daisysl &# 39 ; is a mandarin selection developed at the university of california riverside from an irradiated bud of the diploid mandarin cultivar ‘ daisy ’, a mid - season maturing variety . daisysl has been asexually reproduced by grafting ( budding ) using the standard t - bud method generally used to propagate citrus in california . asexual propagation of the selected tree was first accomplished in january 2003 at the university of california , riverside to produce 20 trial trees on carrizo and c - 35 rootstocks . ‘ daisysl ’ distinguishes itself by being very low seeded ( 2 . 2 seeds / fruit ) in all situations of cross - pollination , differing from ‘ daisy ’ which will set from 16 - 25 seeds / fruit in cross - pollinated situations . in 2010 , some trees of ‘ daisysl ’ were found to produce some fruit with seed counts similar to ‘ daisy ’, but only about 1 - 2 % of all fruit were affected . evaluation of ‘ daisysl ’ mandarin began on the original tree at riverside in 2001 and has continued annually until the present . in riverside , calif . ‘ daisysl ’ fruit matures in winter ( early - december ). ‘ daisysl ’ holds its fruit quality characteristics through february . fruit size is moderately large ( 68 mm ) averaging 135 grams per fruit . fruit are slightly obconate in shape with a very deep orange rind color and an extremely smooth rind texture . flesh color is very deep orange and finely - textured , fruit are juicy , with a rich , sweet and very distinctive flavor when mature . fruit are only moderately easy to peel . tree growth habit is spreading with excellent production commencing in the third year after planting . alternate bearing can be a problem in trees that are not culturally managed to reduce this tendency . cultural practices ‘ daisysl ’ mandarin can be grown according to accepted cultural practices for most mandarin varieties including planting densities of 150 - 250 trees per acre ( 375 - 625 trees / ha ), normal fertilization and pest control practices , and the use of standard rootstocks for mandarins . pruning may enhance production and health of the tree if applied after the second year of full fruit production . other rootstocks adapted to more marginal growing conditions of salinity , high ph or very heavy soils may be useful in those conditions . mid to late season maturing mandarin cultivars in production include ‘ daisy ’ mandarin ( the original cultivar from which ‘ daisysl ’ was derived ), ‘ w . murcott ’ ( afourer ), ‘ fortune ’ mandarin , ortanique mandarin , ‘ temple ’ tangor , ‘ dancy ’ mandarin ‘ minneola ’ tangelo , and the mid - season clementina selections ‘ hernandina ’ and ‘ nour ’. all of these cultivars will be seedy if grown in the presence of a pollenizer . some , including the clementina selections , ‘ fortune ’, ‘ ortanique ’ and ‘ page ’ mandarins will have few seeds if no pollenizer is present . recently released mid to late season cultivars that are very low - seeded include ‘ tango ’ mandarin , ‘ gold nugget ’ mandarin , ‘ tde2 ’ mandarin hybrid ( shasta gold (®) ‘ tde3 ’ mandarin hybrid ( tahoe gold ®), and ‘ tde4 ’ mandarin hybrid ( yosemite gold ®). ‘ daisysl ’ differs from these cultivars in being earlier maturing , having fruit with a smoother rind texture , and a lesser ability to maintain fruit on the tree or in storage for an extended period . trees of ‘ daisysl ’ show similar alternate bearing characteristics to these cultivars . additional differences ( summarized in table 6 ) distinguish it from each of these cultivars . ‘ daisysl ’ mandarin exhibits low seed numbers (& lt ; 2 . 5 seeds per fruit ) under all conditions of cross - pollination . additionally , preliminary evaluations indicate that pollen from ‘ daisysl ’ has low germination rates in culture (˜ 10 - 20 %) and appears not likely to cause high seed numbers in other mandarins , specifically ‘ tango ’, ‘ w . murcott ’ and clementines . a comparison of ‘ daisysl ’ with other low - seeded mid and late - season mandarins is provided in table 6 below . ‘ daisysl ’ is distinctive and superior in having outstanding flavor , an exceptionally smooth rind , reduced alternate bearing , and larger fruit size preferred in some markets , although it retains the tendency of its parent ‘ daisy ’ for fruit to split at levels approaching 20 % in bad years . tree size , growth and fruit production characteristics and fruit quality characteristics have been compared in these evaluations to ‘ daisy ’ mandarin from the same field block . six - year - old ‘ daisysl ’ trees in trials at riverside , and four - year - old trees at the other six sites have been evaluated for from two to four years of fruiting ( see tables 1 and 2 ). tree size and growth characteristics of ‘ daisysl ’ have been consistent with ‘ daisy ’ throughout the evaluations . growth of both the ‘ daisy ’ and the ‘ daisysl ’ selection has been quite spreading ( characterized as ‘ leggy ’) in the first several years of growth followed by a tendency to grow into a more spherical , slightly drooping shape in ensuing years . the nine - year - old ‘ daisysl ’ tree at riverside on carrizo citrange rootstock is 3 . 3 m high and 3 . 7 m wide with a normal upright growth habit yielding a canopy volume of 23 . 65 m 3 . in comparison nine - year - old ‘ daisy ’ control trees have averaged 3 . 2 m tall and 3 . 6 m wide yielding a canopy volume of 21 . 7 m 3 on carrizo citrange rootstock . scion circumference for ‘ daisysl ’ on carrizo rootstock was 38 . 5 cm with the rootstock circumference 54 . 7 cm . scion circumference for the nine - year old ‘ daisy ’ trees averaged 36 . 9 cm on carrizo rootstock and 38 . 2 cm on c35 rootstock . in the younger multi - location trials five - year - old ‘ daisysl ’ trees on carrizo rootstock have averaged 2 . 8 m in height and 3 . 0 m in diameter with canopy volumes of 8 . 48 m 3 and trees on c35 rootstock averaged 2 . 9 m in height and 2 . 7 m in diameter with canopy volumes of 7 . 48 m 3 . leaves of ‘ daisysl ’ are moderately large for a mandarin ( 86 . 1 mm in lengthx47 . 9 mm in width ), ovate in shape and concave in cross - section , with an acute apex with weak emargination and a convex base and are dark - green in color ( adaxial - rhs green 139a , abaxial - rhs green 137c ). petioles are medium in length ( 9 . 5 mm ) and normally lack wings . the selection lacks thorns . flowers of ‘ daisysl ’ are hermaphroditic with greenish - white petals and yellowish anthers and are borne in clusters . pollen viability for ‘ daisysl ’ is moderately low ( 10 - 20 % germination vs . ˜ 75 % germination for ‘ daisy ’), and pollen production is reduced ( 30 - 40 % that of ‘ daisy ’) in comparison to ‘ daisy ’. fruit of ‘ daisysl ’ are slightly obconate in shape with no neck . the fruit has a slightly convex basal end ( moderately depressed ) with a truncate ( slightly depressed ) distal end , and a distinctive areola and non - persistent style . the fruit is large - sized for a mandarin ( classed as jumbo by state of california standards and size 21 for industry packing standards ) averaging 68 . 0 mm in diameter and 60 . 1 mm in height with a very smooth , deep orange rind color ( rhs red - orange n30c ) and slightly conspicuous , slightly raised oil glands . the rind is moderately adherent at maturity and relatively thin averaging 3 . 0 mm in thickness . this rind thinness is implicated in the tendency of ‘ daisysl ’ and its parent ‘ daisy ’ to experience a moderately high level of splitting of fruit , sometimes as high as 20 % of the total crop . the fruit interior has a fine flesh texture with 10 - 11 segments and a semi - solid axis of medium size at maturity . the fruit are juicy , averaging approximately 47 % juice and 135 g in weight . fruit from trees on carrizo and c35 citrange rootstocks average 11 . 9 - 12 . 8 % soluble solids and 1 . 03 - 1 . 28 % acid in early december at six trial locations in california increasing to 14 . 2 - 15 . 8 % soluble solids and 0 . 78 - 0 . 92 % acid in early february . the fruit average 2 . 2 seeds per fruit in the presence of cross - pollination at all locations . seeds , when present , are polyembryonic , yellow - white in color ( yellow - white 158b ) with greyed - yellow ( greyed - yellow 160c ) colyledons and a greyed - yellow ( greyed - yellow 163b ) inner seed coat . full fruit production of ‘ daisysl ’ begins in the third year after planting similar to ‘ daisy ’. a few fruit will set in the second year after planting but not at commercially acceptable levels . fruit production on four - year - old trees averaged 27 - 48 kg at four fruiting trial sites . the original tree at riverside was similar in fruit production in the fourth year and in years 7 , 8 and 9 yielded 77 , 32 and 72 kg of fruit respectively indicating that in the earlier years of production the variety has somewhat of a tendency to alternate bear , similar to ‘ daisy ’. fruit storage trials included storage of washed but not waxed fruit at 5 . 6 ° c . for up to 60 days with fruit samples taken every 14 days for analysis . data indicate that the storage characteristics of ‘ daisysl ’ are fair with some rind deterioration ( rind drying ) and some significant indication of fungal disease problems in 23 % of the fruit . there was no significant deterioration in juice quality or taste over a 30 day storage period in those fruit without fungal pathogens , but with more significant rind deterioration if kept to 60 days . overall daisy can only be considered to be fair in storage ability due primarily to the somewhat susceptible nature of the rind to pathogen organisms . fungicide treatment and waxing might decrease decay and rind deterioration during storage . no susceptibilities to plant or fruit diseases or to pests beyond those normally associated with citrus species have been observed .
‘ daisysl ’ is a mid - season maturing diploid mandarin that combines medium - large sized fruit of excellent quality and production with very low seed content even in mixed plantings . it would likely be successful in the mid - season marketing window that currently has very few low - seeded , high quality cultivars .