Search

Performance of an inter-specific hybrid Fremont mandarin was assessed on different rootstocks in the hot arid regions of India as a potential scion species to expand citrus fruit availability in an arid region. Fremont scion attained superior growth and yield characteristics on Karna khatta rootstock by displaying the greatest plant canopy parameters followed by Rough lemon rootstock. However, the Pectinifera as well as the Troyer citrange resulted in dwarfness of the scion. The scion-rootstock compatibility indicators such as scion rootstock ratio, stionic difference and TCSA which were greatest in the Fremont/Pectinifera combination, confirm that the inhibited tree growth on Pectinifera rootstock was caused by intrinsic features of the rootstock rather than an incompatibility reaction. Furthermore, Karna khatta rootstock resulted in highest fruit yield and related traits followed by Rough lemon and Pectinifera rootstocks. The Pectinifera rootstock resulted in a similar response to all fruit physical attributes i.e., fruit weight, fruit diameter, fruit index and fruiting density, except fruit number. The fruit maturity of Fremont was obtained earliest on Pectinifera, while it was most delayed on Karna khatta and Rough lemon rootstocks. Fruit quality parameters on Pectinifera rootstock were superior to those of common rootstock species (Rough lemon or Karna khatta) including fruit juice content as well as its nutritional constituents like TSS, ascorbic acid, pH, total sugar, organoleptic taste, ripening index, lower content of acidity and rind thickness. The total AAE, total flavonoids, total phenol contents were also noticeably higher than those obtained on other rootstocks, except Troyer citrange. Overall, Fremont mandarin can be considered a promising scion in arid regions to extend the harvesting period of superior quality fruits, especially on dwarfing Pectinifera rootstock. It would further ease harvesting operations vis-a-vis possible attainment of a better micro-climate due to small tree stature and high-density orcharding.

Rootstocks have a significant influence on adaptation to biotic and abiotic stress conditions and quality of fruit. So, choice of rootstock for a specific growing region is an important decision for a grower to make when establishing a commercial citrus orchard. This study was undertaken to assess effects of rootstock and location on quality of orange fruit. The study was conducted over two consecutive years (2017/18 and 2018/19). Scions from the Gunda Gundo orange grove were grafted on rough lemon and sour orange rootstocks and planted in Tigray and Afar, Ethiopia at four sites (Abala, Agulae, Adiha and Rama). The experiment was laid out in Randomized Complete Block Design (RCBD) with four replications. Data on different physico-chemical and bioactive compounds were collected and analyzed using R software (version 4). Compared to sour orange, rough lemon rootstock revealed higher fruit mass (151.96 g, 195.38 g), fruit length (62.27 mm, 68.88 mm) and fruit diameter (65.58 mm, 71.3 mm), in 2017/18, 2018/19, respectively. Among the four locations (Abala, Agulae, Adiha and Rama), higher juice percentage was found in Adiha (43.47% in 2017/18) and Abala (49.87%, in 2018/19). In 2017/18 higher total soluble solid (TSS, 13.87%), TSS/acid ratio (19.18) and fruit rag (32.77%), were obtained at the Rama site. On the one hand, higher vitamin C (826.6 mg • kg−1) and total phenolic content (208 mg • kg−1GAE) were recorded at Agulae than Abala, Adiha and Rama sites from sour orange rootstock. High TSS, TSS/acid ratio and antioxidant were recorded from orange fruits at Rama site. This was expected to have resulted from hot climate conditions at the site. Besides, at a relatively cooler condition of the Agulae site, high phenolic, reduced ferric power and high vitamin C were recorded. Rough lemon rootstock improved fruit size, while rootstock did not affect the contents of TSS, TSS/acid ratio across the sites in both harvesting years.

Biological indexing is based upon the ability of certain plants, referred to as indicator plants or indicators, to produce specific symptoms when inoculated with a pathogen using mechanical means or grafting. In the case of citrus viroids, clonal indicators are grafted on to vigorous rootstocks such as rough lemon (Citrus × granulata Raf.). The 'Arizona-861-S-1' citron clonal indicator (C. medica L.) can detect and bioamplify all citrus viroids; however, for specific citrus variants of the hop stunt viroid (i.e., CVd-IIb and CVd-IIc), the clonal indicator 'Parson's special # 9' mandarin (C. reticulata Blanco) is preferred. Inoculation techniques and symptom expression are described in detail. Other supporting elements, such as greenhouse conditions and propagation techniques, are also presented.

The objective of this work was to determine the influence of eight rootstocks on the yield, fruit quality, and survival of 'Pêra CNPMF D6' sweet orange (Citrus sinensis) trees grown under rainfed conditions in a cohesive soil of the Brazilian Northeast. In 2014-2018, the yield, fruits, and survival of trees planted in 1997 were evaluated in a randomized complete block design. Yield was assessed using annual fruit production, yield efficiency, and the alternate bearing index. Tree survival was considered the percentage of plants that remained alive until 2018. Fruit quality was evaluated by physicochemical attributes. 'Cravo' confirmed its good yield performance. Despite the lower number of trees, the 'Mazoe' rough lemon rootstock induced the highest fruit yield. The 'Cravo' x 'Cleópatra' hybrid and 'Volkameriano' lemon favored the highest trees survival, whereas 'Indio' citrandarin and 'Cravo' lime resulted in intermediate levels. The 'San Diego' and 'Riverside' citrandarins induced shorter tree with a high yield efficiency and a higher alternate bearing index, respectively. Fruits with less juice and mass were induced, respectively, by 'Riverside' citrandarin and 'Volkameriano' lemon. It can be concluded that the 'Mazoe' rootstock induces a higher fruit yield and 'Cravo' x 'Cleópatra' and 'Volkameriano', a greater survival. In addition, all rootstocks, except 'Riverside' and 'Volkameriano', induce fruit that meet the minimum quality requirements. Resumo: O objetivo deste trabalho foi determinar a influência de oito porta-enxertos no rendimento, na qualidade do fruto e na sobrevivência de laranjeiras (Citrus sinensis) 'Pêra CNPMF D6' cultivadas, em regime de sequeiro, em solo coeso do Nordeste brasileiro. Em 2014-2018, foram avaliados, no delineamento de blocos ao acaso, o rendimento, os frutos e a sobrevivência de árvores plantadas em 1997. O rendimento foi avaliado a partir da produção anual de frutos, da eficiência produtiva e do índice de alternância produtiva. A sobrevivência das árvores foi considerada a percentagem de plantas que permaneceram vivas até 2018. A qualidade dos frutos foi avaliada por meio de atributos físico-químicos. 'Cravo' confirmou seu bom desempenho produtivo. Apesar do menor número de árvores, o porta-enxerto limoeiro rugoso 'Mazoe' induziu a maior produtividade de frutos. O híbrido 'Cravo' x 'Cleópatra' e o limoeiro 'Volkameriano' favoreceram a maior sobrevivência das árvores, enquanto o citrandarin 'Indio' e o limoeiro 'Cravo' resultaram em níveis intermediários. Os citrandarins 'San Diego' e 'Riverside' induziram, respectivamente, árvores menores, com alta eficiência de produção e maior índice de alternância produtiva, respectivamente. Frutos com menos suco e massa foram induzidos, respectivamente, pelo citrandarin 'Riverside' e o limoeiro 'Volkameriano'. Conclui-se que o porta-enxerto 'Mazoe' induz maior rendimento de frutos e 'Cravo' x 'Cleópatra' e 'Volkameriano' maior sobrevivência. Além disso, todos os porta-enxertos, exceto 'Riverside' e 'Volkameriano', induzem frutos que atendem os requerimentos mínimos de qualidade.