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

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Physiogenic or Nonpathogenic <strong>Seed</strong> Disorders 253than 150 samples <strong>of</strong> pea seed from England, Hungary, the Netherlands, New Zealand,and the United States. and reported that hollow heart is a common disorder <strong>of</strong>wrinkle-seeded peas. Singh (1974), who tested seeds from Argentina, Czechoslovakia,Denmark, India, Lesotho, the Netherlands, New Zealand, Romania, Scotland,Turkey, and the United States, also concluded that the wrinkle-seeded cultivars havea moderate to heavy incidence <strong>of</strong> hollow heart whereas the smooth-seeded cultivarsshow either no or a very low incidence. Perry and Howell (1965) also observed thatcultivar Alaska, a round-seeded pea, consistently had the least hollow heart.Jain and Singh (1985) examined 304 chickpea seed samples belonging to 297cultivars (254 cultivars desigram and 43 cultivars kabuligram) from India for hollowheart. A total <strong>of</strong> 156 cultivars (61%) <strong>of</strong> desigram and 37 cultivars (86%) <strong>of</strong> kabuligramshowed hollow heart incidence <strong>of</strong> 0.5 to 20% and 0.5 to 62%, respectively.The cavities on the adaxial surface <strong>of</strong> cotyledons were usually identical and rarelydissimilar or on one cotyledon only.Hollow heart in pea may be due to too quick drying <strong>of</strong> immature seed. Perryand Harrison (1973) experimentally showed that predisposition to hollow heart maybe caused by high ambient temperature during maturation <strong>of</strong> seeds on plants, andby drying them when immature. Hollow heart increased with increasing temperaturefrom 35 to 45°C and decreased as seed maturity advanced.Hollow heart has also been reported in Vicia faba and Phaseolus vulgaris (Perryand Howell, 1965) and Tropaeolum majus (Heit and Crosier, 1961).9.2.1.1.1 Hollow Heart and Shape and Size <strong>of</strong> <strong>Seed</strong>sGane and Biddle (1973) observed the relationship between shape <strong>of</strong> seed and incidence<strong>of</strong> hollow heart in seed samples <strong>of</strong> cultivars Lincoln and Kelvedon Wonder.In the former, triangular seeds showed a higher incidence <strong>of</strong> hollow heart, whereasthis occurred in only two <strong>of</strong> the five samples <strong>of</strong> Kelvedon Wonder. Singh (1974)examined samples <strong>of</strong> four cultivars having seeds with three distinct shapes, namely,(1) squarish seeds with depression on two faces; (2) conical seeds with basal depression;and (3) irregular seeds. Squarish seeds formed the bulk in the samples. Nopositive correlation in the incidence <strong>of</strong> hollow heart and seed shape squarish, conicaland irregular was found.<strong>Seed</strong> samples <strong>of</strong> cultivar 4.12.01 7d Turkey had 44% large and heavy and 56%small and light seeds. The hollow heart incidence in small seeds was slightly higher(52%) than in the large seeds (42%) (Singh, 1974).9.2.1.1.2 HistologyThe histology <strong>of</strong> affected cotyledons has been examined in pea (Perry and Howell,1965; Singh, 1974) and chickpea (Jain, 1984). Anatomically, asymptomatic cotyledonsin wrinkle-seeded pea varieties consist <strong>of</strong> parenchyma cells as described undermarsh spot (Figure 9.3B). But the starch grains are compound (Figure 9.3B, C) andthe protoplasmic contents are evenly distributed in the cell.In symptomatic cotyledons, the anatomical symptoms are prominent in the cells<strong>of</strong> mesophyll on the adaxial face, i.e., in the region <strong>of</strong> cavitation. The cells are loosewith large air spaces. The protoplasmic contents are poor and aggregated in thecenter as if plasmolyzed (Figure 9.3D, E). However, the cells on the abaxial face

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