Studies on the Utilizatoin of Polyploidy in Tea Plant (Part 2)
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概要
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Cross-pollinations were reciprocally carried on between diploid and tetraploid tea plants, and self-pollinations of the tetraploid were also tried (1956-1958). Since 1954, open-pollinated progenies of the tetraploid and triploids have been raised. The chromosome numbers of these progenies were determined, and several characteristics of them were investigated.<BR>In the cross, 4x (??)×2x ( ?? ), 35% of pollinated flowers set normal fruits. The seedlings from this cross and from natural crossing of the tetraploid were all triploids. The reciprocal cross, however, gave only a few fruits with abortive seeds. The all trials of selfing of the tetraploid were unsuccessful. From the results written above, it may be suggested that tetraploid is cross-incompatible in cross 2x(??)×4x( ?? ), and show self-sterility as diploid. Seed fertility of the tetraploid was slightly lower than that of the diploids.<BR>The distribution of chromosome numbers among the seedlings of triploid's progenies was examined. In these seedlings, euploids (2x 3x especially a number of 4x) and heteroploids were found, and the latter having very extensive variation of chromosome numbers (2n=31-63). And it was considered that these tetraploids and hyper-tetraploids were originated from unreduced n=45 gamates of the definite triploid varieties( U21, U24).<BR>These obtained polyploids nearly resembled to the pre-examined polyploids in external morphological characteristics. In general, the growth of the heteroploids was very poor, so plant height, stem diameter and leaf size were apparently inferior to those of the euploids, but in spite of such poor growth stomata length, and thickness of leaf were proportionally correlated with the chromosome numbers.
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