No abstract

After refinement, a fluorometric technique was found adequate for quantitatively determining certain gibberellins in the flowers and young fruits of navel sweet oranges. Using this method, significant changes in gibberellins were shown to occur, both in tissue concentrations and total amounts per fruit, in samples collected during the bloom and early period of fruit growth. Two relationships, a correlation between gibberellin concentration and rate of fruit growth, and an effect of total gibberellins per fruit on cumulative fruit growth, were found. These data indicated a cause and effect relationship between endogenous gibberellins and the early stages of fruit growth of the navel orange.

No abstract

The freezing point of detached leaves of young, budded, container-grown ‘Hamlin’ orange plants was an acceptable measure of cold hardiness. Controlled freezing established that the mean leaf freezing point (MLFP) of detached leaves estimated cold hardiness within 0.86°C and was useful to predict the degree of damage to plants exposed to subfreezing temperatures.

A portable unit for determining leaf freezing points (LFP) of citrus leaves is described. This unit has been used extensively in citrus and is suitable for exotherm analysis of a variety of plant species and tissues.