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- Author or Editor: William J. Foster x
`Redwings' and `Gloria' azaleas (Rhododendron × `Redwings' and `Gloria') were treated with foliar sprays of uniconazole, paclobutrazol, or daminozide to suppress bypass shoot development and promote flower initiation and development. Uniconazole at 5 and 25 mg·liter-1 suppressed bypass shoot development of `Redwings' and `Gloria', respectively. Flowering of `Gloria', but not `Redwings', was delayed slightly with uniconazole sprays up to 25 mg·liter-1 ; with the highest uniconazole concentration, 200 mg·liter-1, flowering was delayed as much as 18 days. Flower count of `Gloria' was not affected by lower concentrations of uniconazole, but it was greatly reduced in both cultivars with concentrations above 75 mg·liter-1. Uniconazole was more active than paclobutrazol sprays of similar concentrations or than two daminozide sprays of 3000 mg·liter–1 . Chemical names used: (E)-1-(p-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol (uniconazole); (2RS,3RS)-1-(4-chlorophenyl)-2-(1,1-dimethylethyl)-(1H-1,2,4,-triazol-l-yl-)pentan-3-ol (paclobutrazol); butanedioic acid mono(2,2-dimethylhydrazide (daminozide),
Rooted stem cuttings of Ilex crenata Thunb. `Rotundifolia' were grown in a controlled-environment growth chamber. Root-zone temperatures were controlled with an electric system. Shoot carbon exchange and root respiration rates were determined in response to root-zone temperatures of 28, 32, 36, and 40C for 6 hour·day–1 for 7 days. Photosynthesis was decreased by root zones ≥ 32C, while root respiration increased with increasing root-zone temperature. Decreased photosynthetic rates were not due to increased stomatal resistance.
Early nodulin genes, such as ENOD2, play a role in the first stages of nodulation. Although ENOD2 is conserved among nodulating legumes studied to date, its occurrence and activity have not been studied among woody legumes such as Maackia amurensis Rupr. & Maxim. Our objective was to localize MaENOD2 transcripts during nodule development and describe the anatomy of nodules formed on the roots of M. amurensis in relation to ENOD2 mRNA accumulation. Nodules (<1 mm, 1-2 mm, >2 mm in diameter, and mature) were prepared for light microscopy, sectioned, and stained with safranin and fast green for structural contrast or with the periodic acid Schiff's reaction for starch. The location of ENOD2 transcripts was determined by using in situ hybridization with DIG-labeled sense and antisense RNAs transcribed from a 602-bp fragment of the coding region of MaENOD2. Mature nodules from M. amurensis possessed peripheral tissues, a distal meristem, and a central infected region characteristic of indeterminant development. In situ hybridization showed that MaENOD2 transcripts accumulated in the distribution layer and uninfected cells of the central symbiotic region. Amyloplasts that contained starch grains were identified in these tissues and in the inner parenchyma of the nodule. Throughout nodule development, transcripts were restricted to areas with high levels of stored starch that surrounded cells actively fixing N2. Our results suggest that ENOD2 in M. amurensis may be a cell wall component of tissues that regulate nutrient flow to and from sinks, such as symbiotic regions of a nodule. These data may lead to a better understanding of the role of the ENOD2 gene family during nodulation.
A solid-state, electronic controller was designed and built to maintain de“sired root-zone temperatures in specially designed root heating tubes. The controller uses a thermistor feedback mechanism to an operational amplifier circuit. The tubes were constructed from 7.5-cm-diameter metal pipe, electrical heating tape, a rubber coating, and pipe insulation. Each controller can maintain treatment temperatures in 16 tubes; four tubes at each of four temperatures. Temperatures can be maintained from ambient to 50C with a precision at 35 of ± 0.9C within and between tubes.