Delta Micro Irrigation Final Report

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Each squash was individually weighed and evaluated as being marketable or non- marketable. Squash were considered non-marketable, based on the following criteria: 1) sunburn, 2) excessive scarring (scarring would include raised warts and ridges on squash surface. See Figure to view squash with scarring.), 3) too small (<2Ibs) andlor 3) immature (immaturity was based on the greenness of stem. (See Figure 5 and 6, Appendix A). The Brix level (percentage of soluble solids which consist mostly of sugars) was taken from three squash randomly selected from each plot. The Brix levels were taken with a hand held refractometer (Atago Co., LTD., Tokyo, Japan). Two Kabocha squash varieties 'Ajehei' and 'Kurijiman' were evaluated in these trials. 'Ajchei' and 'Kurijiman' are the two main commercial varieties grown in western Colorado. RESULTS: In 1998 there was a significant difference in the amount of irrigation water applied between the furrow irrigated plots and the subsurface drip irrigated plots. The water applied in the subsurface drip irrigated plots was equivalent to 227,360 gallons of water per acre. The amount of water applied in the furrow irrigated plot was the equivalent to 1,768,340 gallons of water per acre. (The calculation for gallons of water used per acre was calculated by determining the number of gallons used per plant and multiplying it by 2800 plants per acre [number of plants in commercial squash field). The subsurface drip irrigated plots were watered every three to four days with the average irrigation time of approximately 6 hours. The furrow irrigated plots were watered once weekly with the average irrigation time of 17.8 hours at each setting. The low amount of water applied in the subsurface drip irrigated plots is due to only having to apply water directly to the root zone. In furrow irrigation the water must run long enough down the rows to have the necessary time to seep across the bed to the squash roots. Also, while the upper part of the squash beds might be adequately wet, the lower parts of the furrow may not have reached the proper moisture levels. Thus in order to attain proper soil moisture levels at the bottom of the field, the upper parts of the field become oversaturated, wasting water. On the other hand, with subsurface drip irrigation, the bottom and top part of the fields get exactly the same amount of water, while attaining optimum soil moisture levels. The data for 'Ajehei' and 'Kurijiman' were grouped together as there was no significant differences in yield per acre between the two varieties. There were significant differences in squash production between the furrow and drip irrigated plots (Table 1). Overall yields were significantly lower in the furrow irrigated plots, with the exception of the direct-seeded, no-mulch drip irrigated plot. There was a trend for higher yields in those plots which started off with transplanted squash seedlings. The color of the plastic mulch did influence the marketable yield per acre. Among the plots whose squash plants were transplanted, clear mulch and green mulch, produced significantly higher marketable yields. However the yields from the transplanted squash, no-mulch, subsurface drip irrigated plots was not significantly lower than the plastic mulched rows. The color of the plastic mulch did not appear significantly influence the total yield per acre of squash. However, total marketable yield was lower in the black plastic, drip irrigated plots. This group of plots was the outside row of the squash trial. The squash bug, Anasa tristis, concentrated in attacking plants to the outside of the plots. There was no significant difference in average fruit weight across all treatments (average fruit weight ranged from 2.88 to 3.54 lbs). Soluble solids (measured as Brix percentage) was significantly lower for the furrow irrigated, no mulch direct seeded plots. Average Brix levels ranged from 11.29 to 16.37 percent. The wide range in Brix levels cannot be explained at this time. 3