Year: 1991
Type: article
Abstract: ― The objectives of this work were to: a), establish whether maize yield in Balcarce (Argentina 37°45'LS; 58°18'LO) is limited by the source of assimilates or by the number and size of the reproductive sinks; b), establish whether hybrids that differ in length of the growing cycle present differences in their source-sink relationships; c), de- termine to what extent the evolution of carbohydrate (CH) reserves in the plant is modified by different source-sink re- lationships.The experiment was conducted at Balcarce over a 2-year period with 2 hybrids (short season: SPS 240, long season: D2F11).The treatments consisted of 2 levels of source reduction (45 and 55% shading during the grain filling period, GFS), 2 levels of reproductive sink reduction (45 and 55% shading aroung flowering, FS) and an un- shaded control.The different shading treatments had a constant reduction of radiation with variable shading duration (30-38 days).The results indicate the existence of a colimitation by source of assimilates and reproductive sinks be- cause grain yield dropped similarly in response to shading during the flowering and the grain filling periods.FS re- duced grain number/unit area and slightly increased 1 000 kernel weight.GFS reduced 1 000 kernel weight, and to a lesser extent grain number/unit area.The study of dry matter and CH accumulation or remobilization in response to shading at the R3-R5 period, relative to those of the control treatment, was useful to indicate trends toward sink or source limitations.Relative to the control, shading at any period produced a decrease in stem CH content during the treatment period.During the post-shading period, the FS treatments presented a greater CH accumulation in stems than the control.This is explained by the decrease in reproductive sink number that produced a drop in their demand of CH and by the increased importance of the stem as an alternative sink for assimilates.GFS treatments produced a strong increase in CH remobilization rate from stem during the treatment period.The 2 hybrids did not show statisti- cally significant differences in their source-sink relationship.Nevertheless, a tendency toward a source limitation was evident in the long season hybrid. Zea mays = maize / source-sink relationships / carbohydrate remobilizationRésumé ― Rapports source-puits du maïs dans une région tempérée-froide.Les objectifs du travail ont été :ombrage une plus grande accumulation de CH dans les tiges que le témoin.Ceci est expliqué par la réduction du nombre de puits reproductifs qui produit une diminution de la demande de CH, mais aussi par l'augmentation de l'im- portance de la tige comme puits dassimilats.Les traitements GFS ont produit une forte augmentation du taux de remobilisation de CH de la tige pendant le temps d'imposition du traitement (figs 3, 5 et 6; tableau IV et V).Les 2 hybrides n'ont pas montré des différences significatives dans leurs relations source-puits.Cependant l'hybride de cycle long a montré une tendance plus évidente vers la limitation par la source, par une importance plus grande des remobilisations.Zea mays = maïs / relations source-puits / remobilisation de carbohydrates
Source: Agronomie
Authors: SA Uhart, FH Andrade
Language: English
Subfield: Agronomy and Crop Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: bronze
OpenAlex ID: W2021115730