• Authors:
    • Kugbei, S.
  • Source: Journal of Crop Improvement
  • Volume: 25
  • Issue: 3
  • Year: 2011
  • Summary: Production figures in 2008 showed that new private seed enterprises in Afghanistan produced and sold about 12,000 tons of certified wheat seed, which accounted for 95% of the total certified seed produced in the country. At a retail price of about US$1,200 per ton, the enterprises earned an average margin of 20%. When interviewed, the farmers ranked high yield as by far the most important characteristic they sought in improved varieties. Besides yield, the next important attributes were earliness, disease resistance, grain color, and bread making quality. Estimates of on-farm productivity showed that use of improved wheat varieties alone could contribute up to 33% incremental yield under irrigated conditions, whereas the use of quality seed could enhance yield further by 28%. These estimates were obtained under recommended fertilizer rates, in the absence of which yield levels would have declined substantially. Apart from wheat, other major crops the farmers grew varied by regions but in broad terms included rice, vegetables, maize, potato, cotton, barley, watermelon, and alfalfa.
  • Authors:
    • Huang, B. Z.
    • Wu, Y. L.
    • Wei, Y. R.
    • Li, C. Y.
    • Yi, G. J.
  • Source: Acta Horticulturae
  • Issue: 897
  • Year: 2011
  • Summary: China is one of the centres of origin of banana. The crop has been cultivated there for more than 2000 years, and in the last two decades, it has become one of the most important fruit crops in the country. With a production of 8,042,702 tonnes on an area of 311,106 ha in 2008, banana comes in fourth place, only after apple, citrus and pear. As the demand for banana in the country is very high, banana produced domestically can only meet 90% of the demand, the other 10% is met by imported banana. Banana is mainly cultivated in Guangdong, Guangxi, Hainan, Fujian, Yunnan Province and Taiwan. Guangdong's cultivated area and production quantity rank first in China. The banana industry in China has been evolving fast over the past two decades. Indeed, banana production is a crucial industry in each main producing area; it plays an important role in the local economy and rural development. Many high-yielding and good-quality production techniques have been widely adopted by growers, such as micropropagated plantlets, water-saving irrigation, fertilisation, bunch management techniques, etc. Since 2003, the industrialisation of banana production has been promoted effectively through the implementation of the "Banana Industrial Upgrading Plan" developed by the Agricultural Ministry. However, Chinese banana production is still facing many challenges such as pests and diseases, adverse weather conditions and level of industrialisation. More than 3,000 ha of banana plantations have been attacked by Fusarium wilt in Guangdong. Production declined by more than 30% due to cold temperature in 1991-1992, 1999-2000 and 2002-2003, and the damage in 2007-2008 was devastating. In order to promote a healthy and persistent development of the banana industry, the National Industry System of Banana was initiated by the National Agricultural Ministry in 2008. Scientists were organised to tackle key issues, including breeding, cultivation technology, postharvest and processing, marketing and trade.
  • Authors:
    • Shukla, S.
    • Harris, W. G.
    • Obreza,T. A.
    • Sartain, J. B.
    • Schumann, A. W.
    • Mann, K. K.
  • Source: Journal of Plant Nutrition and Soil Science
  • Volume: 174
  • Issue: 6
  • Year: 2011
  • Summary: Variability in soil properties is a complication for fertilization, irrigation, and amendment application. However, only limited progress has been made in managing soil variability for uniform productivity and increased water-use efficiency. This study was designed to ameliorate the poor-productivity areas of the variable sandy soils in Florida citrus groves by using frequent small irrigations and applying organic and inorganic soil amendments. Two greenhouse experiments were set up with sorghum and radish as bioassay crops in a randomized complete block design (RCBD). The factors studied were two soil-productivity classes (very poor and very good), two water contents (50% and 100% of field capacity), two amendments (phosphatic clay and Fe humate), and two amendment rates (10 and 25 g kg -1 for sorghum and 50 and 100 g kg -1 for radish). Amendments applied at 50 and 100 g kg -1 increased the water-holding capacity (WHC) of poor soil by 2- to 6-fold, respectively. The lower rates (10 and 25 g kg -1) of amendments were not effective in enhancing sorghum growth. The higher rates (50 and 100 g kg -1) doubled the radish growth as compared to the control. The results indicate that rates greater than 50 g kg -1 of both amendments were effective in improving water retention and increasing productivity. Irrigation treatment of 100% of field capacity (FC) increased the sorghum and radish growth by about 2-fold as compared with the 50%-water content treatment. The results suggest that the root-zone water content should be maintained near FC by frequent small irrigations to enhance water availability in excessively drained sandy soils. In addition, application of soil amendments in the root zone can enhance the water retention of these soils. Furthermore, managing variable sandy soils with WHC-based irrigation can increase water uptake and crop production in the poor areas of the grove.
  • Authors:
    • Angelocci, L. R.
    • Marin, F. R.
  • Source: Agricultural Water Management
  • Volume: 98
  • Issue: 6
  • Year: 2011
  • Summary: Crop evapotranspiration (ETc) was measured as evaporative heat flux from an irrigated acid lime orchard ( Citrus latifolia Tanaka) using the aerodynamic method. Crop transpiration (T) was determined by a stem heat balance method. The irrigation requirements were determined by comparing the orchard evapotranspiration (ETc) and T with the reference evapotranspiration (ETo) derived from the Penman-Monteith equation, and the irrigation requirements were expressed as ETc/ETo (Kc) and T/ETo (Kcb) ratios. The influence of inter-row vegetation on the ETc was analyzed because the measurements were taken during the summer and winter, which are periods with different regional soil water content. In this study, the average Kc values obtained were 0.65 and 0.24 for the summer and winter, respectively. The strong coupling of citrus trees to the atmosphere and the sensitivity of citrus plants to large vapor pressure deficits and air/leaf temperatures caused variations in the Kcb in relation to the ETo ranges. During the summer, the Kcb value ranged from 0.34 when the ETo exceeded 5 mm d -1 to 0.46 when the ETo was less than 3 mm d -1.
  • Authors:
    • Martin-Gorriz, B.
    • Ruiz-Salleres, I.
    • Gonzalez-Real, M. M.
    • Baille, A.
    • Nortes, P. A.
    • Egea, G.
    • Verhoef, A.
  • Source: Acta Horticulturae
  • Issue: 922
  • Year: 2011
  • Summary: The focus of the work reported here is the impact of severe heat stress conditions on orchards' carbon dioxide exchange rate (NEE, Net Ecosystem Exchange). NEE was monitored by means of the eddy-covariance technique over an irrigated orange-tree orchard during summer 2009 in Southern Spain. In that period, severe heat spells occurred (maximum air temperature and vapour pressure deficit up to 38degreesC and 5 kPa, respectively). Under these conditions, orange trees maintained their transpiration rates at levels similar to those observed for normal sunny days, while canopy stomatal conductance and NEE were strongly reduced, thereby leading to a marked decrease in water use efficiency. The experimental results are discussed in the context of (i) stomatal and non-stomatal limitations to CO 2 exchange and (ii) orchard respiration loss. As the frequency of extreme events is expected to increase in the Mediterranean Basin, our results suggest that water productivity of irrigated orchards may be significantly affected by climate change.
  • Authors:
    • Robles-Gonzalez, M. M.
    • Virgen-Calleros, G.
    • Vazquez-Garcia, M.
    • Medina-Urrutia, V. M.
  • Source: Acta Horticulturae
  • Issue: 894
  • Year: 2011
  • Summary: This work was carried out to determine the influence of seasons of vegetative shoots on the time of flowering and to known the intervals from flowering to fruit harvest of Mexican lime trees. Two experiments on a seven years old Mexican lime trees budded on Sour Orange rootstock were established. In experiment 1, the number of vegetative (VS) and reproductive shoots (RS) on each one of 10 trees were registered weekly during one year, using a metallic ring of one square meter area placed on the tree 1.75 m from the ground. Minimum temperature and rainfall data were also recorded every week. In experiment 2, monthly, ten new vegetative shoots on each one of ten trees were tagged. These shoots were observed every week until they bloom. During the most important periods of blooming, five flowering shoots per tree were chosen to determine interval to harvest. In experiment 1, four VS and two RS flushes were observed. The first period of VS and RS started in autumn and was associated to the initiation of irrigation. The second and more important was registered in January when temperatures were the lowest of the year. Half RS and half VS were recorded during this period. The third and four flushes were mainly VS and occurred during summer months with highest temperatures and the rainy season. In experiment 2, from the vegetative shoots emerging in January, 52% formed reproductive shoots 60-85 days later and 25% also flowered sparsely four to six months later. The remaining shoots (23%) repeated their vegetative activity during June and July. Most of the vegetative shoots initiated in February showed again a vegetative activity during May to July, and only 20% of them changed to reproductive. New vegetative shoots appeared from March to July showed a vegetative activity during the next two to six months. From the vegetative shoots emerged from July to September very few (15%) transformed to reproductive during November-December and the majority became vegetative again, however, most of them changed to reproductive from January to April. Fruits initiating during the winter time lasted 130 to 145 days until harvest. But those fruits emerged during the late spring and summer months reached complete development 90 to 120 days later. These combined phenological characteristics explain the long period of harvest showed by the MLT under tropical semiarid conditions.
  • Authors:
    • Syvertsen, J. P.
    • Dunlop, J. M.
    • Melgar, J. C.
  • Source: HortScience
  • Volume: 46
  • Issue: 3
  • Year: 2011
  • Summary: Oleocellosis or oil spotting on the peel of citrus fruit is a common post-harvest injury caused by improper handling. Mechanical injury allows phytotoxic oil to leak out of oil glands and cause injury to surrounding flavedo cells, resulting in oleocellosis. Mechanical harvesting (MH) of 'Valencia' sweet orange is conducted in late spring, when the next season's fruitlets are in their early stages of development. There is a concern that mechanical injury from harvesting machines can cause oleocellosis and fruit drop of young, green 'Valencia' sweet orange fruitlets, especially late in the harvest season when fruitlets are relatively large. We evaluated the effects of winter drought stress and subsequent late-season MH with a canopy shaker on oleocellosis of 'Valencia' sweet orange fruitlets. In April, mature fruit size, juice content, total soluble solids, and acidity were unaffected by previous winter drought stress treatments. Mechanical harvesting removed ~90% to 95% of mature fruit and 20% to 50% of fruitlets depending on previous drought stress treatments and harvesting date. Beginning 1 week after the late harvest (13 June), attached fruitlets were tagged and visually evaluated approximately every other month to determine oleocellosis injury until the late-season harvest 12 months later. Only 12% of the fruitlets had oleocellosis on more than 30% of their surface area. Up to 75% of the fruitlets from the previously drought-stressed trees had less than 10% of their surface area injured after MH and 11% of these fruitlets dropped before harvest. Nonetheless, there was no significant increase in fruit drop with increased surface area injured nor was juice quality affected at harvest. Overall, fruit surface oleocellosis decreased and healed as fruit expanded, but surface blemishes did not completely disappear. Thus, fruitlet oleocellosis in late-season mechanically harvested trees was cosmetic and did not increase fruit drop nor alter internal fruit quality.
  • Authors:
    • Mennone, C.
  • Source: Informatore Agrario
  • Volume: 67
  • Issue: 27
  • Year: 2011
  • Summary: Techniques to increase fruits size of clementine are mentioned, which include fruit thinning and use of plant growth regulators. The developmental stages of clementine fruits are described. Factors affecting fruit size, including genetic factors, variety, fruit number, competition among developing organs (flowers and fruits), external factors (climatic, edaphic (soil) and cultural practices such as pruning, fertilization, irrigation) and application of growth regulators are discussed. Results are presented of trials conducted in Metaponto, Italy, to investigate the efficacy of some plant growth regulators (triclopyr+MCPA and gibberellic acid (ester)) in increasing size and improving colour and quality of clementine fruits.
  • Authors:
    • Monserrat Delgado, A.
  • Source: Agricola Vergel: Fruticultura, Horticultura, Floricultura, Citricultura, Vid, Arroz
  • Volume: 30
  • Issue: 351
  • Year: 2011
  • Summary: Studies were conducted to determine the most important aspects to consider for the use of herbicides in citrus groves and fruit trees with irrigation. The design of strategies that suit the age of planting and soil characteristics, among others, were based on some of the factors that influence the efficacy and selectivity of the applications and its long-term profitability. To avoid the selection of hard to control weeds on the farm, some treatments described were utilized against some of the most important weed species. Some authorized herbicides in citrus production, with some observations of special interest, was also presented.
  • Authors:
    • Romero, R.
    • Duran, V. H.
    • Jimenez, J. A.
    • Garcia-Tejero, I.
    • Muriel,J . L.
    • Hernandez, A.
  • Source: Acta Horticulturae
  • Issue: 889
  • Year: 2011
  • Summary: Different strategies of deficit irrigation have been studied in an 11-year old citrus trees ( Citrus sinensis L. Osb. 'Navelina') grafted onto Carrizo citrange ( Citrus sinensis L. Osb. * Poncirus trifoliata L. Raf.). A sustained deficit irrigation (SDI) treatment was established, with a water supplied of 60% of the crop evapotranspiration (ET c); and a low-frequency deficit irrigation treatment (LFDI), watered according to the plant-water status. As a control a full irrigated at 100% of ET c was included. Midday stem water potential (Psi stem), stomatal conductance (g s), and micrometric trunk diameter fluctuations were measured during the maximum evapotranspirative demand period to evaluate the plant-water status, and to establish the main relationships between them. The seasonal pattern of the studied variables had a behavior consistent with the applied irrigation volumes. Significant relationships between Psi stem and g s, and the maximum daily shrinkage (MDS) were found. The lowest Psi stem and g s values were registered in the deficit treatments being the MDS significative higher in these treatments than in the control treatment. Yield response was highly influenced by irrigation strategy, being these results for LFDI significant better than SDI. Considering these results and the significant relationships between MDS and Psi stem, LFDI can be a sustainable deficit irrigation strategy, encouraging significant water savings without important impact on yield and fruit quality.