The Influence Of Priming Two Cucumber Cultivar Seeds

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J. Duhok Univ. Vol.13, No.1, (Agri. And Vet. Sciences) Pp 94-102, 2010 irrigation during all physiological stages (Abdel, 1993). The superiority of Aqualduce and Local Syrian cultivars under water scarcity could be attributed to their genetic which reflected the highly performed breeding techniques that had been implicated during screening of the produced seeds by their producing companies. Taka357 is a determinate cultivar of a small vegetative growth possesses little number of leaves composed of broad leaflets; however, high leaf area was inadequate to brought about high leaf area index to compensate with these of indeterminate cultivars. Land coverageratio of determinate cultivars are lower that of indeterminate cultivars which make them more vulnerable to both high irradiance and evapotranspiration adversity and of low competition abilities. Subsequently these Newblack fly and Tiger cultivars were not recommended under drought (Abdel, 1982). Water stressed Aquadulce plants sprayed by 2x10 -3 M ABA manifested the highest plant height (80.5 cm), node number on main stem (19.33). When this cultivar was sprayed by 2x10 - 49 6 M ABA, it exhibited the highest leaflet number per plant (264.67) and plant fresh weight (137.33 g). In addition to that untreated Aquadulce showed the highest plant dry weight (19.87 g). The highest internodes length (5.55 cm) and individual leaf area (20.96 cm) were confined to Taka 357 sprayed by 2x10 -6 M ABA. While the highest number of branches per plant (6.33) was observed in untreated Taka 357 (table, 1). The obtained results suggested that cultivar responses were more overwhelmed by their genome rather than by ABA. There are three reasons that reinforce this phenomenon; the first is that ABA imparted temporary elastic (not plastic) changes in stomata sizes, since ABA was sprayed immediately after re-watering. The second reason is that ABA application and drought acquired the stomata degree of adaptation which enabled them to cope with further high leaf content of ABA (Davies, 1978). The third reason could be referred to hormonal balance during juvenility, in which active ABA undergoes a conversion into inactive ABA for instance dihydrophaseic acid (Srivastava, 2002). Table (1): The effects of varying abscisic acid (ABA) rates on some growth traits of five water stressed fababean cultivars* ** Parameters P h (cm) B no N no L no L a (cm -2 ) L in In l Pdw Pfw Aquadulce 71.15a 4.44ab 18.22a 240.56a 13.82b 4.46a 3.95b 15.47a 126.78a Syrian 64.75a 4b 18.11a 212ab 13.61b 3.88ab 3.59bc 13.22ab 125.11a Taka357 41.14c 5.44a 7.55b 108.66c 19.04a 2.77b 5.5a 9.14c 119.22a Twowaytha 65.6a 3.55b 17.11a 180.56b 12.12b 2.8b 3.82bc 11.44bc 110.11ab Babylon 55.71b 3.44b 17.11a 179b 12.79b 3.07b 3.25c 8.81c 91.22b 0.0 ABA 54.35a 4.46a 14.66a 187.33a 13.01a 3.11a 3.6a 13.08a 116.73a 2x10 -6 M ABA 58.76a 4.26a 15.53a 190.67a 15.04a 3.59a 3.98a 11.59a 122.87a 2x10 -3 M ABA 65.91a 3.8a 16.66a 174.47a 14.78a 3.48a 4.13a 10.17a 103.87a Aqudulce Syrian Taka 357 Twowaytha Babylon 0.0 M 61.8 bd 4.33ac 17.33a 232.67ab 14.49ad 4.48ac 3.74bc 19.87a 132.67a 2x10 -6 M 71.16ac 5ab 18a 264.67a 12.02cd 4.26ac 3.95bc 14.42ab 137.33a 2x10 -3 M 80.5a 4bc 19.33a 224.33ad 14.95ad 4.65ab 4.16b 12.11b 110.33ab 0.0 M 66.2ac 3.66bc 17.33a 193.33be 13.05bd 3.33ac 3.82bc 15.17ab 127.33a 2x10 -6 M 61.86bd 4bc 18.33a 213.33ad 12.12cd 3.52ac 3.38bc 11.86b 126a 2x10 -3 M 66.2ac 4.33ac 18.66a 229.33ac 15.66ac 4.82a 3.56bc 12.62b 122ab 0.0 M 37.5f 6.33a 7b 117.33fg 19.25ab 3.07ac 5.5a 9.79b 119.67ab 2x10 -6 M 39.8f 5ab 7.33b 9.33g 20.96a 2.75ac 5.46a 9.23b 120ab 2x10 -3 M 46.13ef 5ab 8.33b 109.33fg 16.92ac 2.48bc 5.55a 8.42b 118ab 0.0 M 59.13be 4.66ac 15.33a 225.33ad 8.27d 2.46bc 3.87bc 11.84b 108.33ab 2x10 -6 M 63.46bc 3.33bc 17.33a 169.67bf 15.35ac 3.41ac 3.62bc 12.67b 121.67ab 2x10 -3 M 74.2ab 2.66 18.66a 146.67fg 12.73bd 2.52bc 3.97bc 9.82b 100.33ab 0.0 M 47.13df 3.33bc 16.33a 168cf 10cd 2.23c 2.89c 8.73b 95.67ab 2x10 -6 M 57.5ce 4bc 16.66a 206.33ae 14.76ad 4.02ac 3.47bc 9.79b 109.33ab 2x10 -3 M 62.5bc 3.3bc 18.33a 162.67df 13.62bd 2.95ac 3.39bc 7.9b 68.67b ** Ph = plant height; B no = branches number per plant: N no = node number on main stem: L no = leaflet number per plant: L a = leaflet area: L in = leaf area index: In l = internodes length: Pdw = plant dry weight (g.plant -1 ): Pfw = plant fresh weight (g.plant -1 ). * Figures of unshared characters are significant (Duncan, 0.05)
J. Duhok Univ. Vol.13, No.1, (Agri. And Vet. Sciences) Pp 94-102, 2010 Syrian cultivar manifested superiority over Aquadulce, Taka357 and Babylon in the number of normal epidermal cells of leaf upper surface by 8, 23.9 and 13%, respectively, and likewise over Taka357 and Babylon in the leaf lower surface, respectively, by 23.5 and 15.1% (table, 3). The highest aperture width for upper and lower leaf surfaces were accompanied with Taka357 which highly exceeded other cultivars. This cultivar was exceeded Aquadulce and Syrian aperture width of upper leaf surface stoma by 10.6 and 10.8%, respectively, and in stoma: epidermis cells ratio by 18.2 and 25%, respectively, (table, 2). Local Syrian cultivar initially possesses higher epideral cells and stomata numbers per unit area as compared to other cultivars, especially Taka357. Drought highly increases the stomata population for unit area but not for entire leaf. This paradox emerges from the huge effects of drought on cell expansions rather than cell divisions in which new stomata are created, since almost cell divisions are determined during leaf differentiation. There are numerous examples of plasticity in stomata densities within species, with changes readily induced through exposure of developing leaves to changed atmospheric CO2 concentrations (Woodward et al., 2002 and Hetherington and Woodward, 2003). The highest stomata width on leaf upper surface (7.2 μm), stomata aperture (2.7 μm) on leaf lower surface and stoma aperture on leaf upper surface (2.39 μm) were observed in Taka357 sprayed by 2x10 -3 M ABA. Untreated aquadulce revealed the highest magnitude of leaf upper surface stoma length (11.39 μm). The highest number of epidermal cells (6185.5) and stomata length (8.1 μm) on leaf lower surface were coincided by Aquadulce sprayed with 2x10 -3 M ABA (tables, 2 and 3). Twowaytha plants sprayed with 2x10 -6 M ABA displayed the highest stoma number on upper and lower leaf surfaces 1467.7 and 2201.6 stoma.mm -2 , respectively. Finally untreated check of Babylon was superior over other treatments in the ratio of stoma: epidermis on upper and lower leaf surfaces 0.45, 0.5, respectively, and likewise in number of leaf upper surface stoma 1467.7 stomata.mm -2 . Drought resistant plant possesses lower stomata population and larger aperture area to facilitate CO2 exchange that sustains reasonable photosynthesis under drought adversity (Abdel, 1982). Franks et. al. (2001) reported that as a pressure was increased from as low as 0.3 MPa to as high as 5.0 MPa, guard cell volume increased in a saturating fashion. The elastic modulus was calculated from these data and was found to range from approximately 2 to 40 MPa. The data allow inference of guard cell osmotic content from stomatal aperture and facilitate accurate mechanistic modeling of epidermal water relations and stomatal functioning. ABA modifies the stomata dimensions, particularly aperture to acquire plant more efficient CO2 exchanges and thereby photosynthesis. However, it reveals temporary reduction. Terashima et. al. (1988) found that after the ABA treatment, the response of photosynthetic CO2 assimilation rate, A, to calculated intercellular partial pressure of CO2, Pi, and [A (pi) relationship was markedly depressed in H. annuus. A less marked depression was also observed in V. faba. However, when the abaxial epidermis was removed from these leaves, neither the maximum rate nor the CO2 response of photosynthetic oxygen evolution was affected by the application of ABA. 49
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The Influence Of Priming Two Cucumber Cultivar Seeds

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