影響碳水化合物自玉米穗軸轉移至子粒因素之研究-1﹒果穗上位與下位子粒之充實特性

Abstract

本試驗以單雜交玉米臺農351號及臺農育365號為材料，兩者具相同母本及不同父本，且後者子粒充實性優於前者；於1986及1987年秋作進行田間試驗，在吐絲後連續針對果穗上位（自穗基算起之80─90％長度）及下位（20─30％）子粒取樣，以Richards函數法計算子粒充實性狀表現，目的在確定基因型間子粒充實度的差異，供為進一步探討影響碳水化合物自玉米穗軸轉移至子粒因素研究之基礎。試驗結果證實臺農育365號上、下位子粒之水分含量及乾物重於子粒發育初期開始即較臺農351號為高；上位子粒最高充實速率並無基因型間差異，但臺農育365號子粒到達最高充實速率之時間及有效充實期之發生均較早，持續期間較長，亦即在充實前期即具有差異，為導致粒重較高的原因，下位子粒也有相同表現。本文為系列報告之第一篇，將利用相同材料繼續由供源能力及子粒各部位之醣代謝作用探討影響玉米子粒充實之生理及生化因子。 Corn hybrids Tainung 351 (TNG 351) and Tainung Yu 365 (TNGY 365) were used as experimental material. The two hybrids have the same maternal inbred but different paternal inbred. The latter hybrid was superior to the former in kernel-filling characters. Field experiments were conducted in the fall crop season of 1986 and 1987 to study the pattern of dry matter accumulation for kernels positioned at the apical and basal portions of the ear. Results from this experiment will be served as the basis of further study on the factors affecting the translocation of carbohydrates from cob to kernels in corn. Experimental results indicated that differences in water content and dry weight in either apical or basal kernels existed at early kernel development between TNG 351 and TNGY 365. Although there was no significant difference in maximum kernel filling rate between apical kernels of the two genotypes by the calculation of Richards function, the occurrence of maximum filling rate and effective kernel filling were ealier for TNGY 365 than for TNG 351. Longer kernel filling duration was proposed as the major factor in causing genotypic difference in final apical kernel dry weight. Similar results were observed in basal kernels. This is the first report of a series of papers dealing with the source-sink relationship and physiological and biochemical factors related to kernel filling in corn.