International Water & Irrigation

30 statistical differences between treatments in total yield, marketable yield, fruit cluster weight, number of clusters and the various categories of non-marketable fruit, except in blossom-end rot. Blossom-end rot was 0.4%, 0.8% and 1.3% of total yield in the control, -8 kPa and -15 kPa treatments, respectively. The difference between the control and the -15 kPa treatment was statistically significant. There were no differences between treatments in fruit weight, before and after shelf life, and the cluster rachis freshness (Table 4). Average fruit weight decreased in March, regardless of treatment. Rate of ripening and the progress of harvest did not differ between treatments (data not shown). Soil tests : There were no differences in soil salinity between treatments (Fig 6) . The highest salinity was found in the 15-30 cm layer and decreased below 60 cm. Soil water content of the control treatment was higher compared to the tensiometer treatments, in all the soil layers measured (Fig 7) . The -8 kPa soil profile had higher water content compared to the -15 kPa treatment. In the control treatment there was an increase in the water content in the 75-90 cm layer compared to the 30-75 cm layers, indicating probably water percolation due to excessive irrigation. The higher salinity in the 15-30 cm layer as compared to the low salinity bellow 60 cm indicated a higher water uptake due to higher root density in the upper 0-45 cm. Root excavations also showed a high root density in the 0-45 cm layer. Discussion Irrigation is monitored and guided either by agro- meteorological, soil or plant-based measurements. The agro- meteorological approach neglects the measure of The agro-meteorological approach neglects the measure of the soil or the plant water status and therefore requires experimental determination of plant coefficients (KC) for implementation Fig. 2. Soil water tension for the period 11/10/2015- 31/12/2015. A - 8 kPa, B - 15 kPa. Numbers above the pre-set tensions are cases when tension exceeded 2 kPa in the – 8 kPa treatment and 3 kPa in the -15 kPa treatments. Table 3. Yield of tomato Parameter Control - 8 kPa - 15 kPa Total yield (T/ha) 256.8 a 248.6 a 254.1 a Marketable yield (T/ha) 232.7 a 224.0 a 243.4 a No. of Clusters 375730 a 365230 a 377500 a Cluster weight (kg) 1.09 a 1.05 a 1.08 a Single fruits (T/ha) 13.9 a 13.6 a 10.2 a Cracked fruit (T/ha) 0.6 a 0.2 a 0.1 a Rotten fruit (T/ha) 0.2 a 0.1 a 0.7 a Green fruit (T/ha) 13.9 a 13.2 a 13.7 a Small fruit (T/ha) 8.4 a 9.1 a 9.8 a Black-end rot (T/ha) * 0.1 a 2.1 ab 3.2 b * Prob>F = 0.0256 Table 4. Shelf life measurements Date Treatment 18/1/2016 15/2/2016 4/3/2016 10/4/2106 Fruit weight at harvest (g) Control 165 ± 10.7 158 ± 8.0 145 ± 11.7 119 ± 5.8 - 8 kPa 154 ± 11.3 155 ± 21.7 158 ± 8.3 120 ± 0.8 - 15 kPa 151 ± 7.1 155 ± 4.1 133 ± 10.7 112 ± 6.7 Fruit weight after shelf life Control 160 ± 10.7 155 ± 8.0 141 ± 11.7 116 ± 5.8 - 8 kPa 149 ± 11.3 152 ± 21.7 154 ± 8.3 117 ± 0.8 - 15 kPa 146 ± 7.1 152 ± 4.1 129 ± 10.7 111 ± 6.7 Cluster rachis freshness (%) Control 34 ± 12.6 38 ± 6.7 32 ± 6.5 33 ± 5.0 - 8 kPa 37 ± 3.6 37 ± 3.1 39 ± 7.0 33 ± 4.6 - 15 kPa 35 ± 10.1 39 ± 5.0 32 ± 9.3 26 ± 5.2