Effects of crop loads on the growth, nutrient content and fruit quality in three-year-old 'Miyauchi' iyo (Citrus iyo hort. ex Tanaka) Trees
2005
Chikaizumi, S.(Ehime Univ., Matsuyama (Japan). Faculty of Agriculture) | Hino, A. | Mizutani, F.
Effects of crop loads on the current tree growth, nitrogen and starch content of shoots and fruit quality were investigated by using potted three-year-old 'Miyauchi iyo' (Citrus iyo hort. ex Tanaka) trees grafted on trifoliate orange rootstocks. The trees were assigned to five different crop loads such as 0, 2, 5, 7 and 10 fruit per tree. The increasing crop loads reduced the total tree growth in terms of fresh and dry weight. The starch content in the roots was most greatly reduced by increasing crop loads. The starch content in the shoots was the greatest in the two-fruit-loaded trees and decreased with increasing crop loads up to 10 fruit per tree. The starch content in the leaves in non-fruit trees was greater than fruit-loaded trees, among which there were little differences in the starch content. The nitrogen content in the spring leaves and shoots was slightly greater in the fruit-loaded trees compared with non-loaded trees. The nitrogen content in the large roots gradually decreased with increasing crop-loads but there were no such tendencies in middle and small roots. The average individual fruit weight was 326g and 288g in two-fruit-loaded and five-fruit-loaded trees, respectively, whereas it was smaller than 200g in ten-fruit-loaded trees. The rind/flesh ratio became smaller with increasing crop loads. Red coloration was the greatest in five-fruit-loaded trees followed by two-fruit-loaded trees.
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