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Root growth and development of 'Cas' guava (Psidium friedrichsthalianum Berg-Nied.) seedlings during nursery stage

Abstract:

A root growth analysis for 'Cas' guava (Psidium friedrichsthalianum Berg-Nied.) seedlings was established. Seeds were extracted from ripe and healthy fruit harvested at the guava germplasm bank of Centro Frutícola of Zulia, Venezuela (11°00'00" LN, 71°30'00" LW). Seeds were sown in a seedbed that contained sterilized substrate. Seedlings were transferred into bags when they were about eight cm in height. Seedlings were grown in five or ten kilogram polyethylene bags containing three mixtures (1:1, 1:2 and 2:1) of soil and goat manure as substrates. Sampling was done monthly during six months. The variables measured for root growth were main root length, root fresh and dry mass, volume, and area. Treatments were arranged in a factorial, completely randomized design with five replicates. Data were statistically analyzed utilizing the SAS software. SigmaPlot of Jandel Scientific was applied to select the curvilinear regression model that best fitted the results. The model used to adjust the curves was y= a/1+e -(x-xo/b). The equations that represent root volume growth for the proportions 1:1, 1:2 and 2:1 were: y= 9.310e+0/1+e -(z-1.335e+2/2.404e+1)R2=0.94; y= 1.281e+1/1+e -(x-1.335e+2/2.404e+1)R2=0.94;y=10281e -(x-1.379e+2/2,981e+1) R2=0.95 and y=9.659e+3/1+e -(x-5.119e+2/4.894e+1) R2=0.95, respectively. Bag size and soil:goat manure proportions are related with time during nursery stage. Ten kilogram bags and the 1:2 mixtures were appropriate for good root growth and development during six months in the nursery.