Influence of soil moisture regimes on plant water relationships, growth and productivity of wheat (Triticum aestivum L.) cultivars under shallow water table conditions in tarai regions of Uttranchal.

摘要

Field experiments were conducted in Pantnagar on a silty clay loam (Typic Hapludoll) to determine the suitability of wheat cultivars by characterizing their plant water relationships, growth and productivity under shallow water table conditions in the Tarai region of Uttaranchal, India. Treatments consisted of 5 soil moisture regimes (rainfed (control), irrigation at crown root initiation (CRI), irrigations at CRI and flowering stages (well-watered), irrigations when canopy temperature variability was >=0.70 and irrigations at pre-dawn xylem water potential (XWP) of -0.35, -0.65, -0.65, -0.65 and -1.45 MPa at CRI, late tillering, late jointing, flowering and milk stages, respectively, based on the stress day index concept) in the main plot and 8 wheat cultivars (UP 115, UP 368, UP 2113, HD 2281, HD 2285, C 306, WL 410 and RR 21) in the subplot. Under rainfed condition, the highest leaf area index (LAI) was found in C 306 and the lowest in UP 368, while under well-watered condition, the trend was reversed. The maximum percentage reduction in LAI was observed in UP 368 and the minimum in C 306. Under rainfed condition, the highest dry matter accumulation was found in C 306 and the lowest in UP 368. On the other hand, under well-watered condition, it was maximum in HD 2285 and minimum in WL 410. The highest percentage reduction in dry matter was recorded in HD 2285 and the lowest in C 306. Under rainfed condition, the highest XWP was obtained in HD 2281 but under well-watered condition, it was observed in HD 2285. C 306 maintained the lowest XWP under both conditions. The highest difference in XWP between stressed and well-watered condition was found in HD 2285 and the lowest in C 306. Transpiration rate (TR) of HD 2281 was highest under rainfed condition but under well-watered condition, it was highest in UP 368. C 306 maintained the lowest TR under both conditions. At all the crop stages, the highest differences in TR between well-watered and stressed plots was found in UP 368 and the lowest in C 306. C 306 showed the highest leaf diffusion resistance (LDR) under rainfed and well-watered conditions. Grain yield of the cultivars was significantly affected by soil moisture regimes and the interactions were significant. Under rainfed condition, the highest grain yield was recorded in C 306 which was at par with UP 2113 and WL 410 while under well-watered condition, it was the highest in RR 21 which was at par with UP 368, HD 2285 and HD 2281. Under rainfed condition, the maximum reduction in grain yield was recorded in UP 368 and the minimum in C 306 compared to well-watered condition. A significant and positive correlation coefficient between TR and XWP was found, while a significant and inverse relation was found between TR and LDR and XWP and LDR. A linear, positive and significant relationship was found between relative grain yield and LAI. C 306, WL 410 and UP 2113 were the most suitable cultivars for rainfed and UP 368, HD 2285 and HD 2281 for well-watered conditions in shallow water table conditions in the Tarai region of Uttaranchal.