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SDI in the Great Plains​

Session 16. Microirrigation of Fruit Crops

Microirrigation Effects on Two Apple Cultivars and Rootstocks

R. C. Funt, M. C. Schmittgen and J. C. Golden

Newly planted apple trees may require irrigation. They need to grow rapidly, fill in their allotted space, and obtain an early, high yield of apples. This increases early returns and profit. Apple trees on some rootstocks can become stunted at an early age if planted in sandy soil and the soil remains dry. These trees may not continue to grow and may not become fully mature trees. It has been suggested that rootstocks differ in their influence of producing fruit and wood. (Forshey and Elfving, 1989)

Optimal apple fruit size is obtained by a consistent water supply throughout the growing season. The number of fruit per tree increases from the first harvest to tree maturity which requires several years. As the tree size increases and the fruit numbers increase, more water is required. However, the root area has also increased over the same time. The root area, depth and its ratio to the above ground portion differs among rootstocks. The objective of this research was to compare the effects of microirrigation on two different rootstocks. A second experiment was established to test the variation in irrigated trees with the same rootstock.

Keywords: Rootstocks, cultivars, apples, irrigation scheduling

Abstract taken from paper found on pages 470 to 476 in Proceedings of 5th International Microirrigation Congress, April 2-6, 1995, Orlando, Florida. American Society of Agricultural Engineers, 2950 Niles Road, St. Joseph, Michigan 49085-9659, USA. Phone: 616-429-0300 FAX: 616-429-3852 EMAIL: HQ@ASAE.ORG

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Influence of Microsprinklers on Semi-dwarf Apple Trees, Ohio

R. C. Funt, M. S. Biggs, M. C. Schmittgen and J. C. Golden

Large apple fruits (6.25 to 7.5 cm) receive a greater return than fruits less than 6.25 cm in diameter. However, the large size fruit of some cultivars like 'Delicious' can be less firm and lower in calcium (Ca) than smaller size fruits. Low fruit Ca is related to large fruit, excessive vegetative growth (which can be caused by excessive nitrogen and/or a low number of fruit per tree), excessive pruning, and low uptake of Ca and boron (B) from the soil, particularly soils having low Ca.

Over-the-tree sprinkler systems have been used to reduce heat stress, prevent freezing and delay bloom. Generally, such systems may not just apply water but also inject fertilizers; therefore, a response from plants can be influenced in a controlled manner (Proebsting, et al. 1977). Ca plus B treatments supplied to the soil by trickle irrigation to nonspur and spur 'Delicious' trees increased leaf, fruit peel and flesh Ca content (Smith, et al. 1987). However, applying Ca and B as a foliar spray directly to the fruit has been shown to be more effective (Bramlage, et al. 1985).

The effect of applying a Ca/B solution with two 180° microsprinklers (22.2 liters/hr) per apple tree was tested from 1989 to 1993. There were five treatments; a control (no irrigation), irrigation over-and-under-the-tree, and an irrigation with Ca/B solution over-and-under-the-tree were tested. The objective of this paper is to discuss the wetting pattern, effect of microsprinkler placement, fruit size and yield data. the effect of Ca/B on fruit quality will be addressed in another paper.

Keywords: Microsprinkler, injection, irrigation scheduling

Abstract taken from paper found on pages 477 to 485 in Proceedings of 5th International Microirrigation Congress, April 2-6, 1995, Orlando, Florida. American Society of Agricultural Engineers, 2950 Niles Road, St. Joseph, Michigan 49085-9659, USA. Phone: 616-429-0300 FAX: 616-429-3852 EMAIL: HQ@ASAE.ORG

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Soil Sensor Actuated Microirrigation of Apples

M. Meron, R. Assaf, B. Bravdo, R. Wallach, R. Hallel, A. Levin and I. Dahan

A field experiment was initiated in 1992, at Matityahu Hort. Exp. Farm, near Baram, Israel, to develop and test a soil sensor-actuated automatic irrigation system and to optimize sensor actuation thresholds for fruit yield and quality. Evaluation of the effect of wetted soil volumes on water use, fertility and vigor of apple orchards was a secondary objective. Irrigation was applied through one or two drip laterals per row, or by one mini-sprinkler per tree, each arrangement doubling the wetted soil volume from the previous one. Analog output transducer-equipped tensiometers actuated irrigation at preset thresholds of 15, 25, and 35 kPa soil water tensions, and stopped irrigation when tension dropped to 10 kPa at 0.4 m depth, thus eliminating deep percolation. The control system operated as predicted by initial simulation and the feasibility of the concept was demonstrated.

Highest yields were achieved at 25 kPa soil water tension actuation, applying 450-550 mm water. Lower tension thresholds of 15 kPa, with 650-750 mm water applied, did not raise yields but increased fruit size and trunk growth. High thresholds of 35 kPa, with only 350 mm water, decreased both yield and vegetative indicators.

Mini-sprinklers used considerably more water than drippers. No recognizable differences in water use were found between single and double drip lines per row.

More experimentation will be needed to ensure that the optimal threshold (25 kPa) treatment, will maintain high yields, without negatively effecting orchard vigor and longevity.

Keywords: Irrigation control, Automation, Soil suction, Threshold limits, Water use efficiency

Abstract taken from paper found on pages 486 to 491 in Proceedings of 5th International Microirrigation Congress, April 2-6, 1995, Orlando, Florida. American Society of Agricultural Engineers, 2950 Niles Road, St. Joseph, Michigan 49085-9659, USA. Phone: 616-429-0300 FAX: 616-429-3852 EMAIL: HQ@ASAE.ORG

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Effects of Irrigation Periods on Citrus Yield and Fruit Quality in Uruguay

Mario Garcia Petillo

Four irrigation treatments: a) irrigation throughout the growing cycle, b) no irrigation, c) irrigation from bloom to fruit drop and d) irrigation from fruit drop up to harvest, were maintained for four years in "Valencia" and "Washington Navel" oranges (Citrus sinensis (L) Osbeck), "Ellendale" mandarin (Citrus reticulata Blanco x Citrus sinensis (L) Osbeck) and lemon (Citrus limon (L) Burm. f.).

Annual average rainfall was 1150 mm and the average irrigation amount was a) 481, b) 0, c) 93 and d) 388 mm for each treatment respectively.

I rrigation increased "Valencia" yield 41%, "Navel" yield 20% and % lemon yield 29%, as compared with no irrigation. "Ellendale" mandarin results were less consistent. Irrigation increased fruit size in all cases. Fruit quality was also improved by irrigation, increasing juice content, increasing brix:citric acid ratio and reducing peel thickness.

Treatments a) and d), which received more irrigation water, behaved similarly. The same was true for treatments b) and c) which received less irrigation water.

Supplementary irrigation increased yield, fruit size and quality even under the semihumid Uruguayan climate.

Keywords: orange, lemon, mandarin, microirrigation, irrigation management

Abstract taken from paper found on pages 492 to 496 in Proceedings of 5th International Microirrigation Congress, April 2-6, 1995, Orlando, Florida. American Society of Agricultural Engineers, 2950 Niles Road, St. Joseph, Michigan 49085-9659, USA. Phone: 616-429-0300 FAX: 616-429-3852 EMAIL: HQ@ASAE.ORG

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Status of Drip Irrigation Systems in Maharashtra

D. G. Holsambre

Reconnaissance surveys and emission uniformity tests were conducted to study the present status of drip irrigation systems in Maharashtra State. In most cases, the land slopes were not accounted in planning and design of irrigation network. Low head, high discharge pumps were used which were not suitable for drip systems. The emission uniformity of these systems was less than 50%. The emission uniformity varied from 85 to 95% for pumpset selections which were sized to meet the requirement of the drip irrigation systems.

Send filters were not used though the water source contained mud, and algae. Screen filters were used in most of the cases. A venturi injector was used by only one farmer but it was not operatable. Chemical fertilizers were not applied through the drip systems in most cases. A maintenance schedule is provided as a guideline to the farmers.

Keywords: Water availability, pumpset selection, emission uniformity, filters

Abstract taken from paper found on pages 497 to 501 in Proceedings of 5th International Microirrigation Congress, April 2-6, 1995, Orlando, Florida. American Society of Agricultural Engineers, 2950 Niles Road, St. Joseph, Michigan 49085-9659, USA. Phone: 616-429-0300 FAX: 616-429-3852 EMAIL: HQ@ASAE.ORG