Effect of micro-irrigation on the growth and yield of raspberry (Rubus idaeus L.) cv. 'Polana' grown in very light soil

The aim of the study was to present the results of a field experiment carried out in two growing seasons 1999-2000 to study the effect of micro-irrigation on the growth and fruit yield of raspberry (Rubus idaeus L.) cv. 'Polana' grown under open field conditions in the region of Bydgoszcz, Poland. The field experiment was carried out on a very light soil (Typic Hapludolls). The mean content of floatable particles was 7 % in the top soil and 3 % in the sub-soil, while that of humus was 1.19 %. The water reserve to 0.5 m depth of soil at field capacity was 58 mm and the available water 43 mm. Both the experimental years were drier than usual. The experimental factor studied was irrigation. Three irrigation treatments were used: without irrigation (control), micro-sprinkler irrigation and drip irrigation at soil moisture tension of up to - 0.03 MPa. Mean seasonal water rates amounted 328 mm in case of micro-sprinkler irrigation and 207 mm in case of drip irrigation. The experiment was designed as a randomized block with four replications. The plot area was 21 m2 (2.1 x 10 m) and included 20 plants. Raspberries were planted in spring 1999. The cultivar used was 'Polana'. Normal commercial practices were carried out thereafter. The experiment proved that raspberry production was only possible with the use of irrigation. Plants grown on non-irrigated plots yielded only during the first season of cultivation. Vegetative growth of the canes was increased by the irrigation methods used. Irrigation significantly increased marketable yields and berry size of raspberry. Dry matter as well as vitamins A and C contents were affected by the irrigation methods used. Water use efficiency was higher in case of drip system as compared to micro-sprinkler irrigation. The micro-irrigation use was the basic cropping factor of the raspberries cultivated under loose sandy soil conditions.