Abstract
This study aimed to evaluate the productive characteristics, gas exchange and water use efficiency of the banana 'Prata-Anã' clone Gorutuba under different irrigation intervals associated with different emitter heights. Therefore, a field experiment was conducted in a 2 x 4 factorial scheme: two irrigation intervals (daily and every two days) and four emitter heights (50, 70, 90, and 110 cm) in a completely randomized design with four replicates. The irrigation depths applied by the microsprinkler irrigation system were calculated as a function of crop evapotranspiration. The gas exchanges were evaluated during the period of greatest climatic stress, and the productive characteristics were evaluated at harvest. The economic water use efficiency was determined indirectly by considering the production divided by the applied irrigation depth, which was the same in all the treatments. The instantaneous water use efficiency was estimated with an infrared gas analyzer in the critical climatic period. There was no interaction between the irrigation intervals and emitter heights. The two-day irrigation interval resulted in lower values of leaf temperature and photosynthetically active radiation incident on the leaves, resulting in a higher fruit weight and, consequently, higher yields and a higher water use efficiency. The highest fruit weights were obtained at heights of 70 and 90 cm.
Highlights
There was no influence of the irrigation interval on the agronomic variables evaluated: the number of hands per bunch, peduncle weight and the number of leaves per plant, but there was an influence on the total weight of fruits per bunch, which contrasted with the results presented by Silva et al (2015)
This result may be associated with the subdivision of the irrigation depth in the three applications during the irrigation day, even in the two-day irrigation interval, making it possible to optimize the operational management of irrigation system maintenance, which is considered one of the critical points of production
The two-day irrigation interval resulted in lower values of leaf temperature and photosynthetically active radiation incident on a leaf
Summary
The type of irrigation system affects the yield of banana crops, regardless of the use of the same cultivars and similar growing conditions (Sant'ana, Coelho, Faria, Silva, & Donato, 2012), due to differences in the uniformity of water distribution associated with factors such as the emitter position, irrigation angle, working pressure, type of vegetation and emitter height, which affect both the area and volume of wet soil, the intensity and frequency of application, the spatial distribution of the root system, the chemical attributes, and nutrient flux in the soil It can generate changes in phenotypic characteristics (Donato et al, 2010). This attribute can be expressed in several ways: leaf WUE or instantaneous WUE, which is the ratio between the gross carbon fixed by photosynthesis per unit of water transpired for a reduction of 1 kPa of vapor pressure deficit; the WUE of the plant, which corresponds to the ratio between the dry mass produced and the transpiration depth; or, from an economic point of view, WUE considers the ratio between fresh mass production (kg) per unit of transpired water (Donato, Coelho, Marques, & Arantes, 2016).
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