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

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associati<strong>on</strong> with test weight can be partially accounted for<br />

in a sinilar fashi<strong>on</strong>, but the main explanati<strong>on</strong> c<strong>on</strong>es from<br />

the assoeiati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> kernel weight <strong>and</strong> plumpne ss, since,<br />

plump kernels have an increased width to length ratio,<br />

therefore pack more tightly <strong>and</strong> have a higher weight per<br />

unit volume. Since the plunper kernels in thÍs naterial<br />

were the heavier kernels, the associati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> kernel weight<br />

<strong>and</strong> test vreÍght would be expected.<br />

the correlati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> kernel weight with days in post-<br />

anthesis probably reflects the fact that the weight <str<strong>on</strong>g>of</str<strong>on</strong>g> the<br />

kernels develops during this peri.od. The negatrve rerati<strong>on</strong>-<br />

ship wíth heading date exl_sted. because, the earller a geno_<br />

type fJ.owered in a finite growing seas<strong>on</strong>, the l<strong>on</strong>ger was<br />

it's grain deve lopment time.<br />

Fhe posítLve relatÍ<strong>on</strong>ship between kernel weight <strong>and</strong><br />

lodging was due to the type <str<strong>on</strong>g>of</str<strong>on</strong>g> 1odglng measured <strong>and</strong> the<br />

nature <str<strong>on</strong>g>of</str<strong>on</strong>g> the material studied.<br />

Negatíve associati<strong>on</strong>s existed between kernel weight<br />

<strong>and</strong> alphå-amylase <strong>and</strong> soluble amino-nitrogen Levels, in<br />

particular in C-?0-Ì <strong>and</strong> C-?O-2, suggesting that lines with<br />

heavÍer kernels become heavier via inereased carbohydrate<br />

deposLti<strong>on</strong> ât the expense <str<strong>on</strong>g>of</str<strong>on</strong>g> nitrogenous compounds. llow_<br />

ever, the significant posÍtive assocíatL<strong>on</strong> between kernel<br />

weight <strong>and</strong> percent barley nÍtrogen in C-?O-2 indicated that,<br />

at least in that popul_ati<strong>on</strong>, nitrogen deposití<strong>on</strong> was not<br />

hampered in the heavier kernel lines, sugge sting that the<br />

yleld to nitrogen negatj.ve relati<strong>on</strong>shÍp nnay not be either<br />

792

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