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1.
Movement of a putative florigenic promoter from leaves to buds was investigated in two cultivars of mango (Mangifera indica L.) over two flowering seasons through examination of the minimum number of leaves on each stem necessary for floral induction and movement of this component over various distances from stem to stem in isolated branches. The minimum number of leaves on individual stems necessary to induce flowering was less than 1/4 of a cross-cut leaf per stem. The putative florigenic promoter moved from donor stems bearing as few as one leaf to induce flowering in five receiver stems located as far down branches as 100 cm from the donor stem. Evidence suggests that movement of the putative florigenic promoter occurs in phloem and that far more of this component is available in trees than is necessary for floral induction of initiating shoots during cool, floral-inductive conditions of the subtropics. 相似文献
2.
Mature ‘on’ and ‘off’ ‘Manzanillo’ olives trees with three healthy branches of 10–12 cm in diameter were selected to determine changes in nitrogen levels in the bearing shoots after foliar application of urea. Each selected branch of each tree received one of the following treatments: (i) control without urea application; (ii) foliar application of urea to all the current-season leaves; and (iii) foliar application of urea to all the one-year-old leaves. Urea was applied in May, four days after full bloom in the ‘on’ year trees. Each treated leaf was immersed in a test tube containing a 4% urea solution and 0.1% Tween 20 for 5 s. Bearing shoots, composed of both one-year stems and leaves and current-season stems and leaves, were collected at intervals from the beginning of the experiment until 64 days after urea application. Nitrogen was determined in stems and leaves from each part of the bearing shoot, and in fruits during the ‘on’ year. Nitrogen uptake from the leaves was rapidly mobilized from the older to the current-season leaves of the bearing shoot, and thereafter to other storage organs of the tree or to the fruit, which is the largest nitrogen sink in the bearing shoot. No translocation of nitrogen from the current-season leaves to older leaves was observed. The rapid translocation of nitrogen from the younger leaves to other storage organs of the tree could explain the insensitivity of leaf analysis to detect excess nitrogen, since mature leaves from current-season shoots must be sampled to determine the nutritional status of the tree. The failure of leaf analysis to detect excess nitrogen may be a cause of nitrogen over-fertilization in olive orchards. 相似文献
3.
Mango flowering is an important physiological event that sets the start of fruit production. Initiation is the first event that takes place for mangoes to flower. Coincident with shoot initiation, induction occurs based on the conditions present at the time of initiation. Numerous studies with mango trees support the existence of a florigenic promoter (FP) that is continuously synthesized in mango leaves and induces flowering. Translocation experiments suggest that the FP is carried from leaves to buds in phloem. Induction appears to be governed by the interaction of the FP and a vegetative promoter (VP). The FP is translocated as far as 100 cm in subtropical conditions and 52 cm in tropical conditions. In the tropics, floral induction occurs in stems that have attained sufficient time in rest since the previous flush. The age of the last flush is the primary factor governing flowering in the tropics as evidenced by experiments in Colombia. Tip pruning is ideal to synchronize vegetative flush events in the canopy. Potassium nitrate (KNO3) has been shown to stimulate flowering in sufficiently mature stems. Tip pruning and foliar applied KNO3 are effective methodologies that induce synchronous flowering especially in Colombia. Cool temperatures are important for mango floral induction under subtropical conditions. Mangoes grown in the low-latitude tropics rely less on low temperature. Soil and leaf analyses should be conducted to evaluate the nutrient status of trees. 相似文献
4.
为了研究‘地平线’天竺葵的花芽分化特性及光周期对其生长发育的影响,采用石蜡切片
方法观察了花芽分化的过程,探讨了7 种光周期处理对始花期及开花质量的影响。结果表明：（1）‘地平
线’的花芽分化过程可以划分为8 个时期,持续时间大约为9 周;（2）‘地平线’花芽分化时期与各生长
指标（株高、株幅、真叶数和播种周数）均极显著相关,通过回归方程判断其幼龄期在5 片真叶前结束;
（3）‘地平线’为量性短日照植物,促其早花的最佳光周期为昼12 h/夜12 h;（4）较长日照下‘地平线’
的株形高大松散,较短光周期下矮小紧凑。‘地平线’天竺葵在5 片真叶前,采用16 h 日照栽培,可得到
健壮幼苗;5 叶期后,12 h 日照诱导,可促进分枝开花。 相似文献
5.
A new disorder known as fruit pitting has been observed in some Indian mango orchards during the recent years. In this disorder, there is a development of some sunken pits on fruit peel, which distract consumers. Based on preliminary observations, it was observed that deficiency of nutrients could be the cause, and hence systematic studies were conducted in five indigenous cultivars such as ‘Alphonso’, ‘Amrapali’, ‘Dashehari’, ‘Mallika’ and ‘Neelum’, and five exotic mango cultivars such as ‘Edward’, ‘Irwin’, ‘Rosari’, ‘Sensation’ and ‘Tommy Atkins’ with the aim to observe the fruit pitting incidence and degree, and to investigate its probable causes. Our studies indicated that nearly 13% of the mango fruit was affected by fruit pitting with variable degree and magnitude. All indigenous cultivars had higher incidence of fruit pitting than exotic cultivars. ‘Dashehari’ had the maximum incidence of fruit pitting (30.3%), followed by ‘Amrapali’ (28.6%), and ‘Rosari’ the least (3.4%). Our studies indicated that the incidence of fruit pitting in mangoes was nearly 13% with a significant variability among the cultivars (Table 1). Although the concentrations of most of the major nutrients such as N, P, K, Mg, and minor nutrients such as Cu, Mn, Fe, Zn, did not differ significantly. However, the pitted fruit had lower Ca (1.53%) and B (22 mg kg−1) concentrations than normal fruit (2.47% and 38 mg kg−1, respectively), indicating that deficiency of Ca and B probably is the cause for fruit pitting in mangoes. 相似文献
6.
V. J. Kulkarni 《The Journal of Horticultural Science and Biotechnology》2013,88(2):361-367
SummaryDefoliated shoots of cvs Alphonso, Dashehari, Totapari etc. (receptors), could be induced to flower within four weeks during the off-season by veneer grafting them to leafy shoots of the off-season flowering cv. Royal Special (donor) during the non-flowering season. Experiments on defoliating the donor and receptor shoots revealed the crucial dual role of the leaves in flowering. In the ‘floral cycle’, leaves from the donor promoted flowering, whereas leaves on the receptors, in the vegative phase, were inhibitory, and prevented graft-induction of the receptors. Thus, for graft induction, leafy donors and defoliation of receptors were essential. The inhibitory effect of the leaves on the receptors was localized and did not affect flowering of the donor shoots’ The similarity between these findings and those in the herbaceous, day-length sensitive species strengthens the view that flower formation is controlled in the same way in herbaceous and in woody perennial species. A minimum threshold of the floral stimulus appeared to be another requirement for an optimum flowering response. This was concluded from an experiment in which the leafy receptors were defoliated on different dates during the off-season flowering cycle. At the end of cycle, the defoliated receptors produced small panicles, and finally only vegetative shoots, probably indicating sub-threshold levels of the stimulus. Bud activity at the apex in the receptor was also an important pre-requisite for graft-induction. Some veneer-grafted scions which remained dormant during the flowering cycle of the donor and which sprouted much later after the completion of off-season flowering, ‘escaped’ the stimulus and invariably turned out to be vegetative. It is postulated that the cyclic synthesis of the floral stimulus in the leaves in an inductive cycle, and the gap between two such cycles, mainly decides the flowering behaviour of mango cultivars—biennial, annual and multiflowering. Two other requiremets are the absence of non-induced leaves and the synchronization of meristematic activity in the bud with the inductive cycle. Juvenile shoots from one to four year old seedlings could not be graft-induced—unlike the shoots from mature, six year old seeding trees. This juvenility effect continued into the second year when defoliation of the receptor shoots had no effect and failed to induce them to flower. 相似文献
7.
A greenhouse experiment was conducted to study the effects of boron (B) on growth, nutrient status, B distribution and gas exchange parameters of olive plants (Olea europaea L.). One-year-old own-rooted olive plants of the Greek cultivars Megaritiki, Chondrolia Chalkidikis, Amfissis and Kalamon were grown in a sand–perlite medium and irrigated with nutrient solutions containing: 0.27, 0.5, 1, 2.5, 5 and 10 mg L−1 B (0.27 and 10 mg L−1 were considered as control and excess B treatment, respectively). After culturing for 185 days, leaves and stems (from basal and apical part of the shoots) and roots were separately sampled. Our results showed that the final number of leaves per plant was negatively correlated with B concentration in the nutrient solution. Furthermore, in B10.0 treatment, ‘Megaritiki’ had decreased length and number of lateral stems, ‘Chondrolia Chalkidikis’ and ‘Amfissis’ showed decreased length of lateral stems and ‘Kalamon’ decreased length of lateral stems and plant height. In general, dry weight of stems and leaves was not significantly correlated with B concentration in the nutrient solution. B concentration in leaves and stems was linearly correlated with B supply. A linear correlation existed between B concentration of the nutrient solution and that of leaves and stems. At the end of the experiment, B levels in the leaves and stems of B0.27 and B0.5 treatments did not differ significantly. In general, the increase of B concentration in the nutrient solution, negatively affected the nitrogen (N) concentration of leaves and stems while phosphorus (P) and iron (Fe) concentrations were not affected. Furthermore, potassium (K) and calcium (Ca) concentration in stems of plants supplied with 10 mg L−1 B was decreased. In addition, high B supply resulted in increased magnesium (Mg) and manganese (Mn) concentrations in ‘Chondrolia Chalkidikis’ and ‘Amfissis’ and in the decrease of zinc (Zn) concentrations, in all plants. A significant decline in photosynthetic rate at the end of the experiment was observed in the B5.0 treatment regardless of cultivar. 相似文献
8.
To elucidate the fate of photosynthates from different current shoots and their influence on fruit growth and bud differentiation in neighboring spur complex during the period of rapid fruit growth in two late-maturing Japanese pear cultivars: ‘Atago’ and ‘Shinkou’ with contrasting fruit size, 13C labeling of single shoot was done to investigate of C-relations in fruit branches of eight shoot-combinations. The results showed that all of the current shoots investigated (bourse shoots of nonfruiting spur, bourse shoots of fruiting spur, extension shoot, nonfruiting spur, vegetative shoot, and water sprout) could export photosynthates to the neighboring fruit and buds. Water sprouts together with vegetative shoots, bourse shoots, and extension shoots are important source for fruit growth after shoot growth termination during the period of rapid fruit growth in production of late-maturing pears. The carbon transfer rate from the neighboring to the fruit bearing spur is depent (i) on the types of shoot which acts as C source, (ii) on the position of the fruiting spur and (iii) on the source-sink distance. Furthermore, the cultivar difference in carbon partitioning from different current shoot-combinations confirmed that the movement of photosynthates into the fruit was determined by sink strength of the fruit, and ‘Atago’ exhibited a greater relative sink strength of fruit than ‘Shinkou’. In addition, vegetative shoots are very important C sources for fruit growth in ‘Atago’ and the growth pattern of bourse shoot seriously affects C allocated to fruit in ‘Shinkou’. 相似文献
9.
The effect of girdling on abscisic acid, carotenoids content, xanthophylls cycle and non-photoquemical quenching was studied in leaves from different shoot types of containerized two-year-old ‘Loretina’ mandarin during spring flush period. Girdling increased abscisic acid in young leaves and decreased it in mature leaves. These changes were accompanied by a significant increase in leaf carotenoids, carotenoids:chlorophylls ratio, xanthophylls and xanthophylls cycle pool size and its de-epoxidation state in vegetative and multiflowered young leafy shoots. However, changes in de-epoxidation state did not correlate with the energy-dependent non-photochemical quenching. The role of carotenoids and abscisic acid as photoprotecting agents during the oxidative stress caused by girdling is discussed. In conclusion, this study provides evidence linking carotenoids-based photoprotecting mechanisms in the response to the stress induced by girdling in Citrus trees. 相似文献
10.
A. F. Posnette R. Cropley 《The Journal of Horticultural Science and Biotechnology》2013,88(2):119-133
The annual growth of an apple tree in the vegetative condition is distributed in a definite pattern between leaves, stems and roots ; when a crop is borne, this constitutes an additional end-point for growth materials. The disturbances in the pattern of vegetative growth caused by this additional region of utilization are described. Two-year-old apple trees were deblossomed at flowering or defruited on 30th May, and their growth was compared with that of cropping trees. The increments in weight were estimated by samples taken at treatment times.After deblossoming, the trees made extra growth in terms of dry weight, more and larger leaves, and longer stems. The periods of greatest and least growth were the same as for cropping trees. Defruiting also resulted in extra growth, but this came later, and so was out of phase with the growth of fruiting trees. This extra vegetative growth (including more trunk thickening and root growth as well as leaves and new shoots) weighed more than the crop on the fruiting trees. Defruiting had slightly less effect than deblossoming.The diversion of metabolites to the crop changed the pattern of growth in the rest of the tree. Cropping trees had 50% more leaf proportionate to total vegetative increment, and 50% less root, than deblossomed ones. The intervening regions varied roughly according to their position. Despite this greater leafiness of cropping trees, they produced significantly more total dry matter (vegetative growth plus crop) per unit area of leaf.These results are attributed to the greater demanding power of the growing crop in diverting photosynthates from the lower parts of the tree and in increasing the rate of removal of photosynthates from the leaves. 相似文献
11.
The effect of in-row spacing on the vegetative and productive performance of 4-year-old ‘Conference’ (CON) and ‘Williams’ (WIL) pear trees was studied. Analysis of digital images was used to estimate canopy growth and conformation. Fruit quality was determined by measuring fruit weight, flesh firmness, peel color, soluble solid content, and titratable acidity. WIL produced more and more efficiently than CON, especially at closer spacings. WIL canopies were generally bigger than CON canopies, and reduced spacing penalized stem growth and influenced canopy conformation. Root growth and conformation was similar for both cultivars, whereas decreasing in-row spacing reduced root dry weight, length, volume, and spread area only in WIL. Also, WIL trees partitioned more to fruit and leaves compared to CON, and increasing spacing resulted in a relative shift toward vegetative growth. CON fruit was smaller but sweeter and less acidic than WIL fruit. Increasing spacing influenced negatively WIL fruit quality parameters, with the only exception of fruit weight, which was increased. For the range of in-row spacing considered, our results indicate that WIL may represent a more efficient and competitive option than CON for high-density plantings, at least in the early stages of orchard life. 相似文献
12.
The effects of night interruption (NI) were examined on the vegetative growth and flowering of Cymbidium ‘Red Fire’ and ‘Yokihi’. Plants were grown under 9/15 h ambient light/dark (control), 9 h ambient light plus night interruption (22:00–02:00 h) with low light intensity at 3–7 μmol m−2 s−1 (LNI) and 9 h ambient light plus NI with high light intensity at 120 μmol m−2 s−1 (HNI) conditions. The number of leaves, leaf length, number of pseudobulbs and pseudobulb diameter increased in both LNI and HNI compared to controls for both cultivars. While none of the control plants flowered within 2 years, 100% of the ‘Yokihi’ and 80% of the ‘Red Fire’ plants grown under HNI condition flowered. In the LNI group, 60% of the plants flowered in both cultivars. Plants in the HNI group showed a decreased time to visible inflorescence and flowering than those in the LNI group. The number of inflorescences and florets were greater in the plants grown under HNI than those in the LNI group. The tallest plants at flowering were in the HNI group in both cultivars. NI with low light intensity can be used effectively to promote flower induction with increased growth rate during the juvenile stage in Cymbidium. To obtain high quality plants, however, NI with high light intensity strategies should be considered. 相似文献
13.
The floral biology of ‘Koroneiki’, ‘Kalamata’ and ‘Mastoidis’ was studied for three consecutive years to elucidate the potential physiological and genetic controls of inflorescence architecture and phenology and to identify potential genotype-distinguishing characters that could be employed for morphological cultivar discrimination. The first open flowers were mainly observed at position I for ‘Koroneiki’ (83%) while they were mainly located at position II for ‘Mastoidis’ (40%) and ‘Kalamata’ (63%). The last open flowers were principally located at the apical position for ‘Koroneiki’ (46%) and ‘Kalamata’ (68%) and at position II for ‘Mastoidis’ (75%). Most of the first open flowers were perfect for ‘Koroneiki’ (89%) and ‘Mastoidis’ (97%) while lower percentages were observed in the last open flowers (67% and 80%, respectively). Higher percentages of perfect flowers were observed in ‘Mastoidis’ compared to ‘Koroneiki’ in both cases. The average flowering shoots of ‘Kalamata’ produced significantly more flowers (1523/m) compared to ‘Koroneiki’ (1139/m) and ‘Mastoidis’ (1044/m). The half of the flowers in ‘Mastoidis’ were located at position I while the 38% was located at position II and only the 12% at the apex. By contrast, approximately the 80% of flowers in ‘Koroneiki’ and ‘Kalamata’ panicles was equally distributed at positions I and II, while the 18% and 19%, respectively, was located at the apex. A marked relationship was also observed between flower position in the panicle and flower gender. 相似文献
14.
Haifa Kchaou Ajmi Larbi Kamel Gargouri Mohamed Chaieb Fermín Morales Monji Msallem 《Scientia Horticulturae》2010
Changes caused by NaCl-induced salinity on several growth parameters and ions accumulation have been measured in five olive (Olea europaea L.) cultivars (‘Chemlali’, ‘Chetoui’, ‘Koroneiki’, ‘Arbequina I18’, and ‘Arbosana I43’) growing in a greenhouse in nutrient solution pot experiment. One-year-old plants were transplanted to sand–perlite (1:1) culture, and were irrigated with half-strength Hoagland nutrient solution containing NaCl at various levels (0.5, 50, 100 and 200 mM). Salinity induced significant decrease in growth parameters, but to a different extent in each cultivar. Leaf growth and total leaf area per plant were significantly affected by all salinity treatments in all studied cultivars, being ‘Arbequina I18’ the most sensitive cultivar. Leaf drop phenomenon was observed from 60 days after salt application at high salinity treatments, mainly in Arbequina I18. Contrary to leaf area, leaf thickness increased progressively during the experiment. ‘Chemlali’ developed thicker leaves at the two highest salinity treatments when compared to the other cultivars. Na+ and Cl− concentrations were higher in roots than in shoots and leaves in most of the cultivars investigated. The effectiveness of Na+ exclusion mechanism in the roots differed significantly among studied cultivars, working effectively in ‘Chemlali’ (by inhibiting translocation of Na+ to the aerial part) and being much less efficient in ‘Arbequina I18’. Furthermore, leaf abscission can be considered as an additional tolerance mechanism of olive cultivars allowing the elimination of leaves that had accumulated Na+ and Cl− ions. Tolerance to salinity stress was as follows: ‘Chemlali’ > ‘Chetoui’ > ‘Arbosana I43’ > ‘Koroneiki’ > ‘Arbequina I18’. This order of salt tolerance was indicated by lower reduction in plant growth parameters (shoot elongation, trunk diameter, total plant dry weight, internodes length, and total leaf area), the increase of leaf thickness, and by the effectiveness of the exclusion mechanism of Na+ and Cl− in the root system. 相似文献
15.
Shinji Kajihara Junki Itou Noritoshi Katsutani Tanajuro Goto Hideo Shimaji 《Scientia Horticulturae》2009
The arching and high-rack culture systems were developed and patented by Japanese rose growers. Both culture systems have bent canopies (lower bent shoots). In the arching culture system, shoots sprouting from the crown are harvested as cut flowers. However, the high-rack culture system also has a bent canopy originating from the mother stem (upper bent shoots) and flower stems sprout and is harvested at the top of each mother stem. Partitioning of photosynthates originating from bent shoots in arching and high-rack culture systems of rose production was investigated to elucidate how carbohydrates are re-allocated from the bent shoots in different culture systems of roses. At the flowering stage in both culture systems, 50–70% of 13C-photosynthates originated from bent shoots were exported to other parts within 72 h after 13CO2 feeding to the bent shoot. In the arching culture system, photosynthates from lower bent shoots were partitioned mainly to the roots and crown. Similarly, in the high-rack culture system, between 71 and 86% of the exported carbon from the bent shoots were allocated to below the point of bending (roots + crown + mother stems) and only 9–28% was allocated to flowering shoots above the point of bending. In both culture systems, photosynthate translocation from the lower bent shoot directly to flowers was low. Accordingly, bent shoots in rose plants acted as a source of photosynthates, independent of culture system. The height of the bent shoots determined for a great deal in the re-allocation of the photosynthates, and provides a partial explanation for difference in production of cut roses. 相似文献
16.
Bernardo Murillo-Amador Enrique Troyo-Diéguez José Luis García-Hernández Raúl López-Aguilar Narciso Ysac Ávila-Serrano Sergio Zamora-Salgado Edgar Omar Rueda-Puente Cengiz Kaya 《Scientia Horticulturae》2006
Twenty-five genotypes of cowpea (Vigna unguiculata L. Walp.) were tested for salt-tolerance at the vegetative growth stage in pot in the greenhouse experiments at salinity levels of 0, 85, and 170 mM NaCl. Plant survival was the main criterion for classifying genotypes. Other criteria included the ion concentration (Na+ and Cl−) in root and shoot and biomass accumulation. Four local accessions (‘Paceño’, ‘Tardón’, ‘Sonorense’, and ‘Cuarenteño’), three accessions from California (‘CB46’, ‘CB27’, and ‘CB3’), and one accession from the International Institute of Tropical Agriculture (IITA) (‘IT82D-889’) survived at concentrations of both 85 and 170 mM NaCl and were classified as salt-tolerant, while ‘IT96D-666’, ‘IT89KD-288’, and ‘IT93K-734’ from IITA were classified as salt-sensitive. One local accession (‘Sesenteño’), three accessions from IITA (‘PEPH-V Wes-85’, ‘IT86D-719’, and ‘IT95K-1090-12’), and one accession from California (‘CB5’) were classified as moderately salt-tolerant. Eight accessions from IITA (‘IT96D-733’, ‘IT90K-277-2’, ‘IT91K-93-10’, ‘IT91K-118-20’, ‘IT90K-284-2’, ‘IT95K-1088-4’, ‘IT89KD-391’, and ‘IT94K-437-1’) and one from California (‘CB88’) were classified as moderately salt-sensitive. Biomass was affected by both 85 and 170 mM NaCl in all groups of genotypes, however, salt-tolerant and moderately salt-tolerant genotypes showed higher biomass than genotypes classified as moderately salt-sensitive and salt-sensitive. In all genotypes Cl− concentration was higher in shoots than roots and increased as salinity increased. Similarly Na+ concentration increased with increasing salinity. However, in salt-tolerant and moderately salt-tolerant genotypes, Na+ concentration was more in roots than shoots, while in moderately salt-sensitive and salt-sensitive genotypes, Na+ was higher in shoots than roots. 相似文献
17.
The rates of sap flow and xylem vessel features were studied in two-year-old nongrafted and grafted avocado (Persea americana Mill.) trees. Daily sap flow rates were measured with heat and balance stem gauges in clonal Duke 7 (D7) and Toro Canyon (TC) trees and ‘Hass’ clonal scions grafted onto clonal D7 (H/D7) and TC (H/TC) rootstocks. Vessel features as size, number and total vessel area were determined histologically in the stem of the scion and rootstock and the roots of the grafted trees. Significant differences in the sap flow rate were found among the rootstocks, where D7 had a 29% higher sap flow rate than did TC (grafted and nongrafted trees). There were no differences among xylem vessel features in the stems of any of the varieties. However in the roots, D7 had wider and fewer vessels then TC do. Also, D7 had a 19% higher total vessel area than TC. These results suggest that the differences in water consumption of ‘Hass’ on different rootstocks may be associated with differences in the efficiency of the roots to absorb water across conductive tissue which may be linked to differences in the area of xylem vessels in the root. 相似文献
18.
In newly planted orchards, special attention must be paid to fertilization to build up the permanent structure of the trees so that high yield and fruit quality can be reached later on. Nitrogen (N) plays a major role in the fertilization plan, although few studies have assessed its use efficiency in young non-bearing trees, especially in field conditions. In this work, 1–3 years old ‘Rocha’ pear trees, grafted on quince BA29, were planted in a Mediterranean region, and fertigated with 6 g N tree−1 year−1 as ammonium nitrate with 5 at.% 15N enrichment to study the fertilizer N uptake during the vegetative cycle, the overall fertilizer N use efficiency at the end of each year, and the plant–soil N balance for this period. Nitrogen remobilization and the re-cycling of N from senescent leaves were also studied by fertilizing some pear trees with 10 at.% 15N enrichment. 相似文献
19.
Clonal propagation of cherimoya via micropropagation is known to be problematic and its difficulty varies depending on the cultivar used. In order to improve the micropropagation process, the use of successive micrografting was applied to three cherimoya cultivars: ‘Fino de Jete’, ‘Bonita’ and ‘Pazicas’. Grafting nodal tissue onto a rootstock derived from ‘Fino de Jete’ juvenile material improved bud sprouting significantly in all tested cultivars. Rooting of sprouted shoots from non-grafted nodal tissue was extremely poor, however, shoots derived from explants after 1–3 consecutive micrografts displayed enhanced rooting. While ‘Fino de Jete’ and ‘Bonita’ shoots displayed 50% of rooting after two micrografts, Pazicas cultivar shoots required three micrografts to reach this percentage. Rooting was maximum after three micrografts, with 70%, 60% and 50% of rooting for ‘Fino de Jete’, ‘Bonita’ and ‘Pazicas’ shoots, respectively. Rooted plantlets were mycorrhized and acclimatized under greenhouse conditions and displayed a high rate of survival (90–100%) for all cultivars, indicating that the micrografting technique could also have an effect on the acclimation of plants. 相似文献
20.
Floral bud of litchi (Litchi chinensis Sonn.) is a mixed bud that consists of leaf primordia, rudimentary leaves and panicle primordia. According to field observation, the fate of rudimentary leaves depends upon the environment and development of the panicle primordia. Vigorous development of panicle results in abortion of rudimentary leaves. In this study, three types of rudimentary leaves, the upper leaves (UL) which subtended a developing panicle primordium and were bound to abscise after a period of panicle development, the abscising lower leaves (AL) which had an emerging axillary panicle and would abscise under a light external force, and the non-abscising lower leaves (NAL) which subtended a vegetative bud and would develop normally, were sampled from the terminal shoots of cvs. ‘Nuomici’ and ‘Feizixiao’. Ultra-structure of the petiole base in the three types of rudimentary leaves in ‘Nuomici’ was observed. Signs of cell autolysis, e.g., tonoplast disruption and fusion of vacuole and cytoplasm, were found in localized cells in UL, while massive cell death was observed in AL, suggesting that the two types of rudimentary leaves were at different stages of abortion. The UL was at an early stage of abortion, whereas AL at a late stage of abortion. Cell autolysis was not observed in the nonvascular tissues in NAL. In ‘Nuomici’, AL had a significantly lower superoxide dismutase (SOD) activity compared to the UL and the NAL, while the latter two had no significant difference in the enzyme activity. In ‘Feizixiao’, however, no significant difference was found among the three types of rudimentary leaves, although AL had the lowest SOD activity. Peroxidase (POD) activity in AL in both cultivars was significantly higher than that in NAL. The UL had a lower POD activity in ‘Nuomici’, but a higher activity in ‘Feizixiao’ compared to NAL. Ascorbate peroxidase (APX) activity was the highest in NAL, and there was no significant difference between the UL and AL. H2O2 concentration was the highest in AL in the two cultivars. The NAL had higher levels of zeatin plus zeatin riboside (ZRs), auxin (IAA) and gibberellin (GA4+7), and lower levels of abscisic acid (ABA) than AL. Total concentration of IAA, GA4+7 and ZRs (TC) and the ratio of (IAA+GA4+7 + ZRs)/ABA (RTC) in NAL were higher than those in UL and AL in the two cultivars. The RTC in UL was higher than that in AL. The results suggested that abortion of the rudimentary leaves caused by panicle development may involve programmed cell death, reduced antioxidant activity and increased H2O2 and share similar hormonal control (reduced ZRs, IAA and GA4+7 and increased ABA) to the senescence and abscission of mature leaves. 相似文献