• Authors:
    • Olitrault, P.
    • Msatef, Y.
    • Handaji, N.
    • Benazzouze, A.
    • Omari, F.
    • Beniken, L.
    • Benyahia, H.
  • Source: African Journal of Agricultural Research
  • Volume: 6
  • Issue: 4
  • Year: 2011
  • Summary: Alkalinity of Moroccan soils is the major abiotic constraint on citrus production area. The best choice of citrus rootstocks adequate and resistant is a better solution to avoid this problem. The aim of this study is to develop a fast test of citrus rootstocks screening towards alkalinity. The alkaline stress was applied on ten citrus rootstocks two month old, using irrigation with a Hoagland and Arnon solution added with 1 g CaCO 3/L and adjusted at various pH levels 6, 7 and 9. Observations concerned symptoms incidence and severity of iron chlorosis after two months of rearing. Results permitted to classify Poncirus trifoliata and Flying dragon as the most sensitive to alkalinity stresses, whereas, Citrus volkameriana and Citrus macrophylla were resistant. These conclusions are equivalent with those obtained with old citrus rootstocks in field trials.
  • Authors:
    • Singh, J.
    • Bhatnagar, P.
    • Kaul, M.
  • Source: Acta Horticulturae
  • Issue: 922
  • Year: 2011
  • Summary: Studies of variation in plant environmental factors of Kinnow mandarin for at Agriculture Research Station, SriGanganagar district of Rajasthan state in India during 2002-04 with respect to three differential irrigation treatments revealed that overall maximum carboxylation efficiency (A) was estimated at 70% Etc treatment from April to June with a linear trend. It showed depression in September and October followed by a steady rise in November and December months. Stomatal conductance revealed oscillating trend with maximum in 70% Etc treatment for April and May months followed by steep rise in 40% Etc treatment for June-July. It remained static in August and September, but a trend reversal occurred in October-November with maximum stomatal conductance in 100% Etc treatment. The cumulative overall high stomatal resistance in 40% treatment might have attributed to low photosynthetic rates followed by 100% treatment and the better assimilation rates were observed under 70% treatment and were correlated with low rates of stomatal resistance. The daily course of transpiration in all the three irrigation treatments was not closely linked to solar irradiation but rather to leaf temperature. Temperatures of 25-30degreesC are optimal for photosynthesis but temperatures above 30degreesC definitely reduce photosynthetic activity. The annual trend for three consecutive years' data revealed occurrence of cyclic oscillations in photosynthesis, stomatal conductance, stomatal resistance, transpiration rate and photosynthetic active radiation under field conditions. Citrus belong to C3 plants, with photosynthetic rates lower than C4 plants. Assimilation rates ranging from 1.28 to 7.93 mmol m -2 s -1 observed under differential irrigation treatments seem realistic under optimal irrigated conditions of Western Rajasthan.
  • Authors:
    • Mhamdi, M.
    • Boughalleb, F.
    • Hajlaoui, H.
  • Source: Agricultural Journal
  • Volume: 6
  • Issue: 3
  • Year: 2011
  • Summary: Experiments were conducted with lemon ( Citrus limon v. Eureka) and orange trees ( Citrus sinensis cv. Maltese) to determine the optimum NPK fertilizer rates for young citrus trees in greenhouse and field conditions. Greenhouse nursery trees received 0-0-0, 0-25-50, 25-25-50, 50-25-50 or 100-25-50 mg L -1 of N-P 2O 5-K 2O via drip irrigation. The results showed that increased N rates improved leaf number, shoot length, total leaf area and stem diameter. The optimum tree growth was occurred with 50 and 100 mg N L -1. Results also showed that the percentages of N in the leaves were increased in proportion to the amount of N added while the percentage of P and K were decreased. However, the concentrations of Ca, Mg, Fe, Mn and Zn were unaffected by N rates but the leaf Cu concentration increased significantly. Leaf Mg concentration was increased by the presence of K in the nutrition solution. Form this study, we recommended the use of 100 N-25 P 2O 5-50 K 2O mg L -1 for the good growth of nursery citrus plants in the absence of any possibility of deficiency or excessive accumulation of mineral elements. In the second experiment, two fertilizers mix 180-90-180 and 360-90-180 of N-P 2O 5-K 2O kg ha -1 were applied to young citrus tree in field condition. Increased the level of N had no effect on leaf number and stem diameter in Eureka lemon however shoot length and total leaf area were slightly increased and these increment in growth was higher in Maltese orange.
  • Authors:
    • Kuper, M.
    • Billaud, J.
    • Faysse, N.
    • Abdellaoui, E.
    • Bouzidi, Z.
    • Errahj, M.
  • Source: Cahiers Agricultures
  • Volume: 20
  • Issue: 1/2
  • Year: 2011
  • Summary: The design and diffusion of technical innovations in large-scale irrigation schemes in Morocco have generally been understood as necessarily stemming from centralized public policies. This situation tends to mask farmers' local initiatives. We analyzed local networks for innovation and coordination practices among local actors, in the case of the introduction of citrus plantations in an agrarian reform cooperative of the Gharb irrigation scheme. These networks and practices appeared as the motor for innovation around which revolved social and technical stakes and an issue of identity construction. Revealing these dynamics provides guidance for renewing the approaches to support farmers and more generally rural communities.
  • Authors:
    • Scicolone, B.
    • Consoli, S.
    • Capra, A.
  • Source: Acta Horticulturae
  • Issue: 922
  • Year: 2011
  • Summary: Citrus orchards are economically one of the most important crops in South Italy, where climate is semi-arid with scarce rain and high evaporative demand. One way to optimize water resources in this region is to adopt deficit irrigation (DI) strategies, such as regulated deficit irrigation (RDI). In Mediterranean regions, DI criteria have been widely applied and crop physiological responses to water deficit application have been studied in depth, but the profitability of these strategies in commercial orchards is still largely unknown. The objective of this study was to determine the economic feasibility of DI treatment on orange orchards in Sicily (South Italy), by estimating optimum levels of applied water which provide maximum profit under limited resource availability (e.g. land or water). The applied methodology follows the economic analysis on DI suggested by English in 1990. The analysis of the profit/total costs ratio showed that Deficit Irrigation strategies would increase the generated income, thus being more profitable (up to a maximum of 100%) than the current irrigation water supply management in the area.
  • Authors:
    • Thakur, A.
    • Dalal, R.
  • Source: Advances in Horticultural Science
  • Volume: 25
  • Issue: 1
  • Year: 2011
  • Summary: The root distribution pattern of 17-year-old pineapple orange trees budded on Rough lemon, Cleopatra and Troyer citrange rootstocks were studied by root excavation method at four radial distances, 0-75, 75-150, 150-225 and 225-300 cm from tree trunk, and at three depths, 0-15, 15-30 and 30-60 cm. Fibrous root length density (FRLD) and fibrous root length percentage differed significantly at various depths and radial distances among rootstocks. FRLD was closer to tree trunk on both horizontal and vertical planes. Root density decreased from 0.183 to 0.084, 1.051 to 0.238 and 0.238 to 0.095 cm.cm -3 from 0-15 cm to 30-60 cm depth within 0-75 cm radial distances from tree trunk in trees on Rough lemon, Cleopatra and Troyer citrange, respectively. Cleopatra contains the highest 0.231 cm.cm -3 FRLD as compared to 0.051 cm.cm -3 in Rough lemon and Troyer citrange. Troyer citrange has intensive lateral root development with 84% fibrous roots (FR) within 75 cm radial distance, whereas Rough lemon and Troyer has an appreciable amount up to 225 cm distance (extensive lateral). Cleopatra contained 57% FR in upper soil layer (0-15 cm) (intensive vertical). In Rough lemon and Troyer 54% FR are confined to lower depth 15-60 cm (extensive vertical root development). Troyer and Rough lemon had the same vertical, whereas Rough lemon and Cleopatra showed the same horizontal rooting pattern under arid irrigated ecosystem. Thus, irrigation depth and fertilizer placement should be critically rootstock specific.
  • Authors:
    • Verstraeten, W. W.
    • Strever, A.
    • Stuckens, J.
    • Verreynne, S. J.
    • Dzikiti, S.
    • Swennen, R.
    • Theron, K.
    • Coppin, P.
  • Source: Agricultural and Forest Meteorology
  • Volume: 151
  • Issue: 8
  • Year: 2011
  • Summary: This study describes the diurnal and seasonal dynamics of the canopy reflectance, water use and water status of Midknight Valencia citrus trees under semi-arid conditions. Hyperspectral canopy reflectance data was collected on 30 trees at monthly intervals over a period of 16 months in a commercial orchard in South Africa. The mean canopy reflectance in the wavelength range 350-2500 nm followed a clear seasonal trend influenced by environmental conditions and tree phenology. Mean monthly reflectance peaked in summer (~22%) while the lowest value (~15%) was reached in winter with the seasonal changes in the sun's position accounting for a significant proportion of the variations. A sensitivity analysis of a Penman-Monteith transpiration model showed that water use by individual trees changed by up to 13% when the canopy reflectance was varied over the seasonal range of measured values. This suggested that the seasonal changes in tree water use influenced the seasonal trend of the canopy reflectance. Thus monitoring the canopy reflectance of citrus trees could offer information on the tree water status. To test this, sap flow data of water uptake and loss by the trees were compared with the canopy spectra. Sap flow data showed a heavy reliance by the citrus trees on the internally stored water with up to 25% of the daily total transpiration withdrawn from the trees' internal water storage pools when soil water was limited. This depletion of internally stored water, and hence the change in tree water status, was detected using spectral indices based on the first order derivatives of the canopy reflectance centered at two and, at most, four spectral bands. We conclude that even if citrus trees are evergreen, their canopy reflectance changes significantly throughout the year with a considerable impact on tree energy balance and water use. In addition, the contribution of the internally stored water to daily transpiration is a possible indicator of drought stress for citrus trees detectable from changes in canopy reflectance and it has potential applications in irrigation scheduling using canopy level spectral information.
  • Authors:
    • El-Wakeel, F.
    • Eid, M.
  • Source: Journal of American Science
  • Volume: 7
  • Issue: 5
  • Year: 2011
  • Summary: This study was carried out through two successive seasons (2008 and 2009) in a private orange orchard in Qalubia governorate Egypt in a three years old Navel orange trees budded on sour orange rootstock on clay loam soil (Typic Torriorthents). Planting distance was 2.55* meters apart and flood irrigation was used by river Nile water. Two nitrogen rates were used 150 and 300 g N/tree/y in three forms 100% mineral nitrogen (M.N.) as ammonium nitrate, 100% organic nitrogen (O.N.) as compost and mixed (50% M.N.+50% O.N.) each of these treatments with or without K humate addition (6 kg/feddan). All fertilization treatments were divided into equal five doses added every two months from February to October during the two seasons. The obtained results showed that the highest stem thickness increment percentage was recorded by mixed nitrogen form (50% M.N.+50% O.N.). Mixed nitrogen form with K-humate recorded the highest significant value of plant height increment percentage in the first season, but in the second season, using nitrogen form at 150 g N/tree/y without K-humate recorded the highest significant value. Leaf N content had higher significant values with M.N. treatments. Leaf P content showed insignificant differences among treatments. Mixed N source at 300 g N/tree/y without K-humate recorded a higher significant value of leaf K content, in the second season compared with other treatments. Leaf Ca content showed a higher significant value by organic and mixed N form treatments in the first season. Leaf Mg, Fe, Mn and Zn contents increased significantly with M.N. treatments in the first season. While in the second season leaf Fe content had a higher significant value with O.N. treatments. Leaf Mn content illustrated the lowest significant mean level by using N form at 150 g N/tree/y treatment. While, leaf Zn content recorded a higher significant value with mixed nitrogen source at 150 g N/tree/y with K-humate addition compared with all other treatments. From this results we recommended that the mixed sources of N fertilizer (50% M.N.+50% O.N.) at 150 g N/tree/y is the best N fertilizer, and the application of K-humate or humic acid at commercial rate is not recognized for the young Navel orange trees in clay loam (Typic Torriorthents) soil.
  • Authors:
    • Eryigit,T.
  • Source: Yuzuncu Yil Universitesi Journal of Agricultural Sciences
  • Volume: 21
  • Issue: 1
  • Year: 2011
  • Summary: The industrial crops with contribution to national income and industrial sector in terms of providing raw materials have a significant place in our crop production. Agricultural industry in our country has a large capacity, but due to lack of raw materials and financing a significant portion of the installed capacity can not be benefited. Especially in recent years, increasing of population and production decrease in some industrial plants due to the resulting vegetable oil deficit. Our country pays the highest foreign currency to imports of the oil and oil seed crops for closure of this gap after the oil imports. Therefore, the priority should be given to the oil plants within the groups of industrial plants. Igdr has its own microclimate characteristics. The diversity of product design is greater due to the climate and irrigation conditions in the plain. Grains constitute the main products of the region. All kinds of vegetables, olives and citrus fruit except that all the fruits can be grown. Sugar beet and cotton plants of industrial crop and the alfalfa plants of the forage crops have great importance in the development of animal husbandry. However, in recent years, changes in the climate regime, increases in the cultivation of sugar beet, sunflower and rapeseed gave rise to a decrease in the number of the small farmers who planted cotton. Igdr has high agricultural potential, so the alternative species of industrial crops and their varieties will be integrated to the present cultivation of plain by the scientific studies which will be held on industrial crops in the province.
  • Authors:
    • Carneiro, P. T.
    • Melo, A. S. de
    • Soares Filho, W. dos S.
    • Gheyi, H. R.
    • Brito, M. E. B.
    • Fernandes, P. D.
  • Source: Acta Scientiarum Agronomy
  • Volume: 33
  • Issue: 2
  • Year: 2011
  • Summary: Water and soil salinity affects the growth, development and production of fructiferous species, such as citrus. The use of tolerant rootstocks can guarantee the agribusiness of citrus under such conditions. Thus, the sensibility to salinity during the phase of rootstock formation of varieties and selected hybrids was studied. The experiment was carried out in a greenhouse, with five levels of irrigation water salinity [control, tap water with electrical conductivity (EC w) of 0.41 dS m -1, and water with EC w of 1.0, 2.0, 3.0 and 4.0 dS m -1] and seven genotypes, in a randomized block design and five replications each consisting of four plants, during 150 day period. Growth and physiologic variables were evaluated. Significant effects of genotypes and salinity in the variables were observed. The most expressive reduction was found for total dry matter with unit increase of EC w. A linear reduction was observed in hybrids LVK * LVA-009 and TSK * TRENG-256. Among the evaluated genotypes 'Volkamer' lemon was the least sensitive to saline stress.