Kiwi, a fruit with great commercial potential, is becoming increasingly popular in the sub Himalayan region of India. Originally from central China, it is now commercially grown in several countries such as New Zealand, Italy, USA, Japan, Australia, France, Chile and Spain. In India, kiwi was initially planted as an ornamental tree in the Lal Bagh Gardens in Bangalore. However, extensive research and development have resulted in its cultivation for commercial purposes expanding to various regions in India including the midhills of Himachal Pradesh, Uttar Pradesh, Jammu and Kashmir, Sikkim Meghalaya Arunachal Pradesh and the Nilgiri hills.
The Kiwi plant is a deciduous vine that can adapt to different climates and soil conditions. However, in order to produce high-quality fruits, it needs a winter rest period with 700-800 chilling hours below 7`C. If this requirement is not met, the bud break may be delayed. Frost can cause damage to the vine at various stages: (I) in autumn, frost can harm both the crop and non-dormant plants from late October to late November; (II) frost occurring just before or during budburst at the end of winter; and (III) spring frost after budburst. During summer, leaves may suffer from scorching if temperatures exceed 35`C along with high insulation and low humidity.
Sun scald and heat stresses are the main issues encountered when cultivating kiwi in lower areas. In India, kiwi cultivation has been successful at elevations between 800 and 1,500 m above sea level. An annual rainfall of approximately 150 cm is sufficient, and it should be evenly distributed throughout the growing season. The plant’s vigorous vegetative growth, large leaves, and viny habit make it susceptible to damage from strong winds during the growing period. Thus, it is advisable to avoid windy sites or establish windbreaks prior to planting. Kiwi can be grown in various soil types, but deep, fertile, and well-drained sandy loam soils are considered ideal.
A soil pH below 6.9 leads to maximum yield, but a higher pH up to 7.3 has a negative effect due to manganese deficiency. Planting in heavy, wet soils is not recommended as it can harm the plants. Kiwi is a dioecious plant, meaning it produces separate pistillate and staminate flowers. The important commercially grown cultivars include Abbott, which is an early flowering and maturing variety with oblong, medium-sized fruits covered in dense hairs. These fruits are sweet with lower ascorbic acid content and medium titratable acidity. Another important cultivar is Allison.
Abbott-like fruits, but slightly broader in proportion to length. Overlapping and crimped petals, with margins. Early ripening, heavy bearer, and sweet taste. Lower levels of ascorbic acid and titratable acidity. Ideal for Himachal Pradesh. Bruno requires less chilling period. Tapering fruits towards the stem end. Longest among all cultivars. Dark brown fruits with dense, short, bristly hair. Highest levels of ascorbic acid and titratable acidity.
The bearing of the Hayward cultivar is very heavy. Hayward is the most popular cultivar in the world, but it tends to have a biennial bearing pattern. The fruit of the Hayward cultivar is broad and flat, with a wider width compared to its length. It has a superior flavor and high content of sugar and ascorbic acid. This cultivar requires more chilling hours.
The Monty cultivar is a late flowering variety, but the fruit maturity is not late. The fruits of Monty are oblong, similar to the Abbot and Allison varieties. Monty is a highly prolific bearer, although sometimes hand thinning may be necessary to obtain good-sized fruits. The fruit of Monty is wider towards the blossom end and has higher acidity but medium sugar content.
Tomuri is a good pollenizer for the Hayward and Monty cultivars, specifically for late flowering kiwis.
Flowers typically appear in groups of 5, and they are also used to pollinate different cultivars. The most rapid and suitable method of propagation is through cuttings. Various types of stem cuttings, such as hard wood, semi hardwood, and soft wood, have varying techniques and success rates in rooting. The ideal cuttings are 0.5-1 cm thick with short internodes and 15-30 cm long. Hardwood cuttings are prepared during the dormant season (January-February) from the previous year’s summer growth. Well matured dormant shoots with at least three healthy bold buds from the middle of the shoot are used for cutting. The tips of the shoots should be avoided as they have a very low rate of rooting. It is ideal to select cuttings from the central and basal parts, avoiding those with a higher number of spurs. The cuttings are then treated with IBA (500 ppm) for 10 seconds and deeply set in moist rooting medium.
To prevent desiccation and rotting, the top portion of the cuttings are waxed. The highest rooting in open conditions is achieved using a rooting medium consisting of farmyard manure, sand, leaf compost, and soil in equal proportions. The cuttings should be thatched or shaded with shade net and irrigated frequently. Adequate drainage is necessary to keep the nursery bed free of weeds. When the cuttings reach a height of about 15-25 cm, their terminal growth is pinched off to redirect nutrients for root growth and development.
To propagate hardwood cuttings, a mist propagation chamber or polythene house with intermittent mist can be utilized. Successful outcomes have been achieved using a rooting medium consisting of sand, farmyard manure, soil, sawdust, and coal in a ratio of 2:1:2:1:1. To enhance the process, it is recommended to treat the cuttings with a solution containing IBA (2,500 ppm) and NNA (2,500 ppm) for 20-30 seconds. Additionally, misting should occur every 15-20 minutes for 2-3 minutes per session, totaling 5-6 hours daily. Softwood cuttings root more easily and quickly but necessitate greater care and an advanced propagating structure like a mist chamber.
Semi-hardwood cuttings with three buds and a thickness of 0.5-1.0 cm are taken from the middle portion of the current season’s growth in July. A 1 cm wound is made on one side of the base just below the node. The lower leaf on the basal bud is removed, while two leaves are retained but reduced to 20-50% through a circular cut, maintaining their natural shape. The cuttings are treated with sand as the rooting media and exposed to intermittent mist at 10-minute intervals. This method yields a success rate of 70-75%. Kiwi plants can also be propagated through grafting.
Although it takes approximately two years to develop a nursery plant using grafting or budding onto seedlings, this method is the simplest and most cost-effective. Kiwi plants can be cultivated by tongue grafting kiwi seedlings in January-February. Freshly extracted kiwi seeds from ripe fruits require stratification for 10 weeks in various layers of sand under field conditions. In agroclimatic zones where winter temperatures drop below 15°C, kiwi seeds can be planted directly in seed beds during the first two weeks of December.
The seed beds should be mulched with grass until the seeds begin to germinate in order to protect the germinating seeds and baby seedlings from sun scald and direct sun. If left exposed, the young cotyledon leaves will turn brown and develop symptoms of damping off, ultimately resulting in their death. Therefore, as soon as the seeds start to germinate, the mulch should be removed and the seed bed should be immediately covered with Hessian cloth (gunny bag) or with pruning wood thatch until the seedlings have 5-6 leaves. Grafting is best done during the dormant season, and January-February is the ideal time.
The best choice for the rootstock’s thickness scion should be selected and packed in sphagnum moss. If necessary, it can be stored at a temperature of 4`C in a refrigerator. Of the various grafting methods available, whip and tongue are considered ideal. Seedlings are typically ready for budding at the end of their first growing season when the stem diameter reaches approximately 6-8 mm. Scion buds are obtained from the current season’s growth and are inserted on the main stem using the T budding method, approximately 10 cm above ground level. Chip budding performed in mid-February can result in up to 95% bud take.
The bud is tagged firmly with polythene tape to hold it in place. Once the bud has successfully grown, the top of the vine is cut above the join during the next dormant season. It is crucial to protect the young shoot that grows from the bud, as it is delicate and easily damaged. When cultivating and planting vines, it is best to choose gently sloping land. If the land is steep, terraces should be created to plant the vines. Ideally, the vine rows should be positioned north to south to ensure they receive maximum sunlight. Properly preparing the soil is vital for successfully establishing a vineyard.
By December, the preparation of pits, mixing of farmyard manure, and filling of pits should be completed. A kiwi plantation in Kullu, Himachal Pradesh, India is adopting different planting distances based on variety and training system. The T-bar and pergola systems are commonly used for planting. In the T-bar system, a spacing of 4m from row to row and 5-6 m from plant to plant is typical. On the other hand, the pergola system requires a spacing of 6 m from row to row. The ideal time for planting is January. When planting, it is important to ensure that the depth is the same as the plants’ original nursery growth level.
The soil should be firmly placed around the roots. The plants are pruned hard to about 30 cm to encourage vigorous growth. Chinese gooseberry is a dioecious plant; therefore, the interplanting of male plants is essential for fruit production. Adequate pollination is crucial for the development of good-sized fruit, while poor pollination may limit productivity. To have a male clone blooming at the same time as the fruiting variety is grown, it is essential for effective pollination. In India, generally only 2 male clones—Tomuri and Allison—are interplanted.
To ensure every female plant is within direct “sight” of a male, it is crucial to evenly distribute the male plants throughout the area. A common practice is to plant male and female plants in a ratio of 1:9. While having more male plants is beneficial, their presence should not exceed one ninth of the overall area. To achieve this, the male plants can be pruned as their leaders run along the wire, allowing the adjacent female plants to grow into the vacant space. Kiwi plants rely primarily on insect pollination, with honey bees being the most important pollinators.
To achieve rapid and effective pollination in its orchard, a significant population of honey bees is necessary. It is advised to have a small group of 3-4 colonies located at the end of each block measuring 0.5-0.75ha. This arrangement ensures even dispersal of foragers throughout the orchard. The training process for kiwi vine is crucial and requires constant attention. The primary goal of training is to create and maintain a well-structured framework consisting of main branches and fruiting arms. Additionally, training aids in proper soil management, spraying, and harvesting. It is recommended to erect supporting branches prior to planting the vines or promptly thereafter.
There are three types of supporting structures (fences) that are constructed. One common type is a single wire fence, although some growers also use an additional wire, creating a knife-in system. In this system, a 2.5 mm thick tensile wire is strung on top of pillars that are 1.8-2.0 m high above the ground. These pillars, made of wood, concrete, or iron, are erected 6 m apart in a row. It is important to not overstrain the wire tension during installation to prevent it from breaking at the knot under the weight of the crop. A cross arm (1 m) on the pole carries two outrigger wires, creating a training method known as T-bar or overload trellis/telephone system.
In the T-bar system, the laterals from the main branch are trained on a canopy of three wires. For a pergola or bower system, a flat-topped network or crisscross wires are prepared to train the vines. This system is more expensive and difficult to manage but results in higher yields.
In the T-bar system, a strong growing shoot is chosen as the main trunk to support the vine and bring it up to the wire. The trunk is staked and tied at regular intervals to prevent twisting and ensure straight growth.
The vine can be allowed to grow to a height of 2 m and near the wire, at which point one permanent leader can grow in each direction along with the center wire. This can be achieved by training the leader along the wire and training a suitable shoot in the opposite direction as a second leader. Alternatively, the initial shoot can be cut below the wire to stimulate the production of two leader growths, which can then be trained along the wire. From these permanent leaders, temporary fruiting arms are developed at right angles along both sides of each leader, spaced 25-40 cm apart.
These arms are secured to the outrigger wires to maintain their position, taking care to avoid damaging them at their bases. It is important to prevent the leader from tightly twisting around the wire, as this could restrict sap flow and weaken the vine over time. To speed up the development of fruiting arms and maximize production, it is recommended to use robust shoots for training as leaders. Although growth may be slow in the first season, within 3-4 years the fence should have sturdy leaders and fruiting arms in all directions. Pergola Training, or growing vines over a pergola, follows a similar method as the T-bar fence.
The vines are cultivated vertically until they reach a height of two meters near the top of the structure. At that point, one sturdy leader is allowed to grow in each direction along the main wire. To create the canopy of the pergola, a system of fruiting arms is developed from these leaders at a right angle to the wire. On pergolas, these fruiting arms can be retained for a longer period and may be more permanent compared to T-bar structures. Temporary fruiting laterals are allowed to develop on the more permanent fruiting arms. It typically takes around seven years for a pergola to be fully covered with vine growth. Pruning is also performed.
Having knowledge of the growth and fruiting habits of the kiwi vine is crucial for proper pruning. The vine’s annual growth should be between 2-4 meters, but without pruning in both summer and winter, it can become overcrowded and difficult to manage. Kiwi fruits only develop on new growth from buds formed in the previous year. For the current season’s crop, productive growth is limited to the basal 3-6 buds. Shoots that emerge from older wood and are pruned back typically do not bear fruit in their first season. High-quality fruits are produced by vines that receive exposure. If a shoot is pruned just beyond the fruiting bud, it will gradually perish.
To ensure the availability of fruiting areas each year and to maintain young wood, it is necessary to prune kiwi plants. The recommended method is to follow a 3-4 year lateral replacement system, creating a pruning cycle. Initially, a lateral emerging from the main rod is trimmed back in winter to allow space for 4-5 fruiting shoots, with 4-5 bud intervals between each shoot. In spring, any strong uprights or undesirably positioned shoots that have not grown excessively long are pruned. This pruning technique is particularly relevant for the Hayward variety, as only shoots of moderate vigor produce fruit.
Some plants can have their vigorous shoots pulled back to a horizontal position in order to transform them into fruiting wood. This means that during summer pruning, the fruiting arms are shortened, crisscross and shading shoots are thinned out. The key to successful summer pruning is selecting and promoting the correct laterals that will bear fruit in the following year and allowing the vine to be exposed to sunlight. During dormant pruning, the fruiting lateral is cut back to two vegetative buds beyond the last fruit. In the second year, these vegetative buds produce the fruiting shoots which are pruned once again.
The fruits on the lateral shoot are permitted to grow during the third or fourth year. Subsequently, the side branches are eliminated from the primary branch, and additional side branches are chosen and pruned appropriately to maintain a balance between vegetative and reproductive growth for consistent fruit production. To promote the growth of new side branches, any fruiting side branches that have weakened or become overcrowded are removed. As the fruiting arm is pruned in the third year, around one-third of all fruiting arms are pruned from the vine annually.
These are trimmed back to stay as permanent leaders. Pruning while the plants are dormant must be finished by mid February annually. The amount of fertilizer needed varies depending on the fertility of the soil, the age of the vine, and the amount of fruit produced. Kiwi plants remove a higher amount of nutrients due to their increased yield and the removal of summer and winter pruning. Therefore, nitrogen, phosphorus, and potassium should be applied every year, while the application of other elements should be based on specific requirements. Typically, a basal dose of 20 kg of farmyard manure and 0.5 kg of NPK mixture containing 15% nitrogen is applied each year.
After the age of five, it is recommended to apply 850-900N, 500-600g P, 800-900 g K, and farmyard manure annually for kiwi cultivation. Kiwi plants require a sufficient amount of CI to promote healthy shoot and root growth. Conversely, excessive amounts of B and Na can be detrimental. The N fertilizer should be applied twice, with half to two-thirds administered in January-February and the remaining portion after fruit set in April-May. For young vines, the fertilizer should be mixed into the soil around the vine’s perimeter, while for matured vines, it should be evenly distributed across the entire soil surface.
Under dry conditions, applying fertilizer to plants can be harmful. The optimal method of managing soil is through permanent cultivation using clover and keeping the soil clean. In hilly areas where soil erosion is a concern, cultivating sod is justified. This method uses natural weed cover to create a thick layer of soil and organic matter preservation. New Zealand commonly employs clover sod, which can also thrive in our conditions. It’s important to regularly mow the sod or weed cover and utilize it as mulch, with a thickness of 10cm, during the summer. The use of herbicides is also an option.
However, there are several residual herbicides that kiwi fruit is vulnerable to, including Bromocil, Terbacil, Chlorthiamid, and Dichlobenit. Additionally, during the first five years of plantation, it is possible to practice green manuring and intercrop with vegetables and leguminous crops. Due to their vigorous vegetative growth, leaf size, vine habit, and the high humidity in their natural habitat, kiwi plants require a significant amount of water. As a result, they cannot be successfully cultivated in rain-fed areas. Fruit size and crop returns are negatively impacted by moisture stress during the summer, making irrigation essential during the fruit’s growing period.
In order to ensure good economic returns, irrigation is necessary during September and October when the fruit is in its initial stage of growth and development. A satisfactory irrigation schedule for this period is every 10-15 days. Harvesting and postharvest management of kiwi vines typically begin 4-5 years after planting, with commercial production starting 7-8 years later. The specific harvesting period varies depending on the altitude, with fruits maturing earlier at lower altitudes and later at higher altitudes due to temperature differences.
Under Solan conditions, kiwi fruits can be harvested from October end to the third week of November, depending on the cultivars. In contrast, under Shimla conditions, the harvesting period is from the last week of November to December. It is preferable to harvest kiwi fruits with 6.2% TSS, as they are considered ideal. However, delaying the harvesting process negatively affects their storability. The recommended method for harvesting is by snapping off the fruit at the abscission layer at the base of the stalk. It is advised to make at least two pickings. Prioritize the harvesting of larger sized berries first, allowing smaller ones to grow in size and improve in quality.
After harvest, the fruits undergo a process of rubbing with a coarse cloth to eliminate the stiff hairs present on their surface. Solid fruits are then transported to the market. Within two weeks at room temperature, these fruits lose their firmness and become suitable for consumption. On average, each vine yields between 50 and 100 kg of fruits. Vines grown on trellises can yield approximately 25 tons per hectare after seven years. Kiwi fruits have excellent keeping qualities and can be stored in a cool place without refrigeration for up to eight weeks. Alternatively, they can be stored for 4-6 months in a cool environment at temperatures ranging from -0. 6` to 0`C. It is worth noting that there are no kiwi grading standards in India.
However, grading for fruits should be based on weight. In the global market, the minimum export weight for fruits is 72 kg, while the preferred weight is 100 g. In India, fruits weighing 70 g and above are classified as ‘A’ grade, while those weighing between 40 g and 70 g are classified as ‘B’ grade. Packaging for kiwi fruits usually consists of cardboard boxes with a capacity of 3-4 kg. To ensure the fruits remain in good condition for a longer period, polythene liners in storage cases are highly effective in maintaining high humidity. All these considerations are important when determining the grading and packaging requirements for kiwi fruits.
