scholarly journals Planting in Metallized Reflective Mulch Did Not Significantly Benefit Development of New Hybrid Citrus Seedlings

HortScience ◽  
2022 ◽  
Vol 57 (2) ◽  
pp. 200-201
Author(s):  
Ed Stover ◽  
Stephen Mayo ◽  
Randall Driggers ◽  
Robert C. Adair

The U.S. Department of Agriculture citrus scion breeding program is urgently working on developing huanglongbing (HLB; pathogen Candidatus Liberibacter asiaticus)-tolerant cultivars with excellent fruit quality and productivity when HLB-affected. The slow process of assessing new citrus hybrids is a major impediment to delivery of these much-needed cultivars. We generate thousands of hybrids each year, germinate the seedlings, grow them for 2 years in the greenhouse, plant them at high density in a field where the disease HLB is abundant, grow them for 5 to 10 years, and make selections based on tree performance and fruit quality of these HLB-affected trees. Based on promising reports of accelerated citrus growth when grown in a metallized reflective mulch (MRM) system, we tested the hypothesis that the MRM system may accelerate growth and selection of new hybrid seedlings compared with conventional soil culture (CSC). In the MRM system, tree rows are covered with a layer of metallized plastic film and drip irrigation is installed beneath the plastic. In 2 years of analysis, tree canopy volume was significantly greater with MRM in 2020 (27% greater than CSC) but not in 2021, and MRM tree height was greater in 2021 (7% greater than CSC). Mortality was significantly greater with MRM in both 2020 and 2021(in 2021: 32% vs. 17% under CSC), and MRM trees had more chlorotic leaves. Because of staff limitations, plant debris and soil were not routinely cleared from MRM, thus diminishing any benefit from the reflective surface. Better maintenance might have resulted in more sustained evidence of MRM growth benefits. With the current resource availability, the MRM system does not appear to accelerate the assessment of hybrid seedling trees.

2021 ◽  
Vol 64 (5) ◽  
pp. 1611-1624
Author(s):  
Worasit Sangjan ◽  
Sindhuja Sankaran

HighlightsTree canopy architecture traits are associated with its productivity and management.Understanding these traits is important for both precision agriculture and phenomics applications.Remote sensing platforms (satellite, UAV, etc.) and multiple approaches (SfM, LiDAR) have been used to assess these traits.3D reconstruction of tree canopies allows the measurement of tree height, crown area, and canopy volume.Abstract. Tree canopy architecture is associated with light use efficiency and thus productivity. Given the modern training systems in orchard tree fruit systems, modification of tree architecture is becoming important for easier management of crops (e.g., pruning, thinning, chemical application, harvesting, etc.) while maintaining fruit quality and quantity. Similarly, in forest environments, architecture can influence the competitiveness and balance between tree species in the ecosystem. This article reviews the literature related to sensing approaches used for assessing architecture traits and the factors that influence such evaluation processes. Digital imagery integrated with structure from motion analysis and both terrestrial and aerial light detection and ranging (LiDAR) systems have been commonly used. In addition, satellite imagery and other techniques have been explored. Some of the major findings and some critical considerations for such measurement methods are summarized here. Keywords: Canopy volume, LiDAR system, Structure from motion, Tree height, UAV.


1986 ◽  
Vol 26 (5) ◽  
pp. 619
Author(s):  
KR Chapman ◽  
B Paxton ◽  
DH Maggs

Five processing guava clones (GA6- 1, GA7- 12, GA8-30, GA9-35, GA11-56) were tested over 3 cropping years at Nambour, in coastal south-eastern Queensland. Mean marketable yield for the first crop at 2 years of age was 45 kg/tree or 36.23 t/ha at a density of 805 trees/ha. GA11-56, the most acceptable clone for processing, also gave the highest marketable yields of 627, 71.65 and 72.53 t/ha for the first 3 crops. Yield per unit cross sectional area of trunk was a more simple and useful index of yield efficiency than more complex parameters including a fruitfulness index and multiple regressions with yield of north-south canopy spread, number of primary branches and combinations of these and trunk girth. Similarly, trunk - - girth provided at least as good an estimate of tree size as the vigour index. Tree dimension measurements which included east-west canopy spread, north-south canopy spread, tree height, stem height, number of primary branches, crown height, crown radius, tree canopy volume, canopy surface area and an index of crown weight provided no consistent indication of tree size. They were not highly correlated with either accumulated or final yield of the guava. The GA11-56 clone because of its yield, fruit size and other desirable processing characteristics was the only clone that could be recommended for commercial plantings.


1969 ◽  
Vol 85 (3-4) ◽  
pp. 143-149
Author(s):  
Félix M. Román-Pérez ◽  
Agenol González-Vélez

Performance of the rootstocks 'Swingle citrumelo', 'Naronja' and mandarins 'Cleopatra' and 'Sun Chu Sha' on 'Washington Navel' orange [Citrus sinensis (L.)] was evaluated at Corozal and Isabela, Puerto Rico, during the first four years of production. Mean number of fruit per tree was significantly different between locations and among rootstocks for 1996-97 and 1997- 98. Data were not taken in 1998-99 because of damage caused by Hurricane Georges. The first two years the amount of fruit was significantly higher at Corozal than at Isabela, with Swingle producing greatest fruit yield. In 1999-00 (fourth year of production) no significant differences between locations were detected for tree canopy volume. Significant differences for internal fruit quality were detected between locations and among rootstocks for acidity, brix/acidity ratio and pH. No significant differences were observed for brix between locations or among rootstocks.


HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 553d-553
Author(s):  
C.R. Unrath

Historically, most airblast chemical applications to apple orchards used a single “average” water volume, resulting in variability of coverage with tree size and also the greatest variable in chemical thinning. This coverage variability can be eliminated by properly quantifying the tree canopy, as tree row volume (TRV), and relating that volume to airblast water rate for adequate coverge. Maximum typical tree height, cross-row limb spread, and between-row spacing are used to quantify the TRV. Further refinement is achieved by adjusting the water volume for tree canopy density. The North Carolina TRV model allows a density adjustment from 0.7 gal/1000 ft3 of TRV for young, very open tree canopies to 1.0 gal/1000 ft3 of TRV for large, thick tree canopies to deliver a full dilute application for maximum water application (to the point of run-off). Most dilute pesticide applications use 70% of full dilute to approach the point of drip (pesticide dilute) to not waste chemicals and reduce non-target environmental exposure. From the “chemical load” (i.e., lb/acre) calculated for the pesticide dilute application, the proper chemical load for lower (concentrate) water volumes can be accurately determined. Another significant source of variability is thinner application response is spray distribution to various areas of the tree. This variability is related to tree configuration, light, levels, fruit set, and natural thinning vs. the need for chemical thinning. Required water delivery patterns are a function of tree size, form, spacing, and density, as well as sprayer design (no. of nozzles and fan size). The TRV model, density adjustments, and nozzle patterns to effectively hit the target for uniform crop load will be addressed.


1996 ◽  
Vol 1 (1) ◽  
pp. 27-54 ◽  
Author(s):  
I. J. Warrington ◽  
C. J. Stanley ◽  
D. S. Tustin ◽  
P. M. Hirst ◽  
W. M. Cashmore

Agronomy ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1947
Author(s):  
Alson Time ◽  
Claudio Ponce ◽  
Nathalie Kuhn ◽  
Macarena Arellano ◽  
Boris Sagredo ◽  
...  

Abscisic acid (ABA) plays a major role in promoting ripening in sweet cherry, a non-climacteric fruit. Exogenous application of ABA has been performed to study fruit ripening and cracking, but this growth regulator is not used for commercial production. To determine the potential of this growth regulator to improve sweet cherry fruit quality, ABA canopy spraying was assayed in four cultivars. Canopy spraying of S-ABA significantly: (1) enhanced sweet cherry fruit color in ‘Glenred’, ‘Lapins’ and ‘Bing’ cultivars, but not in ‘Royal Rainier’ (a bi-colored cultivar), and (2) decreased fruit size and firmness in ‘Lapins’, ‘Bing’ and ‘Royal Rainier’. Seasonally reproducible effects were seen in ‘Lapins’ (mid/late-maturing) but not in ‘Glenred’ (early-maturing). Canopy spraying of nordihydroguaiaretic acid (NDGA) decreased color and increased fruit size in ‘Lapins’, but not in ‘Glenred’. Direct application of ABA on fruits attached to the tree, without application to the foliage, increased ‘Lapins’ fruit color without reducing size. These results suggest a localized fruit response to exogenous ABA application on fruit color development, but that a decrease in fruit size may be due to the effects of exogenous ABA on the tree canopy foliage.


1993 ◽  
Vol 33 (3) ◽  
pp. 353 ◽  
Author(s):  
AP George ◽  
RJ Nissen ◽  
T Rassmussen

Combinations of 3 methods of controlling tree size (use of the growth retardant paclobutrazol, postharvest topping, and autumn cincturing) were evaluated for their effects on growth, yield, and fruit quality of the low chill nectarine cv. Sundowner in subtropical Australia. Compared with controls over 3 seasons, paclobutrazol used alone reduced tree size by 34-52%, with further reductions when combined with light and severe postharvest topping (by 5-25 and 58-71%, respectively). Yield efficiency (as measured by yield per unit canopy volume) was significantly improved by paclobutrazol and was doubled when paclobutrazol was combined with severe postharvest topping. Although this combination reduced time associated with pruning, thinning, and harvesting, it had the disadvantage of delaying flowering and, consequently, fruit maturity in the subsequent harvest season. Light postharvest topping and autumn cincturing used with paclobutrazol had little effect on yield efficiency, fruit quality, or harvest period. The seasonal pattern of starch reserves for twigs was similar for all treatments, with starch levels falling to a minimum during the early harvest period. Measurements of starch in the major tree organs showed that at very low harvest increments (<10) there was little or no depletion of starch from the twigs and leaves, but as harvest increments increased (range 10-40), there was increasing starch depletion, in order of priority, from the roots, trunks, and limbs.


2002 ◽  
pp. 459-466 ◽  
Author(s):  
M. Forlani ◽  
B. Basile ◽  
C. Cirillo ◽  
C. Iannini

2001 ◽  
Author(s):  
S. D. Tumbo ◽  
M. Salyani ◽  
J. D. Whitney ◽  
T. A. Wheaton ◽  
W. M. Miller

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 595c-595
Author(s):  
Ashok K. Alva

The aim of this study was to investigate soil pH and copper (Cu) interactions affecting Cu phytotoxicity to young citrus trees on different rootstocks. Hamlin oranges on either Carrizo citrange, sour orange, or rough lemon rootstocks were grown on Candler fine sand at varying soil pH (5.0, 5.5, 6.0, 6.5) without additional Cu or soil applied Cu (liquid form; 240 kg Cu/ha; nine pre- and five post-planting applications over a period of 43 months). Increasing soil pH increased tree height, canopy volume and trunk diameter of trees on all three rootstocks, regardless of Cu treatments. Tree growth response to an increase in soil pH was greater in Cu amended as compared to unamended treatments. Response to pH increase above 6.0 was marginal as compared to that for pH increase from 5.0 to 6.0. Leaf Cu concentrations showed negligible differences in response to Cu treatments; however, Cu concentrations in fibrous roots increased by 126 to 152% in Cu amended as compared to unamended treatments.


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