Two Preliminary Reliable Indicators of Earliness in Cotton-II

MATERIALS AND METHODS

A field experiment was conducted at the experimental area CCRI Sakrand during 2001 cotton season, The trial consisted of seven advance strains of CCRI Sakrand (CRIS-79, CRIS-82, CRIS-83, CRIS-85, CRIS-107, CRIS-110 and CRIS-117) and four commercial varieties (CIM-443, CIM-448, NIAB-78 and CRIS-9). The experiments was conducted in Randomized Complete Block Design. The row-to-row distance was maintained at 2.5 feet whereas plants within rows were thinned out to maintain a distance of 8-9 feet in between. Each treatment plot contained seven rows 47.5 feed long. All the agronomical, nutritional and plant protection requirements of the experiment were completed as and when needed. A random number of ten plants from the fourth row of each cultivar per replication were monitored individually for two earliness indicators (days taken to open first flower and node number of first sympodial branch). The data were statistically analyzed for analysis of variance (ANOVA) adopting Steel and Torrie (1980) procedure.

RESULTS AND DISCUSSION

Mean squares obtained from analysis of variance (Table 1) showed highly significant differences among the cultivars for both the characters studied (days taken to open first flower and node number of first sympodial branch). The range recorded for the trait days taken to open first flower (Table 2) was from 44 DAP (CRIS-79, CRIS-85, CIM-443 and CIM-448) to 48 DAP (CRIS-83 and CRIS-9), whereas for second character main stem node number of first sympodial branch was from 5.9 (CRIS-110) to 9.l2 (CRIS-9).

Numbers of days taken to open first flower: There existed highly significant differences among the cultivars for the character number of days taken to open first flower (Table 1). The results demonstrated that two advance strains CRIS-79 and CRIS-85 and two commercial checks CIM-443 and CIM-448 opened their first flower (44 DAP) significantly earlier than other varieties/strains under study thus as suggested by Soils et al. (1989) that the character days taken to open first flower provide reliable estimation of earliness, these four strains/varieties were recorded as early maturing when compared with other varieties. Accordingly CRIS-82, CRIS-83, CRIS-107, CRIS-110, CRIS-117 and CRIS-9 were observed comparatively late as these strains/varieties opened their first flower in the range of 46-48 days after sowing (Table 2). Rehana et al. (2001), Rehana (1999), Aden (1997) and Godoy (1994) have also confirmed that the character days taken to first flower is reliable indicator.

Table 1:	Mean squares obtained from the ANOVA of two preliminary indicators of earliness in eleven upland cotton cultivars
***Highly significant

Table 2:	Mean values of two preliminary indicators of earliness in eleven upland cotton cultivars

According to their results the variety which takes minimum days to open its first flower will record itself as early maturing.

Node number of first sympodial branch: Highly significant differences among the cultivars for the character node number of first sympodial branch were observed (Table 1). CRIS-110 by producing main stem node number of first sympodial branch significantly at lower position (5.9) was observed early maturing variety followed by CRIS-85 and CRIS-107 which had their main stem node number at 6.8 (Table 2). CRIS-9 by producing its first sympodial node number significantly at highest position (9.12) was observed as late variety in the test. All advance strains developed by CCRI Sakrand included in the test significantly produced lower node number of first sympodial branch than two commercial checks NIAB-78 and CRIS-9 were observed earlier than the two checks. The workers like Rehana et al. (2001), Aden (1997), Rehana (1999), Leghari (1997) and Godoy (1994) have also suggested that the varieties with first sympodial node number at higher position are late maturing and vice versa. It is strange to note the un-understandable behavior of CRIS-110 which produced node number of first sympodial branch at lowest position (5.9) and recorded itself as earliest variety in the test but opened its first flower after 46 days of planting and stood in the range of some what late maturing varieties. This variety would had opened its first flower after 43-44 days of planting, this might be due to some experimental error or data recording error.

It was therefore, concluded that decisions regarding selection for earliness can be made early in the season keeping in view the date of opening first flower and node number of first sympodial branch. Variation in maturity of cultivars can be distinguished early in the flowering stage using the above two parameters as suggested by Rehana et al. (2001) , Aden (1997), Rehana (1999) and Godoy (1994). Further crop management decisions regarding insect pest control, irrigation and fertilizer applications can be taken keeping in view the above two preliminary characters as reliable indicators of earliness.