Respiration of petal discs from rose (Rosa hybrida L.) was measured by standard manometric techniques gave evidence for the presence of cyanide-resistant respiration. During early stages of rose petal expansion oxygen uptake by petal discs was only slightly inhibited by ImM KCN. In conjunction with 10−1mM salicyl hydroxamic Acid (SHAM), an inhibitor specific for the alternate cyanide-resistant pathway, 1mM KCN greatly reduced oxygen uptake in these petal discs. SHAM alone had no effect on petal disc respiration.
‘Cara Mia’ rose (Rosa hybrida L.) leaf net photosynthesis rates were measured at four leaf temperatures over a range of irradiance levels. With the four leaf ages measured, a non-rectangular hyperbola with physiologically meaningful parameters was found to adequately represent the photosynthetically active radiation (PAR) responses. Maximal net photosynthetic rates exhibited a convex pattern with temperature with an optimum between 30 and 37C. The PAR compensation and saturation points both increased with temperature.
Difficulty is frequently experienced in displaying associations of quantitative characters such as flower weight and vaselife with qualitative characters such as flower shape, petal attitude, color, and leaf damage in cut roses (Rosa hybrida L.) A scatter diagram technique which accommodates 2 quantitative and up to 12 qualitative characters applied to experiments on rose cultivars and floral preservatives revealed qualitative associations with increased vaselife and flower fresh weight in response to the use of various preservative solutions.
The node position from which axillary buds were isolated from shoots of rose (Rosa hybrida L.) markedly affected their growth and development in culture. Those buds nearest to and furthest from the apex either failed to develop or took the longest time to develop in culture compared to those buds in the middle portion of the stem. Benzylamino purine (BA) at low concentrations (0.03 to 0.3 mg/liter) stimulated the development of the axillary buds of ‘Gold Glow’ but not of ‘Improved Blaze’. A photon flux density (400-700 nm) of 17μE m−2 s−1 for 12 to 24 hours daily was optimum for the stimulation of shoot multiplication, while 66 μE mm−2s−1 for 12 to 24 hr was optimum for root initiation and for subsequent successful transplantation to soil of tissue culture-derived plants. A constant temperature of 21°C resulted in the highest rate of shoot multiplication and root initiation. Plants which initiated roots at 16, 21, or 26° had the highest level of transplant survival. An alteration in the temperature of the 8-hr dark period from 21° did not increase shoot multiplication, although root initiation was enhanced by lowering the night temperature to 11 or 16°. Histological analysis indicated that shoot multiplication of rose shoots occurs through the growth and development of axillary buds. The development of axillary buds is apparently under the repressive influence of the shoot apex, because physical excision of the apex or application to the shoot apex of 2,3,5-triiodobenzoic acid (TIBA) facilitated axillary bud development. Root initiation was affected markedly by the length of time that cultures had been maintained on shoot multiplication medium prior to transfer to rooting medium. This effect may be attributable to the BA in the shoot multiplication medium which may have accumulated in the tissue. If the endogenous cytokinin level is too high, root initiation may be inhibited and if it is too low the shoot undergoes senescence before it becomes cytokinin-autonomous, which occurs after root initiation.
Nutrient solutions containing concentrations of 200, 300, 400, and 500 ppm N were applied to Rosa hybrida cv. Caliente grown under either 18 hours of high pressure sodium light of 110µEm-2s-1 quantum flux density or ambient light. Supplemental light increased yield and decreased foliar N and time to flower compared with ambient light. The lowest N level (200 ppm) produced the highest yield under ambient light, but 300 ppm N was optimum under supplemental light High N concentrations reduced stem grade under ambient light. Stem length, stem diameter, fresh weight, keeping quality, days to flower, and foliar nitrogen were not significantly affected by nitrogen treatment.
Cut flowers of rose (Rosa hybrida L. cv. Samantha) exhibited a longer vase life when opened in solutions containing cobaltous ion (Co2+). The extended vase life in response to Co2+ was related to 1) an increased water uptake into the cut flower, 2) an improved water balance during opening, 3) a delay in loss of fresh weight, and 4) a prevention of the occurrence of bent-neck. A concentration of 1.5 mm Co2+ gave maximum beneficial effects without injury to the cut flower, while a 2.0 mm concentration induced some toxic symptoms on leaves.
6-(benzylamino)-9-(2-tetrahydropyran-yl)-9H-purine (PBA) in lanolin paste was applied to the greenhouse rose, Rosa hybrida L. cv. Red American Beauty, pruned in either a cutback or layback manner, and gibberellic acid (GA3) sprays were applied after bud-break. PBA application generally increased bud-break on both layback and cutback-pruned plants. Gibberellic acid (GA3) sprays did not improve growth of PBA-induced shoots. Layback-pruned plants developed a greater number of renewal canes (those reproductive stems that produced shoots of equal or greater basal stem diam after the first and second pinch) than cutback-pruned plants after growth regulator treatments.
The pentose phosphate shunt (PPS) was shown to be active in roses (Rosa hybrida L.). The C6/C1 ratio indicated that possibly as much as 50% of the glucose oxidized in the rose flower is through the PPS. However, the activity of the PPS in relation to the Embden-Meyerhof-Parnas pathyway-tricarboxylic acid cycle (EMP-TCA) pathway did not change significantly throughout the cut life of the rose. There was a drop in the respiratory rate of petals throughout the cut flower life. The inner petals exhibited a consistantly higher respiratory rate than did outer petals regardless of whether the flower was kept in water or preservative.
‘Forever Yours’ roses (Rosa hybrida L.) grown in 20-liter containers filled with gravel or soil, were irrigated with solutions of varying salinity and composition over a 2-year period. Results indicated that HCO3− ion was highly toxic to rose production, resulting in chlorosis whenever concentrations exceeded 2 meq liter−1. Sodium and Cl− gave increasing problems above 4 meq liter−1. Sulfate was innocuous except as the ion contributed to total salinity of the solution. Yield was significantly reduced when electrical conductivity exceeded 1800 μmhos cm−1, and at 1300 μmhos cm−1 if ion proportions were adjusted. Treatments in soil were highly variable, with effects slower to appear.
14C-sucrose, when taken up into the xylem, moved rapidly into leaves and flower heads of cut roses (Rosa hybrida L.) Outward lateral movement of 14C occurred rapidly along the entire length of stem at a uniform rate, regardless of l4C-sucrose concentration within the xylem and associated tissues. The quantity of 14C inverted sugars found in xylem tissue after uptake of 14C sucrose, and the rapid hydrolysis of sucrose passing through xylem of isolated stem segments suggests the involvement of invertase located in the xylem.