**5.3 Morphological and molecular characterization of Sikkim maize**

'Sikkim Primitive' is a unique landrace discovered in the North-Eastern Himalayan region of India, particularly in the province of 'Sikkim' [24]. This landrace stands out due to its distinct ear and fruiting morphology, which closely resembles that of maize, setting it apart from teosinte where grains are enclosed in a hard fruit case or 'cupule' [21]. Detailed morphological studies conducted by Sachan and Sarkar [13] confirmed the close relationship of 'Sikkim Primitive' with maize. The designation of this landrace as 'primitive' is justified by its remarkable traits, including high prolificacy, sensitivity to photoperiod, small popcorn-like kernels, and the ability to produce abundant pollen. The unique characteristics exhibited by 'Sikkim Primitive' make it an exceptional variety deserving of further investigation and conservation efforts [24].

The plants of the Sikkim Primitive maize, locally known as *murali makai*, were observed to display remarkable prolificacy with each plant bearing 5–6 cobs. They also exhibited excellent popping capacity and several other distinctive traits. The plants

**Figure 13.** *Murali makai stored over the fireplace at Tinvong, Dzongu, North Sikkim.*

*Exploring the Diversity of Maize (*Zea mays *L.) in the Khangchendzonga Landscapes… DOI: http://dx.doi.org/10.5772/intechopen.112566*

were tall, and their stems were thin with loose drooping tassels. The base of the glumes and brace roots displayed anthocyanin colouration. The cobs were medium-sized and carried small seeds with low test weight, weighing 87.90 g [25].

Molecular characterization using 22 SSR markers demonstrated the amplification of unique amplicons, ranging from 100 to 800 bp. Of these markers, bnlg1083, umc1353, umc1128, bnlg1017, bnlg2077, umc2298, and umc2373 displayed distinct amplification patterns. The characterization of these traits and the molecular markers will be beneficial in utilizing Sikkim Primitive maize for genetic improvement and maintaining genetic purity [25].

### **6. Maize-based farming and its significance**

In the region encompassing Sikkim and the Darjeeling Himalayas, maize cultivation is of paramount agricultural significance. This area has emerged as an optimal location for maize farming due to its favorable climatic conditions and suitable soil characteristics. Farmers in this region dedicate substantial land to maize cultivation, making a significant contribution to the overall agricultural output. The agroclimatic conditions within an elevation range of 200 to 2700 meters are particularly suitable for cultivating a diverse range of maize varieties. This includes as many as 26 traditional maize landraces and approximately 15 different hybrid and certified maize varieties, showcasing the rich agricultural diversity of the region.

Farmers in Sikkim and the Darjeeling Himalayas employ a blend of traditional and modern farming techniques to cultivate maize. They adhere to best agricultural practices, encompassing appropriate land preparation, meticulous seed selection, precise planting methods, and effective pest management strategies. These practices are implemented to maximize yield and maintain the overall health of the crop.

The maize production, productivity and area under cultivation in Sikkim from 2017 to 2018 to 2021-2022 is given in **Figure 14**. The area dedicated to maize cultivation in this region during 2021–2022 in Sikkim was 38,458 ± 580 hectares. This substantial figure underscores the significant role of maize farming in the regional agricultural landscape. Additionally, the region boasts an average annual maize production of around 67,692 ± 1243 tonnes [27]. This considerable output highlights the success and potential of maize cultivation in meeting the food requirements of the local population and beyond (**Figure 15**).

Between the years 1981 and 1990, there was a notable increase in maize cultivation in Sikkim, with a 27.6% expansion in acreage. During this period, there was a substantial increase of 174% in total production and 111% in yield per unit. These advancements were primarily attributed to the introduction of high-yielding varieties (HYVs) in Sikkim. However, the subsequent decade from 1991 to 2001 saw a decline in the growth rate, with only a 31.7% increase in total production and a 22.3% increase in yield per unit recorded. Interestingly, despite having more choices of HYVs available during the latter period, the sustained growth seen in the previous decade could not be maintained [28]. However, according to reports from the Agriculture Department of the Government of Sikkim, there has been a significant decrease in the cultivated area from 2012 to 2022, with a reduction of 1892 hectares. While productivity and production levels have remained relatively stable during this period.

Maize cultivation in the region encompasses contributions beyond economic and food security aspects and assumes a pivotal role in supporting the livelihoods of farming communities. Its practice generates employment opportunities, facilitates

#### **Figure 14.**

*Area, production and productivity of maize in Sikkim, India from 2017 to 2022 (data compiled from [16, 26, 27]).*

#### **Figure 15.** *A maize production farm at Martam, near Gangtok.*

rural development, and strengthens the overall resilience of the agricultural sector. Since 2012, a total of 17 high-yielding varieties (HYVs) and hybrid varieties have been introduced in Sikkim. Alongside these introductions, hybrid and certified maize seeds obtained from external sources, such as Pusa Vivek (QPM 9 (Improved), NAC-6004 composite, 33 M66, 66 K99, JKMH-1701, have also been adopted in Sikkim [27]. Based on the experiences shared by farmers in various regions of Sikkim, it has been observed that nine prominent pests have infested the high-yielding varieties (HYVs) and hybrid maize varieties. These pests are the stem borer (*Chilo partellus*), cutworms (*Agrotis ipsilon*), armyworms (*Mythimna separata*), semi-loopers (*Plusia signata*), and cob borers (*Stenchroia elongella*). It is noteworthy that the indigenous landraces of maize exhibit tolerance to many of these pests [29].

*Exploring the Diversity of Maize (*Zea mays *L.) in the Khangchendzonga Landscapes… DOI: http://dx.doi.org/10.5772/intechopen.112566*

A very high intensity of post-harvest infestations have been recorded by insects such as the maize weevil (*Sitophilus zeamais* Mostsch.) and grain moth (*Sitotroga cerealella* Oliv.) in the HYVs and hybrid maize varieties, which have been identified as major storage insect pests. While pest infestation in the indigenous varieties was significantly 80% less as compared to improved varieties.

Continuous efforts are underway to enhance maize production in Sikkim and Darjeeling Himalayas. These initiatives encompass the promotion of improved farming practices, the introduction of high-yielding maize varieties, and the implementation of sustainable agricultural techniques. These endeavors aim to ensure long-term food security, augment farmers' income, and foster comprehensive agricultural development in the region. The maize cultivation in Sikkim has proven to be a vital agricultural activity, contributing to food security, bolstering economic growth, and enhancing the well-being of local communities (**Figure 16**).

#### **6.1 Maize inter-cropping**

The study compared the productivity of intensified cropping systems to traditional maize-fallow systems in the rainfed region of Sikkim Himalayas. The results showed that intensified cropping systems, such as maize (green cobs)– urd bean–buckwheat and maize–rajmah, had significantly higher maize grain equivalent yield and system production efficiency compared to the maize-fallow system. The maize (green cobs)–urd bean–buckwheat system demonstrated the highest relative production efficiency and land use efficiency due to its longer crop duration, while the maize-fallow system had the lowest land use efficiency. These findings highlight the potential of intensified cropping systems to increase agricultural productivity and land use efficiency in the region. The study suggests that promoting the adoption of appropriate intensified cropping systems could contribute to enhancing food security and farm productivity in the rainfed areas of Sikkim Himalayas.

**Figure 16.** *Maize varieties stored under the roof.*
