Changes in o-Diphenol Oxidase During Fibre Development in Cotton

Quantitative and electrophoretic changes in o-diphenol oxidase(o-diphenol: O₂ oxidoreductase, E.C. 1 10,3.1) were studiedduring the entire period of cotton (Gossypium arboreum L. cv.Sanjay) fibre development. A significant increase in o-diphenoloxidase activity was recorded during the fibre initiation phaseand it is suggested that a shift in redox balance towards oxidationmay play an important role in fibre initiation. Low o-diphenoloxidase activity during elongation and its high activity duringthe phase of secondary thickening, together with isoenzyme patterns,suggest an important role of this enzyme in cotton fibre development.The role of o-diphenol oxidase in relation to auxin turnoverand redox balance is discussed. Gossypium arboreum, cotton, fibre development, o-diphenol oxidase, redox balance, auxin turnover     

A new species of Porina from the Andaman Islands, India

A new species of foliicolous lichens, Porina andamanensis , from the Andaman Islands, India, is described and illustrated.     

Studies on the Physiology of Host-parasite Relationship in Orobanche. II. Growth and Mineral Nutrition of Host and Parasite

The effects of Orobanche infection on the growth and mineral compostition of the host were studied. Parallel observations were made in host and parasite. Orobanche infection reduces the height of main shoot, the length of root, the number of branches, and the number and total area leaves per plant. Consequently the fresh and dry weight of the host is also decreased. Infection affects NAR and LAR only slightly but reduces RGR and RLGR at a later period of infection. The retardation in the growth of host seems to be due mainly to a continuous extraction of metabolites and inorganic nutrients. Infection increases the nitrogen, calcium and magnesium content in the host, especially in the leaves. This fact is connected with the retarded growth in the host. The process of absorption is probably not changed. The phosphorus and potassium contents diminish in the infected host, a fact related to the higher translocation to the parasite. The Orobanche plants grow faster during early stages and accumulate 88 % of total dry matter before flowering, The growth stages of Orobanche do not coincide with those of the host suggesting that the parasite is capable of synthesizing its own growth substances. Studies with ₃₂P show that the flow of minerals is mainly in the direction from host to parasite. The major part of the requirement of the parasite is met by the host. Orobanche maintains a higher phosphorus and potassium content in its tissues than the host, while the nitrogen, calcium and magnesium content is lower.     

THE EFFECT OF PROFLAVINE ON DIFFERENT STRAINS OF THE BLUE-GREEN ALGA ANACYSTIS NIDULANS

The growth of the blue-green alga Anacystis nidulans was inhibitedby relatively low concentrations of proflavine. The durationof the lag phase increased linearly with increasing proflavineconcentrations. The alga neither acquired increased toleranceto the drug during the course of six subcultures in proflavine-supplementedmedia nor was there any shortening of lag-phase or increasein final population density following repeated subculture inproflavine medium. The strain obtained after six subcultures in proflavine wasfound to have become more sensitive to streptomycin than theuntreated stock strain. A comparison of sensitivity to proflavine of two streptomycin-resistantstrains and of untreated stock strain of the alga revealed thatthe streptomycin-resistant strains were less sensitive to proflavinethan the untreated strain. The resistance of a strain resistant to 200 µg streptomycin/mlwas lost after it had been cultured once in streptomycin-freebasal medium that had been supplemented with 1 µg proflavineµml.The results obtained provide some indirect evidence for theexistence of episome in A. nidulans. ¹Present temporary address: Division of Biosciences, NationalResearch Council, Ottawa-2, Canada.     

Transport of Sodium in Intact Peanut Seedling

Peanut (Arachis hypogea L.) seedlings readily transported Nato the shoot. The amount of Na transported was linearly relatedto the absorption period (which ranged from 1 to 8 h) and alsoto the external Na level which varied from 0.05 to 1 mM.     

Changes in Paramagnetic Manganese (Mn(II)) and Related Enzyme Activities in Isolated Cucumber Cotyledons During Growth: I. EFFECT OF GIBBERELLIC ACID

Changes in the activities of IAA oxidase, peroxidase, and ascorbicacid utilization (AAU) and in the level of paramagnetic manganese(Mn(II)) have been studied during GA₃-induced growth of theisolated cucumber cotyledons in light or dark. In dark-growncotyledons, where GA₃ fails to evoke any growth response, aninitial decline in the Mn(II) content during the first 8 h isfollowed by a rise which approaches the control value between12 and 24 h. A marked, almost linear increase is observed inMn(II) levels from 48 h onwards. The initial decline in Mn(II)is accompanied by an increase in IAA oxidase activity and decreasedAAU. The large increases obtained at later times, viz. 48 and72 h, appear to be related primarily to the release of manganesedue to the degradation of protein bodies which proceeds underthe action of GA and also to increased AAU. The IAA oxidaseand peroxidase activities are close to control during this period.In light, however, IAA oxidase and peroxidase activities showmarked increase during the first 4 h but no significant changesare observed in Mn(II) level or AAU. The peak of Mn(II) observedat 8 h corresponds with lower activities of IAA oxidase andperoxidase but an increase in AAU. The changes in Mn(II) closelycorrespond with the changes in AAU in light, peroxidase andIAA oxidase activities keeping close to the control. It appearsthat GA action is related to increased Mn(II) due to increasedAAU which may be coupled to the peroxidase-IAA oxidase system.The study confirms the postulate given by us in an earlier paper.     

Partitioning and Utilization of Carbon and Nitrogen for Dry Matter and Protein Production in Chickpea (Cicer arietinum L.)

The partitioning of N and utilization of C in various processesin chickpea (Cicer arielinum L.) was studied at 10 d intervalsfrom 35 to 135 d after sowing (DAS). Dry matter, C and N contentof the plant increased throughout the study period. The maximumamounts of C and N were fixed during the flowering and earlyfruiting phase (75–115 DAS) and the minimum during theseed filling phase (115–135 DAS). Efficiency of nitrogenfixation in relation to net C utilization and respiratory outputof the whole plant, nodules and nodulated root, varied widely,but was maximum during 75–115 DAS. The crop experiencedsevere respiratory losses, particularly during the vegetativephase, when 83% of the total fixed C was lost in respiration.The crop produced 54·6 g of glucose units, 2·36g of seed dry matter and 495 mg of seed protein. Possible reasonsfor the poor efficiency of chickpea, in terms of photosynthateutilization for dry matter and protein production are discussed. Key words: Cicer arietinum, C, N, economy     

Photosynthesis and Transpiration in Rice as Influenced by Soil Moisture and Air Humidity

The paper describes the effect of soil moisture content andair humidity on CO₂ exchange (P_N), CO₂ diffusion resistance(Cr) and transpiration (E) in four varieties of japonica rice(Oryza sativa L.). A decrease in soil moisture content reducedthe rate of photosynthesis to a varying degree in the varieties.Reduction in photosynthesis was attributed to increase in Cr.The effect of low soil moisture on photosynthesis and CO₂ diffusionwas further intensified by decrease in air humidity. By maintaininga high humidity in the air around the leaves however, the effectof soil moisture deficiency was reduced considerably, exceptin Rikuto Norin 21 which was very sensitive to soil-moisturedeficiency alone. Dryness of the air enhanced the transpirationrate, although the increase was relatively less in the plantsfacing a simultaneous water crisis at the root surface. In plantsgrowing under flooded conditions, a decrease in air humiditycaused a slight depression in P_N despite the simultaneous decreasein Cr. Oryza sativa L., rice, photosynthesis, transpiration, diffusion resistance, soil moisture, air humidity