Yield Response of Winter Squash to Irrigation Regime and Planting Density

Abstract

<jats:p>Consumers are increasingly interested in buying local vegetables in the fall and winter. Winter squash is an important vegetable crop for local and regional fall and winter markets, and consumers are increasingly seeking high-culinary value <jats:italic>Cucurbita maxima</jats:italic> types such as kabocha and buttercup. Although consumer demand for kabocha and buttercup squash is increasing, Oregon farmers report they are marginally profitable. The goals of this project were 1) to identify productive kabocha and buttercup varieties for western Oregon when grown with or without overhead irrigation and 2) to describe the effects of planting density on yield, fruit weight, number of fruit per hectare, and fruit per plant. Seven varieties of <jats:italic>C. maxima</jats:italic> winter squash, including kabochas and buttercups, and one interspecific (<jats:italic>C. maxima</jats:italic> × <jats:italic>C. moschata</jats:italic>) hybrid ‘Tetsukabuto’ were grown in a split-split plot randomized complete block design experiment with irrigation as the main plot, planting density as the subplot, and variety as the sub-subplot. Four replications of four different planting densities for eight varieties were grown in 2016 and 2017. Irrigated planting densities ranged from 8611–32,292 plants/ha (0.86–3.2 plants/m<jats:sup>2</jats:sup>) and dryland planting densities ranged from 3827–14,352 plants/ha (0.38–1.4 plants/m<jats:sup>2</jats:sup>) in 2016 and 5741–21,528 plants/ha (0.57–2.2 plants/m<jats:sup>2</jats:sup>) in 2017. The seven <jats:italic>C. maxima</jats:italic> types had statistically comparable yield under both irrigated and dryland production, with an average yield of 33.9 t·ha<jats:sup>−1</jats:sup> with irrigation and 19.4 t·ha<jats:sup>−1</jats:sup> without irrigation. Dryland yields in 2016 and 2017 were 76% and 37% of irrigated yields, respectively. ‘Tetsukabuto’ had the greatest yield (mean, 51.4 t·ha<jats:sup>−1</jats:sup>), the greatest number of fruit per hectare (mean, 12,080), and the greatest number of fruit per plant (mean, 1.94) when grown with irrigation, and yielded comparably with other varieties when grown in dryland production. Planting density impacted the fruit weight, number of fruit per hectare, and number of fruit per plant, although it did not impact yield statistically in both irrigated and dryland production. Average fruit weight decreased linearly from 1.89 to 1.30 kg for the irrigated trials, from 2.04 to 1.56 kg in the 2016 dryland trial, and from 1.42 to 0.93 kg in the 2017 dryland trial as planting density increased from 0.86 to 3.2, 0.38 to 1.4, and 0.57 to 2.2 plants/m<jats:sup>2</jats:sup>, respectively. The number of fruit per hectare increased linearly from 6660 to 10,590 as the number of plants per hectare increased from 8611 to 32,292 plants/ha for the irrigated trials, because even at the lowest planting density, plants did not produce more than two fruit per plant on average across varieties when grown with irrigation. Farmers can manipulate squash fruit size to suit market preferences by changing planting density. The very low 2017 dryland yields were likely a result of unusually high summer temperatures in western Oregon. Increasingly hot summers may render dryland squash production unfeasible in this region.</jats:p>

Site Factors Related to Dry Farm Vegetable Productivity and Quality in the Willamette Valley of Oregon

“…'Early Girl' tomato is reported to have a fruit weight of 1/4 to 3/8 lb and 'North Georgia Candy Roaster' winter squash is reported to have a fruit weight of 8 to 15 lb (Johnny's Selected Seeds). Previous work found that dry-farmed winter squash fruit weight was smaller than irrigated winter squash fruit weight during the hot and dry 2017 growing season; however, in the cool and humid 2016 growing season, there was little difference (Wetzel and Stone 2019). Tomato average fruit weight across all sites decreased over the course of the growing season, probably resulting from decreasing water availability (Giardini et al 1985).…”

“…There was no effect of planting density on average fruit weight for tomato or winter squash. This contradicts Wetzel and Stone (2019), who found that the dry farm winter squash yield was unaffected by planting The dash-dotted line represents the conditional mean for the linear regressions for 2018 and the dotted line represents that for 2019. The dashed line represents the conditional mean for the linear regression for both years.…”

“…Tomato planting density recommendations for dry farming have yet to be proposed for the Willamette Valley. Wetzel and Stone (2019) reported that across all winter squash varieties tested in the Willamette Valley, planting density did not significantly affect yield (tons per acre) of irrigated or dry-farmed winter squash, although higher planting densities reduced the average fruit weight.…”

Effect of Plant Spacing and Mulching on Growth, Yield and Quality of Squash

“…The maximum number of fruits plant -1 (4.67) was obtained from S 3 (1m × 1.5m) while S 1 (0.8m × 1m) gave minimum number of fruits plant -1 (3.76). Wetzel and Stone (2019) who reported higher fruit number with lower population density. The highest individual fruit weight (1.36 kg) was found from S 3 while the lowest individual fruit weight (1.16 kg) was found from S 2 (1m × 1m).…”

Effect of Climate Change on Maize Yield in the Growing Season: A Case Study of the Songliao Plain Maize Belt

“…With the continuous development of the economy and technology, the influence of human social activities is increasing. In addition to temperature, precipitation, and dry and wet conditions, there are also different drip irrigation modes [45], mulching conditions [46], planting densities [47], balanced fertilizers such as nitrogen and phosphorus [48], adaptabilities of maize itself to the environment, and crop management methods, which all affect the yield of maize. Therefore, a multi-factor evaluation model that can be used to evaluate climate variables and their impact on yield remains to be constructed.…”