• Authors:
    • Stuchi, E. S.
    • Souza, M. C. de
    • Goes, A. de
  • Source: Crop Breeding and Applied Biotechnology
  • Volume: 11
  • Issue: 1
  • Year: 2011
  • Summary: A citrus scab disease, caused by Elsinoe fawcettii, is currently found in all citrus areas throughout Brazil. That being, given the importance of this casual agent, the behavior of tangerines and hybrids influenced by this pathogen was evaluated under natural infection conditions. This study was performed with plants around 15 years old without irrigation; 100 fruits of three plants were collected during harvest season, using a grade scale varying from 0 (absence of symptoms) to 6 (severe symptoms) the level of disease severity was determined. Among the cultivars, citrus scab resistance was observed in Citrus deliciosa, C. tangerina, C. nobilis; a mandarin hybrid ( C. nobilis * C. deliciosa) and a satsuma hybrid ( C. unshiu * C. sinensis). Among the other genotypes, symptoms were observed with levels of severity ranging from 1 to 3, indicating moderate resistance.
  • Authors:
    • Carvalho, D. F. de
    • Botrel, T. A.
    • Souza, W. J.
    • Silva, L. D. B. da
  • Source: Revista Brasileira de Engenharia Agrícola e Ambiental
  • Volume: 15
  • Issue: 8
  • Year: 2011
  • Summary: The use of localized irrigation using microtube as emitter under turbulent flow regime can be a technically feasible alternative. The objective of this study was to evaluate the performance of a fertigation system in nursery of citrus plants (greenhouse) projected by universal mathematical model, using the microtubes as emitters, under turbulent flow rate and to compare the development of the fertigated plants by microtubes to the system that use the traditional method with hoses. In the size of the length of the emitters was considered the K coefficient of localized energy dissipation using a microtube with internal diameter of 0,761 mm. The fertigation system presented great performance with clogging degree, Christiansen uniformity and emission uniformity values equal to 0,50; 99,95 and 98,21%, respectively, after 160 days of study. Plants that were grown using fertigation with both microtubes and hoses showed no difference as regards to stem diameter and height. Thus, the use of the microtube under turbulent flow rate presented technical feasible for fertigation system.
  • Authors:
    • Germana, C.
    • Intrigliolo, F.
    • Giuffrida, A.
    • Stagno, F.
    • Continella, A.
  • Source: Acta Horticulturae
  • Issue: 889
  • Year: 2011
  • Summary: During three consecutive years, in a citrus orchard planted with Tarocco 'Meli' and 'Scire' on sour orange ( C. aurantium L.) were verified the differences of the plant water status and the possibility to build an empirical model to estimate the psi pd utilizing stem water potential (psi md) and vapor pressure deficit (VPD md) measured at midday. The first results showed statistical differences during the irrigation season in the two clones water potential. These difference permitted to separate the data of Tarocco 'Meli' and 'Scire'. As a result, two empirical models were built. The 2nd degree equation (Psi pd=a+b 1Psi md+b 2VPD md) was obtained by considering the Psipd as dependent variable, the Psi md and the VPD md as explanatory variables. ANOVA applied to the multiple regression resulted highly significant with P-value
  • Authors:
    • Sungur, S.
    • Sangün, M. K.
  • Source: Food Chemistry
  • Volume: 126
  • Issue: 1
  • Year: 2011
  • Summary: Recently, the exposure to perchlorate was emphasised as an important risk factor for human and especially newborn health. A number of studies were focused on this matter. In this study, samples of soil, vegetable (cabbage, spinach, lettuce, carrot, tomato, red cabbage), fruit (orange, mandarin, lemon, grapefruit), water, milk and fish were taken from 8 different regions of Hatay (Samandag, Krkhan, Reyhanl, Amik Plain, Dortyol, Yayladag, Altnozu, Erzin). An ion chromatography system (Shimadzu C196-E039A model) was used to determine the concentrations of perchlorate in the samples. 2.5 mM Phthalic acid and 2.4 mM tris (hydroxymethyl)aminomethane solutions (pH=4) were used as the mobile phase. A flow rate of 1.5 ml min -1 and oven temperature of 40°C were used during the analysis. The foods had perchlorate concentrations in the range of 0.236-1.218 g kg -1. The perchlorate concentration varied from 0.300.01 to 0.940.02 g l -1 in milk samples. Perchlorate concentrations were determined to be lower in the drinking waters (0.440.03 g l -1) compared to irrigation waters (0.590.03 g l -1). Perchlorate concentrations of the fish samples were ranged from 0.380.01 to 0.610.01 g kg -1.
  • Authors:
    • Ichinokiyama, H.
    • Suzaki, N.
    • Okuda, H.
  • Source: Agricultural Information Research
  • Volume: 20
  • Issue: 3
  • Year: 2011
  • Summary: In commercial orchards of satsuma mandarin in Japan, mulching cultivation has been developed to produce high quality fruit. It is, however, difficult to manage irrigation to produce consistent characteristics such as high fruit quality, fruit productivity, and tree vigor. The principal reason for this is that no simple, easy, and reliable indicator has been developed to evaluate tree water deficits. In this study, we demonstrated that the morning maximum leaf water potential could be estimated using the fruit hardness in the evening of the previous day. To assist farmers in estimating fruit hardness, we developed a set of three silicone rubber balls with different degrees of hardness as a reference tool, and verified their effectiveness. The experiment was performed in 2008 and 2009, and revealed that irrigation management during July and August using the silicone rubber reference balls gave good results, with high fruit quality and high fruit productivity. Fruit hardness estimated using the silicone rubber balls therefore appears to be a good indicator of irrigation management during July and August for mulched citrus orchards.
  • Authors:
    • Yang, G. H.
    • Li, Q.
    • Yang, L. T.
    • Jiang, H. X.
    • Tang, N.
    • Chen, L. S.
  • Source: Biologia Plantarum
  • Volume: 55
  • Issue: 4
  • Year: 2011
  • Summary: Sour pummelo ( Citrus grandis) seedlings were irrigated with nutrient solution containing four boron concentrations ( i.e., 2.5, 10, 25 and 50 M H 3BO 3) and two aluminum concentrations [ i.e., 0 (-Al) and 1.2 mM AlCl 3 . 6 H 2O (+Al)]. It was found that B did not affect, but Al increased, the Al content in the roots. The Al and citrate contents in the -Al leaves either did not change or slightly increased with increasing B concentration. On the other hand, the Al and citrate contents in the +Al leaves rapidly decreased as B concentration increased from 2.5 to 50 M, then decreased at the highest B concentration. The Al and citrate contents were higher in the +Al than in the -Al leaves, except for at 25 M B when they were similar. The leaf malate content did not change in response to B or Al, except for an increase in the +Al leaves and a decrease in the -Al leaves at 2.5 M B. Similarly, the root malate and citrate contents did not change in response to B with or without Al, except for a decrease in the malate and citrate contents in the +Al roots at 50 M B and an increase in the citrate content in the -Al roots at 50 M B. The activities of acid-metabolizing enzymes were less affected by B-Al interactions in the roots than in the leaves.
  • Authors:
    • Hashimoto, A.
    • Ito, R.
    • Togami, T.
    • Kameoka, T.
  • Source: Agricultural Information Research
  • Volume: 20
  • Issue: 3
  • Year: 2011
  • Summary: In Nanki, Mie Prefecture, Japan, the mulching and drip irrigation system produces high-quality fruit despite large variations in the weather. For this cultivation system, we developed a small, stationary agricultural robot, "Field Server", which measures environmental and growing conditions in real time in the orchard. Our goals were to solve the problem of loss of the skills developed by experienced farmers due to a lack of new agricultural workers and aging of farmers, and to cultivate mandarin oranges with the required quality under occasionally severe and highly variable climate conditions. In this research, we demonstrated the ability of Field Server to monitor the agro-environmental conditions that affect plant physiology and the farmer's attitude towards their work and demonstrated the eKo wireless sensor network that was designed for agricultural use. To accomplish our goals, we installed a sensor network to support long-term, stable operation, including optimal placement of sensor nodes, optimal installation of the sensors and modification of network connections with Internet, and developed user-friendly Field Server and eKo data browsing software to help agricultural workers. Long-term data acquisition for a 1-ha agricultural site became possible due to improvements of the eKo system's hardware and software. In addition, the development of databases and related software permitted comparisons of the acquired data with data obtained from nearby AMeDAS stations. The comparison revealed the importance of agro-environmental monitoring (especially for rainfall) close to the production area and of soil moisture measurement to guide irrigation and produce high-quality mandarin oranges.
  • Authors:
    • Merwe, S. van der
    • Verreynne, S.
  • Source: SA Fruit Journal
  • Volume: 10
  • Issue: 2
  • Year: 2011
  • Summary: Sunburn is a major problem on early maturing mandarins such as 'Miho Wase' Satsuma. Currently, optimal irrigation during critical periods and shade nets are the only measures to reduce losses due to sunburn. Previous work using particle film technology (kaolin) on citrus to reduce sunburn was very effective, but the formulation used resulted in insect repercussions. The objective of the study was to determine if products such as Screen TM, Vapor Gard, Silicon and Raynox TM can reduce tree canopy temperature and thereby reduce sunburn on 'Miho Wase' Satsuma mandarins. All treatments were applied three times between December 2009 and January 2010. Screen TM reduced the sunburn incidence (fruit per tree) by 50%, possibly due to reductions in leaf temperature by 2.53C and fruit temperature by 1.73C, without a negative effect on fruit quality. Screen TM increased the sugar content of fruit. Vapor Gard increased fruit temperature, reduced the sugar content of the fruit, and increased sunburn incidence by 16%. Raynox TM, Silicon, and the combination of Screen TM and Vapor Gard had no effect on sunburn incidence.
  • Authors:
    • McClymont, L.
    • McAllister, A.
    • O'Connell, M. G.
    • Whitfield, D. M.
    • Abuzar, M.
    • Sheffield, K.
  • Source: Acta Horticulturae
  • Issue: 922
  • Year: 2011
  • Summary: The METRIC algorithm (Allen et al., 2007) was applied to a Landsat 5 image to assess the range of vegetation cover (measured as Normalised Difference Vegetation Index; NDVI), and rates of evapotranspiration (ET), of major horticultural crops grown in the Sunraysia Irrigation Region of SE Australia. The image represented the period of maximum foliage cover of horticultural crops grown in the Region. The range in mid-season NDVI of almond, grape and citrus crops almost matched the whole-of-season range reported for broad-acre irrigated annual crops grown in Idaho, USA. Alfalfa reference ET (ETr) constituted the upper limit to ET rate seen in Sunraysia crops. The range of ET and NDVI observations in this study therefore complied with limits on ET and NDVI seen in irrigated crops in Idaho, USA. ET-NDVI relationships seen in USA crops appear to provide a useful reference framework for well-watered irrigated crops in cases where ETr is the upper limit on ET. ET rates in Sunraysia crops were strongly related to NDVI. The dependence of ET rates on NDVI, combined with the large range in NDVI, meant that irrigation water requirement varied widely within and between crop types in the Sunraysia region: results support the use of NDVI measures to account for site-specific differences in crop water requirement attributable to vegetation cover. Findings suggest that satellite-based METRIC methods of ET estimation may be used to formulate region- and crop-specific estimates of the crop coefficients (Kcb, Ke, and Kc) required for optimal irrigation water management of horticultural crops.
  • Authors:
    • Chen, J. C.
    • Baez, I.
    • Takeuchi, Y.
    • Sequeira, R. A.
    • Ouyang, G. C.
    • Xia, Y. L.
  • Source: Plant Health Progress - Peer-Reviewed Journal of Appied Plant Health
  • Issue: October
  • Year: 2011
  • Summary: The Asian form of huanglongbing (HLB) is caused by ' Candidatus Liberibacter asiaticus (Las),' a phloem-limited bacterium transmitted by the Asian citrus psyllid, Diaphorina citri Kuwayama. Nutrient management, together with other cultural practices such as pruning and irrigation, for mitigation of the disease has been practiced in China for many years. Our literature review, field survey, and interviews with Chinese scientists and growers indicate that these cultural practices were generally ineffective for the disease management. However, a nutritional approach in conjunction with other cultural practices such as irrigation can maintain grove productivity for a certain time depending on the type of citrus species/cultivars, the age of the trees, the propagation method of the plants, the Asian citrus psyllid (ACP) ( Diaphorina citri Kuwayama) population, and other factors. Symptomatic mature pommelo ( Citrus maxima Merr) and sweet orange ( C. sinensis L. Osbeck) plants can commonly survive and maintain a certain level of productivity for an additional 4 to 5 years, even longer assuming vigorous ACP control.