201. Estimation of soil water deficit in an irrigated cotton field with infrared thermography

• Authors:
  • Misra, R. K.
  • Padhi, J.
  • Payero, J. O.
• Source: Field Crops Research
• Volume: 126
• Year: 2012
• Summary: Plant growth and soil water deficit can vary spatially and temporally in crop fields due to variation in soil properties and/or irrigation and crop management factors. We conducted field experiments with cotton (Gossypium hirsutum L.) over two seasons during 2007-2009 to test if infrared thermography can distinguish systematic variation in deficit irrigation applied to various parts of the field over time. Soil water content was measured with a neutron probe and thermal images of crop plants were taken with a thermal infrared camera. Leaf water potential and stomatal conductance were also measured on selected occasions. All measurements were made at fixed locations within three replicate plots of an irrigation experiment consisting of four soil-water deficit treatments. Canopy temperature related as well with soil water within the root zone of cotton as the stomatal conductance index derived from canopy temperature, but it neglected the effect of local and seasonal variation in environmental conditions. Similarities in the pattern of spatial variation in canopy temperature and soil water over the experimental field indicates that thermography can be used with stomatal conductance index to assess soil water deficit in cotton fields for scheduling of irrigation and to apply water in areas within the field where it is most needed to reduce water deficit stress to the crop. Further confidence with application of infrared thermography can be gained by testing our measurement approach and analysis with irrigation scheduling of other crops. (C) 2011 Elsevier B.V. All rights reserved.

202. Suitability of trunk diameter reference lines for irrigation scheduling with saline water in late mandarin trees with different crop load.

• Authors:
  • Conesa, M. R.
  • Domingo, R.
  • Perez-Pastor, A.
  • Pagan, E.
  • Caro, M.
• Source: Agricultural Water Management
• Volume: 111
• Year: 2012
• Summary: A two year experiment on Fortune mandarin trees (Clementina * mandarina Dancy ( Citrus clementina Hort. Ex. Tanaka * Citrus reticulata Blanco)) grafted onto Cleopatra mandarin ( Citrus reshni Hort. ex. Tanaka) rootstock was carried out with the aim of studying the suitability of midday stem water potential (psi stem) and trunk diameter reference baselines for irrigation scheduling. Plants were drip-irrigated with saline water during the second year (EC 25°C ~ 4 dS m -1). Measurements of psi stem, trunk daily growth rate (TGR) and maximum daily trunk shrinkage (MDS) were related with meteorological variables. Among them, MDS presented the best behavior. The mean temperature during the period 10.00-15.00 h solar time ( Tmd) was the environmental variable that best correlated with MDS, although there were no differences with other T-related variables (daily mean and daily maximum values). MDS data from stage III did not correlate with meteorological variables and fit-linear regressions became better with data from stages I and II (March-October), this being the period which covers 80% of total crop water requirements. Despite the different conditions that the trees were submitted to during the experimental period, i.e. irrigation water with different salinity and crop load, inter-annual differences were not observed in the reference baselines obtained.

203. Effects of drip irrigation regimes and basin irrigation on Nagpur mandarin agronomical and physiological performance.

• Authors:
  • Huchche, A. D.
  • Srivastava, A. K.
  • Panigrahi, P.
• Source: Agricultural Water Management
• Volume: 104
• Year: 2012
• Summary: The scarcity of irrigation water is one of the major causes of low productivity and decline of citrus orchards. The present study was planned with a hypothesis that the drip irrigation (DI) could save a substantial amount of water over surface irrigation, besides improving the yield of citrus plants. The experiment was conducted for 3 seasons during 2006-2009, with 'Nagpur' mandarin ( Citrus reticulata Blanco) plants budded on rough lemon ( Citrus Jambhiri Lush) rootstock in central India. The effects of DI and basin irrigation (BI) on soil chemical properties and crop responses were studied. DI was scheduled every-other-day at 40%, 60%, 80% and 100% of the alternate day cumulative evaporation ( Ecp) measured in Class-A evaporation pan. DI except irrigation at 40% Ecp proved superior to BI, producing more growth and fruit yield of plants. The higher plant growth was recorded with higher regime of DI. The maximum fruit yield in DI at 80% Ecp, using 29% less irrigation water resulted in 111% improvement in irrigation water productivity under this treatment over BI. The heavier fruits, with lower acidity and higher total soluble solids, were harvested in DI at 80% Ecp compared with BI. The significant variation of soil water content at 0-0.2 m depth under DI indicated the confinement of effective root zone of the plants in top 0.2 m soil. The maximum rate of net-photosynthesis, stomatal conductance and transpiration in leafs was recorded in DI at 100% Ecp. However, the plants under DI at 80% Ecp exhibited the highest leaf water use efficiency. The maximum salinity build-up with highest decrease in pH was observed in 0-0.2 m soil under DI, whereas the salinity development was prominent in 0.4-0.6 m soil with an increase in pH under BI. The gain in available macronutrients (N, P and K) and loss of micronutrients (Fe, Mn, Cu and Zn) in soil followed the similar trend of EC. The leaf nutrient (N, P, K, Fe, Mn, Cu and Zn) analysis revealed that DI produced significantly ( P

204. Plant nutrition in response to drip versus basin irrigation in young 'Nagpur' mandarin on inceptisol.

• Authors:
  • Huchche, A. D.
  • Srivastava, A. K.
  • Panigrahi, P.
  • Singh, S.
• Source: Journal of Plant Nutrition
• Volume: 35
• Issue: 2
• Year: 2012
• Summary: Evaluation of drip irrigation treatments scheduled at 40, 60, 80, and 100% of alternate day cumulative pan evaporation (Ecp) against basin irrigation method was undertaken in 1-year-old 'Nagpur' mandarin ( Citrus reticulata Blanco) trees budded on rough lemon [ Citrus jambhiri (L)] rootstock on an alkaline Inceptisol soil type for three seasons during 2003-2005. Growth responses showed significantly ( P≤0.05) higher annual increase in tree height (0.44-0.50 m), scion girth (37-45 mm), and canopy volume (0.508-0.986 m 3) under drip-irrigation except irrigation at 40% Ecp, compared to tree height (0.40 m), scion girth (36 mm), and canopy volume (0.463 m 3) under basin irrigation. The highest magnitude of increase in different growth parameters was observed with drip irrigation at 80% Ecp, which produced the net water saving of 32% over basin irrigation method. Response on leaf nutrient composition under drip irrigation at 80% Ecp likewise produced the similar response, [2.27% nitrogen (N), 1.98% potassium (K), and 121.8 ppm iron (Fe)], significantly ( P≤0.05) higher than under basin irrigation (1.12% N, 1.04% K, and 98.3 ppm Fe), with other nutrients, e.g., phosphorus (P), manganese (Mn), copper (Cu), and zinc (Zn) remained unaffected.

205. Effect of Water Stress on Growth Performance of Bt-Cotton Inoculated with AM Fungi

• Authors:
  • Shinde, B. P.
  • Patale, S. W.
• Source: Adv Pl Sci
• Volume: 25
• Issue: 1
• Year: 2012
• Summary: A study was conducted to determine the effects of arbuscular mycorrhizal (AM) fungi inoculation on growth of cotton grown under well watered and water stressed pot culture conditions. 15 days old cotton seedlings were planted in earthen pots after treatment with or without the AM fungi. Roots were sampled after 45, 90, and 135 days of growth stages to quantify AM fungi. Mycorrhizal colonization was higher in water-stressed plants than well-watered plants. Biomass was higher in mycorrhizal than non-mycorrhizal plants irrespective of water treatments. However the plants irrigated with alternate watering schedule had shown higher biomass and than those treated with daily watering. The improved growth in cotton plants reported here demonstrate the potential of mycorrhizal inoculation to reduce the effects of drought stress and useful for the better performance under stress conditions.

206. Optimal irrigation regime and soil moisture dynamics of cotton crop in Vidarbha region of Maharashtra.

• Authors:
  • Parhad, V. N.
  • Ramamurthy, V.
  • Patil, N. G.
• Source: Journal of Cotton Research and Development
• Volume: 26
• Issue: 1
• Year: 2012
• Summary: An experiment was conducted on farmer's field to observe the effects of different drip irrigation regimes on water use efficiencies (WUE) and soil moisture status for cotton variety NHH44 in Vidarbha region during 2001 and 2002. Treatments were based on open pan evaporation approach. The highest cotton yield was obtained from the least irrigation treatment (T 1). WUE ranged from 0.02 kg/ha/mm in the treatment T 5 to 0.34 kg/ha/mm in T 1. The greatest irrigation water use efficiency (IWUE) was observed in treatment T 1 (2.26 kg/ha/mm), and the smallest IWUE was in treatment T 5 (0.18 kg/ha/mm) in the experimental years, indicating saving of more than 58 per cent irrigation water. Soil moisture status was below 50 per cent of available water capacity (AWC) for 105 days in 2001 as compared to 135 days in 2002 in T 1 implying that light irrigations in place of 6 cm for the clay soils in this part would be preferable and drainage of excess rainwater could be critical to improve yields.

207. Soil chemical properties, leaf mineral status and crop production in a lemon tree orchard irrigated with two types of wastewater.

• Authors:
  • Alarcon, J. J.
  • Gil, M. I.
  • Allende, A.
  • Pedrero, F.
• Source: Agricultural Water Management
• Volume: 109
• Year: 2012
• Summary: The effects of applying different types of treated wastewater on citrus trees were studied in Murcia, in the south-east of Spain. Two treatments with wastewater effluents of different quality were applied for three consecutive years. In the first case, the wastewater received a secondary treatment (conventional activated sludge). In the second case, the irrigation water was a mix of well water and wastewater from a tertiary treatment plant (conventional activated sludge with ultraviolet tertiary treatment). The characteristics of the tertiary treated wastewater make it better for irrigation than the secondary treated wastewater. It was considered that high salinity, Cl and B concentration could be the main restrictions associated with treated wastewater irrigation in both cases, although leaf toxicity levels were not observed. The soil nitrate concentration increased over the experimental time period in both water irrigation treatments. The production was affected by the wastewater quality and the total crop yield was lower in the plots irrigated with secondary treated wastewater. However, in these plots, the fruit-quality indexes such as external colour, weight, peel thickness, firmness, soluble solids, pH, total acidity and maturity index were significantly better than those observed in the plots irrigated with tertiary treatment. The soil microbiological analysis revealed an absence of faecal coliforms, Escherichia coli and helminth eggs in the experimental plots irrigated with tertiary treated wastewater, but with secondary treated wastewater the soil accumulation of faecal coliforms exceeded health standards. In both cases, there was an absence of microbiological contamination on fruits.

208. Nutrients and nonessential elements in soil after 11 years of wastewater irrigation.

• Authors:
  • Montes, C. R.
  • Stoffella, P. J.
  • He, Z. L.
  • Pereira, B. F. F.
  • Melfi, A. J.
  • Baligar, V. C.
• Source: Journal of Environmental Quality
• Volume: 41
• Issue: 3
• Year: 2012
• Summary: Irrigation of citrus ( Citrus aurantium L. * Citrus paradise Macf.) with urban reclaimed wastewater (RWW) can be economical and conserve fresh water. However, concerns remain regarding its deleterious effects on soil quality. We investigated the ionic speciation (ISP) of RWW and potential impacts of 11 yr of irrigation with RWW on soil quality, compared with well-water (WW) irrigation. Most of nutrients (~53-99%) in RWW are free ionic species and readily available for plant uptake, such as: NH 4+, NO 3-, K +, Ca 2+, Mg 2+, SO 42-, H 3BO 3, Cl -, Fe 2+, Mn 2+, Zn 2+, Co 2+, and Ni 2+, whereas more than about 80% of Cu, Cr, Pb, and Al are complexed with CO 3-, OH -, and/or organic matter. The RWW irrigation increased the availability and total concentrations of nutrients and nonessential elements, and soil salinity and sodicity by two to three times compared with WW-irrigated soils. Although RWW irrigation changed many soil parameters, no difference in citrus yield was observed. The risk of negative impacts from RWW irrigation on soil quality appears to be minimal because of: (i) adequate quality of RWW, according to USEPA limits; (ii) low concentrations of metals in soil after 11 yr of irrigation with RWW; and (iii) rapid leaching of salts in RWW-irrigated soil during the rainy season.

209. Partial rootzone drying increases water-use efficiency of lemon Fino 49 trees independently of root-to-shoot ABA signalling.

• Authors:
  • Dodd, I. C.
  • Pérez-Pérez, J. G.
  • Botía, P.
• Source: Functional Plant Biology
• Volume: 39
• Issue: 5
• Year: 2012
• Summary: To determine whether irrigation strategy altered the sensitivity of Citrus leaf gas exchange to soil, plant and atmospheric variables, mature (16-year-old) Fino 49 lemon trees ( Citrus limon (L.) Burm. fil. grafted on Citrus macrophylla Wester) were exposed to three irrigation treatments: control (irrigated with 100% of crop potential evapotranspiration, ET c), deficit irrigation (DI) and partial rootzone drying (PRD) treatments,which received 75% ET c during the period of highest evaporative demand and 50% ET c otherwise. Furthermore, to assess the physiological significance of root-to-shoot ABA signalling, the seasonal dynamics of leaf xylem ABA concentration ([X-ABA] leaf) were evaluated over two soil wetting-drying cycles during a 2-week period in summer. Although stomatal conductance ( gs) declined with increased leaf-to-air vapour pressure deficit (LAVPD), lower leaf water potential and soil water availability, [X-ABA] leaf was only related to stomatal closure in well irrigated trees under moderate (

210. Interactions between irrigation regimes and varieties result in altered cottonseed composition.

• Authors:
  • Pettigrew, W. T.
  • Dowd, M. K.
• Source: Journal of Cotton Science
• Volume: 16
• Issue: 1
• Year: 2012
• Summary: The value of whole cottonseed and cottonseed products has increased as demand has grown from the dairy and food related industries. Although cottonseed composition has previously been documented to be affected by variety, planting date, and irrigation, interactions between varieties and irrigation regimes have not been adequately described. Six different varieties were planted on two planting dates and grown under irrigated or dryland conditions to document how varieties interacted with irrigation regimes to impact various seed composition traits. Variety was a major source of variation for all the seed composition traits quantified. Individual seed mass variation among varieties could explain some of the seed composition variation observed, particularly for protein. For many of these seed composition traits, variety also interacted statistically with irrigation regimes to impact trait expression. Most seed composition traits of the varieties responded in the same direction to irrigation, but there was sufficient variety variation in the response that significant interactions were produced. 'ST 5599BR' often exhibited a different irrigation response compared to the other varieties, particularly for the different fatty acid components. These results indicate that a pairing of varieties and management practices could be utilized to help achieve desired seed composition traits. Although lint production is the primary economic incentive for cotton producers, improved cottonseed composition offers an important, consistent, and reliable secondary revenue stream for producers.