SUMMARYTwo techniques for collection of water-soluble substances, particularly carbohydrates, from the leaf surfaces (phylloplane) of maize {Zea mays L.) were compared in order to explain the oviposition preference ofthe European corn borer.By dipping the leaves in water, smaller amounts of substances were obtained than by spraying water. The total amounts of three sugars (glucose, fructose and sucrose) collected from maize phylloplane ranged from 0-6 to 3-6 mg m"^ of leaf surface.The quantities of these substances varied with the variety of maize, with leaf position, and with the part of the leaf. Sugar ratios on the phylloplane were quite different from those observed within the leaf.
Earlier experiments seemed to indicate a positive correlation between the choice of the oviposition site of Ostrinia nubilalis Hbn. on maize (Zea mays L.) leaves and their carbohydrate content. In the present study a growth regulator, maleic hydrazide (M.H.), is used to increase the soluble carbohydrate content of the plants. It seems that the insect prefers to oviposit on the treated plants which display higher carbohydrate contents. On the other hand the distribution of the egg-masses on the leaf blade is also modified. Plant height has no influence on these choices.
Maize (Zea mays L., hybrid INRA 260) was grown in the greenhouse with mineral nutrition of different sulphate concentrations. Mature seeds from these plants were compared for their free amino acid and protein N forms. For the most S‐deficient sample, the Asx (asparagine + aspartic acid) content increased by 30% as compared with control, while methionine and cysteine decreased (by 25 and 30%, respectively), as well as glycine, lysine, histidine, arginine and tryptophan. In seeds lowest in S the non‐protein N to total N ratio was 77% higher than in the control. Free asparagine dominated in starved seeds (50 mol % of total free amino acids) and was ten‐fold more concentrated than in the control, where proline was the predominant free amino acid. Thus the Asx of non‐protein N reached 28% of the total mol Asx of the whole starved seed. Altered S nutrition had virtually no effect on the amino acid composition of the main protein fractions, but it significantly changed their ratios. Zeins, which are poor in S‐containing amino acids, showed 25% higher level than in seeds supplied with normal S. As a counterbalance, two glutelin subfractions rich in S‐containing amino acids, decreased by 36–71% under limiting S nutrition.
It is concluded that the plant reacts against S deficiency by modifying its N metabolism. Significant accumulation occurred of free asparagine, which is the main form of N transportation. The biosynthesis of seed storage protein occurred through the accumulation of the highest possible protein quantity allowed by the available S‐containing amino acids, i.e. proteins low in S‐containing amino acids were preferentially synthesized.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.