Comparative Morphology of the Grape Berry in Three Cultivars

Abstract

1. The comparative morphology of berry growth of three cultivars, Campbell Earlyearly maturing variety, Muscat Bailey A-midseason maturing variety, and Koshu-late maturing variety, from prebloom to maturity was studied.
2. The duration of period II, a period of delayed increase in berry growth, was shorter in Campbell Early than in Muscat Bailey A or Koshu, although the duration of period I, a period of rapid increase, was nearly in all three cultivars. The duration of period III, a second period of rapid increase in berry enlargement was longer in Koshu than in Campbell Early and Muscat Bailey A.
3. The increase of the inner wall tissue in the pericarp was more rapid than that of the other tissues, especially during the latter half of period I, and consequently the inner wall tissue occupied about 50 percent of the total area in cross section measured at maturity in all three cultivars. The increase in thickness of the outer wall tissue in Koshu was rapid during period III, and was related to berry enlargement in final swell.
4. Inner wall tissue was composed of cells of nearly uniform size and shape, which enlarged similarly during the growth of the berry. The increased rate of cell volume from full bloom to maturity was greatest in Koshu, and was less in Muscat Bailey A and Campbell Early in due order. The cell size in the inner wall measured at maturity. however, was largest in Muscat Bailey A and was smaller in Koshu and Campbell Early. The parenchymatous cell in the inner portion of the outer wall increased only in the radial direction during period II and III, and the cell size in the central portion of the outer wall measured at maturity was larger in Koshu, especially in radial diameter, than that of the two other varieties.
5. The time of the last cell division in both placenta and inner wall was 11 days after bloom for Campbell Early, 7 days after bloom for both Muscat Bailey A and Koshu. The cell number in the inner wall at the time of the last cell division in Campbell Early was approximately twice that in Muscat Bailey A and Koshu. Cell division in the outer wall ceased first in the radial direction 12 days after bloom for Campbell Early, 8 days after bloom for both Muscat Bailey A and Koshu, afterwards cell division continued only in a tangential direction during the latter half of the cell division period. Cell division in a single row of the mid-circumference of the outer wall continued for 19 to 22 days after bloom in the three cultivars. Cell division in the outer wall ceased earlier than in the inner layers of tissue reaching the outer layers in due order. The time of termination of cell division in the peripheral layer of the berry, hypodermis and epidermis was 32 days after bloom for Campbell Early, 35 days for Muscat Bailey A and 38 days for Koshu. The cell number in these tissues, however, was not markedly different among three cultivars.