Air Thermal Units in Relation to Growth and Development of Cotton Plants Through Different Sowing Dates

Abstract

This study was carried out at Shandaweel Agric. Res. Station (Sohag Governorate), Egypt during 2009 and 2010 seasons. At each season three planting date treatments (March 25, April 10 and April 25) were studied on the Egyption cotton Giza 90 cultivar. The experimental design was Randomized Complete Blocks (R.C.B.) with four replications. Obtained results revealed that plant ages 75, 105 and 135 days late sowing obtained the highest number of heat units and resulted in increasing plant height, number of nodes per plant, dry weight per plant, number of leaves per plant, leaf area and leaf area index while, it had no effect on internode length, leaf area index in age 135 days. Number of sympodia per plant increased in favour early sowing due to lower night temperature which lowered the position of early sympodium and inducing early balance between vegetative and fruiting development. Number of leaves, leaf area and leaf area index of early sowing increased slowly through, early season. Late sowing produced the first flower and open first boll in shorter period as compared to early sowing, but it consumed more number of heat units. The highest yield components and yield per unit area was produced from early sowing, where the cotton plants received the highest number of heat units through the growing season as compared to late sowing. Most of these units were utilized in produced the fruiting organs, while late sowing used most of these units in increasing the vegetative growth. The efficiency use of heat units by cotton plants increased in favour of early sowing rather than in late sowings. Best results were obtained when cotton plants were sown early (25 March). Generally, it is recommended to grow cotton early (25 March) for Giza 90 cotton cultivar gave the highest seed cotton yield per feddan rather than the late sowing (25 April) under the condition of this study.

Performance Evaluation of Three Egyptian Cotton Genotypes under Different Thermal Units Related to Different Planting Dates

“…This might due to relatively low temperature of air and at the beginning of the season for early planting (Table 1), which directed the cotton plants to keep the balance between vegetative growth and fruiting capacity while, in late planting, the increase of air and soil temperature. Such findings are in harmony with those obtained by Hamed (2011), Ismail et al (2012, Wenqing et al (2012), Elayan et al (2013) and Elayan et al (2015).…”

“…Planting cotton as early is one of the important factors which control the rank growth through the growing season and consequently increase seed cotton yield. The efficiency use of heat units by cotton plants increased in favour of early sowing rather than in late planting (Hamed, 2011). Late planting obtained the highest number of heat units and resulted in increasing of vegetative growth (Makram et al, 2001).…”

Response of Giza 90 Cotton Cultivar to Sowing Dates and First Irrigation( Al-Mohayat) Time

“…The results in Table (4) show that number of open bolls/plant, seed cotton yield per plant and per feddan significantly increased by early sowing date (25 March).These results could be explained on the basis that early sowing (25 March) encourage cotton plants to form more bolls and give the highest yield /plant which reflected on seed cotton yield /fed. Similar results were concluded by Abdel-Malak et al (1996), Abou El-Nour et al (2000, Makram et al (2001), Saleh et al (2004), El-Hindi et al (2006, El-Sayed and El-Menshawi (2006), Abd El-All (2011) and Hamed (2011). But, boll weight and number of plants at harvest /fed were not affected by sowing dates in both seasons.…”

“…These results may be due to that sowing cotton early on 25 March fit cotton plants to full seasons in order to obtain complete heat units requirements for good growth (Young et al, 1980) which reflected in developing lower location of first fruiting branch (Table 3). Also, these results may be due to relatively high temperature of air and soil in case of late sowing which pushed the cotton plants to form excessive vegetative growth with few fruiting branches through short plant life, while in case of early sowing, the heat units accumulation was slowly, that helped cotton plants to form lower of location of first fruiting node .Similar results were obtained by El-Beily et al, (1996), Makram et al, (2001) and Hamed (2011). But, number of fruiting branches /plant was not affected by sowing dates.…”

“…Also, the maximum number of bolls per plant and yield of seed cotton per plant and per feddan were produced from planting on the first of March. Hamed (2011) found that early sowing (25March) significantly increased number of days to first flower, number of open bolls/plant, seed cotton yield per plant and per feddan in both seasons. While, final plant height at harvest was significantly affected by sowing dates in 2010season only and number of days to first flower in 2009 season only .Meanwhile, number of sympodia /plant ,boll weight and number of plants at harvest /feddan were not significantly affected by sowing dates in both seasons.…”