Accumulated Heat Units and Phenology Relationships in Wheat as Influenced by Planting Dates under Late Sown Conditions

Abstract

The field experiments were carried out at College of Agriculture Farm Rewa and Regional Agricultural Research Station, Kuthulia on Vertic haplurtalfs Soils, during rabi 1981-82, to study the influence of planting dates on Phenology and heat unit relationships under late sown conditions. The wheat cultivar sonalika was planted on 15 Dec., 23 Dec, 31 Dec. 1981 and 7th Jan. 82 at R.A.R.S., Kuthulia and on 16 Dec, 23 Dec, 30 Dec. 1981 and 6 Jan. 82 at College of Agriculture Farm. The results indicated that the requirement of accumulated heat units decreased with delayed planting. Besides growing degree days a unit incorporated the bright sunshine hours is also utilized (H.T.U.). A phenothermal index was also introduced (the AHU per growth day). It was nearly constant irrespective of planting dates and sites. The heat use efficiency decreased from 16.29 to 12.56 X 10"-* q/ha/GDD in case of D, to D4 respectively. A regression for predicting the maturity date for wheat crop using heat units accumulated upto flowering initiation for the Vindhyan region of Central India is developed.

Effects of different sowing dates on the phenology and accumulated heat units in three rapeseed (Brassica campestris L.) varieties

“…The number of days taken for attainment of different phenological stages were in the order S 1 > S 2 > S 3 > S 4 . The S 1 plants took longest time followed by S 2, S 3 and S 4 which corroborates with the findings of Rajput et al 1987, Paul and Sarker 2000, Haidar et al 2003in wheat, Dahiya and Narwal 1989in maize and Alam et al 2007 in barley. For each variety, a definite day was required to attain certain phenological stage of growth.…”

“…So, the lowest heat unit requirement for all the phenological stages in all the varieties was observed in S 4 . Decreased GDD due to late sowing was reported by Rajput et al 1987, Paul and Sarker 2000, Haidar et al 2003in wheat, Dahiya and Narwal 1989in maize and Alam et al 2007 in barley. Among the varieties, BINA Sarisha-5 obtained the highest heat unit for all the sowings at all the phenological stages and the lowest heat unit was found in BARI Sarisha-14 except pod filling.…”

“…Among the climatic factors, temperature plays a key role in determining sowing time and consequently the duration of different phenophases and thus the crop productivity (Tewari and Singh 1993). Influence of temperature on phenology and yield of crop plants can be studied under field conditions through the accumulated heat units system or growing degree-days (GDD) (Chakravarty and Sastry 1983, Rajput et al 1987, Bishroi et al 1995. Though accumulation of degree-days for each developmental stage is relatively constant and independent of sowing date, crop variety may modify it considerably (Phadnawis and Saini 1992).…”

Agrometeorological Indices and Phenology of Basmati Rice (Oryza sativa L.) under Different Dates of Transplanting

“…Among the varieties, the maximum growing degree days were accumulated in variety CSR 30 followed by variety HB 2, PB 1121 and PB 1509 to reach physiological maturity during the crop season. Decrease in heat units with delay in transplanting has also been reported by Singh and Pal (2003) and Rajput et al, (1987 (Table 2). Similar results were also obtained by Sharma et al, (2011) reporting that accumulated growing degree days was higher under early transplanted crop.…”

Variation in Heat and Radiation Use Efficiency of Rice as Influenced by Different Growing Environments and Genotypes

“…Thermal time is an independent variable to describe plant development (Dwyer and Stewart, 1986) and it has been used as a tool for characterizing thermal response in different crops (Rajput et al, 1987;Billore et al, 1992). Light levels also have a profound influence on plant growth.…”