scholarly journals The Significance of Macronutrients in Alternate Bearing ‘Nadorcott’ Mandarin Trees

HortScience ◽  
2018 ◽  
Vol 53 (11) ◽  
pp. 1600-1609 ◽  
Author(s):  
Ockert P.J. Stander ◽  
Graham H. Barry ◽  
Paul J.R. Cronjé
Keyword(s):  
Treatment Effects ◽  
Foliar Spray ◽  
Shoot Development ◽  
Citrus Reticulata ◽  
Alternate Bearing ◽  
Vegetative Shoot ◽  
Current Season ◽  
Standard Practice ◽  
Main Determinants ◽  
Fruit Load

The significance of macronutrients nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) in leaves was studied in relation with their possible roles in alternate bearing of ‘Nadorcott’ mandarin (Citrus reticulata) trees over a period of three seasons. Fruit load (“on,” a heavy fruit load, vs. “off,” a light fruit load) affected the leaf macronutrient concentrations, and the amount of macronutrients removed through the harvest of fruit, i.e., the crop removal factor (g·kg−1), was consistent in both seasons. The crop removal factors were higher for each macronutrient in “off” trees—harvest of 1 kg fruit removed ≈2.3 g·kg−1 N, 0.3 g·kg−1 P, 3.1 g·kg−1 K, 1.0 g·kg−1 Ca, and 0.4 g·kg−1 Mg, compared with 1.3 g·kg−1 N, 0.2 g·kg−1 P, 1.7 g·kg−1 K, 0.6 g·kg−1 Ca, and 0.2 g·kg−1 Mg in “on” trees. Fruit load per tree (kg/tree) of 84, 110, and 52 kg/tree in “on” trees, however, removed ≈217 g/tree N, 28 g/tree P, 296 g/tree K, 100 g/tree Ca, and 35 g/tree Mg, which was 1.5–6 times more than that of fruit loads of 14, 71, and 16 kg/tree in “off” trees. In “off” trees, N, P, and K, and in “on” trees, Ca accumulated in leaves to between 20% and 30% higher concentrations in season 1, but the higher macronutrient status did not manifest in or consistently correlate with intensity of summer vegetative shoot development in the current season, or intensity of flowering in the next season, the two main determinants of fruit load in ‘Nadorcott’ mandarin. Apart from some anomalies, the concentrations of macronutrients in leaves were unaffected by de-fruiting and foliar spray applications of N and K to “on” trees, and showed no consistent relationship with treatment effects on parameters of vegetative shoot development and flowering. Leaf macronutrients in alternate bearing ‘Nadorcott’ mandarin trees, fertilized according to grower standard practice, are not related to differences in flowering and vegetative shoot development, and appear to be a consequence of fruit load and not a determinant thereof.

scholarly journals Fruit Load Limits Root Growth, Summer Vegetative Shoot Development, and Flowering in Alternate-bearing ‘Nadorcott’ Mandarin Trees

2018 ◽  
Vol 143 (3) ◽  
pp. 213-225 ◽  
Author(s):  
Ockert P.J. Stander ◽  
Graham H. Barry ◽  
Paul J.R. Cronjé
Keyword(s):  
Root Growth ◽  
Shoot Development ◽  
Sugar Concentration ◽  
Tree Level ◽  
Alternate Bearing ◽  
Vegetative Shoot ◽  
Carbohydrate Concentration ◽  
Growth Activity ◽  
Return Bloom ◽  
Fruit Load

The objectives of this study were to improve the understanding of the mechanism of alternate bearing and the role of carbohydrates in ‘Nadorcott’ mandarin (Citrus reticulata) trees. Selected phenological responses were measured in natural heavy- (“on”) and low-fruiting (“off”) ‘Nadorcott’ mandarin trees grown under commercial South African production conditions. The relationships with seasonal leaf and root carbohydrate concentrations were evaluated at the shoot-, branch- and tree level over two seasons. Fruit load [R2 = (−)0.80 and R2 = (−)0.73 in seasons 1 and 2, respectively; (P < 0.01)] and the number of newly developed vegetative shoots [R2 = 0.81 and R2 = 0.78 in seasons 1 and 2, respectively; (P < 0.01)] were the most important determinants of return bloom. Sprouting of a higher number of new vegetative shoots from “off” trees compared with “on” trees (“off” = 863 and 1439 vs. “on” = 306 and 766) was not related to leaf carbohydrate concentration. Root sugar concentration peaked during full bloom and higher root growth activity was observed before a higher number of new vegetative shoots developing in “off” trees during summer. The root sugar concentration early in the season was ≈3-fold lower, and root and shoot growth were absent, or lower in “on” trees compared with “off” trees. These results concur with previous research and confirm that fruit load in “on” trees inhibits summer vegetative shoot development, which manifests in poor flowering and an “off” year. This study shows that fruit are the major carbohydrate sink and probably disturb the balance between vegetative shoot development and root growth by limiting carbohydrate allocation to roots.

scholarly journals Vegetative and Reproductive Response to Fruit Load in Two Jojoba (Simmondsia chinensis) Cultivars

Agronomy ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 889
Author(s):  
Aviad Perry ◽  
Noemi Tel-Zur ◽  
Arnon Dag
Keyword(s):  
Vegetative Growth ◽  
Accumulation Rate ◽  
Dry Weight ◽  
High Yield ◽  
Lower Amount ◽  
Simmondsia Chinensis ◽  
Alternate Bearing ◽  
Fruit Removal ◽  
Growing Period ◽  
Fruit Load

Jojoba (Simmondsia chinensis) is a wax crop cultivated mainly in arid and semi-arid regions. This crop has been described as an alternate-bearing plant, meaning that it has a high-yield year (“on-year”) followed by a low-yield year (“off-year”). We investigated the effect of fruit load on jojoba’s vegetative and reproductive development. For two consecutive years, we experimented with two high-yielding cultivars—Benzioni and Hazerim—which had opposite fruit loads, i.e., one was under an on-year load, while the other was under an off-year load simultaneously. We found that removing the developing fruit from the shoot during an off-year promotes further vegetative growth in the same year, whereas in an on-year, this action has no effect. Moreover, after fruit removal in an on-year, there was a delay in vegetative growth renewal in the consecutive year, suggesting that the beginning of the growing period is dependent on the previous year’s yield load. We found that seed development in the 2018 season started a month earlier than in the 2017 season in both cultivars, regardless of fruit load. This early development was associated with higher wax content in the seeds. Hence, the wax accumulation rate, as a percentage of dry weight, was affected by year and not by fruit load. However, on-year seeds stopped growing earlier than off-year seeds, resulting in smaller seeds and an overall lower amount of wax per seed.

scholarly journals The role of small RNAs in vegetative shoot development

2016 ◽  
Vol 29 ◽  
pp. 64-72 ◽  
Author(s):  
Jim P Fouracre ◽  
R Scott Poethig
Keyword(s):  
Small Rnas ◽  
Shoot Development ◽  
Vegetative Shoot

scholarly journals Influence of Nonpermanent Netting on Foliar Spray Deposition, Insect Pest Prevalence, and Production of ‘Nadorcott’ Mandarin (Citrus reticulata)

HortScience ◽  
2019 ◽  
Vol 54 (4) ◽  
pp. 667-675
Author(s):  
Ockert P.J. Stander ◽  
Jade North ◽  
Jan M. Van Niekerk ◽  
Tertia Van Wyk ◽  
Claire Love ◽  
...  
Keyword(s):  
Treatment Group ◽  
Fruit Quality ◽  
Spray Deposition ◽  
Insect Pest ◽  
Foliar Spray ◽  
Fruit Yield ◽  
Control Treatment ◽  
Citrus Reticulata ◽  
Western Cape ◽  
Thaumatotibia Leucotreta

This study aimed to determine the effects of different types of nonpermanent netting (NPN) on foliar spray deposition, insect pest prevalence, and production and fruit quality of ‘Nadorcott’ mandarin (Citrus reticulata) trees in a commercial orchard at Citrusdal (lat. 32 32′31″S, long. 19 0′42″E), Western Cape, South Africa. The deposition quantity (FPC%) of foliar spray volumes of 3500, 7000, or 15,000 L·ha−1 was greater for leaves of control trees compared with leaves treated with NPN during summer (January) (8.8 vs. 6.1; P = 0.0055) and winter (June) (4.8 vs. 3.1; P = 0.0035). Deposition uniformity (CV%) was better for control leaves during summer (64.9 vs. 75.2; P = 0.0062) and winter (59.6 vs. 80.5; P = 0.0014), and deposition quality (ICD%) was better during winter (79.4 vs. 84.2; P = 0.0393). There were no differences in FPC%, CV%, and ICD% for fruit when foliar spray volumes of 3500 and 15,000 L·ha−1 were used for the control and NPN treatment groups during winter. However, with a foliar spray volume of 7500 L·ha−1, fruit from the control treatment group had greater FPC% (19.3 vs. 6.1; P = 0.0262), CV% (70.3 vs. 50.9; P = 0.0484), and ICD% (57.1 vs. 79.9; P = 0.0157). There were no differences in macronutrient concentrations between the leaves of trees subjected to control and NPN treatments, but leaf zinc (<81%; P = 0.0317) and iron (<78%; P = 0.0041) concentrations were lower with the NPN treatment. During short NPN treatments, fruit yield was reduced by ≈37% compared with that after control treatment, and longer NPN treatments had no effect on fruit yield. The reduction in fruit yield with NPN was not related to the effects of NPN on foliar spray deposition or to lower leaf micronutrient concentrations. The lower fruit yield during short NPN treatments was most likely caused by fruit drop that was exacerbated by the removal of the NPN. In the long NPN treatment group, fruit damage caused by sunburn was reduced by 17%, but the outer canopy fruit experienced increased wind damage or scarring. Except for the lower titratable acidity content with the shortest NPN treatment and the higher Brix°:TA ratio with two NPN treatments, NPN did not impact other fruit quality attributes. The use of NPN excluded male wild false codling moths (Thaumatotibia leucotreta) (FCM) males; however, it was still possible to capture a very small amount of mass-released sterile FCM and wild fruit flies under the NPN.

scholarly journals Correlations of Crop Load and Return Bloom with Root and Shoot Concentrations of Potassium, Nitrogen, and Nonstructural Carbohydrates in Pecan

2007 ◽  
Vol 132 (1) ◽  
pp. 44-51 ◽  
Author(s):  
Michael W. Smith ◽  
Charles T. Rohla ◽  
Niels O. Maness
Keyword(s):  
Growth Regulator ◽  
Current Theory ◽  
Nonstructural Carbohydrates ◽  
Alternate Bearing ◽  
Crop Load ◽  
Current Season ◽  
Flower Production ◽  
Previous Season ◽  
Second Growth ◽  
Return Bloom

The current theory of pecan [Carya illinoinensis (Wangenh.) C. Koch] alternate bearing is the “growth regulator–carbohydrate theory” in which flowering is first controlled by growth regulators produced by fruit and leaves, and then by the size of the carbohydrate pool near budbreak. Lack of nitrogen (N) reserves has also been proposed to be limiting after large crops, thus reducing return bloom. Annual production was determined for 12 individual trees for 3 years. Return bloom was monitored on four previous-season shoot types: 1) vegetative shoots, 2) bearing terminal shoots without a second growth flush, 3) bearing lateral shoots without a second growth flush, and 4) bearing shoots that were primarily in the terminal position with a second growth flush. Nonstructural carbohydrates, organically bound N, and potassium (K) concentrations were determined in roots and shoots. Regression analysis was used to determine the effect of yield on subsequent nonstructural carbohydrates, N, and K in the roots and shoots, and their postyield concentrations on subsequent flowering. Alternate bearing was evident because there were reductions of 18%, 16%, and 18% in the percentage of current season shoots flowering for every 10 kg/tree production increase in the previous season's yield in 2002, 2003, and 2004 respectively. Flower production in 2002 decreased by 2.6 flowers/1-year-old branch and 1.6 flowers/1-year-old branch in 2003 for each 10 kg/tree increase in production. The third year of the study, neither previous season shoot type nor yield affected subsequent flower production. The previous year's shoot type did not affect the percentage of current season shoots flowering; however, the previous year's shoots that had a second growth flush produced more flowers the following year than the other shoot types. Results suggested that crop load was not related to nonstructural carbohydrates, N, or K in the roots and shoots during January in these well-managed trees. Stored nonstructural carbohydrates, N, and K were also not related to return bloom. These data suggest that the current “growth regulator–carbohydrate theory” may not be valid in these well-managed trees. Nonstructural carbohydrates, K, and organically bound N do not appear to be critical factors regulating flowering.

IbMADS4 regulates the vegetative shoot development in transgenic chrysanthemum (Dendrathema grandiflora (Ramat.) Kitamura)

Plant Science ◽  
2004 ◽  
Vol 166 (4) ◽  
pp. 847-854 ◽  
Author(s):  
Chenna Reddy Aswath ◽  
Sug Youn Mo ◽  
Sun-Hyung Kim ◽  
Doo Hwan Kim
Keyword(s):  
Shoot Development ◽  
Vegetative Shoot ◽  
Transgenic Chrysanthemum

EMF, an Arabidopsis Gene Required for Vegetative Shoot Development

Science ◽  
1992 ◽  
Vol 258 (5088) ◽  
pp. 1645-1647 ◽  
Author(s):  
Z. R. Sung ◽  
A. Belachew ◽  
B. Shunong ◽  
R. Bertrand-Garcia
Keyword(s):  
Shoot Development ◽  
Vegetative Shoot ◽  
Arabidopsis Gene

scholarly journals The Potential Use of Metamitron as a Chemical Fruit-thinning Agent in Mandarin

2018 ◽  
Vol 28 (1) ◽  
pp. 28-34 ◽  
Author(s):  
Ockert P.J. Stander ◽  
Johané Botes ◽  
Cornelius Krogscheepers
Keyword(s):  
Fruit Set ◽  
Fruit Size ◽  
Fruit Trees ◽  
Fruit Yield ◽  
Citrus Reticulata ◽  
Alternate Bearing ◽  
Fruit Thinning ◽  
Total Carbohydrates ◽  
Leaf Carbohydrates ◽  
Potential Use

Under conditions of profuse flowering and excessive fruit set, citrus (Citrus sp.) fruit need to be thinned to increase the size of remaining fruit, reduce the intensity of alternate bearing, or both. Metamitron was recently developed as a chemical fruit-thinning agent for apple (Malus ×domestica) and pear (Pyrus communis), and it inhibits photosynthesis and is thought to transiently reduce the carbohydrate pool in fruit trees. Citrus trees are sensitive to carbohydrate stress during and immediately after flowering, but the response of citrus to foliar treatment with a photosynthesis inhibitor, such as metamitron, is unknown. The purpose of this study was to evaluate metamitron for its effects on leaf carbohydrates and its ability to chemically thin citrus fruitlets. Significant fruit-thinning effects were found in all the experiments conducted over two seasons. A 300 mg·L−1 metamitron treatment reduced leaf sugars and leaf total carbohydrates, and consistently reduced the total number of fruit per tree in both seasons in ‘Nadorcott’ mandarin (Citrus reticulata), irrespective of the timing of application. In the second season, a reduction in fruit yield was reported with an increase in metamitron concentration, both in mass and number of fruit per tree. A 150 mg·L−1 metamitron treatment in November had no fruit-thinning effects, and fruit yield was not different from the control. The application of metamitron did not increase the fruit size of ‘Nadorcott’ mandarin and had no direct effect on other fruit quality attributes in either season. Metamitron can be used as a chemical fruit-thinning agent to reduce fruit numbers in ‘Nadorcott’ mandarin, but an increase in fruit size or quality should not be expected.

scholarly journals Individual Shoot Defoliation Minimally Affects Pecan Return Bloom

HortScience ◽  
2013 ◽  
Vol 48 (3) ◽  
pp. 314-317
Author(s):  
Michael W. Smith ◽  
Becky S. Cheary
Keyword(s):  
Cultural Practices ◽  
Carya Illinoinensis ◽  
Alternate Bearing ◽  
Current Season ◽  
Fruit Thinning ◽  
Return Bloom

Alternate bearing of pecan [Carya illinoinensis (Wangenh.) K. Koch] remains the leading problem of the industry. Several cultural practices have been developed or improved to mitigate alternate bearing. Premature defoliation was one problem identified that substantially decreased return bloom. The objective of this study was to determine the response of individual shoots exposed to various defoliation treatments. In one study, individual vegetative or bearing shoots were hand-defoliated in mid-September. Defoliation was the basal one-half, distal one-half, entire shoot, or not defoliated. Another study applied the same defoliation treatments to bearing shoots in July, August, or September. Defoliation had minimal effects on return bloom and rarely affected the percentage of current-season shoots fruiting the next year. Defoliation date also had little effect on return bloom. These data indicate that individual shoot response to defoliation was not autonomous and has implications for determining crop overload and needed mechanical fruit thinning.

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