Báo cáo khoa học: Growth relationships between root and shoot in walnut seedlings (Juglans regia L.)

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Báo cáo khoa học: "Growth relationships between root and shoot in walnut seedlings (Juglans regia L.)"Growth relationships between root and shootin walnut seedlings (Juglans regia L.)J.S. Frossard A. Charron A. LacointeLaboratoire de Bioclimatologie, INRA, Centre de Recherches de Ctermont-Ferrand-Theix, Domaine-de-Crouelle, 63039 Clermont-Ferrand, France house. After 1 mo, 10 seedlings per yr wereIntroduction minirhizotrons and grown out- transplanted into doors, under natural conditions (continental cli-It is well known that the periodicity of root mate). Root and shoot growths were measured the year may be thegrowth throughout weekly, during 2 yr for the 1985 and 1986 seed-same as or different from that of shoot lings, and during 1 yr for the 1987 seedlings.growth (Riedacker, 1976; Kramer and From September to March, bud dormancyKoslowski, 1979; Frossard and Lacointe, studied using the MTB test (Bailly and was1988), depending upon the species. It is Mauget, 1989}.difficult to interpret the published resultsbecause they were obtained on trees ofdifferent ages under different climatic Resultsconditions. It is particularly difficult to give preciseanswers to the following questions: 1) is was a high variability between Therethe relative position within the annual plants during both the 1 st and the 2nd yr.cycle of root and shoot growth a general An example of between yr variability ischaracteristic of a given species? In other given in Figs. 1 (1985-1986) and 2words, is there any evolution between (1986-1987).years, in the relative periodicity of root andshoot growth? 2) are the relationships bet- However, the relative growth patterns ofween variables describing growth equiva- the different organs were the same. Therelent throughout the year? Answers to were ’l st yr’ and ’2nd yr’ patterns. Duringthese questions are of particular interest the 1st growing season (sowing yr), rootwhen working on seedling growth and and shoot growth occurred simultaneous-when investigating the carbon allocation to ly; during the 2nd season (2nd yr), leafdifferent organs (Lacointe, 1989). growth began first, followed by shoot elon- gation and root growth came last. In autumn, there was no relationshipMaterials and Methods between dynamics of bud dormancy and root growth (data not shown). No rootFor 3 yr (1985, 1986, 1987), walnuts were sown growth was observed in winter.in early June, in clay soil, and grown in a glass- In order to specify the dynamics of The sowing yr analyses provided 3 very similar figures, and the same was true forrelationships among growth variables, 5 both 2nd yr analyses. The results for theFrench principal components analyses 1985 sowing are presented in Figs. 3were performed, one for each of the 3sowing yr and one for each of the 2nd yr (sowing yr) and 4 (2nd yr). the average values for the 10 Comparison of component weightsstudied: onplants; taking as ’individuals’ the measure- (variables) vs principal components (mea- surement dates), for both years, enabledment dates. For some of them, such as LA or TLR, this synthetic overview of the growth dyna- mics was consistent with that which could be derived from the plots of the co ...