SENESCENCE IN PARENTAL AND F1 PLANTS OF A SHRUNKEN2 SWEET CORN

Senescence occurs at the cellular acid tissue levels. It is under gene tic and environmental control and factors affecting initiation and spe ed of development of senescence can be passed from parental to F-1 pla nts. This study was conducted in the greenhouse and field to determine how senescence patterns in F-1 plants of a shrunken2 sweet corn (Zea mays L.) hybrid compared to those of parental inbreds. Greenhouse grow n plants were left intact and field grown hybrids and parental inbreds had one or both reproductive organs removed or were left intact. Sene scence patterns in stalk internodes were similar in greenhouse and fie ld grown F-1 and inbred plants. Senescence patterns in shank internode s in greenhouse grown plants were different from those of field grown plants. Senescence ratings in stalks increased as developmental stage advanced. Expression of stalk senescence in internodes below the node bearing ears appears to be suppressed by hybrid vigor. In field tests, destruction of the tassel before expansion (decapitation) appears to suppress senescence in internodes above 17, with this effect somewhat dependent on plant developmental stage.