• Authors:
    • Pendergast, L.
    • Torabi, M.
    • Bhattarai, S.
    • Dhungel, J.
    • Chen, X.
    • Midmore, D.
  • Source: Journal of Plant Ecology
  • Volume: 4
  • Issue: 4
  • Year: 2011
  • Summary: Aims Oxygation refers to irrigation of crops with aerated water, through air injection using the venturi principle or the supply of hydrogen peroxide in the root zone, both using subsurface drip irrigation (SDI) system. Oxygation improves water use efficiency (WUE), producing more yield and, and therefore, optimizes the use of drip and SDI. But the efficiency of oxygation is quite possibly dependent on a number of factors. The primary objective of this study was, therefore, to quantify the effects of oxygation, emitter depths and soil type on crop root zone oxygen content, soil respiration, plant physiological response, biomass yield, quality and WUE of three crop species. Methods This study investigated the potential of oxygation to enhance soil respiration, plant growth, yield and water use efficiencies (WUE) of cotton and wheat in experiments in enclosed heavy-duty concrete troughs (tubs) and pineapple and cotton in field experiments. Experimental treatments in tubs for wheat included comparisons between two soil types (vertisol and ferrosol) and superimposed were two oxygation methods (Mazzei air injector and Seair Diffusion System) compared to a control, and for cotton, emitters at two depths using Mazzei air injectors were compared to a control. The field experiments compared Mazzei air injectors and a control for cotton in Emerald and pineapple in Yeppoon, both in central Queensland, Australia. Important findings In all experiments, soil oxygen content and soil respiration markedly increased in response to the oxygation treatments. The O-2 concentration in the crop root zone increased by 2.4-32.6%, for oxygation compared to control at the same depth. The soil respiration increased by 42-100%. The number of wheat ears, leaf dry weight and total dry matter were significantly greater in Mazzei and Seair oxygation compared to the control. Fresh biomass of wheat increased by 11 and 8%, and dry weight of wheat increased by 8 and 3% in Mazzei and Seair oxygation treatments compared to the control, respectively. Likewise, the irrigation water use efficiency increased with oxygation compared to the control in wheat. The yield, WUE and number of other physiological parameters in wheat were enhanced in vertisol compared to ferrosol. The seed cotton yield in the tub experiment increased with oxygation by 14%, and significant differences for fresh biomass, dry matter and yield were also noted between oxygation and the control in the field. Lint yield and WUE both increased by 7% using Mazzei in the cotton field trial during 2008-09. There were significant effects of oxygation on pineapple fresh biomass, and dry matter weight, industry yield and a number of quality parameters were significantly improved. The total fruit yield and marketable increased by 17 and 4% and marketable WUE increased by 3% using Mazzei. Our data suggest that the benefits of oxygation are notable not only for dicotyledonous cotton but also for monocotyledonous wheat and pineapple representing different rooting morphologies and CO2 fixation pathways.
  • Authors:
    • Zalucki, M.
    • Pufke, U.
    • Davies, A.
  • Source: Agricultural and Forest Entomology
  • Volume: 13
  • Issue: 3
  • Year: 2011
  • Summary: Understanding the spatio-temporal dynamics of insects in agroecosystems is crucial when developing effective management strategies that emphasize the biological control of pests. Wild populations of Trichogramma Westwood egg parasitoids are utilized for the biological suppression of the potentially resistant pest species Helicoverpa armigera (Hubner) in Bt-transgenic cotton Gossypium hirsutum L. crops in the Ord River Irrigation Area (ORIA), Western Australia, Australia. Extensive, spatially-stratified sampling during a season of relatively high Trichogramma abundance found that spatial patterns of pest egg parasitism in the ORIA tend toward heterogeneity, and do not necessarily coincide with host spatio-temporal dynamics. Both patterns of host egg density and mean rates of parasitism are not good indicators of parasitoid spatio-temporal dynamics in ORIA cotton crops. Parasitism rates can be significantly higher within the middle strata of the cotton plant canopy before complete canopy closure, despite a similar number of host eggs being available elsewhere in the plant. Spatial variation in egg parasitism by Trichogramma in Bt-transgenic cotton is evident at the between-field, within-field and within-plant scale, and is not solely driven by host spatial dynamics. These factors should be considered when estimating Trichogramma impact on pest species during biological control and spatio-temporal studies of host-parasitoid interactions in general.
  • Authors:
    • Devraj
    • Jain, P.
    • Promila, K.
    • Duhan, B.
    • Bhattoo, M.
  • Source: Journal of Cotton Research and Development
  • Volume: 25
  • Issue: 2
  • Year: 2011
  • Summary: A field experiment was conducted at Research Farm, CCS, Haryana Agricultural University, Hisar during 2007 and its Regional Cotton Research Station, Sirsa during 2008 to find out the optimum crop geometry and fertilizer doses for Bt cotton ( Gossypium hirsutum L.) hybrids RCH134. A closer spacing of 67.5*60 cm gave significantly higher seed cotton yield (3230 and 3906 kg/ha at Hisar and Sirsa, respectively) than other two spacing i.e. 100*45 and 100*60 cm at both the locations. The highest seed cotton yield (3061 and 3902 kg/ha at Hisar and Sirsa, respectively) was recorded with a fertilizer dose of 125 per cent RDF (187.5-75-75 kg/ha N, P 2O 5 and K 2O) as compared to 75 per cent RDF and 100 per cent RDF at both the locations. The crop geometry, 67.5*60 cm and fertilizer dose of 187.5 kg/ha N, 75 kg/ha P 2O 5 and 75 kg/ha K 2O is ideal for getting higher seed cotton yield of Bt cotton RCH134.
  • Authors:
    • Muriel-Fernández, J. L.
    • Durán-Zuazo, V. H.
    • García-Tejero, I. F.
    • Jiménez-Bocanegra, J. A.
  • Source: Functional Plant Biology
  • Volume: 38
  • Issue: 2
  • Year: 2011
  • Summary: The continuous monitoring of crop water status is key to the sustainable management of water stress situations. Two deficit irrigation (DI) treatments were studied during the maximum evapotranspirative demand period in an orange orchard ( Citrus sinensis (L.) Osb. cv. Navelina): sustained deficit irrigation irrigated at 55% crop evapotranspiration (ET C), and low-frequency deficit irrigation treatment, in which the plants were irrigated according to stem water potential at midday (Psi stem). Additionally, a control treatment irrigated at 100% of ET C was established. The daily canopy temperature ( TC) was measured with an infrared thermometer camera together with measurements of trunk diameter fluctuations (TDF), Psi stem and stomatal conductance ( gS). The time course of all physiological parameters and their relationships were analysed, confirming that canopy air temperature differential ( TC- Ta) variations and TDF are suitable approaches for determining the water stress. In addition, the maximum daily shrinkage (MDS) and TC- Ta showed high sensitivity to water stress in comparison to Psi stem and gS. Significant relationships were found among MDS and TC- Ta with Psi stem and gS, for monitoring the crop water status by means of MDS vs Psi stem and TC- Ta vs Psi stem. Thus, the combination of these techniques would be useful for making scheduling decisions on irrigation in orchards with high variability in plant water stress.
  • Authors:
    • Goel, V.
  • Source: Acta Horticulturae
  • Issue: 895
  • Year: 2011
  • Summary: This study discusses how asset positions, cane cultivable practices and chain coordination mechanisms for sugar cane growers vary in Punjab (India). The study is based upon field surveys of cane farmers classified on the basis of cane cultivated area - Group I (below five acres), Group II (five to ten acres) and Group III (above ten acres). Across the three groups of cane growers little variation has been observed in their farm asset positions except for land size and cane cultivable practices. All cane growers enter into informal verbal contracts with several upstream chain partners to lease land, hire labour and purchase operational inputs. In contrast, they all enter into formal written contracts with their downstream chain partners i.e. sugar mills for cane disposal. Upward chain coordination ensures that farmers have sufficient land to achieve some economies of scale for the optimal utilization of complementary farm assets, timely availability of labour and timely availability of other operational inputs. However, owing to frequent and unexpected power cuts, farmers turn to diesel operated pump sets to ensure timely irrigation and open markets for the purchase of fertilizers because cooperative societies are not always able to ensure timely and adequate supplies. Downward chain coordination ensures timely cane disposal for farmers while regular and timely cane supplies to mills. However, cooperative sugar mills often fail to make timely cane payments to farmers. Thereupon, Group II and III sized cane farmers have a propensity to shift to private sugar mills for cane disposal and to divert some part of their land holdings to alternative field crops i.e., paddy/cotton. In contrast, Group I farmers shift to the cultivation of alternative crops.
  • 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:
    • 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:
    • 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:
    • Zaidi, J. H.
    • Matiullah
    • Husaini, S. N.
    • Arif, M.
  • Source: Journal of Radioanalytical and Nuclear Chemistry
  • Volume: 290
  • Issue: 3
  • Year: 2011
  • Summary: Due to the inadequate water sources, usually sewerage water and industrial effluents are being use for irrigation of the agricultural land around the industrial areas in Pakistan wherein crops and vegetables are cultivated. As untreated effluents contain heavy elements, toxic metals and organic pollutants that may find its way through food chain to general public and may cause health hazards. It is, therefore, mandatory to assess the toxic metals in such crops and vegetables. In this regard, samples of corn, millet, cabbage, spinach and potato were collected within the vicinity of industrial areas of the Faisalabad and Gujranwala regions. The food samples were analyzed using neutron activation analysis (NAA) technique. The highest concentration values of Arsenic (1.90.1 g/g) and Cobalt (0.850.01 g/g) were found in cabbage whereas Manganese (91.60.2 g/g), Antimony (0.150.03 g/g) and Selenium (1.10.1 g/g) were observed in spinach and Chromium (9.631.3 g/g) was found in millet crop. The observed concentrations of all the toxic and heavy metals in crops and vegetables are higher than those reported in the literature.
  • 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.