Almond Seedlings Research Articles

The Effect of Alar on Permeability, a Possible Explanation for its Mode of Translocation1,3

Abstract Autoradiographs of girdled and non-girdled almond seedlings treated with 14C-Alar revealed that the growth retardant moved readily from the phloem to the xylem. Autoradiographs of comparable seedlings treated with 14C-sucrose, with and without Alar pretreatment, showed that Alar induced greater leakage of radioactive material from the symplast to the apoplast indicating that the material lowered membrane integrity. This effect of Alar on cytoplasmic permeability was examined by immersing dormant stems, leaf discs, and beet root tissue in solutions of Alar and water. In all tissues, the compound induced greater leakage of cellular contents than water, which is attributed to the ability of Alar to depress utilization of respiratory energy necessary for the retention of solutes in the vacuole.

The nature and development of noninfectious bud failure of almonds

The almond-tree disorder known as almond bud failure occurs to a moderate extent in the Nonpareil and Peerless varieties, but is widespread in the Jordanolo variety chiefly in the Sacramento Valley. Other varieties thought to be affected are the Texas and the Jubilee, although this has not yet been verified. The primary symptom of the disorder is the failure of buds to grow. Secondary symptoms include excessive shoot production, delay in blossoming, and bark necrosis. Tests of Nonpareil, Peerless, and Jordanolo buds and scions have failed to show that the disorder is infectious. Bud failure, however, developed in the growth from a high percentage of buds and scions from affected trees. It is concluded, therefore, that the disorder is bud-perpetuated. Bud-failure symptoms develop in scions growing on different rootstocks, including peach, bitter almond seedlings, and the Texas almond seedling. There is some evidence that vegetative propagation tends to increase the manifestation of symptoms in the Jordanolo variety. Severe pruning of affected trees also apparently tends to increase the severity of symptom expression. Almond bud failure is transmitted through the seed. Fourteen per cent of one lot of seedlings produced from seeds of affected Nonpareil almond trees exhibited loss of buds and bark necrosis within 2 to 4 years after planting.