Aerial Vegetative Parts Research Articles

The source of gibberellins in the parthenocarpic development of ovaries on topped pea plants

The role and source of gibberellins (GAs) involved in the development of parthenocarpic fruits of Pisum sativum L. has been investigated. Gibberellins applied to the leaf adjacent to an emasculated ovary induced parthenocarpic fruit development on intact plants. The application of gibberellic acid (GA3) had to be done within 1 d of anthesis to be fully effective and the response was concentration-dependent. Gibberellin A1 and GA3 worked equally well and GA20 was less efficient. [(3)H]Gibberellin A1 applied to the leaf accumulated in the ovary and the accumulation was related to the growth response. These experiments show that GA applied to the leaf in high enough concentration is translocated to the ovary. Emasculated ovaries on decapitated pea plants develop without application of growth hormones. When [(3)H] GA1 was applied to the leaf adjacent to the ovary a substantial amount of radioactivity accumulated in the growing shoot of intact plants. In decapitated plants, however, this radioactivity was mainly found in the ovary. There it caused growth proportional to the accumulation of CA1. Application of LAB 150978, an inhibitor of GA biosynthesis, to decapitated plants inhibited parthenocarpic fruit development and this inhibition was counteracted by the application of GA3 (either to the fruit, or the leaf adjacent to the ovary, or through the lower cut end of the stem). All evidence taken together supports the view that parthenocarpic pea fruit development on topped plants depends on the import of gibberellins or their precursors, probably from the vegetative aerial parts of the plant.

A mosquito larvicide in Spilanthes mauritiana

The methanol extract of fresh vegetative aerial parts of Spilanthes mauritiana afforded, after repeated chromatographic separations and mosquito larvicidal bioassays, a potent mosquito larvicide N-isobutyl-2 E,4 E,8 E,10 Z-dodeca-2,4,8,10-tetraenamide.The structure of the compound followed from spectroscopic considerations. It gave 100% mortality against third instar larvae of Aedes aegypti at 10 −5 mg/ml.

Allelopathic effects ofParthenium hysterophorus L

Growth inhibitors are washed down from the aerial vegetative parts ofParthenium hysterophorus L. during rain. These get adsorbed to soil particles thereby rendering the substratum inhibitory. The trichomes covering the vegetative parts contain inhibitors. The trichomes which get easily detached from dry parts when happen to settle on leaf surface of other plants in high quantity, reduce the chlorophyll and dry matter content in those species.

The absorption and translocation of zinc-65 inPisum sativum in relation to fruit development

The specificity of zinc accumulation by the first pod ofPisum sativum, variety Alaska, from the leaf in whose axil this pod is borne has been demonstrated. The secondpod receives a relatively insignificant amount of this transported zinc. The distribution pattern is somewhat similar to that previously found for phosphorus but differs in that zinc is translocated from the first bloom-node leaf 2 days prior to anthesis. At this stage no phosphorus is being translocated from this leaf. The preferential accumulation of zinc by the first pod reaches a maximum about 5 days after full bloom and the magnitude of this accumulation, relative to the aerial vegetative parts of the plant, remains essentially constant as the pod approaches maturity. The zinc accumulated by the ovules increases gradually beginning at about the 5th day after full bloom and is accompanied by a decrease in zinc retained by the carpel.