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Open access

John W. White

Abstract

‘Enchantment’, ‘Prosperity’, ‘Harmony’, and ‘Hornback's Gold’ were the hybrid garden-type lilies most adaptable for pot plant use. With 6 or 8 weeks of post-plant-storage, a growth retardant was not required to obtain a final plant height between 30 and 50 cm. With 10 or 13 weeks of post-plant-storage at 0°C, ancymidol [N,N,N-2 tetramethyl-5-(1-methyl-ethyl)-4-[(1-piperidinylcarbonyl)oxy]-benzenamonium chloride] as a 0.5 mg a.i. (.0264% active ingredient) drench applied at shoot emergence or as a 100-ppm spray applied when shoots were 7.5 cm long, effectively reduced height and improved appearance.

The final plant heights of ‘Rainbow Hybrid’, ‘Sutter's Gold’ and ‘Pastel Hybrid’ were maintained between 30 and 50 cm with a 0.5 mg ancymidol drench. However, these cultivars were not as promising for pot plants because of narrow and short leaves and necrosis of lower foliage which detracted from their general appearance. The concentration of ancymidol used did not reduce sufficiently the final plant height of ‘Challenger’. Cost of the bulbs may be a factor when considering the use of cultivars such as ‘Challenger’ and ‘Pepper’ for use as pot plants.

Open access

John W. White

Abstract

Cycocel applied as a 5000 ppm soil drench 31 days after sowing reduced height 8 to 10 cm and caused 8 to 16 days earlier flowering of F1 geranium ‘Carefree Scarlet’ when compared with plants which had not been treated with Cycocel. Manually irrigated plants were shorter, flowered earlier, and were more compact, as measured by fresh weight, than automatically irrigated plants for this Cycocel treatment. Pinched plants were short and well branched but so much delayed in flowering that this method of height reduction would not be acceptable for commercial use.

Open access

John W. White

Abstract

Root loss, interveinal chlorosis, wilting, and reduced growth were typical symptoms of carnations grown in a soil mixture steamed at 100°C and to which a high ratio of NH4 + to NO3 --N in the fertilizer was applied. These symptoms were less apparent and growth was greater in 100°C-treated soil with high NO3 -N and in 71°- or 60°C-treated soil with high NH4 +-N. No symptoms were apparent on plants grown in soil steamed at 71° and 60°C and treated with high NO3 - fertilizer.

Decreases in growth and visual symptoms were associated with high soil concn of soluble and exchangeable Mn or with high concn of NH4 + and NO2 -- N. The primary cause of post steaming injury is believed to be due to excesses of NH4 + and NO2 - rather than Mn. However, Mn appeared to be involved directly in the accumulation of NH4 + and NO2 - in the soil.

Free access

Mary Ann Rose and John W. White

`Celebrate 2' Poinsettias were grown for 8 weeks in a controlled-environment growth room until first signs of bract coloration. In growth stage I (GSI; weeks 1 through 4) low, medium, and high N rates (25, 75, and 125 mg N/liter, respectively) were applied by subirrigation (no leaching). Following floral induction [growth stage II (GSII), weeks 5 to 8], there were nine treatments: all possible combinations of the three N rates in GSI plus three rates (75, 125, and 175 mg N/liter) in GSII. Although >80% of shoot dry weight and >90% of total leaf area developed during growth GSII, reaching an acceptable plant size by week 8 depended on receiving adequate fertilization in growth GSI. In contrast, leaf chlorosis, noted in plants receiving the lowest rate in GSI, was rapidly reversed by increasing the N rate in GSII. Quadratic regression equations fitted to shoot dry weight and leaf area data predicted that using 125 mg N/liter in both growth stages gave maximum responses at week 8. However, using 75 mg N/liter in GSI and 125 mg N/liter in GSII also produced acceptable growth in poinsettias. Our results suggest that some growth restriction imposed by N availability during the first 4 weeks of growth may be acceptable and perhaps desirable to reduce growth regulator use and the environmental impact of overfertilization.

Free access

Mark A. Rose and John W. White

Temperature affects all major plant physiological processes. Traditional methods of controlling greenhouse temperatures use aerial sensors that do not monitor temperatures within each component of the soil-plant-atmosphere continuum.

Bench, pot, plant canopy, and aerial temperatures were monitored using thermocouples and thermistors processed by environmental computers during a wide range of greenhouse conditions. These include diurnal cycles of high and low solar radiation, night periods with and without artificial lighting, and various ventilation and heating conditions. Spatial temperature gradients of 10-22 °C were discovered during both day and night conditions. These spatial variations cause significant differences in average temperatures between and within benches over diurnal and even seasonal cycles.

Preliminary surveys of microclimatic variations that occur within the greenhouse experimental area are essential for choosing the proper experimental design. Continuous environmental monitoring during the experiment is necessary for interpreting experimental results.

Open access

Edmund Jay Holcomb and John W. White

Abstract

The effectiveness of applying a growth retardant gradually in the irrigation water over an extended portion of the crop cycle was investigated. Cycocel can be applied effectively in this manner and control of plant height is comparable to that produced by a single drench application.

Open access

Bruce Bugbee and John W. White

Abstract

The effect of root-zone temperature on young tomato plants (Ly copersicon esculentum Mill. cv. Heinz 1350) was evaluated in controlled environments using a recirculating solution culture system. Growth rates were measured at root-zone temperatures of 15°, 20°, 25°, and 30°C in a near optimum foliar environment. Optimum growth occurred at 25° to 30° during the first 4 weeks of growth and 20° to 25° during the 5th and 6th weeks. Growth was severely restricted at 15°. Four concentrations of gibberellic acid (GA3) and kinetin were added to the nutrient solution in a separate trial; root-zone temperature was maintained at 15° and 25°. Addition of 15 μm GA3 to solutions increased specific leaf area, total leaf area, and dry weight production of plants in both temperature treatments. GA3-induced growth stimulation was greater at 15° than at 25°. GA3 may promote growth by increasing leaf area, enhancing photosynthesis per unit leaf area, or both. Kinetin was not useful in promoting growth at either temperature.

Open access

William R. Faber and John W. White

Abstract

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.

Open access

John W. White and Edward M. Vasilcik

Abstract

A simple to use, accurate, inexpensive, recording evaporation gauge for lysimetric studies with plants in small containers is described. Water losses as large as 264g/day, and as small as lg/hr, were recorded in seedling geraniums grown in a peat-lite medium in 10-cm plastic pots from Jan. 31 to May 23, 1970.

Open access

John W. White and Mark D. Shaw

Abstract

An instrument that actuates an irrigation system in response to a weight loss from a pot-soil-plant system, is described. The instrument utilizes the principle that the pot-soil-plant system can act as an integrator of all factors influencing water uptake and loss. The instrument is essentially a scale which continuously weighs the pot-soil-plant system placed upon it. Provisions are included in the design to compensate for gains in weight as the plant grows.