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Genotype and planting date effects on cotton growth and production under south Portugal conditions – II. Monitoring
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Orientador(es)
Resumo(s)
Monitoring is a frequent practice in the high-yielding cotton producing regions, furnishing precious information to decision making during the
growing season and contributing to understand growth and development of cotton plants. The aim of this work was to determine the influence of
cultivar maturity type and planting date on the main monitoring indexes: plant height (H), number of main-stem nodes (MSN), height-to-node ratio
(HNR) and number of nodes above white flower (NAWF). Six genotypes and three sowing times were studied in one field experiment over two
seasons at Comenda Experimental Station, Alentejo, Portugal. Best regressions of H and MSN to accumulated degree days (DD) along the season
were quadratic models, with significant differences between genotypes and years. Consequently, heat unit’s requirements per each new cm height
and new main-stem node (plastochrons) increase linearly. Between genotype H differences were find just after first-flower (550 DD), whilst MSN
differences were find only after first open boll (1000 DD). Both differences emphasize until the end of the season. Inter-annual differences were
also find in H, at first-flower (500 DD) and in MSN, a bit earlier (400 DD). No planting date influence on H or MSN were detected. Best
regressions of HNR to DD were inverse models, also with significant differences between genotypes and years. ‘Celia’ and early planting dates
presented lower NFFB. Behavior of NAWF since first-flower to cutout (NAWF = 5) was well explained by linear models, regression coefficients
(NAWF decrease per day) showed only between genotype differences. Contradictory signs of maturation types were find. Low H and MSN
plastochrons and low final vigor index suggests precocity but, in contrary, relatively high NFFB, initial vigor index, final H and high number of days
to cutout, suggests late maturing tendencies of our studied cultivars as a whole. Planting date can be underlined as a management practice with
relatively low influence on H, MSN, HNR and NAWF evolution. However, especial attention must be given on the influence of planting date on
NFFB, once this monitoring index is strikingly linked with precocity, feature particularly important for regions with growing season duration
constrains. Further annual monitoring data and analysis is necessary in order to allow their use as decision making tools available to the main cotton
producing regions of southern Iberian Peninsula.
Descrição
Palavras-chave
: Gossypium hirsutum monitoring height number of main-stem nodes height-to-node ratio nodes of first fruiting branch nodes above wh
Contexto Educativo
Citação
Barradas, G. J. P.A; López-Bellido., R.J.(2009).Genotype and planting date effects on cotton growth and production under south Portugal conditions II. Monitoring . Journal of Food, Agriculture & Environment Vol.7 (2)