ISHS Acta Horticulturae 792: V International Symposium on Irrigation of Horticultural Crops
PARTIAL ROOT-ZONE DRYING AS A POSSIBLE REPLACEMENT FOR 'VERDELLI' PRACTICE IN LEMON PRODUCTION |
| Author: | E. Raveh |
| Keywords: | abscisic acid, pigment, water potential, water stress, yield |
| Abstract:
Verdelli practice (withholding water in summer until the tree begins to wilt) is a common method for inducing out-of-season bloom in lemon. However, this technique can be repeated only in alternate years, since it weakens the trees. The present study assessed the use of Partial Root-zone Drying (PRD) as a possible replacement for Verdelli. Four irrigation treatments were compared: (1) Control (C) – trees irrigated as recommended; (2) Fixed-PRD (F-PRD) – a fixed half of the root system was irrigated; (3) Alternate-PRD (A-PRD) – similar to F-PRD except that every third week we alternated the half which was irrigated; (4) Verdelli (V) – water was withheld to the point of wilting. The treatments were conducted for 60 days during the summer, and water supply for PRD treatments was half the recommended amount. Trials were conducted for 2 years. In general, no significant differences were found between F-PRD and A-PRD treatments. Out-of-season bloom was maximal in V trees (46, 198, and 314 flowers tree-1 for C, PRDs, and V treatments, respectively), as was also reflected in summer lemon yield (4.9, 10.4, and 13.4 kg tree-1 for C, PRDs, and V treatments, respectively). Minimum leaf water potential was measured and was lowest in V treated trees (-2.0, -2.4 and -3.3 MPa for C, PRDs and V, respectively). Abscissic acid content, however, was similar in the PRD and V treatments and about 30% higher than in C treatment (162, 227, and 217 pmol ml-1 for C, PRDs and V, respectively). Unlike the summer yield, winter yield was similar in PRDs and C (60-70 kg tree-1): and about 30% higher than in V (35-40 kg tree-1). We conclude that A-PRD has no advantage over F-PRD. When compared to the C and V treatments, the PRD treatments have agronomic advantages. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
