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Effects of reduced plant height on breeding requirements and ...

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wíth yield. fhis group discussed the irnportance <str<strong>on</strong>g>of</str<strong>on</strong>g> the<br />

influence <str<strong>on</strong>g>of</str<strong>on</strong>g> genotypic selecti<strong>on</strong> in correlati<strong>on</strong> studies,<br />

índicating that the genotypes studied may bias c<strong>on</strong>elati<strong>on</strong><br />

data. fn the barley work referred to, the study <str<strong>on</strong>g>of</str<strong>on</strong>g> Nasr<br />

et al., (1973) involved tal1 x short- strawed crosses, <strong>and</strong><br />

the short genotypes were relatively unimproved <strong>and</strong> unadapted.<br />

K<strong>on</strong>ishi's study (K<strong>on</strong>ishi, l-976) involved several Japanese<br />

short statured types <strong>and</strong> a norrnal strain <str<strong>on</strong>g>of</str<strong>on</strong>g> barley. He<br />

noted that the very short types were inferior while the<br />

"not so shortrr types were not ínferior to the normal.<br />

K<strong>on</strong>ishi stated, *For increasing total producti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> a dwarf<br />

mutant, it ís necessary to have l<strong>on</strong>g stems to some extent,<br />

<strong>and</strong> so irnprove the form for light intercepti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> the <str<strong>on</strong>g>plant</str<strong>on</strong>g>.,n<br />

K<strong>on</strong>ishi noted that similar results had been reported for rice<br />

by Kawai (r9Ø) in that all dwarf rice mutants which had<br />

stems shorter than BJ percent <str<strong>on</strong>g>of</str<strong>on</strong>g> the original variety showed<br />

decreased yield.<br />

"Perhaps the most outst<strong>and</strong>ing character <str<strong>on</strong>g>of</str<strong>on</strong>g> semi-dwarf<br />

wheats is resistance to lodging.rt, ( Bríggle <strong>and</strong> Vogel, 1968).<br />

this posÍtive relati<strong>on</strong> between shorter straw <strong>and</strong> <str<strong>on</strong>g>reduced</str<strong>on</strong>g><br />

lodging in wheat has been supported by many observati<strong>on</strong>s.<br />

This led to a statement by Klatt (I9?3), to the effect that,<br />

pri-or to L962, pAant, <str<strong>on</strong>g>height</str<strong>on</strong>g> <strong>and</strong> straw weakness had limited<br />

the yield potential <str<strong>on</strong>g>of</str<strong>on</strong>g> wheat, which was significantly increased<br />

by the first semi-dwarf varieties.<br />

Ch<strong>and</strong>l-er (1969) stated that in rice, the most important<br />

single morphological feature affecting lodging resistance i.s<br />

11

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