Shoot

About: Shoot is a research topic. Over the lifetime, 32188 publications have been published within this topic receiving 693348 citations.

Variation in the shoot calcium content of angiosperms

Abstract: This study describes the variation in the mean relative shoot Ca content within the angiosperms at the ordinal level. Data were derived from studies in the literature in which the shoot Ca content of two or more species had been compared, and from a hydroponic experiment in which plants were selected to represent the relative number of species within each angiosperm order. Across all angiosperms, most of the variation in shoot Ca content occurred at and above the level of the order. Relative shoot Ca contents and variances correlated between literature and experimental data. In general, orders of commelinoid monocots had lower Ca contents than other monocot or eudicot orders. These results are used to illustrate how physiological and ecological hypotheses can be formulated using literature data.

Allelopathic potential of rice hulls on germination and seedling growth of barnyardgrass

Abstract: Hull extracts from 91 cultivated rice cultivars (Oryza saliva L.) were used to determine their allelopathic potential on seed germination and seedling growth of barnyardgrass (Echinochloa crusgalli P. Beauv. var. oryzicola Ohwi). The allelopathic effects of various concentrations of hot and warm water hull extracts from selected cultivars were also investigated. In the initial screening the SR31' extract inhibited germination 59%. The length and dry weight of roots were more affected by hull extract than the shoots. The greatest total seedling length and dry weight inhibition was from the Janganbyeo' warm extracts and was 75 and 96%, respectively. Rice cultivars demonstrating significant allelopathic potential were compared using varying concentrations with a hot or warm extraction procedure. The two extraction procedures displayed different ultra violet (UV) absorption, pH, electrical conductivity (EC), and osmotic potential. Warm extracts exhibited a lower percentage absorbance in the UV range, higher percentage absorbance in the visible range, higher EC (S m 1 ) and osmotic potential (kPa), and showed lower pH than those of hot extracts. As concentration increased, the warm extracts had a greater inhibitory effect on barnyardgrass germination, seedling growth, weight, and caloric content than the hot extracts. The greatest inhibition occurred when the highest concentration (8 g L 1 ) warm water extract was applied. These results suggest that rice hull extracts may be a source of natural herbicide, and warm water may extract more allelochemicals than hot water. There may be genetic differences among rice cultivars for allelopathic potential on barnyardgrass. The breeding of rice cultivars with greater allelopathic potential may be possible.

In vitro propagation of the medicinal herbs Ocimum americanum L. syn. O. canum Sims. (hoary basil) and Ocimum sanctum L. (holy basil).

Abstract: A procedure is outlined for in vitro propagation of two medicinal herbs, Ocimum americanum L. syn. O. canum Sims (hoary basil) and Ocimum sanctum L. (holy basil), using axillary shoot buds. Multiple shoot formation was induced from shoot bud explants of both species on Murashige and Skoog medium (MS) supplemented with benzyladenine (BA). The optimum BA concentrations for shoot proliferation were 0.25 mg/l for O. americanum and 1.0 mg/l for O. sanctum. Incorporation of 0.5 mg/l gibberellic acid (GA3) along with BA in the culture medium resulted in a marked increase in the frequency of axillary branching as well as multiple shoot formation. Shoot buds collected between September through December were most responsive in culture. Shoots of O. americanum were rooted on half-strength MS supplemented with 1.0 mg/l indole-3-butyric acid (IBA), whereas O. sanctum rooted best on medium with 1.0 mg/l naphthaleneacetic acid (NAA). The plantlets were hardened off and successfully established in natural soil, where they grew and matured normally.

Germination, seedling growth and relative water content of shoot in different seed sizes of triticale under osmotic stress of water and NaCl

Abstract: Effect of seed size (small, medium and large) on germination and seedling growth of triticale (xTriticosecale Witm. cv. Presto) at the different osmotic potential of NaCl and PEG solutions were determined in the present study. Germination tests were conducted under five osmotic potential levels (-0.45, -0.77, -1.03, -1.44 MPa, and Control) of PEG 6000 and NaCl. Germination percentage (%) at 4 and 8 th days and also seedling growth traits such as root and shoot length (mm), dry root and shoot weight (mg), root : shoot length (R:S) ratio, and relative water content of shoot (RWC, %) were investigated in this study. The results indicated that decreases in the osmotic potentials caused a reduction in germination percentage and seedling growth. It was seen that drought created by PEG 6000 had more negative effects on germination and seedling growth than that of NaCl. In consequence, the total germinability and seedling growth were higher in large seeds rather than in small seeds in control solution and under osmotic stress. In addition, it was observed that seedlings obtained from larger seeds survived even at the lower osmotic potential of PEG and NaCl; whereas, seedling obtained from small seeds did not survive in the intensive stress.