Molecular Soil Biology 2025, Vol.16, No.6, 306-313 http://bioscipublisher.com/index.php/msb 309 3.2 Morphological and agronomic characteristics of selected varieties In the 21-variety trial in eastern India, plant height, stem number, leaf area index (LAI), dry matter (DM) accumulation, and crop growth rate (CGR) differed clearly among varieties. ‘Kufri Anand’ showed higher LAI and DM. ‘Kufri Pukhraj’ had the highest net photosynthetic rate (NPR) at 60 and 80 d after emergence. ‘Kufri Chipsona-4’ showed the highest stomatal conductance (SCR) at both stages. ‘Kufri Chipsona-3’ and ‘Kufri Surya’ had the highest transpiration rate (TR) at 60 and 80 d (Das et al., 2021). For tuber bulking rate (TBR), ‘Kufri Pukhraj’ showed the highest TBR before 60 d. After 60 d, TBR increased clearly in ‘Kufri Arun’ and ‘Kufri Surya’. By extending and strengthening the late bulking stage, these mid-maturing varieties achieved higher final yields. In the research on genotype and irrigation time, when water shortage occurs during the tuber formation period, the relationship between multiple growth indicators and the yield of individual tubers is very close. The taller the plant, the higher the yield tends to be. The same is true of transpiration rate, photosynthetic rate and water use efficiency. These indicators are all significantly positively correlated with tuber yield, and the corresponding correlation coefficients are 0.92, 0.65, 0.95 and 0.88 respectively. But in the mature stage, the situation is different. The greater the total biomass in the aboveground part, the lower the tuber yield. The two are negatively correlated (r = -0.85). Under conditions of deficient irrigation, high-yield genotypes are more likely to concentrate dry matter in the tubers rather than for the growth of the above-ground parts (Zhang et al., 2025). In the comparative experiment on the Ethiopian Plateau, the number of tubers per plant of 'Belete' was greater, the average tuber weight was larger, and the proportion of commercial tubers was also higher. The dry matter content and starch content of this variety are both higher than those of local varieties. In terms of tuber morphology, it is mainly composed of medium to large tubers, with a relatively high level of dry matter. Under different water treatment conditions, the influence of tuber size distribution on water use efficiency can be further analyzed by combining the size and composition characteristics of these tubers (Tessema et al., 2020). 4 Experimental Design and Crop Management 4.1 Experimental layout In New Brunswick, the research lasted for five years and a total of 88 sites were selected. Each field plot was divided into multiple experimental plots, and replicates were set up, generally no less than three replicates, in order to distinguish the effects of soil texture and soil organic matter on crop yield changes (Singh et al., 2025). In Ethiopia and its plateau areas, variety trials used a randomized complete block design. Each test had three replicates. The plot size was about 9~12 m² (Tessema et al., 2020; Asnake et al., 2023). This study can use a similar split-plot randomized block design. Irrigation level is the main plot factor, with full, moderate, and severe deficit irrigation. Varieties are set in subplots. Each treatment has at least three replicates. Plot size is about 15~20 m². 4.2 Crop management practices The selection of seed potato size is based on previous studies in highland areas. In the highlands of Ethiopia, seed potatoes are classified into small seed potatoes (about 31.5 g), medium seed potatoes (about 57 g) and large seed potatoes (about 77.5 g). Only healthy seed potatoes with good bud eyes will be used. Large seed potatoes can grow taller plants, produce more tubers and have a higher yield (Asnake et al., 2023). The study selected approximately 50~60 g of medium-sized seed potatoes. All plots were applied with the same fertilizers, including 180 kg/ha of NPS and 176 kg/ha of urea, and the field management measures were also the same. 4.3 Irrigation scheduling and application methods Irrigation timing was set using total available water (TAW), the depletion fraction (p), and readily available water (RAW). When p was 0.35, irrigation began after 35% of RAW in the root zone was used. Soil water was tracked with FDR sensors. In the Hexi Oasis, regulated deficit irrigation (RDI) is used based on the soil moisture content in the 0~60 cm soil layer compared to the field capacity (FC). Irrigation starts when the soil moisture drops below a certain level, like 55% of FC. When it reaches the upper limit, such as 65% FC, irrigation is stopped (Li et al., 2025; Pan et al., 2025). Water use was measured with water meters or by dripper flow rate and irrigation time, then converted to mm or m3/ha.
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