Growth of Lettuce, Onion, and Red Beet. 1. Growth Analysis, Light Interception, and Radiation Use Efficiency

Abstract

A field experiment was carried out to analyse the growth of lettuce, onion and red beet in terms of : (a) canopy architecture, radiation interception and absorption ; (b) efficiency of conversion of absorbed radiation into biomass ; and (c) dry matter partitioning. Growth analysis, total solar radiation interception, PAR interception and absorption by the crop canopy, ground cover, maintenance respiration of onion bulbs and red beet storage roots were measured. Models for different leaf angle distribution and ground cover were used to simulate light transmission by the crop canopy.The three crops are shown to have contrasting growth patterns from both a morphological and a physiological point of view. Lettuce showed very high light interception and growth after the early growth stages but, throughout the growth cycle, this leafy crop showed the lowest radiation use efficiency due to the respirational cost of the high leaf area. Onion showed a lower early relative growth rate than lettuce and red beet. This was due partly to the low light interception per unit leaf area in the later stages of growth and partly to the low initial radiation use efficiency compared with the other two crops. On the other hand, thanks to more uniform distribution of the radiation inside the canopy, to the earlier termination of leaf development and to the very low level of bulb respiration, onion showed high radiation use efficiency and was able to produce a large amount of dry matter. Red beet leaf posture and canopy structure resulted in high light interception and absorption. Its radiation use efficiency was lower than that of onion, partly perhaps because of the more adverse distribution of the intercepted radiation fluxes within the canopy and partly because of the high respiration cost of a continuous dry-matter allocation to the leaves. However, this crop can accumulate a very large amount of dry matter as leaf blade development and storage root growth can both continue almost indefinitely, providing continuously available sinks.Ground cover gave a good estimate of the PAR interception only at low values of light interception but, in general, it underestimated PAR interception in all three crops. Ratios between attenuation coefficients established by considering PAR or total solar radiation and LAI or ground cover were calculated.# 1996 Annals of Botany Company

Effect of Light Conditions and Temperature on Fresh Yield of Some Spice Plants Grown in Containers

“…Monteith (1977) was the first who demonstrated that biomass production, in cultivations with appropriate levels of irrigation and fertilization, depends linearly on the quantity of the absorbed light. This dependence is known and has been described in many papers (Warren-Wilson 1981;Jameison et al 1995;Tei et al 1996). Also in the described investigations, a linear correlation was found between the sum of photons absorbed during the period of growth of plants and the fresh mass yield (Fig.…”

Effects of band placement and nitrogen rate on dry matter accumulation, yield and nitrogen uptake of cabbage, carrot and onion

“…by Greenwood et al (1980). In European countries, onion is usually cultivated with higher plant density than in Finland and dry matter accumulations of 7000-13 000 kg ha -1 (Greenwood et al 1992) and 15 000 kg ha -1 (Tei et al 1996) have been reported with 30% higher plant populations compared to my experiment. Brewster (1990a) reports 10 000 to 12 000 kg ha -1 dry weights for spring-sown onion in his experiments, but considers 5000 kg ha -1 dry yield typical of practical farming.…”

Crescimento de planta, partição de assimilados e produção de frutos de melão amarelo sombreado por diferentes malhas

“…O acúmulo de massa seca na planta é resultado do balanço entre a radiação fotossinteticamente ativa incidente e a absorvida pelas folhas, da eficiência média de conversão da radiação absorvida em massa seca e da partição desta entre as partes coletoras de luz, as folhas, e o restante da planta (TEI et al, 1996). Portanto, a maior síntese de fotoassimilados e a partição equilibrada destes entre os diversos órgãos da planta, sob condições de pleno sol, proporcionaram maior precocidade no incremento e também na obtenção dos valores de máximo de massa seca de folha, caule, raiz, fruto e total em relação aos ambientes sombreados no meloeiro.…”