Effect of Seed Priming on Maize in the Western Hills of Nepal

With a view to identify the effect of seed priming technology on maize in the western hills of Nepal, five different varieties of maize including farmers' local were tested during summer seasons of 2004 at three sites of Gorkha, Palpa and Myagdi districts using mother-baby scheme with primed and non-primed treatments. Results of mother trials combined over locations revealed that primed treatments silked three days earlier and matured six days prior to non-primed counterparts. Significant increase in grain yield, average of 11.6% and maximum of 27.8% was recorded. Farmers' response in baby trials combined over locations showed that plant stand after germination in primed treatment was found better as reported by 80% of the respondents.


Introduction
Maize is the most important crop in the hills and ranks second in terms of area (891583 ha) and production (2231517 Mt.) with productivity of 2503 kg ha-1 . It occupies 42.82% area of the total food crops (rice, maize, wheat, millet, barley and buckwheat) in the hills and 26.97% in the country, and contributes 45.42% and 25.90% of the total cereal production in the hills and country, respectively. Similarly, contribution of maize to total edible production (5355232 tons) is 26.82 and to the total requirement (5426631 tons.) is 26.47 percent. Mountain and hilly regions are food deficit and only Terai has surplus edible production. Total edible balance is 71399 tons in negative direction in the country. Out of 75 districts 35 districts have insufficient edible balance (MoAD, 2017). Yield and other advantages of primed seeds over nonprimed are recorded in different crops in different countries. There has been much research during the last several years to test, develop and promote on-farm seed priming in a range of crops, countries and agro-environments. The beneficial effects of seed priming on crop establishment, development and yield have been documented (Parera and Cantliffe, 1994;Chivas et al., 1998;Kulkarni and Eshanna, 1998;Harris et al., 1999Harris et al., , 2001aHarris et al., , 2001bHarris et al., , 2002Anonymous, 2002;Jasi et al., 2000;Krishi, 2058). Currently, seed priming research is ongoing in Bangladesh, Cameroon, Cote d'Ivoire, Gambia, Ghana, India, Kenya, Nigeria, Pakistan, Sierra Leone, Thailand and Zimbabwe.

Experimental Setup
Four varieties of maize namely, Manakamana 1, Manakamana 3, Rampur Composite and Manakamana 5 with primed and non-primed treatments were evaluated at three sites in farmers' field of Gorkha (Katteldanda, Shikhar and Bibinchok), Palpa (Khaseuli, Deurali and Nayarnamatalesh) and Myagdi (Ratnechaur-1, Jyamrukkot and Ratnechaur-1) districts (Table 1). The "Mother-Baby" trials methodology was used for experimentation. In baby trial, a single variety (2 kg seed of each variety) was given to four farmers in each VDC and asked to prime (16-18 hours) half of seed (1 kg) in water, then surface dry and sow using normal practices adjacent to a plot using non-primed seed. Baby trial was managed and led by farmers themselves. In addition to this, a complete set of trial i.e. mother trial (MT) consisting of four improved varieties and one local check was tested in centrally located farmers' field in each VDC using prime and non-prime treatments. Seventeen farmers were involved in testing the technology at each of the three sites in one district and thus, total 153 farmers participated the program. The scheme of a mother-baby trial using four varieties of maize using prime and non-prime treatments is given below in Fig.  1.
In the mother trials, plot size was 3m long 6 rows/variety. Seed rate was 20 kg/ha with spacing of 75 cm x 25 cm. Fertilizers were applied @ 80:40:30 NPK kg ha-1 , respectively. Farm yard manure was applied @10 t/ha. Observations were taken from four central rows on days to flowering, plant and ear height, grain yield and plant stand at harvest from MTs. Data from mother trials were analyzed using MSTATC.

Observations and Data Analysis
Farmers compared the performance of each improved variety with primed and non-primed treatments in baby trials and performance of local in mother trials from planting to post-harvest management. Individual farmer reported his/her own perceptions through a household level questionnaire (HLQ) through matrix ranking. Data in HLQ were recorded as scores where the primed treatment was compared to non-primed counterpart as better, same or worse. The following points were considered in HLQ: ease to planting, time to germination, plant stand after germination, plant height, lodging problem, weed problem, disease and insect pests problem, drought resistance, thickness of maize stover, days to maturity, ear size, grain yield, stover yield and plan for next year planting.

Mother Trial
Varietal differences were found highly significant for tasseling, silking, plant and ear height, and grain yield and significant for number of ears/plot. Location by variety interactions were highly significant for tasseling, silking, plant height, ear height and grain yield. Highly significant priming effects were recorded for tasseling, silking, number of ears/plot and significant for number of plants/plot and grain yield. Location by priming interactions were highly significant for grain yield, significant for days to tasseling and non-significant for rest of the traits. Variety by priming interactions were found significant only for grain yield. Location by variety by priming effects were observed nonsignificant for all the recorded traits. Observations recorded from the mother trials combined over locations have been summarised in Table 2.
In Gorkha, varietal differences were recorded highly significant for days to tasseling and silking, and plant height, significant for ear height and grain yield and nonsignificant for number of plants and ears/plot. Highly significant priming effects were recorded for days to tasseling and silking, number of ears/plot and grain yield. Variety by priming interactions were found non-significant for all the traits. Results have been presented in Table 3. In Palpa, varietal differences were recorded highly significant for days to tasseling and silking, and plant and ear height, significant for grain yield and non-significant for number of plants and ears/plot. Highly significant priming effects were recorded for days to tasseling and silking and number of ears/plot. Variety by priming interactions were found nonsignificant for all the traits. Detail results are summarized in Table 4. In Myagdi, varietal differences were highly significant for all the traits except number of plants/plot. Highly significant priming effects were recorded for all the traits except pant and ear height. Variety by priming interactions were found non-significant for all the traits.
Results have been given in Table 5.

Discussions
Results of mother trials combined over locations revealed that primed treatments silked 3 days earlier and consequently matured 6 days earlier compared to nonprimed counterparts. Likewise, increased number of plants and ears per plot in the primed treatment was observed. Significant increase in grain yield (average of 11.6% and maximum of 27.8% in Manakamana 1) was recorded. Priming effect for grain yield was found not only variety specific but also location specific. Highest grain yield was obtained from the variety Manakamana-3 both in primed (6028 kg ha-1 ) and non-primed (5344 kg ha-1 ) conditions. Similar results were obtained in Pakistan and Zimbabwe by Harris and his colleagues (2002) where seed priming on maize increased grain yield by 17-76% and 14% over nonprimed, respectively .In Gorkha, Grain yield increment ranged from 6.0% for farmers' local to 56.8% for Manakamana 1. Highest grain yield was obtained from the variety Manakamana 3 both in primed (6614 kg ha-1 ) and non-primed (5422 kg ha-1 ) situations. In Palpa district, Variety Manakamana-1 showed better performance of seed priming (16.3% yield increment). Highest grain yield was obtained from the variety Manakamana 3 both in primed (6178 kg ha-1 ) and non-primed (6078 kg ha-1 ) seeds. In Myagdi district, Grain yield increment ranged from 7.9% for Rampur composite to 27.8% for Farmers' local. Highest grain yield was obtained from the variety Manakamana 5 both in primed (5449 kg ha-1 ) and non-primed (4890 kg ha-1 ) environments. Our research findings from both mother and baby trials conducted at nine sites in three districts of Nepal agreed and supported the findings of previous research results carried out in various countries that direct benefits of seed priming in maize are faster emergence, better and more uniform stands, less need to re-sow, more vigorous plants, earlier flowering, earlier harvest and higher and stable grain yield (Chivasa et al., 1998;Harris et al., 1999Harris et al., , 2001bHarris et al., , 2002Rashid et al., 2002). These results were confirmed for maize in Pakistan and Zimbabwe (Harris et al., 1999. However, the previous findings that better drought tolerance and weed control in primed seeds was not supported by our research results.

Conclusion
Varieties namely Manakamana 3, Manakamana 5 and Rampur composite in Gorkha and Palpa whereas Manakamana-3 and Manakamana 5 in Myagdi districts were preferred by farmers. At the same level of management, significant effect of priming in maize grain yield (average of 11.6% and maximum of 27.8% in Manakamana 1) has been observed. Priming effect for grain yield was found not only variety specific but also location specific. Highest grain yield was obtained from the variety Manakamana 3 both in primed (6028 kg ha-1 ) and nonprimed (5344 kg ha-1 ) conditions. However, variety and location specific results on maize seed priming were recorded, and positive impacts of seed priming in grain yield and other quantitative traits have been verified. Therefore, this technology should be promoted and disseminated widely using different varieties at different locations.