second Trial

Ethrel application to tomato flowers proved to be a promising treatments in increasing tomato fruit size and may be yield with ripening delay as found in the first trial. It is also of interest to note that ethrel has been internationally registered for pre and postharvest uses in several fruits including tomatoes (Abeles et al. 1992). It was also found that flower application 2 days after anthesis is not a practical way for commercial treatment. Tomato plants, therefore, were exposed to the same treatments of the first trial one week after flower anthesis of the first cluster. By that time flowers of the third cluster were close to anthesis stage and the corolla was opened in the fourth cluster meaning that the majority of the flowers may benefit from such application.

Ripening acceleration and delayness obtained in the first trial were also emphasized during the second trial when AOA and ethrel were, respectivly, applied to tomato plants not flowers. This was based on the fact that tomato fruit yield during the early harvests was superior with AOA application but higher superiority was obtained with ethrel application at late harvests (Fig. 3). Furthermore, AOA, H2O and ethrel applications showed the same ascending order found in the first trial but in terms of the time for harvesting peak (Fig. 3)ime for harvesting peak (Fig. 3). The increase in fruit average weight found with ethrel application without affecting flower or fruit abscission as well as fruits number / plant (Fig. 4) strongly increased tomato fruit yield of the second trial (Fig. 4). This increase was about 15% over control while a significant reduction by about 7% was obtained with AOA application. It is indicated, therefore, that the yield increase or decrease obtained with ethrel or AOA application, respectively, due entirely to the size variability of the obtained fruit. This was resulted from modulating fruit CD and consequently growth pattern with modifying fruit basal C2H4 level during the early stages of fruit development.

Based on the results obtained from both trials, it can also be indicated that ethrel application during flowering or tomato fruit set stage increased not only fruit yield but also fruit size as one of the fruit major quality factors.


Tabelki dostępne na stronie źródłowej
 
Ostatnia edycja:
S

sub

Guest
aminooxyacetic acid ->

inhibitor syntezy etylenu -> Podobny do AVG: aminoethoxyvinylglyciny

http://www.wiki.haszysz.com/index.php/AVG

http://www.sciencedirect.com/science/article/pii/S0044328X82800081

to można użyć do "hermienia" prawdopodobnie..

Modification of Growth and Sex Expression in Cannabis sativa by Aminoethoxyvinylglycine and Ethephon
H.Y. Mohan Ram, Rina Sett
Department of Botany, University of Delhi, Delhi-110007, India

Summary

Apical application of aminoethoxyvinylglycine (AVG) to female plants (5, 10, 25, 50 and 75 μg per plant) of Cannabis sativa induced the formation of fertile male flowers on the newly formed primary lateral branches (PLBs). 1 μg per plant was found to be ineffective and 100 μg treatment proved inhibitory. In response to 5 to 50 μg treatments the PLBs bore reduced male, intersexual and male flowers, whereas with 75 μg they formed only male flowers.

When AVG (25, 50 μg) was applied to the shoot tips of male plants sprayed with ethephon (1920 mg · 1 -1), the feminization effect caused by the latter was markedly curtailed.

Key words
Cannabis sativa; aminoethoxyvinylglycine; ethephon; growth regulators; reproduction; sex reversal

Aminooxyacetic acid as an inhibitor of ethylenesynthesis and senescence in carnation flowers
Rachel Broun, Shimon Mayak
Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot Israel

Abstract
α-Aminooxyacetic acid delayed ethylene (C2H4) production by cut carnation flowers at a concentration of 3 × 10−4 M. It also prevented the development of petal in-rolling (“sleepiness”) symptoms. The efficacy of inhibition is similar to that reported in apple tissue, but 10 times less efficient than in mung bean hypocotyls. The inhibitor had a slight delaying effect on the response of the flowers to exposure to C2H4. This apparent effect of the inhibitor on the action of C2H4 is discussed. The data are in agreement with the proposal that aminooxyacetic acid inhibits C2H4 biosynthesis.

There are no figures or tables for this document.

Copyright © 1981 Published by Elsevier B.V.
 



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