Histopathology of Seed-Borne Infections - Applied Research Center ...

70 Histopathology of Seed-Borne InfectionsEndosperm: Scanty, remnants around embryo and at the micropylar and chalazalends, cell layers distinct only at ends.Perisperm: Massive, main tissue having reserve food material, enclosed in theconcavity of embryo, cells thin-walled, rich in starch grains.3.4.11 CHENOPODIACEAE (FIGURE 3.12A TO G)(Artschwager, 1927; Bhargava, 1936; Taneja, 1981)External: Seed small to medium, circular-lenticular to reniform, notched, rarelyovoid and beaked (Saeuda) or flat and narrowly obovate (Kochia), brown to black,shining. Di- and polymorphism of seeds known in Atriplex spp. Achenes withattached perianth (seed ball) form planting unit in Beta and Spinacia.Internal: Seed coats two, exotestal, seed epidermis radially or horizontallyelongated, usually thick-walled with stalactites, cells with uniformly thickened outertangential and radial walls (Spinacia) or full of pigmented material (Beta). Stalactitesabsent in both of them. Mesophyll one or two layers, thin-walled, compressed;innercoat membranous formed by inner epidermis, cells narrow tangentiallystretched, full of pigmented contents, cell walls with bands of thickenings. In Kochiaand Salsola the seed coat is membranous and uniseriate.Embryo: Peripheral, curved-horse-shoe shaped, annular or coiled, large, cotyledonstwo, hypocotyledonary root axis usually longer than the cotyledons.Endosperm: Scanty, remnants of one or two layers at micropylar and chalazalends.Perisperm: Massive, enclosed in the concavity of embryo; cells thin-walled,full of starch grains, main storage tissue. Perisperm absent in seeds of Saeuda andSalsola.3.4.12 POACEAE (GRAMINAE) (FIGURE 3.13A TO I)(Kiesselbach and Walker, 1952; Narayanswami, 1953, 1955a,b; Sanders, 1955; Bradburyet al. 1956a,b; Chandra, 1963, 1976)One-seeded indehiscent fruit, caryopsis usually with pericarp and testa fused,form the commercial grain or seed for planting. There is considerable variability inexomorphic and internal features of the caryopsis. This account mainly concernscultivated cereals and millets.External: Caryopsis naked (Triticum, Zea, Sorghum, and Pennisetum) or coveredwith lemma and palea, which are chaffy (Hordeum and Avena) or hard horny (Oryzaand Paspalum); pericarp papery, hyaline, white, easily separating and seed coat welldeveloped, tough (Eleusine); elongated-ovate, elliptic, fusiform, rounded or squarish;smooth, faintly or prominently longitudinally striate, rough, pubescent or spinescents,rarely median groove on ventral surface (Triticum); pale white, yellow, variousshades of red, brown, purplish, grey or black; basal lateral embryo area distinctiveand easily identified in naked types (Zea, Triticum, Sorghum, and Pennisetum);caryopsis scar basal, opposite embryo on ventral side, inconspicuous or conspicuous,rarely floret stalk (rachilla) attached at the base (Hordeum, Avena, and Oryza); innaked grains at the apical end a blunt pointed outgrowth marks the remains of style