Annual Shoot Extension Research Articles

Effect of Fruitlet Thinning on Apple Production and Quality under High Density Plantation

This study, conducted within the Experimental Block of the Division of Fruit Science at SKUAST-K, Shalimar, India, was aimed to thin 5-year-old Fuji Zehn Aztec apple plants. The research was carried out during the years 2020 and 2021and implemented a Randomized Complete Block Design with 11 treatments, including control and various other thinning methods. Chemical and hand thinning were practised at the 12 mm king fruitlet diameter stage. Among the treatments, T9 (NAA+BA@15+140ppm) demonstrated significant results, with the highest trunk girth increment (0.41 cm), annual shoot extension growth (65.46 cm), leaf area (34.71 cm2), fruit drop (39.26%), and the least reduction in return bloom (52.22%). Additionally, T9 resulted in maximum fruit length (79.98 mm), fruit diameter (89.00 mm), fruit weight (224.90 g), fruit volume (197.86 cm3), Soluble Solid concentration (15.87%), SSC : acidity (40.08), total sugar content (11.07%), anthocyanin content (7.14 mg/100g), ascorbic acid content (6.94 mg/100g), and received the highest organoleptic rating score (4.87). However, the highest yield (21.97 kg/tree), yield efficiency (1.50 kg/cm2), fruit firmness (8.36 kg/cm2), hue angle (68.57°), and acidity (0.59%) were recorded in the control group. Notably, T1 (Hand thinning @ 2 fruitlets retained per cluster) achieved the highest fruit retention (97.97%) and the maximum leaf-to-fruit ratio (27.50). These findings shed light on the potential benefits and trade-offs associated with different fruitlet thinning methods in high-density apple plantations. Understanding these effects can aid orchard management practices to optimize both production and fruit quality.

Impact of organic and inorganic fertilizers on tree growth and quantitative traits of Kinnow (Citrus nobilis Lour × Citrus deliciosa Tenor)

The continuous application of huge amount of chemical fertilizers degrades the quality, health and productivity of the soil. In future production scenario, use of chemical fertilizers in combination with organic sources of nutrients may play an important role in improving soil health and also helps to sustain optimum production of good quality and quantity of Kinnow. Based on this, the present investigation was carried out during 201518 at Department of Horticulture, Khalsa College, Amritsar (Punjab), to study the impact of various organic and inorganic fertilizers on vegetative growth, fruit physical parameters and yield traits of Kinnow. Treatments were laid out in randomized block design with various combinations of Azotobacter, Phosphate solubilizing bacteria, Vesicular arbuscular mycorrhiza, Trichoderma, Farmyard manure, Azospirillum, vermicompost and inorganic fertilizers based on recommended dose of fertilizers (RDF). It was observed that maximum vegetative growth of annual shoot extension (39.70 cm), trunk girth (6.42 cm), leaf area (30.17 cm2) and tree spread (N-S -13.83% and E-W-15.43%); physical characters like fruit/plant (619.32); yield (102.98 kg/plant), fruit length (6.86 cm), fruit breadth (7.81 cm), fruit weight (233.06 gm), fruit volume (220.55 cc) and juice content (56.36%) were recorded with combination of RDF + VC + PSB + VAM followed by RDF + Azotobacter + PSB + VAM while lower performance was observed in treatment with RDF (100%) alone. Based on this, it was concluded that both organic and inorganic fertilizers improved the physicochemical properties of soils which ultimately helps to improve the vegetative and quantitative traits of fruit plants due to increase in uptake of various nutrients and photosynthates in plant.

Weed Management in Apple Cv. Royal Delicious by Using Different Orchard Floor management Practices

ABSTRACT In this study, 19-year-old apple orchard at Arabal, Shalimar, Jammu and Kashmir, India, was selected during 2015 and 2016. Forty-five trees were treated with paddy straw mulch, paddy straw mulch followed by glyphosate @ 2.0 l ha−1, oxyflourfen @ 1.0 l ha−1, oxyflourfen @ 1.0 l ha−1 followed by glyphosate @ 2.0 l ha−1, atrazine @ 3.0 kg ha−1, atrazine @ 3.0 kg ha−1 followed by glyphosate @ 2.0 l ha−1, pendimethalin @ 2.0 l ha−1, pendimethalin @ 2.0 l ha−1 followed by glyphosate @ 2.0 l ha−1, bicolor polythene mulch, cowpea, white clover, clean cultivation, farmer practices, zero weeds and control. Three replications were maintained in a randomized complete block design. Minimum weeds (0.0) and weed control efficiency (100%) were recorded in zero weeds, bicolor polythene mulch and in paddy straw mulch followed by glyphosate. High levels of soil nutrients, large annual shoot extension (49.3 and 50.2 cm) and leaf area (77.83 and 78.57 cm−2) with maximum fruit yield (82.03 and 80.60 kg/tree) were recorded in paddy straw mulch followed by glyphosate during 2015 and 2016, respectively. Paddy straw mulch followed by glyphosate can be used for effective weed control with improved yield and growth characters of apple.

Influence of prohexadione-calcium and paclobutrazol on growth, yield and mineral content of pear cv. Clapp’s favourite

Present investigation was carried out to study the influence of growth retardants viz., prohexadione-calcium and paclobutrazol on mineral content of pear cv. ‘Clapp’s Favourite’ during the year 2015-2016. The experiment was laid out with thirteen treatments, replicated thrice on 12 year-old-pear tree with uniform vigor and health under uniform cultural practices. The treatment comprised of single and double spray of growth retardants i.e., prohexadione-calcium (100 ppm, 200 ppm and 300 ppm) and paclobutrazol (100 ppm, 200 ppm and 300 ppm). The first spray of these growth retardants was given at complete petal fall stage and second at four weeks after first spray. The orchard soil was moderately deep with good fertility status. Results revealed that both the growth retardants had showed a significant influence on the studied characters. The plants sprayed twice with prohexadione-calcium @ 200 ppm (T9S2) recorded minimum annual shoot extension growth of 16.92 cm and leaf area (22.20 cm2) alongwith increase in fruit yield (51.24 kg). Highest value for calcium (Ca) in leaves and fruits of pear (574.00 mg & 71.24 mg, respectively) was recorded when plants were sprayed twice with prohexadione-calcium at 300 ppm. Results also revealed that application of prohexadione-calcium application at 200 ppm sprayed twice (T9S2) resulted in significant increased in potassium content of the pear leaves and fruits i.e. 98.40 mg and 22.78 mg, respectively. However minimum value for potassium content was recorded in control (T1S0). Double spray of prohexadione-calcium @ 200 ppm was effective in reducing the annual extension growth, leaf area and increasing the fruit yield and calcium and potassium content in leaves and fruit.

Effect of organic and inorganic mulches on growth, yield and fruit quality of peach cv Redhaven

The present study was carried out on the effect of mulch materials on growth, yield and fruit quality of peach [Prunus persica (L) Batsch] cv Redhaven at experimental block of Department of Fruit Science, Dr YS Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh during 2019-2020. Various types of mulches like grass mulch, black polyethylene mulch, silver red polyethylene mulch, polyethylene mulch, nylon mulch mat and coir mulch were evaluated in this experiment. The results of the study showed that plant growth, yield and fruit quality of peach were significantly affected by all the mulching treatments as compared to control. The maximum increase in tree height, spread, volume, annual shoot extension growth, fruit set, lowest fruit drop, fruit yield, leaf area, leaf chlorophyll content, fruit size, weight and volume were recorded in the plants under black polyethylene mulch which was statistically at par with nylon mulch mat. The maximum fruit quality parameters like total soluble solids, titratable acidity, reducing and non-reducing sugars were recorded under nylon mulch mat.

Stem pruning severities affect growth, physiological and quality consequences in high density planting system of mango (Mangifera indica) in Shiwalik foothills

The study evaluated the influence of shoot pruning intensities on physiological and quality consequences of mango under square system of planting between 2014 and 2016 in Shiwalik foothills. Three mango cultivars, viz. Mallika, Dashehari, and Amrapali, planted under high density were selected purposely. Tip pruning of frost injured shoots significantly influenced growth, flowering, yield and quality traits of the cultivars compared to un-pruned trees. The results revealed early flower initiation with peak period of flowering among the treatments. Shoot pruning slightly delayed but more uniform flowering comparative to control. After 20th harvest season, the cultivar significantly affected generative parameters (TCSA, TCV, CA and yield efficiency). Number of sprouted shoots per scaffold branch (primary, secondary) was highest in Dashehari followed by Amrapali and Mallika irrespective of shoot differentiation. Dashehari recorded maximum length of panicles, length of flowering shoot, number of panicles/shoot, fruited panicles, fruit set, and fruit retention with least fruit drop when the shoots were pruned in frost affected twigs (terminal branches) shoot differentiation. The best yield and yield efficiency over the 20th leaf harvest was recorded in Mallika followed by Amrapali and Dashehari. Variable shoot pruning intensities showed significant effects on fruit physical-biochemical traits and foliar nutrient concentration of the cultivars. DOP indexing showed close agreement to diagnose N, P, K, Mg, Fe, Cu, Zn and Mn excess among different cultivars studied. PCA of agromorphometric and fruit quality traits was also worked out. prin4 accounted for 99.5% (agro-morphometric traits) and 97.9% (fruit quality) of the cumulative variance of cultivars. PCA-F1 had the highest positive loadings (plant height, tree girth, annual shoot extension growth TCSA, and TCV) followed by PCA-F2 (yield). None of the significant differences were obtained when the calculated factor scores of PCA-F1, PCA-F2 and PCA-F3 for attributes analyzed. Conclusively, shoot tip pruning could be recommended for restoring maximum production and quality fruits in high density square planting system of mango.

Response of prohexadione calcium and paclobutrazol on growth and physio-chemical characteristics of pear cv. Clapp's Favorite

The present investigation was conducted to study the response of growth retardants on pear cv. Clapp's Favorite during the year 2015–2016. The experiment was laid out with thirteen treatments replicated thrice on 12 year-old-trees with uniform vigour and health under uniform cultural practices. The treatment comprises of single spray and double spray of growth retardants (prohexadione calcium @ 100, 200 and 300 ppm and paclobutrazol @ 100, 200 and 300 ppm). The first spray of growth retardants was applied at petal fall stage and second spray was four weeks after first spray. The plants sprayed twice with prohexadione calcium @ 200 ppm (T9S2) recorded minimum annual shoot extension growth (16.92 cm), internodal length (1.82 cm) and leaf area (22.20 cm2) along with increase in fruit set (18.34%) and minimum fruit drop (32.45%). Increased fruit yield (51.24 kg), yield efficiency (4.08) and following year return bloom (24.04%) was noticed in T9S2 treatment. Prohexadione calcium sprayed twice @ 200 ppm (T9S2) also increased fruit weight (82.85 g), TSS (13.21%) and total sugars (10.23%) closely followed by the double spray of prohexadione calcium @ 300 ppm sprayed twice which was also effective in enhancing the fruit firmness (6.15 kg/cm2) followed by treatment T12S2 i.e. paclobutrazol @ 200 ppm double spray (6.07 kg/cm2). Double spray of prohexadione calcium @ 200 ppm was effective in reducing the vegetative characters and increasing yield and fruit quality characters.

Single-provenance mature conifers show higher non-structural carbohydrate storage and reduced growth in a drier location.

Since growth is more sensitive to drought than photosynthesis, trees inhabiting dry regions are expected to exhibit higher carbohydrate storage and less growth than their conspecifics from more humid regions. However, the same pattern can be the result of different genotypes inhabiting contrasting humidity conditions. To test if reduced growth and high carbohydrate storage are environmentally driven by drought, we examined the growth and non-structural carbohydrate (NSC) concentrations in single-provenance stands of mature trees of Pinus contorta Douglas and Pinus ponderosa Douglas ex C. Lawson planted at contrasting humidity conditions (900 versus 300 mm of annual precipitation) in Patagonia, Chile. Individual tree growth was measured for each species and at each location as mean basal area increment of the last 10 years (BAI10), annual shoot elongation for the period 2011-14, and needle length for 2013 and 2014 cohorts. Additionally, needle, branch, stem sapwood and roots were collected from each sampled tree to determine soluble sugars, starch and total NSC concentrations. The two species showed lower mean BAI10 and 2013 needle length in the dry site; P. ponderosa also had lower annual shoot extension for 2011 and 2014, and lower 2014 needle length, in the dry than in the mesic site. By contrast, NSC concentrations of all woody tissues for both species were either similar or higher in the dry site when compared with the mesic site. Patterns of starch and sugars were substantially different: starch concentrations were similar between sites except for roots of P. ponderosa, which were higher in the dry site, while sugar concentrations of all woody tissues in both species were higher in the dry site. Overall, our study provides evidence that reduced growth along with carbon (C) accumulation is an environmentally driven response to drought. Furthermore, the significant accumulation of low-molecular weight sugars in the dry site is compatible with a prioritized C allocation for osmoregulation. However, since this accumulation did not come at the expense of reduced starch, it is unlikely that growth was limited by C supply in the dry site.

Response of Perlka (Calcium cynamide) on Plant Growth and Production of Kinnow Mandarin(C.nobilis XC.deliciosa)in Sub Montane Low Hill Zone of Himachal Pradesh

Perlka, a multifunctional fertilizer was tested in kinnow mandarin as a soil application at four different doses, 500 g, 1000 g, 1500 g and 2000 g per tree and its effect on plant growth and production was compared against the soil application of CAN (800 g and 1600 g/tree). Perlka and CAN were applied during the month of February & May in two equal splits. Effect of Perlka application on annual shoot extension, fruit production and fruit quality was recorded. Annual shoot extension in kinnow mandarin was observed significantly more with the Perlka treatment 1000 g per tree when compared to other Perlka treatment (500 g, 1500 g and 2000 g) and as well as the CAN application. Significant improvement in response to soil application of Perlka (1000 g) when compared to other Perlka treatments including the application of CAN was observed for fruit size, fruit weight and fruit volume. Biochemical analysis of fruits showed variable results for total soluble content of kinnow fruits in response to different treatment. Maximum TSS (10.3° B) was observed with the treatment of 800 g CAN and 2000 g Perlka individually. Maximum fruit yield (32.18 Kg) per tree was obtained with 1000 g Perlka application followed by 1600 g CAN. Perlka application at 1000 g per tree resulted in significant improvement in annual shoot growth and tree health particularly by exhibiting resistance against collar rot and root rot fungi caused by Phtopthora citrophora, Phtopthora nicotiane in all of the trees receiving perlka in comparison to CAN treatments, fruit yield and other fruit quality parameters of the fruits in kinnow mandarin. The highest BC ratio of 3.5 was obtained in trees of kinnow mandarin treated with 1000g of perlka per tree.

Morphological and Growth Characteristics of Newly introduced Exotic Apple varieties on M9T337 Rootstock in Kashmir valley

The study was undertaken to make preliminary assessment for morphological and growth characteristics of new exotic apple varieties viz., Super Chief Sandidge, Gala Red Lum, Fuji Zehn Aztec, and Golden Clone B imported from Italy on M9T337 rootstock and planted at a distance of 1.5× 3m on four wire trellis system (2222trees/ha) in an experimental orchard of SKUAST-K established in spring 2013. Characteristics like Tree height (m), TCSA (cm2), canopy area (cm2), incremental growth of tree height (cm), shoot length (cm), number of shoots, intermodal length (cm), annual shoot extension (cm) and leaf area (cm2) were recorded. Super Chief Sandidge was observed to be highly dwarf variety in terms of tree morphology and Fuji Zehn Aztec as moderate. Growth characteristics were highest in Golden clone B and lowest in Super Chief Sandidge. On the basis of vegetative behavior, variety Super Chief Sandidge planting at the rate of 3906 trees/ha can be recommended to utilize the inter-tree space more efficiently and for high productivity.

‘D’Anjou’ Pear Shoot Growth and Return Bloom, but Not Fruit Size, Are Reduced by Prohexadione-Calcium

Prohexadione-calcium (P-Ca) was applied to ‘Anjou’ pear (Pyrus communis L.) trees in the lower and upper Hood River Valley (HRV), Oregon, to determine its effectiveness for managing the excessive vigor of ‘Anjou’ under different growing climates. Vegetative growth and development (weekly shoot growth rate, total annual extension growth, number of initiated shoots, internodal length, and number of nodes), yield (fruit number and fruit size), and return bloom dynamics were evaluated between 2010 and 2013. P-Ca consistently reduced shoot elongation by ≈40% in all years and at both sites when doses of 250 ppm were applied in early spring (i.e., ≈5 cm of annual shoot extension) compared with untreated trees. Shorter shoots were the result of both reduced internodal growth and fewer nodes. In the cooler, upper HRV, a single P-Ca application controlled shoot elongation for the entire season, but in the warmer, lower HRV, a second flush of growth was generally observed ≈60 days after the first application. A subsequent P-Ca application (250 ppm) provided added growth control in some instances. Yield was unaffected by P-Ca the season of application; however, in one year, an increase in fruit number indirectly led to reduced fruit size; otherwise, fruit size was unaffected by P-Ca. Postharvest fruit quality was not influenced substantially by P-Ca. Return bloom, however, was consistently reduced by P-Ca. Return yield, the year after P-Ca application (recorded in 2013 only), was reduced in proportion to the decrease in return bloom relative to untreated trees. In 2012, ethephon was also evaluated, alone or in combination with P-Ca. When applied on its own either once (150 ppm, 5-cm growth), or twice [150 ppm, 5-cm growth; 300 ppm, 57 days after full bloom (DAFB)], ethephon did not affect vegetative growth or yield components but did improve return bloom and return yield relative to other treatments; however, when combined with P-Ca, ethephon did not reverse reductions in return bloom or return yield induced by P-Ca. The most effective ethephon treatment for promoting flowering and return yield (300 ppm, 57 DAFB) was not tested in combination with P-Ca. We conclude that P-Ca is an effective tool for controlling vigor of ‘Anjou’ trees, but the decrease in return bloom requires additional investigation. Further work testing combinations of ethephon and P-Ca are warranted to optimize growth and productivity of ‘Anjou’ trees.

Retrospective analysis of tree architecture in silver fir (Abies alba Mill.): ontogenetic trends and responses to environmental variability

Understanding the effects of exogenous factors on tree development is of major importance in the current context of global change. Assessing the structure development of trees is difficult given that they are large and complex organisms with lifespan of several decades. We used a retrospective analysis to derive the ontogenetic trends in silver fir development and assess the effects of climate or light environment on tree architecture. Thanks to the identification of relevant growth markers (bud cataphylls and pseudo-whorl branches), a retrospective analysis allowed to record annual shoot extension and to date them on silver firs of various sizes under different environmental conditions. The length of successive annual shoots located on different axes clearly show gradual trends related to the physiological age of meristems. Within- and between-tree variations are noted due to the plasticity of development and growth induced by light environment and climate. Retrospective analysis is an efficient method for getting information on the history of trees architecture and subsequently to relate it to environmental factors.

Interactions between vegetative and generative growth and between crop generations in fig tree ( Ficus carica L.)

Yield in fruit trees strongly depends on the balance between vegetative growth and fruiting. This balance is particularly complex in fig tree ( Ficus carica L.), in which two generations of figs (Breba and Main crop) develop along an annual shoot and compete with two consecutive growth seasons. For better understanding the interaction between vegetative growth and fruiting in this species, we studied their dynamics throughout three growth seasons on five fig cultivars grown in center-east Tunisia. Shoot elongation was measured at regular intervals from mid-March until mid-December and the number of reproductive buds and fruits were counted at four dates each year.In all cultivars, annual shoot extension exhibited two consecutive phases with unequal duration, separated by a growth cessation. Reproductive buds and fruits number were closely dependent on shoot length. Significant positive correlations were found between Breba crop figs number of current season and shoot length of previous season (0.83 ≤ r ≤ 0.98) and between Main crop figs number of current year and shoot length of current season (0.83 ≤ r ≤ 0.95). The Main crop amount exerted a strong influence on the current shoot growth as well as on fruiting in the following year: a heavy Main crop load of current season reduces vegetative growth and crop load of Breba for the next year. Similarly, high Breba crop load negatively affected the Main crop load for the current year. The results support the idea of the close interaction between vegetative and reproductive growth in each fig generation and growth flush. By contrast, the strong competition between fig generations appears to be indirect and mediated by the competition between vegetative and reproductive growth. A synthetic scheme of the complex interactions that govern fig generations and vegetative growth rhythmicity in the fig tree is proposed. The data are discussed in terms of the opportunities to manipulate tree growth to enhance fruiting efficiency of fig tree.

Post-transplant crown allometry and shoot growth of two species of street trees

Transplanting recovery of urban trees is an essential first step in their acclimation from nursery to challenging urban growing sites. Changes in crown allometry during this period are not well known. We followed annual shoot extension, crown structure and leaf area of Alnus glutinosa and Tilia × vulgaris street trees for six years from transplanting into their growing site. The growing site of Tilia trees suffered from excessive soil moisture whereas the Alnus site was more normal regarding soil water relations with periods of drought. The transplanting recovery of Tilia trees was delayed due to the deleterious influence of excessive soil water, but Alnus trees recovered substantially within the first 2–3 years. Leaf area in relation to branch basal area changed throughout the research period, indicating tree adaptation to new growing conditions.

Limited plasticity of shoot preformation in response to light by understorey saplings of common walnut (Juglans regia)

Background and aims Analysis of the variability of organogenesis and extension (two basic processes of primary growth) is needed to improve our understanding of architectural plasticity in trees. An example of such plasticity is the difference in size between fully grown shoots found at different positions on the tree. The contribution of preformation processes to these differences was explored by determining the intraspecific variability of shoot preformation of main stems of understorey saplings of Juglans regia. Methodology In 2007, two samples of annual shoots that differentiated in 2006 were taken from saplings growing in a Mediterranean mixed forest in the south of France. At the first sampling, the terminal winter bud of each parent shoot was dissected and the nodes of these buds were counted. For the second sampling, annual shoot growth was measured after the 2008 growing season. The percentage of light transmitted through the understorey was determined by hemispherical photographs. Principal results The effect of plant development (ontogeny) on the number of preformed leaves and the annual shoot extension was strong. Light availability also contributed to explaining differences in the length of annual shoots. The impact of light on the number of preformed leaves was minimal. Conclusions Ontogeny (onset of branching) and reduced irradiance both affected leaf preformation in buds of annual shoots, with ontogeny being the more influential. The results suggest that the shoot preformation did not contribute to the plasticity of morphology of annual shoots. Light availability was more influential and promoted annual shoot extension.

Drepanocladus longifolius (Amblystegiaceae), an addition to the moss flora of King George Island, South Shetland Islands, with a review of Antarctic benthic mosses

Drepanocladus longifolius (Mitt.) Paris is recorded for the first time from King George Island, South Shetland Islands, in the maritime Antarctic. It was col- lected in West Lake during the 23rd Chinese National Antarctic Research Expedition in 2006-2007. The moss was found at a depth of 5-6 m attached to the bed of the lake. The stems of the moss are about 1-1.5 m in length. The moss exhibits seasonal growth patterns, with shorter branch internodes, more widely spaced leaves and more branches in summer than in winter. Most of the branches are initiated in summer. The annual shoot extension is about 3-6 cm, which implies that the plants must be at least 15 years of age. The distribution of aquatic moss species and records in Antarctica is outlined and discussed and the nomenclature of previous reports clarified.

Fitness implications of late bud break and time of burning in Lannea edulis (Sond.) Engl. (Anacardiaceae)

Many woody plants of savannas have massive underground parts (“lignotubers”) and diminutive aboveground parts with phenologies that are triggered by fire. Lannea edulis (Anacardiaceae) represents this life form and is widely distributed in south central Africa. The phenology of L. edulis was monitored on 42 permanently marked shoots over a 3-year period, from 2002 to 2004, and under three fire treatments (early and middle dry season burning, and fire protection) to determine whether (i) fire affected time of bud break and (ii) time of fruit ripening affected seed germination. Statistical analyses revealed that shoot reproductive status and fire treatments significantly affected time of bud break and the lag between bud break and leaf production. Shoot reproductive status explained 27% ( P<0.001) while the interaction between reproductive status and fire treatments explained 34% ( P<0.0001) of the variation in time at bud break. The appearance of the first leaf was delayed by 4 weeks in reproductive shoots compared with vegetative shoots. Shoot reproductive status explained 28% ( P<0.0001) of the variation in the lag between bud break and appearance of the first leaf suggesting the existence of resource competition between reproduction and vegetative growth. However, reproductive status and fire treatments did not affect shoot size and leaves produced because replacement shoots after dieback due to fire were as long as shoots surviving from previous years due to insignificant annual shoot extension among the latter. There was high autocorrelation in the germination rate of seed-lots with seeds from fruits ripening early having a significantly higher germination rate (47% in 2002 and 89% in 2004) than those from fruits ripening later (3% in 2002 and 53% in 2004). Since time at bud break and fruit ripening were linked, it is proposed that late bud break results in reduced fitness in L. edulis because of reduced seed germination rate. Early and late dry season fires that delay bud break and destroy reproductive structures, respectively, also reduce this measure of fitness.

Periods of organogenesis in mono- and bicyclic annual shoots of Juglans regia L. (Juglandaceae).

The organogenetic cycle of shoots on main branches of 4-year-old Juglans regia trees was studied. Mono- and bicyclic floriferous and vegetative annual shoots were analysed. Five parent annual shoot types were sampled between October 1992 and August 1993. Organogenesis of summer growth units was monitored between 16 Jun. and 3 Aug. 1993. Variations over time in the number of nodes, cataphylls and embryonic green leaves of terminal buds were studied. The number of nodes of parent shoot buds was compared with the number of nodes of shoots derived from parent shoot buds. The spring growth units of mono- and bicyclic shoots consist exclusively of preformed leaves which were differentiated, respectively, during the spring flush of growth (mid-April until mid-May) or the summer flush of growth (mid-June until early August) in the previous growing season. Thus, winter buds may consist of flower and leaf primordia differentiated in two different periods during annual shoot extension. The summer growth units of bicyclic shoots consist of preformed leaves that were differentiated in spring buds during the spring flush of growth in the current growing season. Bud morphology is compared between spring and summer shoots.

Growth pattern and architectural analysis of nine important multipurpose trees in an arid region of India

Nine multipurpose tree species (Acaciacatechu (L.f.) Willd., Acacianilotica (L.) Delile, Albizialebbeck (L.) Benth., Azadirachtaindica A. Juss., Dalbergiasissoo Roxb., Meliaazedarach L., Morusalba L., Prosopiscineraria (L.) Druce, and Ziziphusmauritiana Lam.) growing in the dry monsoonic climate of northwestern India showed a wide variation in growth pattern and shoot architecture. Six-year-old trees growing in plantation monocultures were sampled. The growing period varied from 194 days in D. sissoo to 301 days in A. nilotica. Annual shoot extension and radial growth varied from 20.6 to 111.2 cm and from 2.2 to 9.3 mm, respectively. Significant differences were found (P &lt; 0.05) among species and among positions within the crown of each species. Dalbergiasissoo, M. azedarach, and Morusalba completed most of their growth in 120 days during the initial dry part of the growing season; these species apparently are able to utilize food reserves of the preceding year for growth. The remaining species showed a more exploitive growth strategy, having a longer period of growth which began in the dry season, but most shoot extension was completed during the rainy season that followed. Branch angle also differed significantly (P &lt; 0.05) among crown positions of each species, except A. nilotica and D. sissoo.

Regrowth and Palatability of Acacia Shoots Following Pruning by African Savanna Browsers

Stands of two species of African Acacia were monitored for 1 yr in a natural savanna ecosystem, to compare shoot regrowth and leaf chemistry in lightly browsed and heavily browsed trees. Where ungulates concentrated at a seasonal waterhole, A. nigrescens was more severely browsed than the thornier and finer leafed A. tortilis. Shoot regrowth in heavily browsed A. nigrescens more than compensated for herbivory, as net annual shoot extension was not significantly different from that in light browsed trees. Foliage of heavily browsed A. nigrescens was higher in nutrients and lower in condensed tannins than foliage of light browsed trees. We propose that severe pruning by browsing ungulates reduces intershoot competition for nutrients, promoting rapid shoot regrowth. Carbohydrate demands of rapid regrowth reduce carbon—based secondary metabolite synthesis. This results in patches of highly palatable browse that attract further browsing, generating a browsing regrowth feedback loop. Such patches may be considered analogous to grazing lawns.