Calcium and phytochrome control of leaf unrolling in dark-grown barley seedlings

The red light-stimulated component of unrolling in sections from 7-d-old dark-grown barley (Hordeum vulgare L.) leaves is inhibited by ethyleneglycol-bis-(-aminoethyl ether)-N,N,N,N-tetracetic acid (EGTA). A free-Ca²⁺ activity of less than 40 M restores the ability to respond to red light, but only if supplied within 1 h of red light. Magnesium ions are an ineffective substitute. At least two processes in unrolling appear to be Ca²⁺-sensitive.Fluence-response measurements indicate that the levels of the far-red-absorbing from of phytochrome (Pfr) still present 4 h after red-light treatment should be above saturation for the unrolling response; consequently, loss of Pfr does not explain the loss in effectiveness of Ca²⁺ during prolonged EGTA treatment. However, if a further red-light treatment is given simultaneously with Ca²⁺ addition 4 h after the initial light stimulus, then full unrolling occurs in EGTA-treated sections. These data indicate that, under normal circumstances, a functional change in the properties of Pfr must occur, uncoupling it from the transduction chain.Abbreviations EGTA ethyleneglycol-bis-(-aminoethylether)-N,N,N,N,-tetracetic acid - FR far-red light - Mes 2-(N-morpholino)ethanesulphonic, acid - Pfr far-red absorbing form of phytochrome - Pr red-absorbing form of phytochrome - R red light     

Leaf ultrastructure of C4 species possessing different Kranz anatomical types in the cyperaceae

The leaf ultrastructure of NADP-malic enzyme type C₄ species possessing different anatomical features in the Cyperaceae was examined: types were the Rhynchosporoid type, a normal Kranz type in which mesophyll cells are adjacent to Kranz cells, and Fimbristyloid and Chlorocyperoid types, unusual Kranz types in which nonchlorophyllous mestome sheath intervenes between the two types of green cells. They show structural characteristics basically similar to the NADP-malic enzyme group of C₄ grasses, that is, centrifugally located chloroplasts with reduced grana and no increase of mitochondrial frequency in the Kranz cells. However, the Kranz cell chloroplasts of the Fimbristyloid and Chlorocyperoid types exhibit convoluted thylakoid systems and a trend of extensive development of peripheral reticulum, although those of the Rhynchosporoid type do not possess such particular membrane systems. The suberized lamella, probably a barrier for CO₂ diffusion, is present in the Kranz cell walls of the Rhynchosporoid type and in the mestome sheath cell walls of the other two types, and tightly surrounds the Kranz cells (sheaths) that are the sites of the decarboxylation of C₄ acids. These ultrastructural features are discussed in relation to C₄ photosynthetic function.     

Morphology and ontogeny of stem xylem elements inSarcandra glabra (Thunb.) Nakai (Chloranthaceae): Additional evidence for the occurrence of vessels

Very recentlySarcandra, which had long been known as the only vesselless genus in Chloranthaceae, was found by Carlquist to have vessels in root secondary xylem. The present study further shows on the basis of observations of the xylem ontogeny that vessels occur in stem metaxylem ofSarcandra glabra as well, thus offering additional evidence for the occurrence of vessels in the genus, virtually in all Chloranthaceae. Metaxylem elements of the stem are thicker than the other tracheary elements in general and have scalariform pittings at the end wall, and their ontogeny indicates that, as the surrounding cytoplasm disintegrates, pit membranes at the end wall disappear at least in some elements, resulting in a perforated end wall, i.e., vessel perforation. The present study further shows thatChloranthus spicatus, which is closely related toSarcandra, may have an incomplete perforation plate because of retaining membranes at places on the plate. An evolutionary state of the “vesselless” condition in Chloranthaceae is discussed.     

The ecology of a beech forest on Mt. Sanpoiwadake,Hakusan National Park,Japan II. The correlation of the subassociation within the Lindero membranaceae-fagetum crenatae association and environmental parameters

Detailed examination of a sample plot covered by the Lindero membranaceae-Fagetum crenatae association on Mt. Sanpoiwadake, Hakusan National Park, revealed a number of correlations between the distribution of subassociations and environmental factors. The subassociations on the south-facing slopes receive deep snow cover in winter with rapid melting in the spring. They occur on porous, freely draining soils, typical of the general range of brown forest soils. Conversely, on the north-eastern slopes there are widespread late-snow patches which delay leaf development and expansion and which provide an abundant water supply well into early summer. Under these conditions, bleached soil horizons have developed with iron pan formation, resulting in poor soil drainage, strongly correlated with quite different plant communities.     

Bias in leaf area — sapwood area ratios and its impact on growth analysis in Pinus contorta

Summary Two alternative estimators of individual tree leaf area (A₁) area are used to derive estimates of leaf-area index (L) for 40 plots in Pinus contorta Dougl. stands. One estimator of A₁ is based on the common assumption of a constant ratio between A₁ and sapwood cross-sectional area at breast height (A_s). The second estimator of A₁ accounts for tree-to-tree variation in the relation between A₁ and A_s. The apparent relationship between stand growth and leaf-area index is strongly dependent on the way leaf area is estimated. When L is derived from a constant A₁A_s ratio, stand growth appears to be strongly correlated with L. However, when L is based on estmates of A₁ that account for tree-to-tree variation in the A₁ — A_s relation, stand growth is seen to be only weakly related to L. Stand structure, quantified as percent live-crown, accounts for a great deal of the observed variation in leaf-area efficiency. These contrasting relationships illustrate the importance of unbiased estimates of L in interpreting the link between stand-level processes and leaf area.Utah Aggriculural Experiment Station Journal Paper No. 3333     

Studies on the morphology and anatomy of the Antarctic nudibranch genera Pseudotritonia Thiele, 1912 and Telarma Odhner, 1934 with a discussion of the family Gharcotiidae Odhner, 1926 (Nudibranchia: Opisthobranchia)

The external morphology and anatomy of the Antarctic nudibranchs Pseudotritonia quadrangularis Thiele, 1912, P. gracilidens Odhner, 1944 and Telarma antarctica Odhner, 1934 are redescribed. Both genera, which were only known by two or one specimen, do not possess a cnidosac, but there is a terminal swelling at the termination of the digestive glandular ramifications in P. gracilidens. This sac is composed of cells with a large vacuole. A glandular stripe on the right side of the body above the genital openings, nephroproct and anal papilla is considered to be a synapomorphy for both genera. The validity of the family Charcotiidae and the affinities to the aeolid genus Notaeolidia Eliot, 1905 and taxa of the Arminacea are discussed.     

Genetics of leaf blight resistance in wheat

Summary Studies on the genetics of leaf blight caused byAlternaria triticina using generation mean analysis revealed that additive components played a major role, but that dominance components also contributed significantly in controlling the variability for leaf blight resistance in wheat crosses. Furthermore, the additive x additive type of epistasis was predominant in the first three crosses, whereas in the fourth cross additive x dominance (j) and dominance x dominance (1) components of epistasis were most significant. Because of this it may be desirable to follow a simple recurrent selection scheme for higher tolerance, to isolate resistant plants from the segregating populations derived from crosses of parents of diverse origin following the pedigree method of breeding. CPAN-1887 was very tolerant to leaf blight in the present study and should be utilized in hybridization programs to develop leaf-blight-resistant varieties.     

黄淮海平原高产田作物群体结构特征

本文利用实测资料分析了高产田作物群体结构特征。精播高产栽培麦田春季最大蘖数12×10~6/ha,群体最大叶面积指数5.5—6.0,成穗4.5—5.25×10~6/ha。传统高产栽培麦田春季最大蘖数15—18×10~6/ha,群体最大叶面积指数6.0—6.5,成穗6.0—7.5×10~6/ha。小麦营养生长与生殖生长期叶日积比,精播高产栽培麦田是1∶0.89,传统高产栽培麦田为1∶0.73。夏玉米种植密度主要受叶倾角的影响。紧凑型玉米品种的叶倾角大于65°,种植密度7.5—8.25×10~4/ha;平展型玉米品种的叶倾角小于50°,种植密度5.25—6.0×10~4/ha。     

The morphology,taxonomy and evolution ofRhodocoma (Restionaceae)

The vegetative and reproductive morphology, culm and rhizome anatomy and seed surface micromorphology ofRhodocoma are described. It is shown that this variation is best contained by recognizing three new species in the genus. These new taxa are described, and the phylogeny of the genus is investigated by cladistic analysis. The environmental parameters and distributions of the species are related to the cladogram. This suggests that the species are at present ecologically separated, and indicates that the speciation may have been sympatric. This is the first support for the hypothesis that sympatric speciation may have been important in the speciose Cape flora.