Volume 90, Issue 1
February 1981, pages 1-89
pp 1-7 February 1981
The development of the zygote following sexual union inZeuxine longilabris exhibits a predetermined polarity and patternized sequence of developmental stages leading to the initiation of cotyledonary and epicotylary activity in adjacent sectors, both being terminal on the embryonal axis. The cotyledonary growth is incipient and the epicotylary sector is distinguishable only by histological distinctivity. The initiation and trend of growth of the asexual embryo totally deviates from that of its sexual counterpart. Although incipient and inconsistent polarity becomes established in the dividing nodular cell system eventually the embryos end up as a spindle-shaped structure of homogeneous cells where not even the initiation of root and shoot polar differentiation is seen either within or without. Under these circumstances the asexual embryos are broadly comparable to the earlier stages in the development of embryoids in free cell cultures.
pp 9-29 February 1981
The foliar sclereids in 134 species ofBoronia have been studied on the basis of revealed morphological data. The vein-endings display three types, namely conventional tracheids, terminal tracheoids and terminal sclereids. Terminal trecheoids and terminal sclereids are classified into distinct types. They are of considerable morphogenic interest.
pp 31-43 February 1981
The present work has revealed that 32 out of 38 taxa ofIsopogon possess variously shaped sclereids of diffuse pattern. Some species have grotesquely mis-shapen sclereids with thick wall and blunt arms. They are designated as gnarlyform sclereids. Further, the taxonomic problems alluded to by Bentham are discussed in relation to the types of foliar sclereids.
pp 45-51 February 1981
Peronosclerospora sorghi, produced a maximum of 10,800 conidia/cm2 of diseased sorghum leaves at 100% relative humidity but only about 3600 conidia at 85% relative humidity underin vitro conditions. The sporulation was totally inhibited at 80% relative humidity and below. Infected sorghum leaves kept in darkness after completion of the previous crop of the spores, did not sporulate in continuous darkness even at the optimum relative humidity and temperature. Optimum temperature for sporulation is 21–23° C, 31° C and 30° C are minimum and maximum respectively. At 26° C and above, conidiophores were malformed and produced only a few conidia. For conidial germination, 21–25° C were optimum while at 13° C conidial germination was as low as 52%. At 32° C, 80% germination was recorded but 35° C and above no germination occurred. After inoculation with conidial suspension, a minimum of 3 hr moisture was essential to induce systemic infection.
pp 53-58 February 1981
Vein-endings, free vein-endings, isolated vein-endings and isolated tracheids are discussed and distinguished. Vein-endings whether simple or branched may or may not terminate in terminal tracheids. The nature of vein-endings is uniseriate inSolanum species while multiseriate inCestrum species. Tracheids at the vein-tips increase cell diameter and are variable in size, shape and orientation. Tracheids at junction of free arms of the veins are observed inWithania somnifera Isolated vein-endings, isolated free vein-endings and isolated tracheids are noticed inCestrum diurnum, C. nocturnum andSolanum surattense.
pp 59-69 February 1981
Cytomorphology ofSolanum melongena L. var. Nurki Baigan,S. incanum L. and theirF1 hybrids was studied. The fertility of the hybrids was as high as 48·60. A study of meiosis of the hybrids revealed a close genetic relationship between the two species. The plants ofF3 progeny were tested againstPhomopsis vexans andLeucinodes orbonalis. Two plants of high yield with resistance to both the organisms were selected. TheF4 progeny of each selection was morphologically homogeneous and resistant, under field conditions, toP. vexans andL. orbonalis. The fruits matured to edible stage about 16 days earlier than the fruits of ‘Nurki Baigan’.
pp 71-78 February 1981
Protein content declined in the endosperm while an increase was noticed in root and shoot of young seedlings ofS. vulgare andZ. mays. Seedlings of both plants in light had a larger pool of α-alanine, leucine-phenylalanine, glutamic acid, aspartic acid, valine, asparagine, serine-glycine and γ-aminobutyric acid than other amino acids. Tyrosine, proline, threonine and tryptophan which were recorded in light could not be detected in dark. Asparagine and glutamine increased with the seedling growth in most of the samples studied. Phosphoenolpyruvate and pyruvic acid constituted the bulk of keto acid pool while succinate, malate and citrate of organic acid pool. Protein content and citric acid level were found higher in light than in dark grown seedlings of both plants. The higher level of PEP and pyruvic acid in young shoots in light and their sharp decline at advanced stages may be due to a shift from C3 to C4 metabolism.
pp 79-84 February 1981
The mature stony endocarp ofRauvolfia serpentina L. Benth. ex Kurz consists different types of monomorphic sclereids; brachysclereids, macrosclereids, fusiform sclereids and filiform sclereids. They vary from each other in cell wall thickness, shape and size. They develop from parenchymatous cells undergoing a series of changes in their shape nearly at the post fertilization till the maturity of the fruit.
pp 85-89 February 1981
The tricytic stoma is studied on the basis of published literature and illustrations. It is found that it may be formed in a variety of ways. These are classified and reviewed.