Low Irrigation Levels Research Articles

Control of Japanese Beetle Larvae with Insecticide Mixtures, 1997

Abstract The study was conducted in the short rough alongside a golf course fairway at Urbana Country Club, Urbana, IL. The fairway, short, and long rough consisted of Kentucky bluegrass. A RCB design was used because an outlet for the fairway’s irrigation system was directly opposite block 1, resulting in successively lower levels of irrigation and JB infestation from block 1 through 3. Plots were 5 X 10 ft and were arranged in a single row. Insecticide applications were applied in 3 replications on 16 Sep. Liquid applications were applied with a watering can, and the granular application (Dylox) was shaken from a measuring spoon. Insecticides were watered into the soil within 30 min after all applications were completed with approximately H inch irrigation. At the time of application, it was partly cloudy, 80°F, 50% relative humidity, and with winds < 10 mph. Soil pH was 6.1 with no thatch and was moist at application and 21 DAT. Grub sampling was conducted with a 6-inch diam sod sampler taking five scattered samples in each plot. All the JB grubs were counted in each ⅕ ft2 sample and the numbers were added together in each plot to obtain a ft2 measure. An ANOVA was conducted on the data and means separated by LSD test at P = 0.05.

Effect of Fall Irrigation Level in `Mauritius' and `Floridian' Lychee on Soil and Plant Water Status, Flowering Intensity, and Yield

The effect of fall irrigation level in `Mauritius' and `Floridian' lychee (Litchi chinensis Sonn.) on soil and plant water status, flowering intensity, and yield the following year was studied in a field during 2 consecutive years. At the end of the second vegetative flush after harvest (1 Oct. 1994 and 10 Oct. 1995), four irrigation treatments were initiated: 0.5, 0.25, 0.125, and 0 Class A pan evaporation coefficients designated 100%, 50%, 25%, and 0%. The three lower irrigation levels effectively stopped shoot growth, suggesting the 50% treatment to be the threshold for shoot growth cessation in both years. For both years, flowering intensity and yield in the 100% treatment were lower than those following the other three treatments. Soil and plant water-stress indicators responded to the water-stress irrigation treatments. However soil water-potential values were highly variable relative to plant water potentials. Stem water potential differed more markedly between treatments than leaf water potential. Midday stem water potential appeared to be the best water-stress indicator for irrigation control. Midday stem water potential in both years was correlated with midday vapor-pressure deficit, suggesting that the threshold for irrigation control should take into account evaporative demand.

Modeling the effect of capillary water rise in corn yield in Portugal

There are regions in Europe such as Italy, Portugal, or Holland in which capillary water rise plays an important role in crop water regimes. The objectives of this work were: to modify an existing simulation model (CERES-maize) by including a capillary rise submodel; to use it for predicting the production function of corn grown above a shallow ground water table; and to compare model prediction with experimental results in Portugal. It is assumed that the capillary rise determines the initial conditions of soil water profile within the root zone, just before the sowing day. The model was used to simulate several theoretical and experimental situations for forage corn. Simulation results showed that the production function reaches an optimal yield when the best combination of soil, air and water is obtained. Capillary rise has a negative effect on yield, at high irrigation level. At low irrigation level, the best combination of air and water was obtained when ground water table depth was about 1 m below surface. The good determination coefficient (r2=0.92) indicated that results of simulations were in good agreement with experimental results. It is concluded that upward flow from shallow water is a significant component in the irrigation water balance of corn.

Effects of irrigation and N fertilizer application on sugarcane yield and quality

Sugarcane requires substantial inputs of both water and nitrogen to achieve maximum yields. This study was conducted to evaluate the effect of reduced water availability on sugarcane growth, quality and yield as well as its effects on responses to N fertilizer. Irrigation treatments consisted of scheduling water application at different soil moisture depletion levels. Higher soil inorganic N levels and differences in soil N due to irrigation level and N application rate occurred in the second ratoon, a dry season with low yields and low total N uptake. Plant N concentration was greatest with the least irrigation; uptake of N by well-irrigated crops was greater but it was diluted within the plants through greater biomass production. Plant N concentration also increased with increasing N application rate. As irrigation levels increased, sugar yields increased, a function of both increasing cane yield and increasing sucrose content. Cane yields responded to N application only in ratoon crops, an indication that adequate N was already available in the plant-cane crop. Responses to N application were greatest at the high irrigation level and were not as pronounced at the lower irrigation level, indicating that if water is limiting, sugarcane cannot take advantage of increased N availability.

Effect of gypsum, deep ripping, and irrigation on determinate tomatoes

Treatments of gypsum, deep ripping, and level of irrigation were applied to alluvial soils at Carnarvon, Western Australia, to assess the effect on yield of determinate tomatoes. Yield was increased (P<0.05) from 3 1.9 to 41.5 t/ha when gypsum (5 t/ha) was applied and increased (P<0.05) with level of irrigation (65.6 t/ha at 699 mm v. 14.9 t/ha at 270 mm). Blossom end rot and total soluble solids in fruit were significantly (P<0.05) higher at low and medium irrigation (355 mm) levels than at the high level. Total soluble solids increased significantly (P<0.05) when gypsum was applied to deep-ripped treatments. Dispersion of soil colloids was significantly (P<0.05) reduced by gypsum. Deep ripping to 0.6 m removed the soil hardpan but had no effect on tomato yield or dispersion.

Soybean Cultivar Yield Response to Benomyl, Nitrogen, Phosphorus, and Irrigation Levels

AbstractSoybean [Glycine max (L.) Merr.] production for greatest yield involves intensive management of resource inputs. Proper cultivar selection, irrigation, and P application on P‐deficient soils have all been shown to increase yields. Nitrogen applications have resulted in variable yield effects. Under sprinkler irrigation, several diseases caused by species of Diaporthe [D. phaseolorum var. sojae (Lehman) Wehm., and D. phaseolorum var. caulivora Athow. G Caldwell.] and Phomopsis longicolla Hobbs, the Diaporthe/Phomopsis complex may also be yield limiting. This disease complex includes pod and stem blight (PSB), Phomopsis seed decay (PSD), and stem canker. In order to determine the combined influence of cultivar, irrigation level, fertility level, and disease control, field experiments were conducted in 1986, 1987, and 1988 at the South Central Research and Extension Center near Clay Center, NE to evaluate these possible soybean yield limiting factors. All combinations of two levels of benomyl [methyl‐l‐(butylcarlbamoyl)‐2‐benzimidazole carbamate] fungicide (0 and 1.12 kg ha−1 applied at R3 and R5), two levels of N (0 and 134.4 kg ha−1) and P (0 and 67.2 kg ha−1), and two cultivars (determinate Hoyt and indeterminate Zane) were tested at two nonreplicated levels of irrigation. Nitrogen and P application seldom increased seed yield. A yield increase (517 kg ha−1, 1986; 396 kg ha−1, 1987; 215 kg ba−1, 1988) occurred when benomyl was applied to Hoyt soybean under a high level of irrigation. Less of a yield response to benomyl was obtained with later‐maturing Zane, for both cultivars at the lower irrigation level, and during a year of below normal rainfall. Benomyl application decreased the incidence of PSB and increased seed size, but did not consistently affect PSD based on seed appearance. Stem canker was never observed during the course of this study. Yield increases were primarily the result of increased seed size associated with delayed maturity doe to PSB control and increased number of seeds per pod due to benomyl's possible growth regulatory properties. This research indicates that, contrary to previous reports in the northern USA, pod and stem blight can be a yield‐limiting factor with or without the development of Phomopsis seed decay under high‐yield environments.

EFFECT OF IRRIGATION AND FERTILITY LEVELS ON NUTRIENT CONTENT, UPTAKE AND RECOVERY IN RABI MAIZE.

Experiments at Banaras Hindu University, Varanasi (U.P.) on rabi maize during 1985- 1986 and 1986-1987 revealed that N and K,O content of plants (shoot + leaves) increased with increasing irrigation levels but decreased with advancement in age of crop. The P₂O, content was lower at higher irrigation levels as compared to lower irrigation levels and the PO, content increased with advancement in age of crop. Uptake and recovery of N, P,O, and KO increased with increasing levels of irrigation.

Water-Table Contribution to Alfalfa Evapotranspiration and Yields in Sandy Soils

ABSTRACT IN a lysimeter experiment, four constant water-table depths and three irrigation levels were evaluated for their effects on annual alfalfa yields and growing season evapotranspiration (ET) for 2 years. Alfalfa yields were depressed and ET was excessive for the shallow (46 cm) water-table depth. The 2 years of cropping data, after an alfalfa establishment year, and excluding data from the shallowest (46 cm) water-table depth, indicated that growing-season ET values were 55.3, 64.2, and 69.3 cm with average yields of 14.0, 14.9, and 14.4 t/ha and water use efficiency (WUE) values of 4.0, 4.1, and 4.9 cm/t/ha respectively for 0.3, 0.8 and 1.3 irrigation levels (combinations of surface-applied irrigation plus rainfall that were equivalent to 0.3, 0.8, and 1.3 times calculated ET). The water table, through subirrigation, provided a sizable contribution to actual ET, which increased as level of surface irrigation decreased. Subirrigation provided 38.4% of total ET for the low (0.3) irrigation level, compared to only 0.6% of total ET for the high (1.3) irrigation level.

Influence of Lower Levels of Irrigation and Fertilization on wheat Production

The field studies on the effect of irrigation and fertilization on production potential of wheat during 1979-80and80-81 revealed that any reduction in recommended fertilizer and irrigation levels reduced grain yield significantly. Two post-sowing irrigation given at CRI and milky stages increased mean grain yield by 10 g/ha (62.5%) over control. Two more irrigation applied at jointing and flowering stages increased 4 q/ha in mean grain yield. Mean grain yield reduced by 3.7 and 3 q ha when recommended fertilizer dose (80-60-40) was re- duced upto 66-6 and 33,3 percent respectively. Irrigation water use efficiency and nutrient response decreased with increasing levels of irrigation and fertilizer doses.

Effect of Polyethylene Mulch and Summer Irrigation Regimes on Subsequent Flowering and Fruiting of ‘Olympus’ Strawberry1

Abstract Strawberries [Fragaria × ananassa Duch. cv. Olympus] were planted in 2 successive years and grown at 3 levels of drip irrigation, with and without polyethylene mulch. Differential irrigation was applied only during 1 (1977) or 2 (1978) months during the summer and all treatments were irrigated equally during the following spring. In both summers, the soil water potential at 20-cm depth was maintained above −0.5 bars for the highest level of irrigation and fell below −11 bars at the low level. Mulch conserved soil moisture at the 2 lower irrigation levels in 1977, but this effect was nearly absent in 1978 conditions. The highest irrigation regime had about 22% more flowers and 18% more fruit than the lowest regime in the spring of the first harvest season in both plantings. Mulch only increased flowering in the 1977 planting (12%), whereas the number of fruit was increased about 11% by mulch in both plantings. The high yield capacity of ‘Olympus’ was confirmed (37.8 MT/ha). Mulch increased the yield of the 1978 planting 18%, despite its lack of effect on the number of flowers in that year. This suggests a spring influence on yield. The highest irrigation regime out-yielded the lowest regime by 13% in the first crop of both plantings, although this increase was significant only in the 1977 planting. The second year crop of the 1977 planting yielded 21% less than the first year, and failed to show significant treatment differences in flower number or fruit yield despite much larger plant size with mulch and higher irrigation levels. The yield component which showed the greatest decline between years was the percentage fruit set. In general, mulch and greater summer irrigation increased fruit yield less dramatically than they enhanced vegetative growth. However, the 13% to 18% increases may represent a significant economic gain because the typical yield of ‘Olympus’ is much higher than other Pacific Northwest cultivars. Mulch also produced a greater water use efficiency.

Vegetative Growth Response of ‘Olympus’ Strawberry to Polyethylene Mulch and Drip Irrigation Regimes1

Abstract Two field plantings of strawberries [Fragaria × ananassa Duch. cv. Olympus] were grown with and without black polyethylene mulch at 3 levels of drip irrigation and differential irrigation was maintained after plant establishment for 1 month in 1977 and 2 months in 1978. During the driest portion of each year the soil water potential at 20 cm depth remained above −0.5 bars for the highest level of irrigation, and fell below −11 bars at the lowest level. Mulch conserved soil moisture at the 2 lower irrigation levels in 1977, but this effect was minor in 1978. Vegetative growth was increased by both irrigation and mulch. The number of leaves produced during the first growing season was 30% (1977) and 25% (1978) greater in the high than the low-irrigation regime. Mulching improved leaf production 27% (1977) and 14% (1978). Most of these vegetative differences between treatments were still apparent at fruit harvest the following July. During a second year of treatments on the 1977 planting, the number of leaves was further enhanced by mulch and high irrigation. At the subsequent fruit harvest, 2-year-old plants had more leaves than those 1 year old, but the leaf area per plant averaged 27% lower. Leaf and crown dry weights of either 1- or 2-year-old plants at fruit harvest were slightly greater due to irrigation and significantly higher due to mulch, whereas root dry weight was unaffected by either treatment. The amount of summer irrigation required to sustain vigorous vegetative growth in mulched plants was only one third that of unmulched strawberries.

Corn and Alfalfa Production as Influenced by Irrigation and Salinity

AbstractYields of corn and alfalfa were determined where both salinity and water stress were imposed. Yields of corn (Zea mays L.) at Logan, Utah in 1975 were decreased by salinity or water stress (caused by low irrigation levels) in direct relation to the decrease in evapotranspiration. The decrease in evapotranspiration was caused by a decrease in soil water depletion, indicating that salinity influenced soil water availability. Corn yields at Vernal, Utah in 1974 were decreased by salinity, but to a considerably lesser extent by low irrigation, probably because of water flow upward into the root zone from a water table. Alfalfa (Medicago sativa L.) yields at Vernal in 1974 were not decreased by salinity or by low irrigation rates, because of water supplied by a water table and used by roots below the zone of salinity.

Performances of Six Grass Species under Different Irrigation and Nitrogen Treatments1

SynopsisGrass species varied in response to N, particularly at high rates of application. Species response to irrigation was similar, except for orchardgrass, which was adversely affected by low irrigation levels in 1959 and consequently showed the greatest response to irrigation treatment. Neither irrigation nor nitrogen affected the characteristic yield decline of species in mid‐ and late season. Decreases in yields of species as stands aged varied among species and were greater at low than at high irrigation and nitrogen levels.

On the significance of the middle arch: Ramiro H. Pavón-Caballero, M.D., Holguin, Cuba

Sclerotinia sclerotiorum is a necrotrophic fungal pathogen that causes white mold of dry bean (Phaseolus vulgaris L.). Chemigation with fungicides is used for disease control, but effectiveness of this application method and impact of irrigation level on residual fungicide activity in the plant over time under field conditions has not been well characterized. To assess the best method of application and fungicide for disease control, we conducted field studies in three field sites in São Paulo State in Brazil. Contact fungicide, fluazinam, was applied via center pivot at three irrigation levels (2.5, 5.1, 10.1 mm) at the Itaí field site in 2013. Fluazinam and procymidone (systemic) were independently applied via sprinkler at three irrigation levels (3.0, 4.5, 6.0 mm) in 2013 and four irrigation levels (2.5, 5.0, 7.5, 10.0 mm) in 2014 at the Pereiras field site. Fungicides were also applied at the Pereiras site using a backpack sprayer in 2014. Three successive fungicide applications were made at Pereiras in 2013 and two successive applications made at Pereiras in 2014. Three leaves from each treatment of the four replicated plots were collected in 2-day intervals after application, and fungicide residues assessed using a detached leaf bioassay. Lesion areas were used to estimate percent disease control. Regardless of fungicide or application method, disease control decreased over time (ANCOVA; P < 0.05). Area under the disease progress curve estimated from leaf lesion areas showed chemigation at the lowest irrigation level provided the best control in five of six trials of fluazinam and four out of five trials of procymidone. Ground applications were equally effective, showing no difference from chemigation at the lowest irrigation level in most comparisons. The percent reduction in number of S. sclerotiorum sclerotia, disease incidence and dry bean yield were evaluated at Pereiras in both years. Procymidone reduced the number of sclerotia formed. However, yield was only higher for treatments that included procymidone at Pereiras in 2013. Overall, results indicate that both lower irrigation level and ground application slow the loss of residual fungicide activity and reduce the total disease lesion area. Results from this study indicate that procymidone may be better able to reduce S. sclerotiorum sclerotia formation, which may be an important consideration for long-term disease management.