Poor fruit setting in strawberries. II

Abstract

1 . This is a report on a preliminary investigation of the causes of insufficient fruit setting in the strawberry variety Jucunda, especially its clone JK3 2. From field experiments in different localities it was concluded :a . that raw weather increases the percentage of malformed fruits (nubbins) in Jucunda, especially in clone JK3, and b . that interplanting with a good pollen variety (Deutsch Evern) may decrease this percentage .3 . An insufficient pollination may take place in the centre of too closely planted beds . 4. Bees do not improve fruit setting in Jucunda . 5 . Usually the development of good anthers in Jucunda is not abundant, which means that the quantity of pollen produced is not large . 6 . The quality of the pollen, expressed as a percentage of morphologically good pollen, of the bad clone JK3 was sometimes a little lower than that of the good clones of Jucunda . 7 . Meiosis in the anthers of clone JK3 was normal . 8 . The fruit setting of the variety Deutsch Evern was good at all temperatures of the range of 10-26'C, whereas that of Jucunda was only good at 17-26"C . At 14 0 C and lower the fruit setting in Jucunda was reduced to zero . 9 . As the phenomena of this type of unfruitfulness are greatly influenced by the growth conditions of the plants, further investigation of this problem will be carried out under controlled conditions .

Factors Affecting the Quality andIn VitroGermination Capacity of Strawberry Pollen

“…Therefore, the positive effect of GA 3 on stamen length under SD should be considered as a growth phenomenon not interfering with the quality of pollen. In this respect our results concur with previous observations by Kronenberg et al (1959).…”

“…Pollen deformation as a cause of inadequate pollination and fertilization may lead to poor fruit set and in certain cultivars such a trait can be passed on to progeny (Braak, 1968). According to Kronenberg et al (1959) morphological aberrations in pollen may constitute an inheritable trait and on this basis strawberry cultivars may be considered "good or bad." 'Pajaro' seems to fall in the latter category.…”

“…Reduced fruit set and the formation of deformed fruits (nubbins), as a result of stamen sterility and poor pollen quality (Kronenberg, 1959;Kronenberg et al, 1959), may significantly curtail production in some strawberry cultivars, especially for early yield under greenhouse conditions. Inadequate chilling of plants (Risser, 1985), low temperatures (<17°C) (Braak, 1968) and low light intensity (Smeets, 1976;Smeets, 1980) shortly before and during flowering, are the main reasons of anther and pollen degeneration.…”

Flower and early fruit development in a diploid strawberry, Fragaria vesca

“…Berry size varies according to Xower position, number of carpels, and number of fertilized achenes. Primary fruit are larger than secondary fruit, and Xowers with greater pollination success produce larger berries (Kronenberg 1959). During early fruit development, a more accurate determinate of fruit developmental stage is the embryo morphology within the seeds on the berry, and not berry size.…”

Defining Strawberry Uniformity using 3D Imaging and Genetic Mapping

“…Simple, classical studies which remove all or part of the achenes from undeveloped pseudocarps has led to a cessation in the auxin “swelling signal” in the area beneath each achene and thus uneven fruit development 2 . In a similar fashion to achene removal, uneven pollination of the carpels, or absence of achene development, are the main causes of uneven pseudocarps 3 . Uneven successful pollination can be caused by damage to flowers through high temperature, frost or precipitation 1 .…”