A STUDY OF DEVELOPMENT, FLOWER QUALITY AND FERTILIZATION IN GLADIOLUS (Gladiolus grandi orus Hort.)

Abstract

San Martín Texmelucan, Puebla, is the main producer of gladiolus (Gladiolus grandiflorus Hort.) in México. Technical information on this crop is limited and losses in production and quality are common during the growth period. The present study was performed to evaluate the effect of four rates of fertilization (DF) expresed in kg ha^-1: 65 N - 14.9 P – 171 K - 16.6 Mg - 31.2 Ca (DF1); 40.5 N – 24 P – 171 K -23 Mg - 37.2 Ca - 0.2 B - 8.5 S (DF2); 81 N – 24 – 171 K - 23 Mg - 37.2 Ca - 0.2 B (DF3); y 81 N – 24 P – 171 K - 23 Mg - 37.2 Ca (DF4), on flower growth and quality and on plant health of two varieties, ‘Borrega roja’ (BR, red flower) and ‘Espuma’ (E, white flower). The growing degree-days (GDD) needed for several phenological stages (seedling emergence leaf emergence, spiking, commercial maturity, and physiological maturity of the corm) were estimated. Plant height, leaf area index and percent of diseased plants were measured. The biologic cycle was 111 d for BR (1424 GDD) and 129 d (1662 GDD) for E; and both varieties produced seven leaves and 13 flower buds. BR grew faster over the cycle. Differences in earliness appeared since the emergence of the sixth leaf (931 GDD and 956 GDD for BR and E, respectively). At the end of the cycle, E was higher (P < 0.05) in plant height (127.0 cm), leaf area index (1.5), accumulation of degree days to physiological maturity (1662 GDD) and flower area (10.8 cm²). There was no effect of fertilizer rates on crop growth and development. Rate DF2 reduced plant mortality to 3.3 % without affecting crop growth and flower quality. Treatments with high nitrogen content (DF3 and DF4), had more than 4.8 % of dead plants due to diseases.