Root Morphology and Yield of Wheat (Triticum aestivum L.) Crop under Reduced Irrigation in Delhi (India) Weather Conditions

Aims: Water is one of the most valuable resources for the survival of civilization. Assured supply of water is necessary for sustainable agriculture. Wheat (Triticum aestivum L.) is an important staple food crop in India and is cultivated in different agro-ecological regions of northern, eastern and central parts of the country occupying 25.4 million hectare (M ha) and nearly 54% of its area is irrigated. A sizeable 46% area under wheat is still rain dependent which often is faced with reduced irrigation thus decreased crop yield. The aim of this study is to facilitate the farmers of this reason in taking the appropriate decisions as regards providing supplemental irrigation with limited water supply conditions so that comparable yields could be obtained with the water application to critical crop growth stages.
That constitutes about 27% of the irrigated area of India. Changing climate has resulted into recurrence of long rainless spells during winter season (rabi) at places in India known for extensive wheat production which is main staple food of the masses. Wheat crops growth and performance is adversely affected by soil moisture stress so is the growth of roots and consequently the nutrient uptake that reflects into the yield and yield attributes. Hence, the main objectives of present study were to access, the effect of reduced irrigation on yield attributes, root development, dry matter accumulation and partitioning of wheat (Triticum aestivum L.) crop under reduced irrigation in Delhi (India) during winter (rabi) weather conditions.
Study Design: Randomized Block Design (RBD) with four replicates.
Place and Duration of Study: Field experiments were conducted at the W-3 Experimental Farm of the Water Technology Centre, IARI, New Delhi during the rabi cropping season of 2011-12. Indian Agriculture Research Institute (IARI) is located at New Delhi (28º38’N, 77º10’E) at an elevation of 248 m above MSL. The crop was sown in the month of Novemebr and harvested at the end of April of the next year. The sandy loam soils of the experimental area, where the field experiments were conducted can be characterized as having low water holding capacity. Delhi falls in the semi arid climatic conditions. The experimental design for the experiment was Randomized Block Design (RBD), replicated four times. The present experiment used a high yielding cultivar of wheat variety HD 2967 having the growth period of 120 days.
Methodology: For root analysis, the roots were taken from a depth of 0-90 cm and were analyzed for different properties like root length, surface area and volume using root scanner (EPSON expression 1640XL, Japan). The same roots were then used for measuring wet mass and kept in an oven at 70ºC for three days before taking dry mass (Figs. 3 and 4). WinRhizoTM software was used with an approved scanner, Yield and yield attributes were measured using standard experimental procedures. Observations on plant growth (crop morphometry, photosynthetic activity (LAI), dry mass partitioning), soil moisture dynamics and yield of wheat (Triticum aestivum L.) crop were taken under a well structured schedule.
Results: There was no significant difference in the plant height in the early stages (30 days after sowing (DAS)) in wheat during the winter (rabi) season of 2011-12. However, in the later stages i.e., during late vegetative and reproductive phases, various treatments exhibited significant differences in yield and yield attributes. Also, in number of tillers/m2 and leaf area index (LAI) a highly significant differences were observed among treatments. It was worth noticing that skipping irrigation in CRI and milking stages has significant decrease in the dry matter accumulation even though the treatment with no water deficiency (T8) recorded highest dry matter accumulation. Significant differences among the treatments were also observed especially in root length. The treatment T1 with no irrigation (Control) recorded in significant reduction with T8 treatment (no water deficiency), which clearly indicated that root of the crop elongated in stress condition to fulfill its metabolic activities. crop tries to utilize the available soil moisture in this case. Root length has also shown a direct correlation with soil moisture availability.
Conclusion: Skipping of irrigation during tillering stage has drastically reduced the elongation of root among all the treatment. T4 treatment (100% soil moisture deficient at booting stage) has resulted in highest root length which indicates that irrigation is critical during the flowering and milk stages of wheat. Root surface has been drastically reduced in treatment T1 (No irrigation in all growth stages).