Annals of Arid Zone 36(2): 139-141, 1997

Variability and Correlations Among Growth Attributes in Sapota

P. Viswanath1, M. AI-Gabry and S.K NadafAgricultural Research Center. P.D. 50 Rumais,Ministry of Agriculture & Fisheries. Sultanate of Oman

Abstract: The data on growth attributes, of four-year-old pre-bearing sapota (Acinuszapota L.) trees planted in 1991 at the experimental orchard of Agriculture ResearchCenter, Rwnais, Sultanate of Oman, were subjected to analysis of variability andcorrelations. Among the five growth attributes studied, canopy volume had the highestrange of variability (16.70 to 47.50 m3) followed by E-W spread (2.90 to 4.40m), tree height (2.06 to 3.44 m), N-S spread (2.90 to 4.40 .m) and trunk girth(0.230 to 0.380 cm). Of the fifteen character associations (r values), the correlationsassociated with the canopy volume were found to be positive and significant, whichcould be used in predicting behavior of plant in terms of it's future growth anddevelopment.

Key words: Growth attributes, variability,

Sapota (Achras zapata L.) is one ofthe important tropical fruit crops grownin the Sultanate of Oman. It is rich incarbohydrates with 18-21 % total sugars(Singh et al., 1963). It's tolerance to highsalinity, upto 8 dS m-I of irrigation water,is reported earlier (Ahmad and Ismail, 1991;Ayers and Westcot, 1985). Under prevailinghighly saline conditions in different regionsof Oman (Zidgali et al., 1993), growingsapota appears to be one of the viablealternatives to other salt sensitive fruit crops'such as mango. Although sapota attainsinitial bearing from second or third yearof planting, the economic yields can beobtained from seventh year onwards (Boseand Mitra, 1985). Growth attributes suchas tree height, trunk girth, N-S spread, E-Wspread and canopy volume were observedto have genetic association with fruit yield

I. Corresponding author: P.O. Box 777, P.Code 121,Sultanate of Oman.

correlations, sapota.

(Reed, 1928) and these associations wouldbe valuable in predicting yields in fruittrees (Shikhamany et al., 1978). Such in-formation, especially on pre-bearing stageof the tree, could be more useful in fore-casting it's future yielding ability well inadvance. In addition, growth characterswould act as potential phenotypic indicesfor selection of trees in a large population.Information on this aspect in sapota is lim-ited and hence the present investigationwas undertaken, utilizing pre-bearing sapotatrees, to know the nature of variability andcorrelations among growth attributes.

Materials and Methods

The study was carried out on four-year-old pre-bearing sapota trees in the experi-mental orchard of Agriculture ResearchCenter, Rumais, Sultanate of Oman. Themaximum and minimum temperatures, andrelative humidity during the period of study

140 VISWANATII et 01.

Table I. Range, mean, standard e/7'Or and coefficiel./t of variation for growth attlibutes il/ sapota

Character Range Mean SEm± C.V.%Tree height (m) 2.06-3.44 2.85 0.09 13.00Tnmk girth (cm) 0.23-0.38 0.30 0.01 15.20N-S spread (m) 3.20-4.30 3.57 0.08 8.80E-W spread (m) 2.90-4.00 3.65 0.10 10.50Canopy volume (m3) 16.70-47.50 29.88 2.03 26.40

was 30-350C, 12-280C and 43-90%, re-spectively. The soil at the experimental,site is sandy loam in nature (EC 2.5, pH7.3, available P 3.4 mg kg-I soil, availableK 58.5 mg kg-I soil; CaC03 38% antisols).The experimental trees were planted during1991 at a spacing of 8 x 8 m and wereirrigated with water of 8 dS m-I throughbubblers laid in between two basins. Eachtree was fertilized with tl)e recommendeddose of 500 g N, 200 g P and 300 gK each year. The tree basins were coveredwith a black polythene mulch of 300 gaugeto conserve soil moisture and reduce weedpopulation. The observations in respect ofgrowth characters such as tree height (m),trunk girth (cm), N-S spread (m), E-W

• 3spread (m) and canopy volume (01 ) wererecorded during August 1995 on ten rep-resentative sapota trees. Tree height wasmeasured from base to tip of the last leaf,whereas, trunk girth was recorded at a heightof 45 cm above the ground level (Pearce, ,1953). Tree spread on N-S and E-W were

measured from last tip of the leaves onboth the directions. The experimental datawere subjected to both, analyses of vari-ability and simple correlations accordingto Gomez and Gomez (1984) with the aidof M Stat computer programme.

Results and Discussion

The data on the range, mean, standarderror (S.E.) and coefficient of variation (CV%) in respect of growth attributes suchas tree height, trunk girth, N-S spread, E-Wspread and canopy volume are presentedin Table 1, while all possible correlationcoefficients (r) among five growth attributesare given in Table 2. The canopy volumehad the highest range of variability (16.70to 47.50 m3 with 2.03 S.E.) followed bytrunk girth (23.00 to 38.00 cm with 1.01S.E.), E-W spread (2.90 to 4.40 01 with0.10 S.E.), tree height (2.06 to 3.44 01

with 0.09 S.E.) and N-S spread (2.90 to4.40 01 with 0.08 S.E.). Canopy volumehad the mean of 29.88 013, while trunk

N-S spread0.0800.4930.615*

Table 2. CO/7'e1ation coefficiellts among growth attlibwes

Character Trunk girthTree height 0.674*Tmnk girth 0.445N-S spread 0.360E-W spread 0.832***Significant at 0.05%; ** Significant at 0.01%.

E-W spread0.4470.734**

Canopy volume0.728**

GROWTH ATIRIBUTES IN SAPOTA 141

girth had 30 em. E-W spread recorded thehighest mean (3.65 m) followed by N-Sspread (3.57 m) and tree height (2.85 m).Among the fifteen character associations(r values), only five correlations were posi-tive and significant. Of them, four cor-relations were associated with the canopyvolume. Canopy volume had the highestand positive correlation with E-W spread(0.832") followed by that with trunk girth(0.734··) and tree height (0.728··) whileit is positively associated with N-S spread(0.615\ Similarly, trunk girth was posi-tively associated with tree height (0.674\Such associations involving growth attrib-utes and also yield in sapota were earlierreported by very few authors (Reed, 1928;Sudds and Anthony, 1928; Shikhamany etal., 1978) and these can be applied, notonly in predicting future growth behaviorof trees in terms of their yielding abilityat the stage of their economic bearing, butalso as phenotypic indices for selectionand improvement as inferred in earlier in-vestigations.

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