• Authors:
    • Otero, A.
    • Goni, C.
  • Source: ISHS Acta Horticulturae
  • Issue: 889
  • Year: 2011
  • Summary: Supplementary irrigation in Citrus sinensis (L.) Osbeck 'Spring' navel and Citrus unshiu Marcow trees were studied according to fruit development stages on the northwestern region of Uruguay (32S, 58W) from 2000 to 2009. The effective rainfall (Pe) variability between consecutive years is bigger than the reference evapotranspiration (ETo) variability; despite the annual water balance seems to be adequate for excellent yields. Water deficit occurs at different intensities during fruit growth stages I, II and III. Supplementary irrigation was necessary in 'Spring' navel and satsuma 'Owari' during stage I and II, although 'Spring' navel requires occasionally irrigation during stage III. The major irrigation impact was to increase the fruit weight but not the number of fruits. The increment in the marketable fruit was related to the best size distribution of the fruits, also it was verified an attenuation on the alternate bearing. An inverse and significant relationship was found between the ETo/Pe ratio and the relative yield reduction in the stage I (R 2=0.73) and in stage II (R 2=0.91); and between the ETo/Pe and the fruit weight in satsuma 'Owari', (R 2=0.56) (R 2=0.85) respectively. The yield reduction between trees without irrigation and all year irrigated represents 20% in 'Spring' navel and 40% in satsuma 'Owari'. Maximum water application of 1000-1200 m 3 ha -1 was required for irrigated trees on stage I and between 1800-2000 m 3 ha -1 for the stages I+II. In a close up view, supplementary water is required to reach maximum marketable yield and alternate bearing reduction in citrus production in temperate conditions.
  • Authors:
    • Efent'ev, A. N.
    • Grigorov, M. S.
  • Issue: 4
  • Year: 2011
  • Summary: Maize cultivation has a great potential in Russia with the current area under crop of 2.5 million ha and the prospective grain yield of 2.38 t/ha by 2015. The main reason for unstable yield of maize grain in Russia is water shortage in arid climate conditions of steppe zone. An author gives an overview of maize cultivation techniques in arid areas including fertilization, different irrigation methods, irrigation norms and regimes, irrigation machinery, as well as maize cultivars suitable for dry climate conditions. Effects of irrigation rate and fertilization on productivity of maize hybrid Povolzhskii 20 SV were studied in the production enterprise "Lider" of the Volgograd region in 2010. The maximal grain yield of 6.65 t/ha was achieved by applying irrigation rate of 3600 m 3/ha and 220:100:60 kg of NPK/ha.
  • Authors:
    • Trentin, G.
    • Maldaner, I. C.
    • Radons, S. Z.
    • Heldwein, A. B.
    • Grimm, E. L.
    • Bosco, L. C.
  • Source: Revista Brasileira de Engenharia Agrícola e Ambiental
  • Volume: 15
  • Issue: 2
  • Year: 2011
  • Summary: The objective of this study was to determine the effect of different levels of irrigation and chemical control on yield and occurrence of Late Blight in potato cv. Asterix, at Santa Maria - RS. Two experiments were conducted at the Crop Science Department, Federal University of Santa Maria. One experiment was carried out during spring-summer, 2005/2006 and the second, during fall 2006. The experimental design was a complete randomized, with four replications. The Blitecast model was used to indicate the timing of spraying, by accumulating severity values (VS). Sprinkler irrigation was used corresponding to 1.0, 0.75, 0.50 ETm and no irrigation. Results showed that in dry and high temperature periods, yield was affected by irrigation, mainly when crop water demand was supplied with 100% ETm. During wet periods, yield was affected by the efficient control of Late Blight. The Blitecast model with a severity value of 18 (Bli18) was the most efficient for controlling the disease. Irrigations applied at least every three days did not affect Late Blight incidence and development.
  • Authors:
    • Gutierrez-Martin, C.
    • Gomez Gomez, C. M.
  • Source: Spanish Journal of Agricultural Research
  • Volume: 9
  • Issue: 4
  • Year: 2011
  • Summary: This paper develops a general preference model to explain farmers' decisions. Contrary to better known and most commonly used simulation models, the one presented in this paper allows to calibrate, simulate and explain farmers' decisions without assuming linear preferences (as in many multi criteria decision models) or unobservable implicit cost functions (as in positive mathematical programming models). The model is calibrated for crop decisions in the Genii Cabra irrigated area in the Guadalquivir valley (South Spain) as the resulting empirical model is used to study how farmers react by adjusting these decisions when efficiency in the use of water is improved under different scenarios regarding water use rights. The main conclusion of the paper is that the potential water savings from enhancing irrigation technique (636 m(3) ha(-1)) are overcome by increasing water demand due to higher per drop water productivity when sunflower is replaced by maize. For that reason water price increases and/or reduction of water use rights is a necessary condition to convert water savings through improved efficiency into lower water use and better conserved water sources.
  • Authors:
    • Leib, B. G.
    • Gwathmey, C. O.
    • Main, C. L.
  • Source: Journal of Cotton Science
  • Volume: 15
  • Issue: 1
  • Year: 2011
  • Summary: Cotton ( Gossypium hirsutum L.) responses to supplemental irrigation need to be reassessed in humid, short-season environments. We conducted a 4-year study on a Typic Hapludalf at Jackson TN, to measure yield and maturity responses of contemporary cultivars to supplemental irrigation; to describe boll retention and distribution patterns associated with maturity responses; and to estimate the percentage of years in which yields may respond to irrigation. Treatments consisted of three rates of supplemental drip irrigation (nominally 3.81, 2.54, and 1.27 cm wk -1, adjusted for rainfall and prior irrigation), plus a non-irrigated check. Irrigation increased lint yields significantly in 3 of 4 years, with quadratic rate responses. The average yield increase was 38% at the 2.54-cm wk -1 rate. Yields were maximized with 35 to 37 cm of total water (irrigation+rainfall) between 40 and 120 days after planting. Yields were limited more by the accumulation of heat units than water supply in 2009. Irrigation delayed crop maturity by an average of 0.56 days for every additional cm water from irrigation or rainfall. Full irrigation expanded the effective fruiting zone on the plant from about 6.6 to 8.5 sympodial branches, increasing first position boll retention, but it delayed crop maturity mainly by shifting the location of the highest harvestable boll. Response to water supply showed that a yield response to irrigation could be expected in years with
  • Authors:
    • Xu, Y. L.
    • Gao, S.
    • Wang, J. C.
    • Han, X. F.
  • Source: Journal of China Agricultural University
  • Volume: 16
  • Issue: 3
  • Year: 2011
  • Summary: To explore the effect of under-mulch-drip irrigation on canopy photosynthesis, canopy structure and yield formation of hybrid cotton planted in Xinjiang, an experiment with limited drip irrigation was carried out under field condition. The results were as follow: limited drip irrigation caused water deficiency in cotton field, reduced canopy apparent photosynthesis (CAP) and leaf area index (LAI); under this treatment, the canopy respiration rates (CR) and the ratio of CR to total CAP were higher in fully flowering stage but fell rapidly in full boll stage. The limited drip irrigation increased leaf mean foliage inclination angle (MFLA), transmission coefficient for diffuse penetration (TCDP) and transmission coefficient for radiation penetration (TCRP), with low light interception rate; On the other hand, excessive drip irrigation promoted the over-rapid growth of hybrid cotton, canopy leaf source capacity (CLSC) and high dry matter accumulation. But CR increased rapidly at late growth stage, and CAP was at its minimum level, result in low yield. In the case of hybrid cotton, under appropriate irrigation treatment, CAP was higher, and LAI increased sharply. It maintained at a higher LAI level at late stage, so it had a steady growth and optimal leaf physiological function which led to higher yield. Studies showed that the suitable amount of drip irrigation for Zhaofeng-1 in South Xinjiang was 3 000-4 125 m 3/nm 2. Its corresponding yield was 7 714.3-8 289.5 kg/hm 2. The ideal canopy photosynthesis characteristic and canopy structure targets of hybrid cotton were discussed.
  • Authors:
    • Hassanpanah, D.
  • Source: African Journal of Biotechnology
  • Volume: 10
  • Issue: 2
  • Year: 2011
  • Summary: This experiment were conducted on the 3 cultivars of potato (Agria, Satina and Caesar) and 4 irrigation regimes (after 30 mm evaporation from class A evaporation pan, after 30 mm evaporation from class A evaporation pan with spraying by potassium humate, after 60 mm evaporation with spraying by potassium humate and after 60 mm evaporation from class A evaporation pan) in 3 locations of Ardabil in northwestern Iran and in 2 years (2007-2008), experimental design was split plot with 3 replications. Potassium humate sprayed (250 ml ha -1) in the 3 stages of emergence, before tuberization and during tuberization period. Combined analysis of variance showed that were significant differences between locations, years, irrigation regimes and cultivars and their interaction on tuber yield. The analysis of variance for the AMMI model of tuber yield showed that environments, cultivars * environments interaction and AMMI component1 were significant. Results show that Agria and Caesar cultivars had high tuber yield in all of sites and 4 irrigation regimes in 2 years, caesar cultivar had the less slop, S.E., MS-TXL, MS-REG and MS-DEV among other cultivars and was the most stable cultivar. The Agria cultivar has adapted in Alarog, Hassanbarog and Khoshkeroud sites under normal and normal with potassium humate conditions, Caesar and Satina cultivars in Alarog, Hassanbarog and Khoshkeroud sites under stress with potassium humate and stress conditions in order to ensure their yield stability and economic profitability.
  • Authors:
    • Hebbar, K. B.
    • Mayee, C. D.
  • Source: Current Science
  • Volume: 100
  • Issue: 11
  • Year: 2011
  • Summary: There are several reasons why plants wilt. Some of them are over-watering, lack of water, too much sun, not enough sun, too many/much fertilizers, diseases caused by infection, etc. Wilt due to lack of water or other environmental factors generally occurs gradually and hence, the cause of those can be studied and accordingly it can be controlled by devising appropriate management strategies. Moreover, plants recover with appropriate control measures and continue to yield. In this review, we discuss a typical wilt which is sudden and occurs within a few hours. Hence, understanding the cause and devising a control measure are difficult. Its sporadic distribution and untimely occurrence further complicate the effort to find the cause of this wilt. Unlike the wilt mentioned above which occurs due to lack of water, sudden wilt occurs when the soil is suddenly saturated by a downpour of rain and the sun later shines bright and hot. Paradoxically, the physiological responses, i.e. wilt symptoms to those induced by either drought or flooding are similar. However, the causal mechanism is different. Here, we demonstrate that the imbalance in uptake and loss of water under flooding is the cause of sudden/parawilt of cotton. We also discuss how plants with rapid growth rate and climate factors like bright sunshine and high temperature accentuate the problem of parawilt in cotton.
  • Authors:
    • Lu, X.
    • Xie, X.
    • Wang, H. J.
    • Ye, J.
    • Hou, Z. A.
    • Hou, S.
  • Volume: 47
  • Issue: 9
  • Year: 2011
  • Summary: A field experiment was conducted to study cotton growth and nitrogen uptake in response to different water and nitrogen application rates under drip irrigation with saline water. Three irrigation water salinity levels were set as 0.35 (S 1), 4.61 (S 2) and 8.04 (S 3) dS/m; two water and nitrogen application rates were set as 405 (L 1), 540 (L 2) mm and 240 (N 1), 360 (N 2) kg/hm 2, respectively. The results showed that plant height of cotton were influenced significantly by water salinity, application rates of water and interaction between them, and the interaction among water salinity, water application rate and nitrogen application rate at earlier growth stage, but mainly affected by water application rate at the later stage. The order of plant height were S 2 > S 1 > S 3 with water application 540 mm (L 2), while no significant difference were found on the growth of plant height between two nitrogen rates. The dry matter accumulation of the cotton stem and leaves are influenced significantly by the interaction among water salinity, application rates of water and nitrogen application, but cotton bolls and total dry matter accumulation are not significantly influenced by the interaction. Nitrogen uptake of cotton was influenced significantly by water salinity, application rates of water and nitrogen, and interactions between two of them or among the three factors. Total nitrogen content of cotton reduced with water salinity increasing, but increased evidently when water application rate was increased. Those results suggest that higher water application rate can enhance nitrogen uptake of cotton under drip irrigation with saline water.
  • Authors:
    • Loveys, B. R.
    • Hutton, R. J.
  • Source: Agricultural Water Management
  • Volume: 98
  • Issue: 10
  • Year: 2011
  • Summary: In Australian irrigated citriculture, fruit yield and quality outcomes are not tightly related to levels of plant available water, which raises the possibility of using mild water stress applied to part of the root zone, i.e. partial root zone drying, to stimulate physiological mechanisms that reduce tree water use by changing the relationship between stomatal conductance and ambient evaporative conditions. The PRD technique alternates irrigation such that one side of the tree root zone is allowed to dry whilst the other side is irrigated. This significantly reduces the wetted soil volume at any point in time, whilst always maintaining a readily available water supply to part of the root zone. By adopting this irrigation strategy water use of mature Navel orange trees C. sinensis (L.) Osbeck was reduced and water use efficiency was increased. The technique did not induce excessive fruitlet drop and crop yield was unaffected. Both fruit size and juice percentage slightly decreased whereas total soluble solids percentage (TSS) and juice acid percentage increased. As water use was reduced and juice quality attributes were increased, this technique has obvious benefits for juice fruit production. PRD offers an advantage over conventional deficit irrigation strategies because it helps reduce water use by separating the biochemical signaling responses to water deficit in the dry part of the root zone from the physical effects of reduced stomatal conductance due to lower water availability, allowing developmental processes associated with plant growth to remain unperturbed. Irrigating a reduced root zone volume in this way reduces crop water requirement. However, it is also important to understand that this technique pushes the crop to its limits and should only be applied to well established healthy trees. When applying PRD irrigation, it is important that water is supplied with sufficient frequency and depth of wetting to meet the water needs of the whole plant.