The date palm (Phoenix dactylifera L.) is a long‐lived, dioecious, arborescent monocotyledon which must be propagated vegetatively by offshoots to maintain clones. An extensive breeding program begun in 1948 at Indio, California, to obtain superior lines has resulted in the production of several seedling populations of known parents. These were used to study the genetic control of isozymes of alcohol dehydrogenase, esterase, glutamate oxaloacetate transaminase, phosphoglucose isomerase and phosphoglucose mutase from leaf tissue. The five enzyme systems are specified by seven polymorphic genes with 14 alleles. Additional polymorphism was found in two other species of Phoenix. Twenty‐six female and 20 male date palm cvs. were genotyped to provide, insofar as is known, the first single‐gene markers for the date palm and perhaps for any arborescent monocotyledon.

No abstract

Inflorescence primordia in the date palm (Phoenix dactylifera L.) differentiate within axillary buds in November in the Coachella Valley, California. The rachillae are initiated as small mounds without subtending bracts on the flattened apex of the rachis and are enclosed by the prophyll. A single bract subtends each flower primordium. Flower primordia are initiated in an acropetal sequence along the rachillae. Although mature flowers are functionally unisexual, early development is similar in staminate and pistillate flowers. Six perianth parts are initiated within two alternating whorls: the sepals and the petals. Six stamens are initiated in two alternating whorls of three stamens each, the first opposite the sepals and the second opposite the petals. Lastly, three separate carpels are initiated. Pistillate and staminate flowers are identical and apparently bisexual at this stage. The two flower types diverge developmentally when the stamens become bilobed and elongate in the staminate but not the pistillate flowers. The pistillodes in the staminate flowers form rudimentary stigmatic surfaces at the tip of the carpels and meristematic lumps corresponding to the position of the ovule in normal carpels. The staminodes mature in the pistillate flowers as small triangular projections. Meiosis occurred in staminate and pistillate flowers (in March 1979) when the staminate flowers were about 5 mm long and the pistillate flowers were about 3 mm long.

Nutrient medium can be sterilized using a household-type microwave oven. The required microwave treatment time was influenced by the oven's microwave power intensity (70 to 700 W), vessel type, volume of medium employed, and the presence of energy sink water reservoirs (ESWR). Growth rates of strawberry (Fragaria vesca L.) shootlets, lemon [Citrus limon (L.) Burm. f.] fruit halves, or carrot (Daucus carota L.) callus cultured on either microwaved or autoclaved media were similar. Microwaving and autoclaving appeared to reduce GA3 activity compared with medium containing filter sterilized GA3. Chemical name used: gibberellic acid (GA3).

The total number of vesicles within the fruits of several species of the Aurantioideae (Rutaceae) was determined. Two distinct vesicle shape types are recognized: superior and inferior. There was a significant correlation with the number of juice vesicles per fruit and the number of segments found within the fruit. Citrus species (e.g., grapefruit and pummelo) containing fruit composed of many segments (e.g., 10-14 and 20, respectively) correspondingly contained more vesicles per segment than those citrus species (e.g., kumquat and mandarin) containing fruit with few segments (4 and 7-10, respectively). Significant correlations were found between vesicle number and segment area or segment weight. Large segments weighed more and contained more vesicles than small segments. Seed number per fruit or per segment did not have significant correlation with the number of vesicles produced per fruit or per segment. A formula, based upon a partial fruit analysis, to estimate the total number of vesicles in a fruit within 5% of the actual number is presented. The number of vesicles produced in fruit was found to be influenced by environment. Fruit from trees of 'Eureka' lemon and 'Improved' Meyer lemons grown inside a temperature controlled greenhouse contained more vesicles than fruit from trees grown outdoors.