EFECTO DE LA DISPONIBILIDAD DE AGUA EN EL SUELO SOBRE LA PRODUCTIVIDAD DEL CARDO (Cynara cardunculus L.) / Effect of the soil water resource on the cardoon (Cynara cardunculus L.) yield

AUTOR(ES)
DATA DE PUBLICAÇÃO

1999

RESUMO

In the present work it is studied the effect of different hydric soil levels on the aerial dry weight biomass productivity of the cardoon (Cynara cardunculus L.), basing it on the soil water profile absorption at different levels, Water Use Efficiency (WUE) and root growth. In order complement and to explain the high yields of the crop, it was also been studied the photosynthetic activity under low temperature conditions. The water consumption evaluation was performed for two different irrigation treatments. The first one (A), representing the average precipitation in Madrid for the period 1960-1990 (425 mm), and the second one (B), with the maximum annual precipitation over the same period, monthly distributed at the same rate as the treatment A. Monthly irrigation amounts were distributed each 15 days. Soil water content measurements were recorded every 15 days, before and 48 h after irrigation, during 96/97 and 97/98 growing cycles, using a neutron probe meter. From Septembre to February there is an accumulation of water in the soil profile and from March to June, the amounts uptaken by the plant is higher than the water supplied by irrigation or rain. Due to its root system depth, the cardoon can support those conditions using the soil water reserve that has been accumulated over the winter-fall period. The consumption data showed that the cardoon is able to absorb around 33 % of the total evapotranspiratated water from the soil layers below 30 cm depth. Crop yield was followed during the 95/96, 96/97 and 97/98 growing cycles. The highest aerial dry weight biomass yields were achieved in the third growing period, with an average of 1.5 kg.m-2 for the treatment A and 1.9 for the B one. Water Use Efficiency figures of 3.13 g of dry matter per liter of water for treatment A and 2.92 for the B one, were obtained during the 97/98 growing cycle. These figures puts the cardoon at a higher level than most of the C3 species and similar of some of the C4 traditional agricultural crops, as corn. Root system growth evaluation was studied by means of poliethylene tubes, that were filled with a sand + manure mixture (80:20) and using plants of three different origins (transplanted, in vitro meristem cultivation and direct seed). The results showed that the cardoon root system, in the first growing cycle, is capable of achiving a depth of 500 cm, with an average of 54.6 % of the total root dry weight in the first 30 cm of the soil profile, 37.9 % between 30 and 120 cm and 7.5 % between 120 and 500 cm. Photosynthetic activity under low temperature conditions (4.0 6.0 C) represents around 33 % of the optimum rate, average of 17 mol.m-2.s-1 under 20 30 C, giving a good support to explain the high aerial dry weight biomass production of the crop, mainly if it is considered that during winter time the crop can produce around 7 t.ha-1 of aerial dry weight biomass.

ASSUNTO(S)

cynara cardunculus biomassa agroenergética manejo e tratos culturais eficiencia en el uso del agua - eua sistema radicular fitotecnia cardo biomasa

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