No abstract

O objetivo do trabalho foi avaliar o efeito da irrigação, a aplicação de vinhaça e fertirrigação mineral via irrigação por gotejamento enterrado nos valores biométricos na fase de maturação, produção de colmos, qualidade do caldo da cana-de-açúcar e rendimento de açúcar teórico recuperável. O experimento foi instalado em blocos ao acaso, com quatro tratamentos e cinco repetições. Os tratamentos foram: adubação mineral sem irrigação; irrigação e fertirrigação de NPK com adubos minerais; irrigação e fertirrigação com vinhaça, suprindo o K e complementação do NP com adubos minerais, além de irrigação e fertirrigação com vinhaça, suprindo o NK e complementação do P com adubos minerais. O sistema de irrigação utilizado foi o gotejamento subsuperficial. Os tratamentos irrigados promoveram alterações no número de perfilhos e índice de área foliar quando comparados com o cultivo de sequeiro, independente do manejo da fertirrigação. A fertirrigação com vinhaça suprindo o K proporcionou maior Brix e produção de colmos, quando comparada ao cultivo não irrigado. A irrigação e a fertirrigação com a vinhaça atendendo ao NK, proporcionaram maior rendimento teórico de açúcar recuperável, quando comparado com o do cultivo sem irrigação.

The water availability at early phenological stages is critical for crop establishment and sugarcane varieties show differential performance under drought. Herein, we evaluated the relative importance of morphological and physiological plasticity of young sugarcane plants grown under water deficit, testing the hypothesis that high phenotypic plasticity is associated with drought tolerance. IACSP95-5000 is a high yielding genotype and IACSP94-2094 has good performance under water limiting environments. Plants were grown in rhizotrons for 35 days under three water availabilities: high (soil water matric potential [Ψm] higher than -20 kPa); intermediate (Ψm reached -65 and -90 kPa at the end of experimental period) and low (Ψm reached values lower than -150 kPa). Our data revealed that morphological and physiological responses of sugarcane to drought are dependent on genotype and intensity of water deficit. In general, IACSP95-5000 showed higher physiological plasticity given by leaf gas exchange and photochemical traits, whereas IACSP94-2094 showed higher morphological plasticity determined by changes in leaf area (LA) and specific LA. As IACSP94-2094 accumulated less biomass than IACSP95-5000 under varying water availability, it is suggested that high morphological plasticity does not always represent an effective advantage to maintain plant growth under water deficit. In addition, our results revealed that sugarcane varieties face water deficit using distinct strategies based on physiological or morphological changes. When the effectiveness of those changes in maintaining plant growth under low water availability is taken into account, our results indicate that the physiological plasticity is more important than the morphological one in young sugarcane plants.

Palavras-chave: Lycopersicum esculentum Mill., manejo da água, irrigação localizada, fertirrigação, cultivo protegido. ABSTRACT Tomato development and yield under different irrigation frequencies in greenhousePlant cultivation in substrate under greenhouse conditions needs technical knowledge to promote water and nutrient use efficiency. In this work were evaluated the tomato development and yield under different irrigation frequencies cultivated in greenhouse. The experiment was carried out in Campinas, São Paulo State, Brazil, from November, 2003 to April, 2004. The experimental design consisted of six treatments in randomized blocks with four replications. The treatments consisted of the irrigation frequencies: five, four, three, two and one times a day and irrigation on alternating days. The irrigation was applied by drip irrigation system. The substrate consisted of coconut fiber. The one, three, four and five times a day irrigation frequency provided better total marketable tomato yield. The greater number of fruits and average weight of fruit were obtained under the one, two, three, four and five times a day irrigation frequencies. The irrigation frequency once a day and alternating days provided greater number of no marketable fruits.

RESUMOObjetivou-se, com esta pesquisa, avaliar o efeito da irrigação, da fertigação mineral e da vinhaça, aplicadas via irrigação por gotejamento subsuperficial, no número de perfilhos, produção de colmos, qualidade tecnológica e rendimento de açúcar recuperável, nos três primeiros ciclos de cana-soca. Os tratamentos foram: T1NI -Cultivo não irrigado com adubação mineral; T2I -Cultivo irrigado e fertirrigado com fertilizantes minerais; T3Iv -Cultivo irrigado e fertirrigado com a vinhaça suprindo o K e complementação do NP via fertilizantes minerais e T4IV -Cultivo irrigado e fertirrigado, com a vinhaça suprindo o NPK. No ciclo da primeira canasoca não houve efeito dos tratamentos sobre as variáveis; já nos ciclos subsequentes o T2I e o T3Iv exibiram maiores números de perfilhos, 17,4 e 17,2 perfilhos m -1 na segunda cana-soca e 16,6 e 16,0 perfilhos m Sugarcane fertigated with vinasse under subsurface drip irrigation in three cycles of cane-ratoon ABSTRACT The objective of this study was evaluate the effect of irrigation and fertigation with mineral fertilizer and vinasse applied by subsurface drip irrigation, in the number of tiller, stem yield, technological quality of sugarcane and yield of recoverable sugar in first three cycles of ratoon cane. The treatments were: T1NI -cultivation without irrigation with mineral fertilization; T2I -cultivation fertigated with mineral fertilizers; T3Iv -cultivation fertigated with the vinasse supplying K and complementation of NP with mineral fertilizer; T4IV -cultivation fertigated with the vinasse supplying NPK. In the cycle of the first ratoon cane, there was no effect of treatments on the variables, already in the subsequent cycles, the T2I and T3Iv showed higher numbers of tillers, 17.4 and 17.2 tiller m -1 , in the second ratoon cane and 16.6 and 16.0 tiller m -1 in the third ratoon cane, respectively. The stem yield was amended with the T4IV obtaining the higher yield, 179.6 Mg ha -1 , in the second ratoon cane, and the T2I and T3Iv in the third ratoon cane, 151.5 and 151.0 Mg ha -1 , respectively. There was no treatment effect on the technological quality and in the second ratoon cane the T3Iv and T4IV showed higher yield of sugar, 25 and 25.9 Mg ha -1 , respectively.