عنوان مقاله [English]
Drought is one of the most important environmental factors that influences yield and quality of tomato (Solanum lycopersicum Peralta & Spooner)in arid and semi-arid regions. Drought stress causes different physiological effects on plant growth. Vegetable crops are more sensitive to water shortage and any deficit in providing water requirement of plant leads to considerable reduction of yield. For future global food security, water use in agriculture must become sustainable. Agricultural water-use efficiency and water productivity can be improved by many approaches and strategies. Super absorbent polymers (SAP) as a soil improvement substance, covering soil by different types of mulches and blocking a part of sun light by shading have been used effectively to increase the water use efficiency sustainability of production in agricultural systems. But, still there is a limited knowledge on interactions of SAPs, plastic mulches and shading under deficit irrigation on yield and quality of tomato.
Material and Methods
In order to evaluate the effects of SAP, black plastic mulches and decreasing light intensity under deficit irrigation on yield and quality of tomato ‘Early Urbana VF 132- 7171’ fruits, the current research carried out in a field experiment at department of Horticulture, Ilam University during 2014 using a 3 × 8 × 3 split plot assay based on a randomized complete block design (RCBD) with two factor. The main factor was including three irrigation intervals (once after 3, 6 or 9 days equivalent to soils field capacity) and sub-factor was including eight treatments viz., mulch, superabsorbent, shading, mulch + superabsorbent, mulch + shading, superabsorbent + shading, mulch + shading + superabsorbent and control. Light intensity was measured by a digital exposure meter ‘Mastech MS6610’. Data were subjected to ANOVA using SAS software version 9.3. Verification of significant differences was done using Duncan's Test at 5% probability level.
Results and Discussion
Analysis of variances revealed that effects of irrigation intervals, treatments and their interactions were highly significant on total yield, potential yield, marketable yield, blossom end rotten fruits yield, sunburned fruits yield, cracked fruits yield, average weight of fruits and number of main and lateral branches. Also, effects of treatments on number of days to 50 percent flowering, plant height and fruit wall thickness and effects of irrigation intervals on fruit shape index were significant at 5 percent of probability level. Results showed that increasing irrigation intervals decreased yield and its important components and increased blossom end rot, and cracked fruits. Increasing irrigation intervals from 3 to 9 days decreased 50 percent of total and marketable yield and quadrupled percentage of blossom end rotten fruits. Although shading improved total and marketable yield, but recording the highest number of days to 50 percent flowering for plants grown under shade of Saran® clothes, proved that shading delays harvesting of tomato. The maximum of total and potential yields produced by superabsorbent + shading + mulch treatment and the highest percentage of marketable fruits recorded for superabsorbent, mulches and shading + mulch, respectively. Application of shading clothes alone or along with mulches or superabsorbent minimized the percentage of sunburned fruits. The biggest fruits produced by treatments in which mulches were participated. Increasing irrigation intervals to six and nine days extremely decreased percentage of marketable and blossom rotten fruits, while increased cracked fruits.
Generally, for short irrigation intervals, superabsorbent + shading + mulch compound treatment and for extreme water deficit conditions and irrigation intervals more than six days adding superabsorbent A200 (10 g.plant-1, mixing into 30 cm depth of soil) is recommended to improve yield and quality of tomato crop.