An Automatic Aeroponics Growth System for Bamboo Seedling and Root Observation

According to the biological characteristics of bamboo seedling, an automatic aeroponics growth system is developed for bamboo seedling and root observation, which can prepare good condition of water-fertilizer, air and warm during bamboo seedling. The ultrasonic atomizer is used to atomize the nutrient solution to the ultrafine particles of 1-5 microns diameter. Compared with traditional piezometrical atomization, this method can not only improve atomization efficiency of nutrient solution to promote uniform absorption at the roots, but also avoid the phenomenon of root-washing. In addition, considering the significant effect of temperature and humidity on bamboo root growth, a temperature-humidity control system is designed for automatic control of water-fertilizer and temperature in bamboo root growth environment. The system supplies an experimental platform with features of simple structure and convenient control. In the procedure of bamboo seedling, bamboo rhizome and shoot can grow fast because of enough moisture nutrition, good breathing, and low growth resistance. Furthermore, it is also convenient for morphologic observation of bamboo roots.

Patterns of Root Production and Mortality during Transplant Establishment of Landscape-sized Sugar Maple

Root system regeneration after transplanting of large trees is key to successful establishment, yet the influences of different production systems and transplant timing on root growth remain poorly understood. Patterns of new root production and mortality were therefore measured for 1 year after transplanting landscape-sized Acer saccharum Marsh. (sugar maple). Trees were transplanted into root observation chambers (rhizotrons) from two production systems, balled-and-burlapped (B&B) and pot-in-pot (PIP), in November, December, March, April, and July and compared with non-transplanted trees. Although root production stopped in midwinter in all transplants and non-transplanted field-grown trees, slight wintertime root production was observed in non-transplanted PIP trees. Root mortality occurred year-round in all treatments with highest mortality in winter in the transplanted trees and spring and summer in the non-transplanted trees. Non-transplanted PIP trees had significantly greater standing root length, annual production, and mortality than non-transplanted field and transplanted PIP trees. For B&B trees, greatest standing length, production, and mortality occurred in the April transplant treatment. Production and mortality were roughly equal for non-transplanted trees, but production dominated early dynamics of transplanted trees. Overall, increases in root length occurred in all treatments, but the magnitude and timing of root activity were influenced by both production system and timing of transplant.

Patterns of Root Growth in Grape and Apple in Relation to Shoot Phenology

Growers plan most of their horticultural activities around certain shoot phenological stages, such as bloom, veraison, and harvest. Timing of root growth in relation to these stages of the shoot is of interest in fertilization scheduling and in understanding carbon allocation demands of the root system. With the recent use of minirhizotron root observation tubes, a much greater understanding of patterns of root growth has been made possible. In Fredonia, N.Y., 5 years of root investigation in `Concord' grape indicate considerable variability in timing of root flushes. Root flushes could occur any time between bloom and veraison, but were generally not observed after harvest. Wine grapes in the Napa Valley exhibited similar patterns. In apple, root flushes may occur at bloom, but often not after harvest. Consequently, we rarely observed the bimodal distribution of root flushes commonly depicted in textbooks for apple and grape. Our data suggest that general perceptions of the timing of root growth may be in error.

Transplant Timing Affects First-season Root Growth of Turkish Hazelnut (Corylus colurna L.)

Rapid posttransplant root growth is often a determining component of successful establishment. This study tested the effect of transplant timing on first-season root growth dynamics of bare-root Turkish hazelnut trees. Trees were either harvested and planted in the fall (F-F), harvested in the fall and planted in the spring after holding in refrigerated storage (F-S), or harvested and planted in the spring (S-S). All trees were transplanted into 51-L containers, adapted with root observation windows. Root growth began in F-F and F-S trees 1-2 weeks before spring budbreak, but was delayed in S-S trees until ≈3 weeks after budbreak. Budbreak was 6 days earlier for fall-harvested than for spring-harvested trees. No new roots were observed before spring. Root length accumulation against observation windows (RL) was delayed for S-S trees, but rate of increase was similar to F-F and F-S trees soon after growth began. Seasonal height, trunk diameter growth, and RL were similar among treatments. Surface area of two-dimensional pictures of entire rootballs was not correlated with seasonal RL.

Effects of Preemergence Applied Herbicides on Pampas Grass

Pampas grass seedlings in 72-cell pack containers were transplanted into containers with a root observation window (17.8 × 10.2 cm) and treated with selected preemergence applied herbicides. Root numbers were counted in the upper and lower 8.9 cm of the viewing window until 16 days after treatment (DAT) when the windows became full of roots. Root growth in both the upper and lower window was suppressed with application of Factor 65 WG and Pendulum 60 WDG at the X and 2X rates at 16 DAT. Ronstar 2G and Pendulum 2G at the recommended rates and nontreated control plants had similar root numbers at 16 DAT. At 16 DAT, the greatest number of club roots formed on plants treated with the dinitroaniline herbicides; Pendulum 2G, Pendulum 60 WDG, and Factor 65 WG. Shoot growth was not affected by treatment.

Réaction géotropique des différents types de racines chez l'hévéa (Hevea brasiliensis)

To describe the different types of geotropic reactions of hevea (Hevea brasiliensis), young seedlings were cultivated in root observation boxes and submitted to a double gravistimulation (90° rotation of the minirhizotrons in the vertical plane). It was demonstrated that the taproot is a strongly orthogeotropie organ since it resumed rapidly its prestimulation vertical position. Morphological and morphogenetic modifications were associated with the geotropic response: reduced speed of growth coupled with a reduction of the apical diameter as well as an alteration of ramification density in the curving zone and the following one. Early secondary roots showed a somewhat reduced orthogeotropism that was weaker as the growth direction before gravistimulation was more distant from the vertical. Secondary roots of the acropetal sequence were semiplagiotropic, that is only those roots oriented upward after the gravistimulation resumed, more or less, the original direction. Tertiary roots didn't respond to the gravistimulation and therefore were ageotropic. Complementary observations conducted in large laboratory rhizotrons showed that late forming secondary roots were plagiotropic in their younger stages, thereafter loosing most of their sensitivity to gravity. Quaternary roots were ageotropic. On the basis of these data, a geotropic gradient was defined within the hevea root system, where the strongly responding taproot and late secondary roots are opposed to the weakly or nonresponding tertiary and quaternary roots. Functional significations of these differential geotropic reactions in different hevea root types are discussed. Keywords: geotropism, gravistimulation, root system, growth, development, morphogenesis, root observation box, Hevea brasiliensis. [Journal translation]

Root and Stem Growth Patterns of Young `Mauritius' Lychee Trees

`Mauritius' lychee (Litchi chinensis Sonn.) trees were planted in root observation chambers in July 1990 to determine the pattern of root and stem extension growth during 12 months. Root and stem lengths were measured at intervals ranging from 7 to 18 days from Aug. 1990 until Aug. 1991. During each period of active canopy growth, up to six stem tips were tagged and measured. Root growth was determined by measuring tracings of the extension of each root in a visible plane of the glass wall of the observation chambers. Stem growth was cyclic, with distinct periods of rapid extension followed by periods with no extension. In contrast, root growth was fairly continuous with only three periods of no visible root extension. Mean absolute extension rates were higher for stems than for roots. There were no consistent relationships between the timing of root and stem extension growth.

Root and Stem Extension of Young Papaya Plants

`Red Lady' and `Tainung #1' papaya plants were grown in nursery trays with cells 5.1 cm in diameter. After 10 weeks, mean height of the `Red Lady' plants was 10.1 cm and that of the `Tainung #1' plants was 9.3 cm. Each of five plants per cultivar was planted between two root observation windows, one at 45 cm and the other at 95 cm. Roots reached the 45-cm observation window in 30 days, when mean height of the `Red Lady' plants was 18.7 cm and that of the `Tainung #1' plants was 13.0 cm. Roots reached the 95-cm observation window in 55 days, when mean height of the `Red Lady' plants was 55.4 cm and that of the `Tainung #1' plants was 40.6 cm. Thus, root extension during these initial 55 days was 17 to 18 mm per day for both cultivars, and stem extension during this period was 8.7 mm·d–1 for `Red Lady' and 5.5 mm per day for `Tainung #1'. Root extension declined for both cultivars to ≈12 mm·d–1 by the initial bloom period, then further declined to ≈4 mm·d–1 during and after the initial fruit set stage. Stem extension increased to about 19 mm·d–1 after the plants were established and remained at this rate until well into the stage of heavy fruit set and growth, when it declined to about 8 mm·d–1. The amount of fruit set influenced root characteristics more than cultivar.