Evaluation of CIP bred clones for expansion of potato production in the coastal areas of Bangladesh

A set of International Potato Center (CIP)-bred potato clones was evaluated for their salt tolerance and productivity in replicated field trials in three coastal districts of Bangladesh, namely, Chittagong, Patuakhali and Satkhira. In each year of experimentation from 2011 to 2015, salinity levels increased progressively during the season and varied with time and place. Evaluation and selection were carried out using GGE biplot analysis and mean yield across the test sites; and the best performing clones were selected for the next year’s trial. Of the original fifteen test clones, two (CIP 301029.18 and CIP 396311.1) were selected for evaluation in the regional yield trial with cvs. Diamant and Asterix as checks. In the regional yield trial, across locations, CIP 301029.18 was the highest (21.8 ton/ha) and CIP 396311.1 (21.3 ton/ha) was the 2nd highest yielder such that CIP 301029.18 produced 64.0% higher yield and CIP 396311.1 produced 32.4% higher yield compare to their corresponding check varieties Diamant and Asterix. Similar ranking was found under farmers’ field conditions. Finally, these 2 clones CIP 301029.18 & CIP Research Article Open Access © 2016 Abdullah Al Mahmud et al., published by De Gruyter Open. This work is licensed under the Creative Commons Attribution 3.0 Public License. Abdullah Al Mahmud*, Mohammad Hossain, Bimal Chandra Kundu, E.H.M. Shofiur Rahaman, Mohidul Hasan, Monower Hossain, Enamul Haque, Atikur Rahman, Mahabub Alam Patwary, Hafizur Rahman, Shahidul Islam Khan, Abu Kawochar, Biresh Kumar Goswami, Jahangir Hossain, Mohinder Singh Kadian, Merideth Bonierbale Evaluation of CIP bred clones for expansion of potato production in the coastal areas of Bangladesh *Corresponding author: Abdullah Al Mahmud, International Potato Center, CIP-SWCA, Banani, Dhaka-1213, Bangladesh, E-mail: Mahmud.tcrc@gmail.com E.H.M. Shofiur Rahaman, Mohidul Hasan, Monower Hossain, Enamul Haque, International Potato Center, CIP-SWCA, Banani, Dhaka-1213, Bangladesh, Mahmud.tcrc@gmail.com Mohammad Hossain, Bimal Chandra Kundu, Atikur Rahman, Mahabub Alam Patwary, Hafizur Rahman, Md. Shahidul Islam Khan, Md. Abu Kawochar, Biresh Kumar Goswami, Jahangir Hossain, Bangladesh Agricultural Research Institute, Joydebpur, Gazipur, Bangladesh Mohinder Singh Kadian, International Potato Center, CIP-SWCA, New Delhi, India Merideth Bonierbale, International Potato Center (CIP), Lima, Peru 190   A. Al Mahmud, et al. The present research was undertaken to i) evaluate and select CIP-bred potato clones best suited for the coastal areas in successive clonal generations; and to ii) estimate and validate the yield performance of the selected CIPbred clones under saline condition in the coastal areas of Bangladesh. 2 Materials and Methods Evaluation and selection for salinity tolerance was initiated in 2011-12 with 15 CIP–bred clones recommended for subtropical lowland conditions of Bangladesh. The research program was designed to coincide with sequential experimental field trials comprising Preliminary yield trial (PYT), Secondary yield trial (SYT), advanced yield trial (AYT) and regional yield trial (RYT) to select the best suited salinity tolerant potato clones/varieties for the coastal region of Bangladesh. All trials (PYT, SYT, AYT & RYT) were conducted at the same locations of Satkhira (22°44’ N Latitude, 89°06’ E Longitude), Patuakhali (21°83 N Latitude, 90°14 E Longitude) and Chittagong (Latitude 22°18’ N Latitude, 91°49’ E Longitude) from 2011 to 2015 (Plate 1). The country’s most popular potato varieties Diamant and Asterix were used as check varieties in SYT, AYT and RYT, where white and red skinned CIP-bred clones were compared with cv. Diamant and Asterix, respectively. Field trials were conducted following randomized complete block design (RCBD) in replicated plots (3) of 3.0 m x 3.0 m size where plant spacing was 60 cm x 25 cm. The PYT, SYT and AYT were planted in the 3rd to 4th week of November with the exceptions that the 2014-15 RYTs were planted on 1st December (Chittagong and Patuakhali where excessive soil moisture delayed planting) and 9th November (Satkhira). Edaphic information (Quddus, 2009) on experimental sites are represented in Table 1. To validate and compare the experimental trial yield of the 2 CIP clones with the yield in farmer’s field conditions additionally 5 farmers’ field trials were conducted in Chittagong (1) Patuakhali (2) and Satkhira (2). Fertilizer was applied @ 160-44-132-15 kg/ha of N, P, K and S, respectively. Full amount of P, K and S and 50% of N were applied as basal and the remaining amount of urea was top dressed at 35 days after planting. Yield and efficiency (Munns, 2002). Such physiological changes result in decreased plant growth (Mensah et al., 2006) and consequently reduced crop yield. Such decrease in growth caused by salt stress has been observed in potato (Farhatullah and Raziuddin, 2002; Shaterian et al., 2005). The reduction in growth following salinity treatment is explained as being due to accumulation of excess amounts of Na+ and Clwhich are toxic to plants and adversely affect yield (Munns, 2002). The average yield of potato in Bangladesh is only 19.37 ton/ha (BBS, 2014); although the yield potential, or achievable yield, has been reported to be as high as 40  ton/ha. There is thus significant scope for increasing the yield of potato by narrowing the yield gap (Rahman et al., 2007). With growing demand for more food to meet the needs of a growing population, it becomes imperative to explore the possibilities of increasing the potential of Bangladesh’s vast saline lands for increased production of food crops. The ability of plants to tolerate and thrive in saline soil has great importance in agriculture indicating salinity tolerance as a desirable trait of crop varieties (Mahmood et al., 2000). Hence selection and breeding of cultivars that can grow and provide economical yield under saline conditions may make a significant contribution to growing food needs. Genotypes grown in different environments show significant fluctuations in yield performance. Therefore, multi-environment trials (MET) were suggested as a means to evaluate yield stability performance of genetic materials under varying environmental conditions (Yan and Rajakan, 2002). GGE biplot is an effective tool for: i) mega-environment analysis (e.g. “which-won-where’ pattern), where specific genotypes can be recommended for specific environments (Yan and Kang, 2003; Yan and Tinkler, 2006); ii) genotype evaluation (the mean performance and stability) and iii) environmental evaluation. The approach is based on principal component analysis to fully explore MET data. In order to develop salinity tolerant potato varieties for Bangladesh, the Tuber Crops Research Centre (TCRC) of Bangladesh Agricultural Research Institute (BARI) and the International Potato Center (CIP) joined forces in 2010 to systematically assess selected advanced bred potato genotypes for their tolerance to saline conditions. Table 1: Agro-ecological zone, land type and soil type of the experimental sites Experimental location Name of the agro ecological region (AEZ) AEZ covered in the region Land type, Soil type Patuakhali and Satkhira Ganges Tidal Floodplain AEZ 13 Medium low, low Heavy silt clays, alkaline Chittagong Chittagong Coastal Plain & St. Martin’s Coral Island AEZ 23, 24 High, medium high, medium low Grey silt loam, Silt clay loam Salinity tolerance of potato  191 plant growth from planting to harvesting using a portable EC meter (Model. HI9813-5, Hanna Instruments, supplied by-Invent Technologies LTD. House-119, Flat B-1, Road-01, Block-F, Banani, Dhaka-1213, Bangladesh). 3 Results and Discussion The level of soil salinity was measured in research and farmer’s field trials at different stages of plant growth (Planting to harvesting). Salinity levels varied with time and place and gradually increased in the dry period (December-March) peaking just before the monsoon rains yield contributing characteristic’ data were recorded following CIP protocol (CIP, 2006) and were statistically analyzed using STAR software (Developed by Biometrical Division, IRRI) and GGE bi-plot analysis was performed using R software (Version 3.0.0). Plant height and vigor were recorded at 60 days after planting (DAP). Plant vigor and senescence data were taken on 1-5 scales where for the former, 1 represents very low vigor and 5 very high vigor, while for the later 1 is low (senescent) and 5 is high (green). Salinity levels of the experimental fields were measured at planting and during different crop stages from 2011 to 2015 and in on-farm trials in 2014-15 at different stages of Plate Plate 1: Three experimental sites and tidal surge (saline prone) areas of Bangladesh Figure 2: Salinity level of salt tolerance trial during different growth to harvest stages of potatoes at Chittagong, Patuakhali & Satkhira during 2014-15 crop seasons Planting Time Emergence Vegetative Tuber formation Tuber bulking Tuber maturation Harvesting Chittagong 0.3 0.5 0.6 0.8 0.8 0.9 0.9 Patuakhali 0.4 0.5 0.7 1.0 1.4 1.6 1.8 Satkhira 0.4 0.5 0.5 0.8 1.0 0.8 0.8 1900n1900rral 1900n1900rral 1900n1900rral 1900n1900rral 1900n1900rral 1900n1900rral Sa lin ity le ve l ( ds m -1 ) Chittagong Patuakhali Satkhira Chittagong

The present research was undertaken to i) evaluate and select CIP-bred potato clones best suited for the coastal areas in successive clonal generations; and to ii) estimate and validate the yield performance of the selected CIPbred clones under saline condition in the coastal areas of Bangladesh.

Materials and Methods
Evaluation and selection for salinity tolerance was initiated in 2011-12 with 15 CIP-bred clones recommended for subtropical lowland conditions of Bangladesh. The research program was designed to coincide with sequential experimental field trials comprising Preliminary yield trial (PYT), Secondary yield trial (SYT), advanced yield trial (AYT) and regional yield trial (RYT) to select the best suited salinity tolerant potato clones/varieties for the coastal region of Bangladesh. All trials (PYT, SYT, AYT & RYT) were conducted at the same locations of Satkhira (22°44' N Latitude, 89°06' E Longitude), Patuakhali (21°83 N Latitude, 90°14 E Longitude) and Chittagong (Latitude 22°18' N Latitude, 91°49' E Longitude) from 2011 to 2015 (Plate 1). The country's most popular potato varieties Diamant and Asterix were used as check varieties in SYT, AYT and RYT, where white and red skinned CIP-bred clones were compared with cv. Diamant and Asterix, respectively.
Field trials were conducted following randomized complete block design (RCBD) in replicated plots (3) of 3.0 m x 3.0 m size where plant spacing was 60 cm x 25 cm. The PYT, SYT and AYT were planted in the 3 rd to 4 th week of November with the exceptions that the 2014-15 RYTs were planted on 1 st December (Chittagong and Patuakhali where excessive soil moisture delayed planting) and 9 th November (Satkhira). Edaphic information (Quddus, 2009) on experimental sites are represented in Table 1. To validate and compare the experimental trial yield of the 2 CIP clones with the yield in farmer's field conditions additionally 5 farmers' field trials were conducted in Chittagong (1) Patuakhali (2) and Satkhira (2).
Fertilizer was applied @ 160-44-132-15 kg/ha of N, P, K and S, respectively. Full amount of P, K and S and 50% of N were applied as basal and the remaining amount of urea was top dressed at 35 days after planting. Yield and efficiency (Munns, 2002). Such physiological changes result in decreased plant growth (Mensah et al., 2006) and consequently reduced crop yield. Such decrease in growth caused by salt stress has been observed in potato (Farhatullah and Raziuddin, 2002;Shaterian et al., 2005). The reduction in growth following salinity treatment is explained as being due to accumulation of excess amounts of Na + and Clwhich are toxic to plants and adversely affect yield (Munns, 2002).
The average yield of potato in Bangladesh is only 19.37 ton/ha (BBS, 2014); although the yield potential, or achievable yield, has been reported to be as high as 40 ton/ha. There is thus significant scope for increasing the yield of potato by narrowing the yield gap (Rahman et al., 2007). With growing demand for more food to meet the needs of a growing population, it becomes imperative to explore the possibilities of increasing the potential of Bangladesh's vast saline lands for increased production of food crops. The ability of plants to tolerate and thrive in saline soil has great importance in agriculture indicating salinity tolerance as a desirable trait of crop varieties (Mahmood et al., 2000). Hence selection and breeding of cultivars that can grow and provide economical yield under saline conditions may make a significant contribution to growing food needs. Genotypes grown in different environments show significant fluctuations in yield performance. Therefore, multi-environment trials (MET) were suggested as a means to evaluate yield stability performance of genetic materials under varying environmental conditions (Yan and Rajakan, 2002). GGE biplot is an effective tool for: i) mega-environment analysis (e.g. "which-won-where' pattern), where specific genotypes can be recommended for specific environments (Yan and Kang, 2003;Yan and Tinkler, 2006); ii) genotype evaluation (the mean performance and stability) and iii) environmental evaluation. The approach is based on principal component analysis to fully explore MET data.
In order to develop salinity tolerant potato varieties for Bangladesh, the Tuber Crops Research Centre (TCRC) of Bangladesh Agricultural Research Institute (BARI) and the International Potato Center (CIP) joined forces in 2010 to systematically assess selected advanced bred potato genotypes for their tolerance to saline conditions.

Results and Discussion
The level of soil salinity was measured in research and farmer's field trials at different stages of plant growth (Planting to harvesting). Salinity levels varied with time and place and gradually increased in the dry period (December-March) peaking just before the monsoon rains yield contributing characteristic' data were recorded following CIP protocol (CIP, 2006) and were statistically analyzed using STAR software (Developed by Biometrical Division, IRRI) and GGE bi-plot analysis was performed using R software (Version 3.0.0). Plant height and vigor were recorded at 60 days after planting (DAP). Plant vigor and senescence data were taken on 1-5 scales where for the former, 1 represents very low vigor and 5 very high vigor, while for the later 1 is low (senescent) and 5 is high (green

Mean yield performance and selection of CIP clones for RYT
The average yield performance of CIP genotypes at 3 different locations during 2011-12, 2012-13 and 2013-14 are presented in Table 2. In each trial the CIP-bred clones responded differently in the saline soil at three coastal districts. During selection of the best clones in the ( Fig. 1, Fig. 2 and Fig. 3). In the experimental field during 2014-15, comparatively higher salinity was recorded at Patuakhali (Fig. 2) whereas in the farmer's field higher salinity was recorded at Satkhira (Fig. 3). In these two locations, increased salinity levels were recorded at the tuber maturation to harvesting stage and such raising in salinity levels may be due to higher capillary movement of ground water, low rainfall and higher temperature.  Level of significance ** ** ** ** ** = Significant at 0.01 level of probability biplot display showed that CIP-139 was the best suited genotype at Satkhira and Chittagong, CIP-112 at Patuakhali and CIP-102 at Chittagong (Fig. 4). Considering mean yield and stability performance from the biplot analysis ( Fig. 4 and 5) 5 clones viz., CIP-102, CIP-111, CIP-112, CIP-130 and CIP-139 were selected for inclusion in the AYT at the same locations in 2013-14. In the advanced yield trial (AYT) during 2013-14, CIP-139 was the mean highest yielder and CIP-102 was the 2 nd highest yielder (Table 3). The "Which won where /What" pattern of biplot display showed that CIP-139 was the best suited genotype at Satkhira and Chittagong and CIP-102 at Patuakhali. Considering the preliminary yield trial (PYT) the mean yield performance over three locations, tuber shape, size, color of the skin and overall appearance were considered, and 8 clones  were selected for secondary yield trial (SYT) in the 2012-13 crop season. GGE bi-plot analysis was used during 2012-13 to support the selection of the best suited CIP clones for 2013-14 in 3 different saline environments. The polygon of a biplot is the best way to visualize the interaction patterns between genotypes and environment (Yan and Kang, 2003). The "Which won where /What" pattern of  Significant variation was found in yield at all locations and the yield ranged from 10.38 to 37.53 ton/ha (Table 4). At Satkhira, CIP-102 produced the highest yield (37.53 ton/ ha) followed by CIP-139 (31.04 ton/ha) and Asterix (27.70 ton/ha). At Chittagong, the highest yield was found in CIP-102 (16.71 ton/ha) followed by CIP-139 (16.37 ton/ha) and Asterix (13.75 ton/ha). Diamant (10.38 ton/ha) was the lowest yielder at Chittagong. CIP-139 produced the highest yield (16.40 ton/ha) followed by CIP-102 (11.32 ton/ha) and Diamant (10.67 ton/ha). At Satkhira, higher tuber yield were produced by the CIP clones and check varieties due to low level of salinity in the growing period, on the other hand at Patuakhali lower tuber yields were produced due to higher level of salinity. Considering all locations, the highest mean tuber yield was observed in CIP-102 (21.85 ton/ha) with CIP 139 (21.27 ton/ha) being the 2 nd highest yielder. CIP-102 produced 64.03% higher yield and CIP-139 produced 32.35% higher yield compare to their corresponding check varieties Diamant and Asterix, respectively.

Farmers' field performance
Among the 5 farmers' field trials, tuber yield ranged from 9.06 to 33.83 ton/ha, where the highest was found in CIP-102 at Chittagong and the lowest was in Asterix at Satkhira (Table 5). Considering the mean yields under farmers' field conditions, CIP-102 (25.79 ton/ha) was the highest yielder and produced 22.86% higher yield mean yield and stability performance of bi-plot display ( Fig. 6 and 7) 2 clones viz., CIP-102 and CIP-139 were selected for inclusion in the regional yield trial (RYT) at the same locations in 2014-15.

Plant canopy and yield performance of CIP clones in RYT
On average, plants of all tested clones/varieties were taller at Satkhira where planting was earlier than at the other two locations and plants were on average smaller at Patuakhali where planting was late, corresponding to the increase in salinity levels with time. At the same time, plant vigor ranged from 3.67 to 5.00. CIP-102 and CIP-139 produced more vigorous plants at all locations than check varieties Diamant and Asterix (Table 3). The plant vigor score indicated that CIP-102 and CIP-139 have the capability to thrive under saline conditions. Salinity effect was evidenced as more rapid advance of senescence. Senescence started at 60 days after planting and gradually increased with plant age but differed among clones (Fig. 8). At tuber-bulking stage the check varieties Diamant and Asterix showed higher senescence than CIP-102 and CIP-139. At 81 days after planting, the highest senescence was found in Asterix and Diamant. CIP clones CIP-102 (3.00) and CIP-139 (2.88) showed comparatively less senescence. At 88 days, CIP clones CIP-102 and CIP-139 were found green at all locations due to salinity tolerance while Diamant and Asterix were completely dried up (Fig.8).  Level of significance Genotype (G) Location (L) G x L ** ** ** Level of significance Genotype (G) Location (L) G x L ** ** ** ** = Significant at 0.01 level of probability